Six Degrees et. al. v. X-Chem

7/27/2019 Six Degrees et. al. v. X-Chem

1/44

IN THE UNITED STATES DISTRICT COURT AUG 1 2 2013EASTERN DISTRICT OF ARKANSAS MESW McCORMACK. CLERKNORTHERN DIVISION JBA ;;puD AKy. bktJ c L . ~

SIX DEGREES, LLCand GREG CONRAD PLAINTIFFSv.X-CHEM,LLC DEFENDANT

COMPLAINTSix Degrees, LLC ("SD") and Greg Conrad ("Conrad") (collectively, "Plaintiffs") for

their complaint against X-Chem, LLC ("X-Chem"), state as follows:PARTIES

1. Plaintiffs bring this action for patent infringement and request injunctive reliefand damages. Specifically, Plaintiffs seek injunctive relief, preventing X-Chem from continuingto infringe Plaintiffs' patents, which will also serve to prevent future patent infringement by endusers. This case assigned to District Judge \J',\$q.l,

and to Magistrate Judge ~ u.ocr2. Greg Conrad is an individual residing in Pocola, Oklahoma.3. SD is an Arkansas limited liability company with its principal place of business

located at 122 N. 11th Street, Fort Smith, Arkansas 72901.-4. X-Chem is a foreign limited liability company domiciled in Louisiana but

registered to do business in Arkansas. X-Chem maintains an office at 2549 Pangburn Road,Heber Springs, Arkansas. 72543. X-Chem may be served via its registered agent, TheCorporation Company at 124 W. Capitol Avenue, Suite 1900, Little Rock, Arkansas 72201.


2/44

JURISDICTION AND VENUE5. This action arises under the patent statutes of the United States, 35 U.S.C. 101,

et seq. This Court has subject matter jurisdiction over these claims under 28 U.S.C. 1331 and28 U.S.C. 1367. Further, the Court has jurisdiction for the patent infringement claim under 28U.S.C. 1338(a).

6. Venue is proper in this judicial district pursuant to 28 U.S.C. 1391 and 28U.S.C. 1400(b). X-Chem has committed acts of infringement and has a regular and establishedplace of business in the judicial district.

7. This Court has personal jurisdiction over both parties to this action. Specifically,SD has its principal place ofbusiness in Fort Smith, Arkansas and is wholly-owned by Conrad.X-Chem operates an office in Heber Springs, Arkansas. Further, X-Chem has availed itself ofthe privilege of conducting activities within Arkansas, thus invoking the benefits and protectionsof Arkansas's laws.

FACTS8. On December 25, 2007, the United States Patent and Trademark Office (the

"USPTO") issued United States Patent No. 7,311,144 (the "'144 Patent") to Conrad for anapparatus and method for increasing well production. A copy of the '144 Patent is attached asExhibit A.

9. On March 22, 2011, the USPTO issued United States Patent No. 7,909,101 (the"'101 Patent") to Conrad for an apparatus and method for increasing well production. A copy ofthe '101 Patent is attached as Exhibit B. The '144 Patent and the '101 Patent are referred tocollectively herein as the "Patents." Conrad owned the Patents throughout the period of the XChem's infringing acts and still owns the Patents.

2


3/44

10. One device covered by the Patents is a certain type of capillary string assembly(the "Invention"). In general, capillary strings can be used to deliver chemicals at the downholeend of a gas well to increase gas production.

11. The Patents also cover a method ofusing the Invention to deliver chemicals at thedownhole end of a gas well to increase gas production.

12. Through the years, both Plaintiffs and Defendant have engaged in the business ofproviding services to owners and operators of gas wells.

13. On December 13, 2011, the Plaintiffs and Defendant entered into an agreement(the "Agreement") pursuant to which Defendants purchased assets from Plaintiffs. A copy oftheAgreement is attached as Exhibit C. The assets included equipment and inventory related toservicing gas wells, including items used to make the Invention covered by the Patents.

14. Pursuant to Section 4 of the Agreement, Plaintiffs agreed to license the Patents toX-Chem for one-year (the "License") in exchange for a royalty payment equal to two percent(2%) ofX-Chem's operating income during the License period.

15. Section 4 of the Agreement also allows X-Chem to use the Patents if it purchasesatomizers fitted to serve as a component of the Invention (the "Atomizers") from SD followingexpiration of the License. X-Chem agreed to pay SD a royalty in connection with the purchaseof the Atomizers covering X-Chem's use of the Patents.

16. The License expired on December 13, 2012 and since June 1, 2013, X-Chem hasnot purchased any of the Atomizers from SD and therefore has no right to make or use theInvention or employ the methods covered by the Patents.

17. X-Chem did not pay Plaintiffs the royalty for the License as required underSection 4 of the Agreement.

3


4/44

18. Under the Agreement and the License, Defendant has used the Patents to generatesubstantial revenue for itself but has failed to compensate Plaintiffs.

19. Upon information and belief, since June 1, 2013, X-Chem has infringed and isstill infringing the Patents by making, selling, using and installing devices that embody theInvention, and X-Chem will continue to do so unless enjoined by this Court.

20. Upon information and belief, since June 1, 2013, X-Chem's installation ofdeviceswhich infringe on the Patents has induced infringement of the Patents by end users.

21. The infringement of the Patents by X-Chem and end users threatens to causePlaintiffs extreme damage and irreparable injury.

22. Further, Plaintiffs' ability to license the Patents is hampered because theinfringing devices are not properly marked with patent numbers, causing confusion among welloperators and owners as to whether a license is necessary to use devices and employ methodscovered by the Patents.

23. Upon information and belief, X-Chem's misconduct has been committedintentionally and willfully with knowledge of Plaintiffs' rights and in deliberate disregard ofsuch rights.

24. As a direct and proximate result ofX-Chem's misconduct, Plaintiffs have sufferedand will continue to suffer irreparable harm for which they cannot be adequately compensated bymoney damages, entitling Plaintiffs to injunctive relief against X-Chem that would prohibit X-Chem from illegally infringing the Patents.

25. As a direct and proximate result of X-Chem's misconduct, Plaintiffs are entitledto recover from X-Chem all gains and profits realized by X-Chem as a result of its misconduct,

4


5/44

the amount of any royalties X-Chem owes Plaintiffs under the Agreement and all costs andexpenses incurred by Plaintiffs in this action, including reasonable attorneys' fees.

COUNT I - PATENT INFRINGEMENT26. Plaintiffs reassert, restate and incorporate by reference paragraphs 1 through 25 as

if fully set forth here.27. By taking the actions described above, X-Chem has infringed, and will continue

to infringe the Patents by making, selling, using and installing devices and employing methodsthat infringe the Patents.

28. As a direct and proximate result ofX-Chem's misconduct, Plaintiffs have sufferedand will continue to suffer irreparable harm for which they cannot be adequately compensated bymoney damages, entitling Plaintiffs to injunctive relief against X-Chem that would prohibit XChem from illegally infringing the Patents.

29. As a direct and proximate result of X-Chem's misconduct, Plaintiffs are entitledto recover from X-Chem all gains and profits realized by X-Chem as a result of its misconductand all costs and expenses incurred by Plaintiffs in this action, including reasonable attorneys'fees.

COUNT II- BREACH OF CONTRACT30. Plaintiffs reassert, restate and incorporate by reference paragraphs 1 through 29 as

if fully set forth here.31. The Agreement is a valid and enforceable contract with proper consideration.32. Plaintiffs performed their obligations under the Agreement and have not waived

their right to insist upon full and complete performance of the Agreement from X-Chem.

5


6/44

33. X-Chem breached the Agreement by failing to pay Plaintiffs all royalties they areentitled to receive under the Agreement.

34. X-Chem's breach of the Agreement caused damage to Plaintiffs.35. Plaintiffs are entitled to recover from X-Chem the amount of the royalty X-Chem

owes Plaintiffs under the Agreement and all other damages, costs, and expenses incurred byPlaintiffs in this action, including reasonable attorneys' fees pursuant to Ark. Code Ann. 16-22-308 and Fed. R. Civ. P. 54.

JURY DEMAND36. Plaintiffs request a trial by jury.

PRAYER FOR RELIEFWHEREFORE, Plaintiffs request a jury trial on any issues so triable, and Plaintiffs

respectfully pray for the following relief:(1) preliminary and permanent injunctions prohibiting X-Chem, its employees,

agents, officers, directors, attorneys, representatives, successors, affiliates, subsidiaries andassigns, and all those in concert or participation with any of them, from:

(a) making, using, offering for sale, selling, exporting, installing or otherwiseapplying any and all devices or methods that violate either the '144 Patent or the '101 Patent;and

(b) inducing others to infringe upon the '144 Patent or the '1 01 Patent;(2) judgment against X-Chem awarding Plaintiffs cumulative damages sustained

resulting from X-Chem's unlawful acts of patent infringement in an amount to be proven at trialand that the amount of such damages be increased by up to three times as provided by law;

6


7/44

(3) judgment against X-Chem awarding Plaintiffs cumulative damages sustainedresulting from X-Chem's breach of contract in an amount to be proven at trial;

(4) an award of pre-judgment and post-judgment interest;( 5) an award of Plaintiffs' costs and expenses, including without limitation Plaintiffs'

reasonable attorneys' fees incurred in this case;(6) an order directing X-Chem to file with the Court and serve upon counsel for

Plaintiffs, within thirty days after the entry of such order, a report in writing and under oathsetting forth in detail the manner and form in which X-Chem has complied with this Court'sorders; and

(7) all other relief, in law or in equity, to which Plaintiffs may be entitled, or whichthe Court deems just and proper.

