An Investigation into the Effect of Gravel Pack on Retrograde-Gas Condensate Well Performance in Shale

Mahmoud Hajaga Awnour

Problem Report Submitted to the Benjamin M. Statler College of Engineering and Mineral Resources at West Virginia University

in partial fulfillment of the requirements for the degree of

Master of Science In

Petroleum and Natural Gas Engineering

Kashy Aminian, PhD., Chair Sam Ameri , M.S.

Daniel E. Della-Giustina, PhD.

Department of Petroleum and Natural Gas Engineering

Morgantown, West Virginia 2015

Keywords: Utica Shale, Gravel Pack, Hydraulic Fracturing, Fracture Width,

Fracture Conductivity, Gas Condensate, Gravel Pack Length, Mesh Size, Frac-Pack.

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Abstract

An Investigation into the Effect of Gravel Pack on Retrograde- Gas Condensate Well Performance in Shale

Mahmoud Hajaga Awnour

This study investigates effects of various gravel packing parameters, and gravel pack activities on

Well Performance of wet gas bearing shale horizontal wells by means of utilizing reservoir PVT data,

field well data and downhole assembly. Scholarly papers have been published on effects of hydraulic

fracturing parameters on shale dry gas production and shale oil production and not much has been done

to in investigating gravel packing. Therefore, this study investigates effect of gravel packing and gravel

pack parameters on wet gas (retrograde-condensate bearing gas) horizontal well performance in shale.

This study investigates parameters, such as gravel pack permeability, gravel pack length, and gravel pack

type.

Well gravel packing will be modeled using the Petroleum Experts’ PROSPER Software. VLP/OPR

and IPR curves will be generated in order to investigate parametric effects of gravel packing on

maximum wet gas rate MMscf/d (Gas and Condensate). Frac- Pack stimulation will be modeled using

MFrac software, in order to investigate the optimum gravel pack type. The result indicate 20/40 Jordan

Sand is the optimum gravel pack type that produced the highest fracture width of (0.785in), which will

ensure highest fracture conductivity. The study established and recommends that we use 30/50

Econoprop, since the ceramic proppant pack has a higher stress tolerance, with (0.729in) fracture width,

compared to (0.623in) fracture width of the commonly used 30/50 Interprop pack.

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Acknowledgements

I owe debt of gratitude to many individuals and organizations writing this thesis, my thank

goes to Dr. Aminian for directing and supervising this research work. I am also grateful to

Professor Sam Ameri for his contribution and advice during the preparation of this research.

My thanks, also, go to all the faculty of the WVU Petroleum and Natural Gas Engineering

Department for the assistance in various ways in the courses taken as a graduate student

in the department. Also, my thank go to my wife for being there for me when I needed her

most. She gave me the strength to carry on with my research. Finally, I would like to

thank Dr. Daniel E. Della-Giustina for accepting the invitation to be on my project

committee.

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Table!of!Contents!Abstract .............................................................................................................................................. ii

Acknowledgments. ............................................................................................................................ iii

Table of Contents. .............................................................................................................................. iv

List of Figures……………………………………………………………………………………..vi

List of Tables………………………………………………………………………………………viii

Nomenclature………………………………………………………………………………………ix

Chapter 1- Introduction ...................................................................................................................... 1

Chapter 2- Literature Review ............................................................................................................. 2

Utica Shale .......................................................................................................................................... 4

Future Development of the Utica Shale ............................................................................................. 5

Gravel Packing ................................................................................................................................... 8

Frac- Pack ........................................................................................................................................... 9

History of Gravel Pack ..................................................................................................................... 10

Sand Control ..................................................................................................................................... 11

Proppant Strength ............................................................................................................................. 14

Conductivity ..................................................................................................................................... 14

Dry, Wet and Retrograde- Gas Condensate Reservoirs …………………………………………14

Chapter 3- Methodology ................................................................................................................... 18

Chapter 4-Results and Discussion .................................................................................................... 29

Effect of Gravel Pack Length on Well Performance ........................................................................ 30

Effect of Gravel Pack Permeability on Well Performance ............................................................... 32

Effect of Gravel Pack Type on Well Performance ........................................................................... 34

Effect of Gravel Pack Type on Fracture Width ................................................................................ 37

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Chapter 5- Conclusion and Recommendation .................................................................................. 38

Chapter 6- Reference ........................................................................................................................ 39

Appendix A ....................................................................................................................................... 42

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List!of!Figures!!Figure 1Utica Shale USGS "sweet spots (USGS) .............................................................................. 6

Figure 2 Distribution of dry and wet gas in the Utica shale play (Utica Shale Blog) ........................ 7

Figure 3 Utica shale Isobath map (Utica Shale Blog) ........................................................................ 7

Figure 4 Typical components of a frac completion (Michael J, 2007) ............................................... 9

Figure 5 Relative sandface areas for gravel packing, high-rate water packing, and frac packing.