QUATTLEBAUM, GROOMS,TULL & BURROW PLLC111 Center Street, Suite 1900Little Rock, AR 72201(501) 379-1700

Carter, Ark. Bar No. 2009073W. Price, II, Ark. Bar No. 2007168Attorneys for Six Degrees, LLC and Greg Conrad

7


8/44

(12) United States PatentConrad(54) APPARATUS AND METHOD FORINCREASING WELL PRODUCTION USINGSURFACTANT INJECTION(76) Inventor: Greg Allen Conrad, 501 E. Hamon,Pocola, OK (US) 74902( *) Notice: Subject to any disclaimer, the tenn of thispatent is extended or adjusted under 35U.S.C. 154(b) by 13 days.(21) Appl. No.: 10/905,993(22) Filed: .Jan. 28, 2005(65) Prior Publication Data

US 2006/0076139 AI Apr. I 3, 2006Related U.S. Application Data

(60) Provisional application No. 60/617,837, filed on Oct.12, 2004.(51) Int. Cl.

E21B 43122 (2006.01)(52) U.S. Cl. .................................... 166/270.1; 166/309(58) Field of Classification Search ............. 166/270.1,

(56)I66/300, 309, 3 I0, 242.3See application file for complete search history.

References CitedU.S. PATENT DOCUMENTS

2.620,740 A 1211952 Garrett et al. ............. 417/113

I IIII 111111111111111111 1111111111 1111111111 111111111111111 11111111US007311144B2(IO) Patent No.: US 7,311,144 B2Dec. 25, 200745) Date of Patent:

3,050,121 A 3,0%,819 A 3,980,136 A5,033,550 A 5,152,343 A 5,535,767 A 5,871,049 A6,405,803 B16,619,402 B I 2001/0017157 AI*2004/0060703 A I 2004/0262011 A 1

* cited by examiner

8/1962 Garrett et al. .. . . . .. . 166/2857/1963 White, Jr. et al. . ..... .... 166/309911976 Plummer eta!.711991 Johnson et al. . ..... ..... .. 166/3721011992 Kilgore ................... 166/242.27 1996 Scbnatzmeyer et al. . . 13 7/1211999 Weaver eta!.6/2002 Giroux et al.9/2003 Amory et al. ... ... . . .. . 166/3708/2001 Pringle ..... ..... ..... ..... ... 13711554/2004 Stegemeier et al. ........ 166/3101212004 Huckabee et a!. ... . . . 1661369

Primary Examiner-David BagnellAssistant Examiner-Daniel P Stephenson(74) Attorney, Agent, or Firm.l. Charles Dougherty(57) ABSTRACTAn apparatus and method for injecting surfactant into a wellfor coal bed methane (CBM) recovery, tight sand gasextraction, and other gas extraction techniques provides forthe mixing of surfactant and water near the downhole end ofthe well, maximizing water removal for gas recovery. Theapparatus may include a check valve that feeds a nozzle toatomize the spray of surfactant into the well production tube.Surfactant is not sprayed directly into the formation, therebyprotecting the formation from damage and recovering sur-factant even in the case where water is not present. Thecapillary tube feeding surfactant to the check valve may beplaced externally to the production tube to facilitate ease ofcleaning and clearing of the production tube.

17 Claims, 4 Drawing Sheets

EXHIBITa


9/44

U.S. Patent Dec. 25, 2007 Sheet 1 of 4 US 7,311,144 B2


10/44

U.S. Patent

\\

Dec. 25, 2007

'!A - - \~ ~ ~ ~ \ '

\\\\

\\\\

Sheet 2 of 4

\\\\

\_j

US 7,311,144 B2


11/44



12/44



13/44

US 7,311,144 B21

APPARATUS AND METHOD FORINCREASING WELL PRODUCTION USINGSURFACTANT INJECTIONThis application claims the benefit of U.S. provisionalpatent application No. 60/617,837, filed Oct. 12, 2004.

BACKGROUND

2the pressure on the face of the fractured mineral is releasedto allow for the extraction of the hydrocarbon fuel, thefracture in the formation would normally close back up.When proppants are added to the fracturing fluid, however,the fracture does not close completely because it is held openby the proppant material. A channel is thus formed throughwhich the trapped hydrocarbons may escape after pressure isreleased.Although course fracturing of this type is very successfulThe present invention relates to gas recovery systems and 10 in some applications, it has not proven particularly useful inmethods, and in particular to an apparatus and method for the recovery of CBM. Coal fines recovered with the waterincreasing the yield of a methane well using direct injection and methane during CBM extraction will quickly foul the

of surfactant at the end of a well bore incorporating a well when course fracturing techniques are used. This neces-downhole valve arrangement. sitates the frequent stoppage of CBM recovery in order thatIt has long been recognized that coalbeds often contain 15 the production tubing may be swabbed or cleaned. It hascombustible gaseous hydrocarbons that are trapped within been found that course fracturing will significantly reducethe coal seam. Methane, the major combustible component both the long-term productivity and ultimate useful life of aof natural gas, accounts for roughly 95% of these gaseous CBM well.hydrocarbons. Coal beds may also contain smaller amounts While traditional fracturing has proven unsuccessful inof higher molecular weight gaseous hydrocarbons, such as 20 CBM extraction, all coal beds contain cleats, that is, naturalethane and propane. These gases attach to the porous surface fractures through which CBM may escape. As hydrostaticof the coal at the molecular level, and are held in place by pressure is decreased at the cleat by the removal of ground-the hydrostatic pressure exerted by groundwater surround- water, methane within the coal will naturally desorb anding the coal bed. move into the cleat system, where it may flow out of the coalThe methane trapped in a coalbed seam will desorb when 25 bed. CBM may thus be withdrawn from the coalbed in thisthe pressure on the coalbed is sufficiently reduced. This manner through the well, without the necessity in manyoccurs, for example, when the groundwater in the area is cases of any artificial fracturing methods. CBM explorationremoved either by mining or drilling. The release ofmethane and well placement strategies thus are highly dependentduring coal mining is a well-known danger in the coal upon a good knowledge of cleat placement within theextraction process. Methane is highly flammable and may 30 coalbed of interest.explode in the presence of a spark or flame. For this reason, If artificial fracturing processes are used to stimulatemuch effort has been expended in the past to vent this gas production in CBM wells, they must be very gentle so as notaway as a part of a coal mining operation. to harm the coalbed cleats, and thereby reduce rather than

In more recent times, the technology has been developed increase well production. Acids, xylene-toluene, gasoline-to recover the methane trapped in coalbeds for use as natural 35 benzene-diesel, condensate-strong solvents, bleaches, andgas fuel. The world's total, extractable coal-bed methane course-grain sand have been found to be detrimental to good(CBM) reserve is estimated to be about 400 trillion cubic cleat maintenance. Recent experience in coalbeds in thefeet. Much of this CBM is trapped in coal beds that are too Arkoma Basin indicates that a mixture of fresh water with adeep to mine for coal, but are easily reachable with wells biocide, combined with a minimal amount of frictionusing drilling techniques developed for conventional oil and 40 reducer, may be the least damaging fracturing fluid. Thenatural gas extraction. Recent spikes in the spot price of failure to use gentle fracturing methods and other goodnatural gas, combined with the positive environmental production practices elsewhere in a coal bed can evenaspects of the use of natural gas as a fuel source, has damage production at nearby wells.hastened development of coal-bed method recovery meth- Regardless ofwhether a fracturing liquid is used in CBMods. 45 extraction, some means must be provided for the removal ofThe first research in CBM extraction was performed in the the significant quantity of groundwater expelled as a result1970's, exploring the feasibility of recovering methane from of the process. One study found that the average CBM wellcoal beds in the Black Warrior Basin of northeast Alabama. removed about 12,000 gallons of water per day. Pump jacksCBM has been co=ercially extracted in the Arkoma Basin and surfactant (soap) introduction are the most co=on(comprising western Arkansas and eastern Oklahoma) since 50 means of removing this water. Pump jacks, which have been1988. As of Mar. 2000, the Arkoma Basin contained 377 used for decades in traditional petroleum extraction, simplyproducing CBM wells, with an average yield of 80,000 pump water out of the well by mechanical means. A pumpcubic feet of methane per day. Today, CBM accounts for is placed downhole, and is connected to a rocking-beamabout 7% of he total production of natural gas in the United activator at the wellhead by means of an interconnectedStates. 55 series of rods. Pump jacks are expensive to install, operate,While some aspects of CBM extraction are common to and maintain, particularly in CBM applications where borethe more traditional means of extracting oil, natural gas, and cleaning is required more often due to the presence of coalother hydrocarbon fuels, some of the problems faced in fines. The presence of the pump jack at the end of the wellCBM extraction are unique. One co=on method generally also requires lengthier downtimes when maintenance isused to extract hydrocarbon fuels from within minerals is 60 performed, reducing the cost-efficiency of the well.hydraulic fracturing. Using this technique, a fracturing fluid In contrast to the pump jack method, the surfactantis sent down a well under sufficient pressure to fracture the method relies upon the hydrostatic pressure within the wellface of the mineral formation at the end of the well. itself to force groundwater up through the borehole and outFracturing releases the hydrocarbon trapped within, and the of the extraction area. The surfactant combines with thehydrocarbon may then be extracted through the well. A 65 groundwater to form a foam, which is pushed back upproppant, such as course sand or sintered bauxite, is often through the well by hydrostatic pressure. The water/surfac-added to the fracturing fluid to increase its effectiveness. As tant mixture is then separated from the devolved methane


14/44

US 7,311,144 B23

gas and disposed of by appropriate means. Ideally, not allwater is removed at the point of CBM extraction; rather,only enough water is removed such that the hydrostaticpressure in the area of the borehole is reduced just enoughthat the methane bound to the coal will desorb. In this way,damage to the coalbed cleats in the area of the borehole isminimized. Care must be exercised to prevent the surfactantfrom entering the coal formation, since this too may damage

4the well. In actual practice, the lines used to deliver this gel(typically 3fs inch stainless steel tubing) cannot he made toreach to the bottom of the well, since the weight of thecapillary tubing is not sufficient to overcome the frictionalforce arising from contact with the tubing walls, due to thearc in the horizontal well "elbow." Again, as in the case ofthe soap stick, foam will not be formed at the end of the wellwhere it is needed most.the coalbed cleats and reduce the production rate andlifetime of the well. 10 Another disadvantage of he gel capillary tube approach isthat the tubing is employed inside the main production tubein the well; thus when the main production tube plugs orotherwise requires maintenance, the gel delivery tubing will

Two methods are commonly used today for the introduction of surfactant into a CBM well. One method is thedropping of"soap sticks" into the well. The soap sticks forma foam as they are contacted by water rising up through thewell, thereby forming foam that travels up and out of the 15well due to hydrostatic pressure. The second method is toattach a small tube inside the main production tube and pourgelled surfactant into this tube. The surfactant travels downthe tube through the force of gravity, capillary action, or itsown head pressure, eventually depositing the gel into the 20flow of water in the well and forming a foam. Again, thisfoam rises back up through the well for eventual removal.Use of either of these methods is believed by the inventor toincrease well production on average by 10-200/o.Although a significant amount of CBM is extracted 25through vertical drilling methods, horizontal drilling methods have become more common. The general techniques forhorizontal drilling are well known, and were developed forconventional extraction of oil and natural gas. In the usualcase, the well begins into the ground vertically, then arcs 30through some degree of curvature to travel in a generallyhorizontal direction. Horizontal wells thus contain a bend or"elbow," the severity of which is determined by the drillingtechnique used. It is believed that horizontal drilling mayresult in better extraction rates ofCBM from many coal beds 35due to the way in which coalbeds tend to form in long,horizontal strata. One analysis has shown that "face" cleatsin coalbeds appear to be more than five times as permeableas "butt" cleats, which form orthogonally to face cleats. Ahorizontal well can increase productivity by orienting the 40lateral section of the well across the higher-permeabilityface cleats. As a result of these effects, the area drained bya horizontal well may be effectively much larger than thearea drained by a corresponding vertical well placed into thesame coalbed stratum. Horizontal well CBM extraction thus 45promises greater production from fewer wells in a givencoalbed. The first horizontally drilled CBM wells in theArkoma Basin were put in place around 1998.While horizontal drilling promises improved theoreticalproductivity over vertical drilling in many instances, it raises 50several problems of its own that are unique to CBM extraction. It may be seen that the deposit of a "soap stick" in ahorizontal well will result in the movement of the soap stickonly to the bottom of he "elbow"of he well. The soap stickis carried by gravity to this point, but will not proceed past 55the point where the well turns. Thus this method will formno foam at the end of the well bore at all; foam is onlyformed at the point where the soap stick comes to rest. Theinventor has recognized that increased productivity wouldresult from the production of foam at the end of the well, 60which is just at the point where the water is being extractedfrom the coal bed seam. The soap stick will never reach thispoint.Likewise, the method of introducing a surfactant bydripping a gel into the well also suffers when horizontal 65drilling techniques are used. Gravity, capillary action, orhead pressure are the only agents moving the gel down into

impede efforts to clean, clear, or otherwise maintain theproduction tube. This is a particular problem in CBMextraction because of he fouling problems presented by coalfines, and the resulting need to regularly swab or clean thewell tubing. Finally, since the gel is not introduced underpressure, it cannot adjust to the hydrostatic pressure at theend of the well. This pressure is dependent upon the depthof the well and the height of the water table. If the hydro-static pressure is significantly less than the gel pressure, thenthe gel may flow out the production tube and into the coalbed, thereby damaging the coal bed cleats and retardingfuture production. If the hydrostatic pressure is significantlygreater than the gel pressure, then the gel will flow little ornot at all, producing minimal foam and impeding removal ofgroundwater and thus reducing CBM extraction rates.

While this discussion has focused on CBM extraction,another developing area for the recovery of natural gas fromunconventional sources is the extraction of natural gas fromsandstone deposits. Sandstone formations with less than 0.1millidarcy permeability, known as ''tight gas sands," areknown to contain significant volumes of natural gas. TheUnited States holds a huge quantity of these sandstones.Some estimates place the total gas-in-place in the UnitedStates in tight gas stands to be around 15 quadrillion cubicfeet. Only a small portion of this gas is, however, recover-able with existing technology. Annual production in theUnited States today is about two to three trillion cubic feet.Many of the same problems presented in CBM extractionare also faced by those attempting to recover natural gasfrom tight gas sands, and thus efforts to overcome problemsin CBM extraction may be directly applicable to recoveryfrom tight gas sands as well.

What is desired then is an apparatus for and method ofintroducing surfactant into a borehole for CBM extraction,tight sand gas extraction, or other types of gas-recoveryoptions, where such apparatus and method is well-suited tohorizontally drilled wells and that produces foam at the tipof the borehole for optimal groundwater removal, whilepreventing the flow of surfactant into the formation itself inconditions of potentially varying hydrostatic pressure.

SUMMARYThe present invention is directed to an apparatus andmethod for injecting surfactant into a well utilizing a capillary tube and injection subassembly. The injection subassembly comprises a hydrostatic control valve and nozzle thatinjects surfactant through an atomizer arrangement at thedownhole end of the production tube in the well. Thecapillary tube travels along the outside of the productiontube rather than the inside, thereby leaving the inner portion

of he production tube unobstructed. The hydrostatic controlvalve allows the pressure at which the surfactant is injected


15/44

us 7,311,144 825

to be controlled, such that the surfactant atomizes and shearswith the gas and wate r at the downhole end of he productiontube with greater efficiency.This apparatus and method results in a number of important advantages over prior art techniques. The surfactantmay be directed at exactly the point where it is needed most,that is, at the downhole end of the production tube. Bythoroughly mixing the water with surfactant at this pointthrough the use of an atomizer on the valve, water may bemore efficiently drawn out of the formation and up through 10the well tube. Since the surfactant is being directed into theproduction tube, rather than into the formation itself, there isno danger of significant quantities of surfactant being introduced into the formation, thereby reducing well yields. Evenin the case when no water is present, the surfactant will be 15brought back to the surface by the flow of gas up through theproduction tube since it leaves the valve in an atomizedstate. The valve is adjustable to allow for the depth of thewell, such that the optimum pressure may be applied toresult in good foam body without excessive pressure, 20thereby minimizing any damage to the formation and maximizing the usable life of the well. Compared to typicalsurfactant introduction methods that yield increased wellproduction of 10-20%, testing of the present invention inCBM extraction, as well as tight sand gas extraction, has 25yielded production increases of over 100% in most cases.

6FIG. 3 is a cut-away view of a valve subassemblyaccording to a preferred embodiment of the present invention.FIG. 4 is a cut-away view of a preferred embodiment ofthe present invention installed in a borehole.

PREFERRED EMBODIMENTSWith reference to FIG. 1, the downhole injection subassembly 10 of a preferred embodiment of the present invention for use in connection with CBM extraction may bedescribed. Although the discussion of the preferred embodiment will focus on CBM extraction, it may be understoodthat the preferred embodiment is applicable to other gasextraction techniques, including without limitation tightsand gas extraction.Downhole injection subassembly 10 is designed fordeployment at the end of a production tube for placement ina well. The external portions of downhole injection subassembly 10 are composed of production tube tip 12 andinjection sheath 14. In the preferred embodiment, productiontube tip 10 is a tube constructed of steel or other appropri

ately strong material, threaded to fit onto the downhole endofa production tube. In the preferred embodiments, production tube 10 is sized to fit either of the most common 2%inch or 27/s inch production tube sizes used in CBM extrac-tion. In alternative embodiments, other sizes may be accommodated. The distal end of production tube tip 10 may bebeveled for ease of entry into the well casing. In theIt is therefore an object of he present invention to providefor an apparatus and method for injecting surfactant into awell such that surfactant and water are mixed at or near theend of the well production tube.It is a further object of he present invention to provide foran apparatus and method for injecting surfactant into a wellsuch that surfactant and water arc well mixed in order tomore efficiently move water from the downhole formation.

30 preferred embodiment, the hollow interior of productiontube tip 10 is kept clear in order to minimize blockage andfacilitate periodic swabbing and cleaning.

It is also an object of the present invention to provide for 35an apparatus and method for injecting surfactant into a wellsuch that surfactant is inhibited from entering the formation.It is also an object of the present invention to provide foran apparatus and method for injecting surfactant into a wellsuch that surfactant does not significantly enter the forma- 40tion even when no water is present.It is also an object of the present invention to provide for

Attached at the downhole end of production tube tip 12 bywelding or other appropriate means is injection sheath 14.Injection sheath 14 protects valve/sprayer subassembly 16,as shown in FIG. 2. Like production tube tip 10, injectionsheath 14 may be constructed of steel or another appropriately strong material. In the preferred embodiment, the tip ofinjection sheath 14 is tapered in a complementary way tothat of production tube tip 12, thereby forming a pointed"nose" on the end of the production tube that eases insertionof the production tube into a well.