(SLB,2007) ....................................................................................................................................... 11

Figure 6 Sand control completions methods: A. Screen only B.External C. Open hole gravel pack

internal or cased hole gravel pack D. High-Rate gravel pack E.Frac-pack. (Modern Fracturing.,

2007) ................................................................................................................................................. 13

Figure 7 Reliability of sand control completions for gas well (after King, 2000) ........................... 13

Figure 8 Phase Envelope .................................................................................................................. 16

Figure 9 Condensate Yield ............................................................................................................... 17

Figure 10 3000 ft Lateral well .......................................................................................................... 18

Figure 11 Reservoir Pressure Distribution after 30 days (No Gravel Packing or Hydraulic

Fracturing) ........................................................................................................................................ 18

Figure 12 Model System Summary .................................................................................................. 19

Figure 13 PVT data Input ................................................................................................................. 20

Figure 14 Separator Train Input ....................................................................................................... 20

Figure 15 PROSPER Interface ......................................................................................................... 21

Figure 16 Well Deviation Survey ..................................................................................................... 21

Figure 17 Well Deviation Survey Plot ............................................................................................. 22

Figure 18 Downhole Equipment ....................................................................................................... 22

Figure 19 Geothermal Gradient ........................................................................................................ 23

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Figure 20 Equipment Data ................................................................................................................ 23

Figure 21 Inflow Performance Input ................................................................................................ 24

Figure 22 Gun Type and Perforation database in PROSPER ........................................................... 25

Figure 23 PVT Compositional Input ................................................................................................ 26

Figure 24 Dual Porosity Model ........................................................................................................ 26

Figure 25 Hydraulically Fractured Well Model ............................................................................... 27

Figure 26 Gravel Pack Modeling ...................................................................................................... 28

Figure 27 Average Heat Capacity .................................................................................................... 28

Figure 28 Gravel Pack Length Input ................................................................................................ 30

Figure 29 Gravel Pack Length Gas VLP/IPR ................................................................................... 31

Figure 30 Gravel Pack Length Condensate VLP/IPR ...................................................................... 31

Figure 31 Gravel pack permeability Input ........................................................................................ 32

Figure 32 Gravel pack permeability Gas VLP/IPR .......................................................................... 33

Figure 33 Gravel pack permeability Condensate VLP/IPR .............................................................. 33

Figure 34 Isopac Gravel Pack Type Result ...................................................................................... 35

Figure 35 Ottawa Gravel Pack Type Result ..................................................................................... 35

Figure 36 Carbolite Gravel Pack Type Result .................................................................................. 36

Figure 37 Prop Type vs. Avg Frac Width ........................................................................................ 37

Figure A-1 MFrac launcher main screen……………………………………………………….…42

Figure A-2 MFrac Data Options …………………………………………………….....................42

Figure A-3 Wellbore Hydraulics …………………………………………………………….……43

Figure A-4 Wellbore Hydraulics, Profile………………………………………………………….44

Figure A-5 Zone Selection ……………………………………………………………………….44

Figure A-6 Treatment Schedule …………………………………………………………………..45

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Figure A-7 Summary Information ………………………………………………………………..45

Figure A-8 Fracture Characteristic Plots ………………………………………………………....46

Figure A-9 Width Profile Contours……………………………………………………………….46

Figure A-10 Fracture Profiles …………………………………………………………………….47

Figure A-11 Height &Width vs Length …………………………………………………………..47

Figure A-12 Report Generation ………………………………………………………………… .48

!List!of!Tables!

Table 1: Completion design for Utica Shale ..................................................................................... 3

Table 2: Input and Investigated Parameter…………………………………………………………18

Table 3: Gravel Pack Type, Mesh Sizes an ..................................................................................... 34

Table 4: Gravel Pack Type Result Summary . ................................................................................. 36

Table 5: Gravel Pack Type Used for Frac-……………………………………...………………….37

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Nomenclature !!VLP: Vertical Lift Curves

OPR: Outflow Performance

IPR: Inflow Performance

GP: Gravel Pack

MMscf: Millions standard cubic feet

MMMscf: Billions standard cubic feet

Bcf: Billions standard cubic feet

Mscf: Thousand standard cubic feet

Stb: Standard barrels

Bbls: Barrels Scf: Standard cubic feet

Rcf: Reservoir cubic feet

Rb, Reservoir Barrels

Wf: Fracture Width.

NPV: Net Present Value

h: Height (ft)

!∆!= Differential Pressure.

µ= Viscosity (cP)

L= length (ft)

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Chapter 1 Introduction

The study investigates the effect of grave pack, and gravel pack parameters on well

performance in the Utica formation. This study also investigates the effect of different gravel pack

on the fracture width. A gravel pack is a downhole filter and is applied in this study with a view to

understand its performance in preventing the production of any unwanted sand formation. In order

to investigate the Well performance, the gravel pack is modeled by using petroleum experts’

prosper software. The vertical lift curve, outflow curve, and inflow performance curve are

generated in order to understand effects of gravel pack parameters on Well performance.