Referring now to FIG. 2, the components of valve/sprayersubassembly 16 may be described. Nozzle 18 is mountedan apparatus and method for injecting surfactant into a wellsuch that the pressure at which surfactant is injected isadjustable.It is also an object of the present invention to provide foran apparatus and method for injecting surfactant into a wellsuch that a minimum pressure is utilized for drawing water/surfactant from a well, thereby reducing formation damage.

45 near the end of production tube tip 12, and oriented such thatsurfactant introduced to nozzle 18 is sprayed into productiontube tip 12. In the preferred embodiment, an opening isprovided in the side of production tube tip 12 for thisIt is also an object of the present invention to provide for soan apparatus and method for injecting surfactant into a wellthat significantly increases gas yields over conventionalsurfactant introduction methods.These and other features, objects and advantages of the

present invention will become better understood from a 55consideration of the following detailed description of thepreferred embodiments and appended claims in conjunctionwith the drawings as described following:

purpose. The size of this opening is roughly one-fourth of aninch in diameter in the preferred embodiment, althoughother sizes may be employed in other embodiments basedupon the exact size and construction of nozzle 18. Nozzle 18is preferably of the atomizer type, such that surfactantintroduced to nozzle 18 under appropriate pressure will beatomized as it leaves nozzle 18 and enters production tubetip 12. Provided that water is present at the end of productiontube tip 12, this water will be thoroughly mixed with thesurfactant thereby forming a foam, which will then be forcedto the surface through the production tube along with theDRAWINGS 60 evolved gas due to the hydrostatic pressure in the formation.

FIG. 1 is an elevational view of a downhole tube assemblyaccording to a preferred embodiment of the present invention.FIG. 2 is a partial cut-away exploded view of a downholetube assembly and injection subassembly according to apreferred embodiment of the present invention.

Feeding surfactant to nozzle 18 is valve 20. As explainedfurther below in reference to FIG. 3, valve 20 opens to allowsurfactant into nozzle 18 when the appropriate pressure isapplied to the incoming surfactant. The pressure required to65 open valve 20 will depend upon the hydrostatic pressure atthe end of the production tube where valve 20 is located. Inthe preferred embodiment, valve 20 is threaded on either end


16/44

US 7,311,144 B27

to receive nozzle 18 and fitting 22. Fitting 22 is used toconnect valve 20 to capillary tube 24. In the preferredembodiment, fitting 22 connects to valve 20 using pipethreads, and connects to capillary tube 24 using a compression, flare, or other tube-type fitting. In alternative embodiments, fitting 22 may be omitted if valve 20 is configured soas to connect directly to capillary tube 24.

8as drilled to protect the well from collapse. The mostcommon casing 44 sizes are 41/2 inches and 51/2 inches. Sincethe most common production tubing sizes are 2% inches and27/s inches, this size disparity leaves sufficient room forproduction tube 42 to be easily inserted and removed fromcasing 44. The size disparity also allows additional room forcapillary tube 24 to be mounted to the exterior of productiontube 42, with periodic banding 26 as described above, inorder to feed valve/sprayer subassembly 16.The above-ground components of the preferred embodi-ment include a chemical pump, soap tank, and defoamertank (not shown) as are known in the art. Pumps such as theTexstream Series 5000 chemical injectors, available fromTexstream Operations of Houston, Tex., may be employed.

Banding 26 is used to hold capillary tube 24 againstproduction tube tip 12 and the production tube along itslength. Banding 26 is preferably thin stainless steel for 10strength and corrosion-resistance, but other appropriate flexible and strong materials may be substituted. In the preferredembodiment, banding 26 is placed along capillary tube 24roughly every sixty feet along its length. At the surface,capillary tube 24 may be routed through a wing port in thewell head (not shown) and packed offwith a tube connection 15 The soap tank may be a standard drum to contain surfactantmaterial that is fed through the pump. The defoamer tank,the purpose of which is to separate gas from the surfactantfor delivery, may be constructed from a standard reservoirto pipe thread fitting similar to fitting 22 (not shown).Capillary tube 24 m ay then be connected to a pump mechanism providing surfactant under pressure. with a top-mounted gas outlet.Now with reference again to FIGS. 1-4, a method ofrecovering gas from a well according to a preferred embodiment of he present invention may be described. A horizontal

well is drilled and cased with casing 44 in a manner asknown in the art. Valve/sprayer subassembly 16 is then fitted

Referring to FIG. 3, the internal components of valve 20 20may now be described. Seat 28 and body 30 of valve 20define a passageway through which surfactant may passfrom capillary tube 24 (by way of fitting 22) into nozzle 18,and then out into production tube tip 12. Seat 28 and valvebody 30 may be fitted together as by threading. Lower0-ring 40 provides a positive seal between seat 28 an d body 25 to downhole injection subassembly 10, such that nozzle 18is situated to direct the spray of surfactant into productiontube tip 12. Downhole injection subassembly 10 is thenfitted to the downhole end of production tube 42. Capillarytube 24 is next attached to fitting 22 of downhole injection30 of valve 20. Lower 0-ring may be of conventional type,such as formed with silicone, whereby a liquid-proof seal isformed. In the preferred embodiment, Seat 28 and valvebody 30 are preferably formed of stainless steel, brass, orother sufficiently durable and corrosion-resistant materials.Flow of surfactant through valve 20 is controlled by theposition of ball 36. Ball 36 is preferably a 3fs inch diameterstainless steel ball bearing. Ball 36 may seat against upper0-ring 38, which, like lower 0-ring 40, is preferably formedof silicon or some other material capable of producing aliquid-proof seal. When seated against upper 0-ring 38 atseat 28, ball 36 stops the flow of surfactant out of valve 20and into nozzle 18.Ball 36 is resiliently held in place against upper 0-ring 38by spring 34. Spring 34 may be formed of stainless steel orother sufficiently strong, resilient, and corrosion-resistantmaterial. The inventor is unaware of any commerciallyavailable spring with the proper force constant, and thusspring 34 in the preferred embodiment is custom built forthis application. Spring follower 32 fits between spring 34and ball 36 in order to provide proper placement of ball 36with respect to spring 34. As will be evident from thisarrangement, a sufficient amount of pressure placed on thesurfactant behind ball 36 within valve seat 28 will overcomethe force of spring 34, forcing ball 36 away from uppero-ring 38 and allowing surfactan t to flow around ball36, intothe interior of valve body 30 around spring 34, and out ofvalve body 30 and into nozzle 18. Once this pressure isreleased, or reduced such that it may again be overcome bythe force of spring 34, valve 20 will again close and preventthe flow of surfactant through valve 20. Valve 20 thusoperates as a type of one-way check valve, regulating theflow of surfactant into nozzle 18 and ensuring that surfactantonly reaches nozzle 18 if a sufficient pressure is provided.This ensures that surfactant will be properly atomized bynozzle 18 upon disposition into production tube tip 12regardless of the downhole hydrostatic pressure within theexpected range of operation.Referring now to FIG. 4, the use of the invention withrespect to the recovery of gas in a CBM well may bedescribed. CBM wells are generally lined with a casing 44

30 subassembly 10. It may be noted that capillary tube 24 ispreferably provided on a large roll, such that it may be fedforward as production tube 42 is fed into casing 44. Atregular intervals, preferably approximately every 60 feet orso, capillary tube 24 is fastened to production tube 42 using35 banding 26. This operation continues until production tubetip 12 reaches the bottom of the well, situated at theformation of interest for gas recovery.

The arrangement described herein with respect to thepreferred embodiment provides for a production tube 42 that

40 is free of all obstacles, allowing unrestricted outflow of gasthrough production tube 42 to the surface. This feature isparticularly important for gas production in "dirty" wellssuch as those drilled into coal formations for CBM recovery.In such environments, an unusually high number of con-45 taminants will enter the well. It will thus be necessary toperiodically swab production tube 42 and to remove coalplugs from production tube 42. With production tube 42remaining otherwise open, it is a simple matter to run a swabthe length of production tube 42 in order to clear obstacles.so Otherwise, it would often be necessary to remove production tube 42 from casing 44 in order to perform maintenance.Removal of production tube 42 increases the equipmentmaintenance cost associated with the CBM extraction ope ration, and further causes significant downtime during CBM55 extraction.As gas recovery begins, surfactant is forced into capillarytube 24 under sufficient force to overcome the combinedforce of spring 34 and the downhole hydrostatic pressureand thereby open valve 20. In the preferred embodiment,60 valve 20 is constructed such that surfactant is injectedthrough nozzle 18 at a pressure of no less than 300 pounds

per square inch. This pressure ensures that the surfactant isatomized upon entry into production tube tip 10, therebycreating the best foam when mixed with available water. The65 production of high-quality foam lowers the hydrostatic headpressure at the bottom of the well, allowing gas to flow upproduction tube 42 along with the foam utilizing only the


17/44

US 7,311,144 B29 10

hydrostatic pressure at the bottom of the well. The elimination of external pressure to force gas upward minimizes thedamage that might otherwise occur to the formations fromwhich gas is recovered, which would lower production ratesand expected well lifetime.

3. The apparatus of claim 2, wherein said spray nozzle isoriented to spray toward the interior of said production tube.4. The apparatus of claim 3, wherein said production tubecomprises an orifice through which said spray nozzle is

s positioned relative thereto so as to spray into said interior ofsaid production tube.t may be noted that the feature of directing nozzle 18 intoproduction tube tip 12, rather than into the formation, isparticularly important in CBM recovery. The long lateralstrata common to coal formations do not allow for a homogenous porosity state of coal/gas. Thus the water and gasinflux across the face of the formation are very erratic intypical horizontal wells. If it should occur that the hydrostatic pressure drops and water is not present at productiontube tip 12, the surfactant still will be carried in an atomizedstate up and out of the production tube 42, rather than into 15the formation. As already noted, surfactant introduced intofue formation will lower the output and operational lifetime

S. The apparatus of claim 2, further comprising a pluralityofba nds binding said capillary tube and said production tubetogether, said bands spaced along the length of said capillaryIO tube.

of the well.In addition, the ability to vary the pressure at valve 20 isparticularly useful with regard to such wells due to the 20erratic nature of the hydrostatic pressure across a formation.The pressure of the surfactant introduced to valve 20 isvaried in response to an observation of foam quality at theoutput of production tube 42. In the preferred embodimentthis operation is performed by visual inspection and hand 25manipulation of the pressure, although automatic sensingequipment could be developed and employed in alternativeembodiments of the present invention. The pressure ofsurfactant can be optimized in a matter of minutes, since theonly delay in determining foam quality is the time that is 30required for foam to reach the top of production tube 42.Previous methods would require days of production andsubsequent yield analysis before an optimum surfactantintroduction rate could be determined, due to the delaycaused by slowly trickling surfactant down the casing of 35production tube 42. The pressure at valve 20 can also beadjusted according to well depth, which is a factor in thehydrostatic pressure present. In the preferred embodiment,the pressure at valve 20 may be adjusted to correspond toexpected hydrostatic pressures at depths of anywhere from 40500 to 20,000 feet.The present invention has been described with referenceto certain preferred and alternative embodiments that areintended to be exemplary only and not limiting to the fullscope of the present invention as set forth in the appended 45claims.

6. The apparatus of claim 1, wherein said resilient member comprises a spring.7. The apparatus of claim 6, wherein said valve furthercomprises a seat, and further comprises a ball in communication with said spring, wherein said spring biases said ballagainst said seat, closing said valve when said ball restsagainst said seat.8. The apparatus of claim 6, wherein said spring compresses to open said valve upon the application of a pressure

of about 300 pounds per square inch.9. A method of recovering a gas from a well, comprising

the steps of:(a) injecting a surfactant through a capillary tube attachedto a production tube;(b) limiting surfactant flow from the capillary tube to anatomizing nozzle wherein surfactant flow is enabledonly when the surfactant is under sufficient pressure toatomize when it exits the atomizing nozzle;(c) spraying the atomized surfactant from the capillarytube into the production tube near a downhole end ofthe production tube, such that water and gas present atthe downhole end of the production tube combine withthe atomized surfactant to form a foam at the downholeend of the production tube;(d) recovering the foam formed at the downhole end of heproduction tube at a surface end of he production tube.10. The method of claim 9, wherein said injecting step

comprises the step of adjusting the pressure of the surfactantin the capillary tube to overcome the downhole pressure inthe well.11. The method of claim 10, wherein said step of adjustingthe pressure of the surfactant in the capillary tube comprisesthe step of adjusting the pressure of the surfactant in thecapillary tube to be at least about 300 pounds per square

inch.What is claimed is:1. An apparatus for gas recovery in a well, comprising:(a) a production tube comprising a downhole end, andfurther comprising an exterior and interior;(b) an atomizing surfactant spray nozzle attached nearsaid downhole end of said production tube and adapted

12. The method of claim 10, wherein said step of adjusting the pressure of he surfactant in the capillary tube furthercomprises the steps of observing the quality of the foam50 emerging from the production tube and adjusting the pressure in accordance therewith.

to spray a surfactant;(c) a surfactant check valve attached to said spray nozzlesuch that said check valve may deliver surfactant to 55said nozzle when said valve is open, wherein said valvecomprises a resilient member having a force constantsufficiently high to prevent flow of surfactant to saidspray nozzle unless the surfactant is under sufficientpressure to atomize the surfactant at the spray nozzle; 60and(d) a surfactant capillary tube attached to said check valvesuch that said capillary tube may deliver surfactant tosaid valve.

2. The apparatus of claim 1, wherein said spray nozzle, 65said check valve, and said capillary tube are attached at saidexterior of said production tube.

13. An apparatus for gas recovery comprising a surfactantdelivery system, the apparatus comprising:(a) a production tube comprising an open production tubedownhole end, and further comprising a productiontube exterior and interior;(b) a surfactant delivery tube extending along said production tube exterior and comprising a delivery tubedownhole end;(c) a surfactant delivery tube check valve in communica-tion with said delivery tube down hole end; and(d) an atomizina surfactant delivery tube spray nozzle incommunication with said surfactant delivery tubecheck valve, wherein said surfactant delivery tubespray nozzle extends into said production tube interiornear said production tube downhole end;


18/44

US 7,311,144 B211

wherein said check valve is operable to prevent flow ofsurfactant to said spray nozzle unless the surfactant isunder sufficient pressure to atomize the surfactant at thespray nozzle.14. The apparatus of claim 13, further comprising an sinjection sheath positioned adjacent said production tubeexterior at said production tube downhole end, said injectionsheath encapsulating said surfactant delivery tube spraynozzle.15. The apparatus of claim 14, wherein said injection 10sheath comprises an angled tip.16. The apparatus of claim 15, wherein said productiontube downhole end comprises an angled tip.17. A method for recovering a gas from a boreholecomprising a downhole water level, comprising the steps of: 15(a) inserting a gas recovery assembly into the borehole,wherein the gas recovery assembly comprises a production tube with an open downhole end, a deliverytube positioned at an exterior side of the production

12tube, and a spray nozzle in communication with thedelivery tube and extending into the interior of theproduction tube near the downhole end, wherein theproduction tube downhole end is positioned at or belowthe downhole water level;(b) injecting a surfactant under pressure into the deliverytube and through the spray valve to the spray nozzle;(c) atomizing the surfactant at the spray nozzle andthereby forming a gas-containing foam at the downholeend of the production tube by allowing surfactant flowonly when the surfactant is under sufficient pressure toatomize when it exits the spray nozzle;(d) passing the gas-containing foam up through the production tube from the downhole end by means ofhydrostatic pressure; and(e) recovering the gas-containing foam at an uphole endof the production tube.

* * * * *


19/44

. .c12) United States PatentConrad(54) APPAR


20/44

' .

U.S. PATENT DOCUMENTS6,619,402 Bl6,880,639 B2 7.341,108 B2

912003 Amory et al.412005 Rhodes et al.3/2008 ~ a i z e r et al.

US 7,909,101 B2Page 2

. ....... 166/3212001/0017157 AI2004/0060703 A I2004/02620 II A I

* cited by examiner

81200 I Pringle4/2004 Stegerneier et al.12/2004 Huckabee et al.


21/44

U.S. Patent Mar. 22, 2011 Sheet 1 of 4 US 7,909,101 B2


22/44

U.S. Patent Mar. 22,2011 Sheet 2 of 4 US 7,909,101 B2

\\ !t\ _ .,

I \ '\ ~ ~~ ~ \\\ \

\

\\\

\) \ ~ ~_.


23/44



24/44



25/44

us 7,909,101 821

APPARATUS AND METHOD FORINCREASINGWELL PRODUCTION

CROSS REFERENCE TO RELATEDAPPLICATIONS

2other hydrocarbon fuels, some of he problems faced in CBMextraction are unique. One common method generally used toextract hydrocarbon fi.Jels from within minerals is hydraulicfracturing. Using this technique, a fracturing fluid is sentdown a well under sufficient pressure to fracture the face ofthe mineral formation at the end of the well. Fracturingreleases the hydrocarbon trapped within, and the hydrocarbonmay then be extracted through the well. A proppant, such ascourse sand or sintered bauxite, is often added to the fractur-

This application is a continuationofand claims the benefitofU.S. utility patent application no. 101905,993, filed on Jan.28, 2005, and entitled "Apparatus and Method for IncreasingWell Production Using Surfactant Injection," now U.S. Pat.No. 7,311 ,144, which in tum claimed the benefit of U.S.provisional patent application no. 601617,837, filed on Oct.12, 2004, and entitled "Apparatus and Method for IncreasingWell Production Using Surfactant Injection." Each of theseapplications is incorporated herein by reference.

10 ing fluid to increase its effectiveness. As the pressure on theface of the fractured mineral is released to allow for theextraction of the hydrocarbon fuel, the fracture in the fonnation would normally close back up. When proppants areadded to the fracturing fluid, however, the fracture does not

TECHNICAL FIELD15 close completely because it is held open by the proppantmaterial. A channel is thus formed through which the trappedhydrocarbons may escape after pressure is released.Although course fracturing of his type is very successful insome applications, it has not proven particularly useful in thehe present invention relates to gas recovery systems andmethods, and in particular to an apparatus and method forincreasing the yield ofa methane well using direct injection ofsurfactant at the end of a well bore incorporating a downholevalve arrangement.

20 recovery of CBM. Coal fines recovered with the water andmethane during CBM extraction will quickly foul the wellwhen course fracturing techniques are used. This necessitatesthe frequent stoppage of CBM recovery in order that theproduction tubing may be swabbed or cleaned. It has beenBACKGROUND OF THE INVENTION 25 found that course fracturing will significantly reduce both thelong-term productivity and ultimate useful life of a CBMwell.t has long been recognized that coalbeds often containcombustible gaseous hydrocarbons that are trapped withinthe coal seam. Methane. the major combustible component ofnatural gas, accounts for roughly 95% of these gaseous 30hydrocarbons. Coal beds may also contain smaller amountsof higher molecular weight gaseous hydrocarbons, such asethane and propane. These gases attach to the porous surfaceof he coal at the molecular level, and are held in place by thehydrostatic pressure exerted by groundwater surrounding the 35coal bed.The methane trapped in a coalbed seam wiJJ desorb whenthe pressure on the coalbed is sufficiently reduced. Thisoccurs, for example, when the groundwater in the area isremoved either by mining or drilling. The release ofmethane 40during coal mining is a well-known danger in the coal extraction process. Methane is highly flammable and may explode

While traditional fracturing has proven unsuccessful inCBM extraction, all coal beds contain cleats, that is, naturalfractures through which CBM may escape. As hydrostaticpressure is decreased at the cleat by the removal of ground-water, methane within the coal will naturally desorb andmove into the cleat system, where it may flow out of the coalbed. CBM may thus be withdrawn from the coalbed in thismanner through the well, without the necessity in many casesof any artificial fracturing methods. CBM exploration andwell placement strategies thus are highly dependent upon agood knowledge of cleat placement within the coalbed ofinterest.

I f artificial fracturing processes are used to stimulate pro-duction in CBM wells, they must be very gentle so as not toharm the coalbed cleats, and therehy reduce rather thanincrease well production. Acids, xylene-toluene, gasolinebenzene-diesel, condensate-strong solvents, bleaches, andin the presence of a spark or flame. For this reason, mucheffort has been expended in the past to vent this gas away asa part of a coal mining operation.In more recent times, the technology has been developed torecover the methane trapped in coa !beds for use as natura I gasfuel. The world's total, extractable coal-bed methane (CBM)reserve is estimated to be about 400 trillion cubic feet. Much

45 course-grain sand have been found to be detrimental to goodcleat maintenance. Recent experience in coalbeds in theArkoma Basin indicates that a mixture of fresh water with abiocide, combined with a minimal amount of friction reducer,of his CBM is trapped in coal beds that are too deep to mine 50for coal, but are easily reachable with wells using drillingtechniques developed for conventional oil and natural gasextraction. Recent spikes in the spot price of natural gas,combined with the positive environmental aspects of the useof natural gas as a fuel source, has hastened development of 55coal-bed method recovery methods.The first research in CBM extraction was performed in the1970's, exploring the feasibility of recovering methane fromcoal beds in the Black Warrior Basin of northeast Alabama.CBM has been commercially extracted in the Arkoma Basin 60(comprising western Arkansas and eastern Oklahoma) since1988. As of March 2000, the Arkoma Basin contained 3 77producing CBM wells, with an average yield of80.000 cubicfeet of methane per day. Today, CBM accounts for about 7%

may be the least damaging fracturing fluid. The failure to usegentle fracturing methods and other good production practices elsewhere in a coal bed can even damage production atnearby wells.Regardless of whether a fracturing liquid is used in CBMextraction, some means must be provided for the removal ofthe significant quantity of groundwater expelled as a result ofthe process. One study found that the average CBM wellremoved about 12,000 gallons ofwater per day. Pump jacksand surfactant (soap) introduction are the most commonmeans of removing this water. Pump jacks, which have beenused for decades in traditional petroleum extraction, simplypump water out of the well by mechanical means. A pump isplaced downhole, and is connected to a rocking-beam activator at the wellhead by means of an interconnected series ofrods. Pump jacks are expensive to install, operate, and main-

of the total production of natural gas in the United States.While some aspects ofCBM extraction are common to themore traditional means of extracting oil, natural gas, and65 tain, particularly in CBM applications where bore cleaning isrequired more often due to the presence of coal fines. Thepresenceof the pump jack at the end of the well also requires


26/44

US 7,909,101 B23

lengthier downtimes when maintenanc e is perfom1ed, reducing the cost-efficiency of the well.

In contrast to the pump jack method, the surfactant methodrelies upon the hydrostatic pressure within the well itself toforce groundwater up through the borehole and ou t of theextraction area. The surfactant combines with the groundwa-ter to form a foam, which is pushed back up through the well

4production offoam at the end of the well, which is just at thepoint where the water is being extracted from the coal bedseam. TI1e soap stick will never reach this point.

Likewise, the method of introducing a surfactant by dripping a gel into the well also suffers when horizontal drillingtechniques are used. Gravity, capiiJary action, or head pressure are the only agents moving the gel down into the well. Inactual practice, the Jines used to deliver this gel (typically Vsinch stainless steel tubing) cannot be made to reach to the

10 bottom of the well, since the weight of the capillary tubing isnot sufficient to overcome the frictional force arising fromcontact with the tubing waiJs, due to the arc in the horizontalwell "elbow." Again, as in the case of he soap stick, foam will

by hydrostatic pressure. The water/surfactant mixture is thenseparated from the devolved methane gas and disposed of byappropriate means. Ideally, not all water is removed at thepoint of CBM extraction; rather, only enough water isremoved such that the hydrostatic pressure in the area of theborehole is reducedjust enough that the methane bound to thecoal will desorb. In this way, damage to the coalbed cleats inthe area of he borehole is minimized. Care must be exercised 15to prevent the surfactant from entering the coal formation,since this too may damage the coalbed cleats and reduce theproduction rate and lifetime of the well.

not be formed at the end of the well where it is needed most.Another disadvantage of he gel capillary tube approach is

that the tubing is employed inside the main production tube inthe well; thus when the main production tube plugs or otherwise requires maintenance, the gel delivery tubing willimpede efforts to clean, clear, or otherwise maintain the pro-wo methods are commonly used today for the introduc

tion of surfactant into a CBM well. One method is the dropping of "soap sticks" into the well. The soap sticks form afoam as they are contacted by water rising up through theweiJ, thereby forming foam that travels up and out of the weiJdue to hydrostatic pressure. The second method is to attach asmall tube inside the main production tube and pour gelledsurfactant into this tube. TI1e surfactant travels down the tubethrough the force of gravity, capillary action, or its own headpressure, eventually depositing the gel into the flow of waterin the weiJ an d forming a foam. Again, this foam rises back upthrough the well fo r eventual removal. Use of either of thesemethods is believed by the inventor to increase well production on average by 10-20''/o.Although a significant amount of CBM is extractedthroughvertical drilling methods, horizontal drilling methodshave become more common. The general techniques for horizontal driiJing are well known, and were developed for conventional extractio n of oil and natural gas. In the usual case,the weiJ begins into the grou nd verticaiJy, then arcs throughsome degree of curvature to travel in a generaiJy horizontaldirection. Horizontal weiJs thus contain a bend or "elbow,"the severity of which is determined by the drilling techniqueused. It is believed that horizontal drilling may result in betterextraction rates of CBM from many coal beds due to the wayin which coalbeds t end to form in long. horizontal strata. Oneanalysis has shown that "face" cleats in coal beds appear to bemore than five times as permeable as "butt" cleats, whichform orthogonal ly to face cleats. A hori7.0ntal well ca nincrease productivity by orienting the lateral section of thewell across the higher-permeability face cleats. As a result ofthese effects, the area drained by a horizontal well may beeffectively much larger than the area drained by a corresponding vertical well placed into the same coalbed stratum. Horizontal weiJ CBM extraction thus promises greater productionfrom fewer wells in a given coalbed. The first horizontall ydrilled CBM weJis in the Arkoma Basin were put in placearound 1998.

20 duction tube. This is a particular problem in CBM extractionbecause of the fouling problems presented by coal fines, andthe resulting need to regularly swab or clean the well tubing.Finally, since the gel is not introduced under pressure, itcannot adjust to the hydrostatic pressure at the end of he well.

25 This pressure is dependent upon the depth of he well an d theheight of he water table. I f he hydrostatic pressure is significantly less than the gel pressure, then the gel may flow out theproduction tube and into the coal bed, thereby damaging thecoal bed cleats and retarding future production. If the hydro-

30 static pressure is significantly greater than the gel pressure,then the gel will flow little or not at all, producing minimalfoam and impeding removal of groundwater and thus reducing CBM extraction rates.

While this discussion has focused on CBM extraction,35 another developing area for the recovery of natural gas from

unconventional sources is the extraction of natural gas fromsandstone deposits. Sandstone formations with less than 0.1millidarcy permeability, known as "tight gas sands," areknown to contain significant volumes of natural gas. The

40 United States holds a huge quantity of these sandstones.Some estimates place the total gas-in-place in the UnitedStates in tight gas stands to be around 15 quadrillion cubicfeet. Only a small portion of his gas is, however, recoverablewith existing technology. Annual production in the United

45 States today is about two to three trillion cubic feet. Many ofthe same problems presented in CB M extraction are alsofaced by those attempting to recovernatural gas from tight gassands, and thus efforts to overcome problems in CBM extraction may be directly applicable to recovery from tight gas

50 sands as well.What is desired then is an apparatus for and method of

introducing surfactant into a borehole for CBM extraction,tight sand gas extraction, or other types of gas-recoveryoptions, where such apparatus and method is well-suited to

55 horizontally drilled wells and that produces foam at the tip ofthe borehole for optimal groundwater removal, while preventing the flow of surfactant into the formation itself inconditions of potentially varying hydrostatic pressure.

While horizontal driiJing promises improved theoreticalproductivity over vertical drilling in many instances, it raisesseveral problems of its own that are unique to CBM extraction. It may be seen that the deposit of a "soap stick" in a 60horizontal weiJ wiiJ result in the movement of the soap stickonly to the bottom of the "elbow" of he well. The soap stick

BRIEF SUMMARY OF THE INVENTIONThe present invention is directed to an apparatus and

method for injecting surfactant into a well utilizing a capillarytube an d injection subassembly. The injection subassemblycomprises a hydrostatic control valve an d nozzle that injectssurfactant through an atomizer arrangement at the downlloleend of the production tube in the well. The capillary tube

is carried by gravity to this point, but wiiJ not proce ed past thepoint where the well turns. Thus this method will form nofoam at the end of he well bore at aiJ; foa m is only formed at 65the point where the soap stick comes to rest. The inventor hasrecognized that increased productivity would result from the


27/44

us 7,909,101 825

travels along the outside of he production tube rather than theinside, thereby leaving the inner portion of the productiontube unobstructed. The hydrostatic control valve allows thepressure at which the surfactant is injected to be controlled,such that the surfactant atomi7.es and shears with the gas andwater at the downhole end of he production tube with greaterefficiency.This apparatus and method results in a number of important advantages over prior art techniques. The surfactant mayhe directed at exactly the point where it is needed most, that is, 10at the downhole end of the production tube. By thoroughlymixing the water with surfactant at this point through the useof an atomizer on the valve, water may be more efficientlydrawn out of the formation and up through the well tube.Since the surfactant is being directed into the production tuhe, 15rather than into the formation itself, there is no danger ofsignificant quantities of surfactant being introduced into theformation, thereby reducing well yields. Even in the casewhen no water is present, the surfactant will be brought hackto the surface by the flow of gas up through the production 20tube since it leaves the valve in an atomized state. The valveis adjustable to allow for the depth of the well, such that theoptimum pressure may he applied to result in good foan1 bodywithout excessive pressure, thereby minimizing any damage

6FIG. 2 is a partial cut-away exploded view of a downholetube assembly and injection subassembly according to a pre

ferred embodiment of the present invention.FIG. 3 isacut-awayviewofavalvesubassemblyaccordingto a preferred embodiment of the present invention.FIG. 4 is a cut-away view of a preferred embodiment of hepresent invention installed in a borehole.DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, the downhole injection subassembly 10 of a preferred embodiment of he present inventionfor use in connection with CBM extraction may be described.Although the discussion of the preferred embodiment willfocus on CBM extraction, it may be understood that thepreferred embodiment is applicable to other gas extractiontechniques, including without limitation tight sand gasextraction.Downhole injection subassembly 10 is designed fordeployment at the end of a production tube for placement in awell. The external portions of downhole injection subassembly 10 are composed of production tube tip 12 and i ~ j e c t i o nsheath 14. In the preferred embodiment, production tube tip10 is a tube constructed of steel or other appropriately strongmaterial, threaded to fit onto the downhole end of a production tube. In the preferred embodiments, production tube 10 issized to fit either of the most common 23/s inch or 27/ inchproduction tube sizes used in CBM extraction. In alternativeembodiments, other sizes may be accommodated. The distal

to the formation and maximizing the usable life of the well. 25Compared to typical surfactant introduction methods thatyield increased well production of 10-20%, testing of thepresent invention inCBM extraction, as well as tight sand gasextraction, has yielded production increases of over 100% inmost cases. 30 end of production tube tip 10 may be beveled for ease of entryinto the well casing. In the preferred embodiment, the hollowinterior of production tube tip 10 is kept clear in order tominimize blockage and facilitate periodic swabbing andIt is therefore an object of the present invention to providefor an apparatus and method for injecting surfactant into awell such that surfactant and water are mixed at or near theend of the well production tube.It is a further object of the present invention to provide for 35an apparatus and method for injecting surfactant into a wellsuch that surfactant and water are well mixed in order to moreefficiently move water from the downhole formation.It is also an object of he present invention to provide for an

apparatus and method for injecting surfactant into a well such 40that surfactant is inhibited from entering the formation.It is also an object of he present invention to provide for anapparatus and method for injecting surfactant into a well suchthat surfactant does not significantly enter the formation evenwhen no water is present.It is also an object of he present invention to provide for anapparatus and method for injecting surfactant into a well suchthat the pressure at which surfactant is injected is adjustable.

45

It is also an object of he present invention to provide for anapparatus and method for injecting surfactant into a well such 50that a minimum pressure is utilized for drawing water/surfactant from a well, thereby reducing formation damage.It is also an object of he present invention to provide for anapparatus and method for injecting surfactant into a well thatsignificantly increases gas yields over conventional surfac- 55tant introduction methods.These and other features, objects and advantages of thepresent invention will become better understood from a consideration of the following detailed description of the preferred embodiments and appended claims in conjunction with 60the drawings as described following:

cleaning.Attached at the downhole end of production tube tip 12 bywelding or other appropriate means is injection sheath 14.Injection sheath 14 protects valve/sprayer subassembly 16, asshown in FIG. 2. Like production tube tip 10, injection sheath14 may be constructedof steel or another appropriately strongmaterial. In the preferred embodiment, the tip of injectionsheath 14 is tapered in a complementary way to that of pro-duction tube tip 12, thereby forming a pointed "nose" on theend of the production tube that eases insertion of the production tube into a well.Referring now to FIG. 2, the components of valve/sprayersubassembly 16 may be described. Nozzle 18 is mounted nearthe end of production tube tip 12, and oriented such thatsurfactant introduced to nozzle 18 is sprayed into productiontube tip 12. In the preferred embodiment, an opening is pro-vided in the side of production tube tip 12 for this purpose.The size of this opening is roughly one-fourth of an inch indiameter in the preferred embodiment, although other sizesmay be employed in other embodiments based upon the exactsize and constructionofnozzle 18. Nozzle 18 is preferably ofthe atomizer type, such tha t surfactant introduced to nozzle 18under appropriate pressure will be atomized as it leavesnozzle 18 and enters production tube tip 12. Provided thatwater is present at the end ofproduction tube tip 12, this waterwill be thoroughly mixed with the surfactant thereby forminga foam, which will then be forced to the surface through theproduction tube along with the evolved gas due to the hydro-static pressure in the formation.BRIEF DESCRIPTION OF THE SEVERALv1EWS OF THE DRAWINGS

FIG. 1 is an elevational view of a downhole tube assemblyaccording to a preferred embodiment of he present invention.

Feeding surfactant to nozzle 18 is valve 20. As explainedfurther below in reference to FIG. 3, valve 20 opens to allow65 surfactant into nozzle 18 when the appropriate pressure isapplied to the incoming surfactant. The pressure required toopen valve 20 will depend upon the hydrostatic pressure at the


28/44

us 7,909,101 827

end of the production tube where valve 20 is located. In thepreferred embodiment, valve 20 is threaded on either end toreceive nozzle 18 and fitting 22. Fitting 22 is used to connectvalve 20 to capillary tube 24. In the preferred embodiment,fining 22 connects to valve 20 using pipe threads, and con- 5nects to capillary tube 24 using a compression, flare, or othertube-type fitting. In alternative embodiments, fitting 22 maybe omitted if valve 20 is configured so as to connect directlyto capillary tube 24.Banding 26 is used to hold capillary tube 26 against pro- 10duction tube tip 12 and the production tube along its length.Banding 26 is preferably thin stainless steel for strength andcorrosion-resistance, but other appropriate flexible and strongmaterials may be substituted. In the preferred embodiment,banding 26 is placed along capillary tube 24 roughly every ISsixty feet along its length. At the surface, capillary tube 24may he routed through a wing port in the well head (notshown) and packed offwith a tube connection to pipe threadfitting similar to fitting 22 (not shown). Capillary tube 24 maythen be connected to a pump mechanism providing surfactant 20under pressure.Referring to FJG. 3, the internal components of valve 20may now be described. Seat 28 and body 30ofvalve 20 definea passageway through which surfactant may pass from capillary tube 24 (by way of fitting 22) into nozzle 18, and then 25out into production tube tip 12. Seat 28 and valve body 30may be fitted together as by threading. Lower 0-ring 40provides a positive seal between seat 28 and body 30 of valve20. Lower 0-ring may be of conventional type, such asformed with silicone, whereby a liquid-proof seal is formed. 30In the preferred embodiment, Seat 28 and valve body 30 arepreferably formed of stainless steel, brass, or other sufficiently durable and corrosion-resistant materials.Flow of surfactant through valve 20 is controlled by theposition of ball 36. Ball 36 is preferably a %inch diameter 35stainless steel ball bearing. Ball 36 may seat against upper0-ring 38, which, like lower 0-ring 40, is preferably formedof silicon or some other material capable of producing aliquid-proof seal. When seated against upper 0-ring 38 at seat28, ball 36 stops the flowofsurfactantoutofvalve 20 and into 40nozzle 18.Ball 36 is resiliently held in place against upper 0-ring 38by spring 34. Spring 34 may be formed of stainless steel orother sufficiently strong, resilient, and corrosion-resistantmaterial. The inventor is unaware of any commercially avail- 45able spring with the proper force constant, and thus spring 34in the preferred-embodiment is custom built for this application. Spring follower 32 fits between spring 34 and ball 36 inorder to provide proper placement of ball 36 with respect tospring 34. As will be evident from this arrangement, a suffi- 50cient amount of pressure placed on the surfactant behind ball36 within valve seat 28 will overcome the force of spring 34,forcing ball 36 away from upper a-ring 38 and allowingsurfactant to flow around ball 36, into the interior of valvebody 30 around spring 34, and out of valve body 30 and into 55nozzle 18. Once this pressure is released, or reduced such that

8described. CBM wells are generally lined with a casing 44 asdrilled to protect the well from collapse. The most commoncasing 44 sizes are 41/2 inches and 51h inches. Since the mostcommon production tubing sizes are 23fs inches and 27/sinches, this size disparity leaves sufficient room for production tube 42 to be easily inserted and removed from casing 44.The size disparity also allows additional room for capillarytube 24 to be mounted to the exterior of production tube 42,with periodic banding 26 as described above, in order to feedvalve/sprayer subassembly 16.The above-ground components of the preferred embodiment include a chemical pump, soap tank, and defoamer tank(not shown) as are known in the art. Pumps such as theTexstream Series 5000 chemical injectors, available fromTexstream Operations of Houston, Tex., may be employed.The soap tank may be a standard drum to contain surfactantmaterial that is fed through the pump. The defoamer tank, thepurpose of which is to separate gas from the surfactant fordelivery, may be constructed from a standard reservoir with atop-mounted gas outlet.Now with reference again to FIGS.1-4, a method of recovering gas from a well according to a preferred embodiment ofthe present invention may be described. A horizontal well isdrilled and cased with casing 44 in a manner as known in theart. Valve/sprayer subassembly 16 is then fitted to downholeinjection subassembly 10, such that nozzle 18 is situated todirect the spray of surfactant into production tube tip 12.Downhole injection subassembly 10 is then fitted to thedownhole endof production tube 42. Capillary tube 24 is nextattached to fitting 22 of downhole injection subassembly 10.It may be noted that capillary tube 24 is preferably providedon a large roll, such that it may be fed forward as productiontube 42 is fed into casing 44. At regular intervals, preferablyapproximately every 60 feet or so, capillary tube 24 is fastened to production tube 42 using banding 26. This operationcontinues until production tube tip 12 reaches the bottom ofthe well, situated at the formation of interest for gas recovery.The arrangement described herein with respect to the preferred embodiment provides for a production tube 42 that isfree of all obstacles, allowing unrestricted outflow of gasthrough production tube 42 to the surface. This feature isparticularly important for gas production in "dirty" wellssuch as those drilled into coal formations for CBM recovery.In such environments, an unusually high number of contaminants will enter the well. It will thus be necessary to periodically swab production tube 42 and to remove coal plugs fromproduction tube 42. With production tube 42 remaining otherwise open, it is a simple matter to run a swab the length ofproduction tube 42 in order to clear obstacles. Otherwise, itwould often be necessary to remove production tube 42 fromcasing 44 in order to perform maintenance. Removal of pro-duction tube 42 increases the equipment maintenance costassociated with the CBM extraction operation, and furthercauses significant downtime during CBM extraction.As gas recovery begins, surfactant is forced into capillarytube 24 under sufficient force to overcome the combined forceof spring 34 and the downhole hydrostatic pressure andthereby open valve 20.ln the preferred embodiment, valve 20is constructed such that surfactant is injected through nozzle18 at a pressure of no less than 300 pounds per square inch.This pressure ensures that the surfactant is atomized uponentry into production tube tip 10, thereby creating the bestfoam when mixed with available water. The production ofhigh-quality foam lowers the hydrostatic head pressure at the

it may again be overcome by the force of spring 34, valve 20will again close and prevent the flow of surfactant throughvalve 20. Valve 20 thus operates as a type of one-way checkvalve, regulating the flow of surfactant into nozzle 18 and 60ensuring that surfactant only reaches nozzle 18 if a sufficientpressure is provided. This ensures that surfactant will beproperly atomized by nozzle 18 upon disposition into production tube tip 12 regardless of the downhole hydrostatic pressure within the expected range of operation. 65 bottomof he well, allowing gas to flow up product ion tube 42along with the foam utilizing only the hydrostatic pressure atthe bottom ofthewell . The elimination ofextemal pressure toReferring now to FIG. 4, the use of the invention withrespect to the recovery of gas in a CBM well may be


29/44

(us 7,909,101 82

9force gas upward minimizes the damage that might otherwiseoccur to the fonnations from which gas is recovered, whichwould lower production rates and expected well lifetime.

It may be noted that the feature of directing nozzle 18 intoproduction n1be tip 12, rather than into the formation, isparticularly important in CBM recovery. The long lateralstrata common to coal formations do not allow for a homogenot)s porosity state ofcoal/gas. Thus the water and gas influxacross the face of the formation arc very erratic in typicalhorizontal wells. I f t should occur that the hydrostatic pres- 10sure drops and water is not present at production tube tip 12,the surfactant still will be canied in an atomized state up andout of the production tube 42, rather than into the formation.As already noted, surfactant introduced into the fom1ationwill lower the output and operational lifetime of the well. 15

In addition, the ability to vary the pressure at valve 20 isparticularly useful with regard to such wells due to the erraticnature of the hydrostatic pressure across a formation. Thepressure of the surfactant introduced tovalve 20 is varied inresponse to an observation of foam quality at the output of 20production tube 42. In the preferred embodiment this operation is performed hy visual inspection and hand manipulationof the pressure, although automatic sensing equipment could

103. Th e apparatus of claim 1, wherein said valve comprises

a spring, a seat, and a ball in conununication with said springand said seat, and wherein said spring bias es said ball ag:Jinstsaid seat, thereby closing s:Jid valve when said ball restsagainst said seat.

4. Th e apparatus of claim 3, wherein said spring compresses to open said valve if the pressure on the fluid withinsaid capillary tube is g.reater tlun the downhole hydrostaticpressure.

5. The apparatus of claim 4, wherein said spring compresses to open said valve upon the application of a pressureof about 300 pounds per square inch greater than the downhole hydrostatic pressure.

6. The apparatus ofclaim 1, wherein said valve is operableto open if the pressure on the fluid within said capillary tubeis greater than the downhole hydrostatic pressure.

7. The apparan1s of claim 6, wherein said valve is operableto open upon the application of a pressure of about 300pounds per square inch greater than the downhole hydrostaticpressure.

R_ The apparatu> of claim 1, further comprising a production tube positioned within the well.9. The apparatus of claim 8, wherein said capillary n1be ispositioned outside of said production tube.

be developed and employed in alternative embodiments of hepresent invention. The pressure of surfactant can be opti- 25rnized in a maner of minutes, since the only delay in determining foam quality is the time that is required for foam toreach the top of production tube 42. Previous methods wouldrequire days of production and subsequent yield analysisbefore an optimum surfactant introduction rate could bedetermined, due to the delay caused by slowly trickling surfactant down the casing of production tube 42. The pressure atvalve 20 can also be adjusted according to well depth, which

10. The apparatus of claim 9, further comprising a pluralityof bands binding said capillary tube to said production tube.

11. The apparatus of claim 9, further comprising a nozzleanached downstream of said valve whereby the fluid is deliv-

30 ered from said valve through said nozzle into s:Jid productiontube.

is a factor in the hydrostatic pressure present. In the preferredembodiment, the pressure at valve 20 may be adjusted to 35correspond to expected hydrostatic pres:;ures at depths ofam--where from 500 to 20,000 feet.

The present invention bas been described with reference tocertain preferred and alternative embodiments that areintended to be exemplary only and not limiting to the full 40scope of the present invention as set forth in the appendedclaims.

What is claimed is:

12. The apparatus of claim 11, wherein said productiontube comprises an orifice and wherein s:Jid nozzle is dire ctedto deliver the fluid through said orifice and into the interior ofthe production tube.

13. Th e apparatus of claim 9, further comprising a nozzleattached downstream of said valve whereby the fluid is delivered from said valve through said nozzle near a downhole endof said production tube.

14. The apparatus of claim 1, wherein the fluid is a liquid.15. Th e app:lratus of cl:Jinl 14, wherein the liquid is a

surf..qctant.!. An apparatus for hydrocarbon recovery in a well comprising a downhole portion. the apparatus comprising: 16.A methodofrecovering a hydrocarbon from a well with45 an apparatus, the well comprising a production t11be, the(a) a capillary tube comprising a downhole end, wherein

said downhole end is positioned within the downholeportion of the well;(b) a fluid introduced into said capillary n1be, wherein thefluid is different from species naturally existing in the 50well and wherein the fluid is mixed with a hydrocarbonin the well to form a hydrocarbon foam comprised of thefluid and the hvdrocarbon;(c) a pump operable to apply to said fluid a pressure sufficient to overcome a hydrostatic pressure in the downhole 55portion of the well; and(d) a valve anached at said downhole end of said capillarytube. wherein said valve is a one-way valve operable toopen and thereby deliver the tluid from said capillarytube through the valve and into the downhole portion of 6


30/44

us 7,909,101 8211

(d) directing the fluid from outside of he production tube toinside the pro

Date post:	02-Apr-2018
Category:	Documents
Upload:	priorsmart
View:	217 times
Download:	0 times

Six Degrees et. al. v. X-Chem

Documents