This study sought to assess how frac pack affects the fracture width in the Utica formation.

Also, the study examines many frac packs treatment using different gravel pack types in order to

choose the optimum gravel pack in the Utica formation that would ensure high fracture width,

thereby providing high conductivity. In order to assess the effect of gravel pack type on fracture

width, the frac pack is modeled by using Mfrac software. Frac pack is simply a combination

between hydraulic fracturing, and gravel pack, and that is why it is called frac pack treatment.

The main objectives of gravel pack, frac pack treatments are to stop or minimize any sand or

solid production from the formation, maximizes the well production rate, and lastly maintains the

well performance over the well life. Frac-Pack treatment has shown increased productivity in

many different formations.

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Chapter 2 Literature Review

Linda Anumele’s MS thesis on “A Strategic Study and Economics of Optimum Well Design

for the Utica,” discusses the effect of lateral length, fracture treatment and fracture half- length on

dry Utica shale gas production; however, her work failed to discuss other vital lingering parameters

which will be evaluated herein with respect to well performance (maximum gas and condensate

rate) of the well at a fixed THP (Tubing Head Pressure) of 500 psi. These lingering parameters,

which were not investigated by Linda, such as the effect of major gravel packing activities on Well

Performance of retrograde-gas condensate producing horizontal shale wells and neither did she,

evaluate the effect of the aforementioned parameters on wet gas production from shale.

In an SPE Paper titled “Investigation of Methods to Improve Utica Shale Hydraulic Fracturing in

the Appalachian Basin” by J. Paktinat, et al, discuss the need to enhance our understanding of the

necessary technology to extract the hydrocarbons from the Utica shale. The paper also suggests that

the higher percentage of fines and clays have a negative impact on the conductivity of the pack,

thereby suggesting the use of clay stabilizer. This study recommends the use of proper gravel pack

to eliminate or reduce the use of chemicals, and control fines production. The authors shared their

field experience by giving us an example of the typical completion design used in the Utica

formation as shown in table 1 below.!!

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Table 1: Completion design Utica Shale.

Rudy Welling’s “Conventional High Rate Performance” discusses gravel pack and frac-

pack in the Gulf of Mexico but his study failed to apply the use of gravel pack and frac-pack in

the Utica formation. Welling has not drawn any similarity or made reference to the possibility of

the application of the same process in the Utica formation, which is an important subject that

this study examined. There is also Bob Burton’s “Comparison of inflow Performance and

Reliability of Open Hole Gravel Pack and Open Hole Stand-alone Screen Completion,” which

was conducted in high permeability formation like other similar engineering works on this

aspect of drilling. Despite his outstanding research and publication on his aspect, Burton’s work

failed to address the application of the same process in the Utica formation, which is a low

permeability formation, and it is this reservation to investigate the application of this

engineering process in the Utica formation that this study addresses.

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It is expected that the application of this process in the Utica formation would disclose

certain variations based on the differing land formation between Utica and the Gulf of Mexico.

This engineering work will be carried out in the Utica formation and the process being applied

in other formation would be the same process to be applied in the Utica formation. The fact that

it was never applied in the Utica formation allowed room for a try to determine the suitability or

otherwise for the application of this engineering process in the Utica formation.

It is possible to ask, why this process has not been applied to the Utica formation despite

the fact that this process had been widely accepted and applied in the US and other parts of the

world? Despite all these published works on this engineering process, no research has been

carried out on this process in the Utica formation and the reluctance or hesitation to carry it out

in the Utica informed brought to light the need for this research on the Utica formation, so that it

could unravel available explanations as to why such engineering process has not been used in

the Utica formation.

Utica Shale

The Utica Shale is located in New York, in the northeast US. The Utica Shale is a “stratigraphic unit

of the Ordovician age in the appalcinan basin” (Alpha). It lies within most part of the northeast of the

US and some part of Canada. The Utica Shale derived its name from Utica city in New York. Also,

the Utica shale extends to other parts of the US especially Pennsylvania, Ohio, Kentucky, Maryland,

Tennessee, Virginia and West Virginia, (Alpha). In Canada, some parts of Montreal are part of Utica

Shale that affected construction of parts of the Montreal metro. The latter, has in the recent past,

became the target of gas and oil exploration in eastern Ohio and Pennsylvania, where it was

estimated to be around 8000 to 14000 ft. deep, (Alpha).

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The year 2011 witnessed drilling and permits for drilling in the Utica Shale in Ohio, which

reached record high. The thickness was measured to have reach 500 ft. and 50 ft. towards the margin

of the basin. Presently, Ohio dominates the exploration and development of the Utica Shale and

there are expectations that exploration activities could spread into Western and Northwestern

Pennsylvania. The rock portion of the Utica Shale is extensive and in the US, it lies in some part of

Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, West Virginia and Virginia. It

could also be found “beneath parts of Lake Ontario, Lake Erie and part of Ontario, Canada.” (Alpha)

Future Development of the Utica Shale

According to Ohio.gov article “Utica Shale - The Natural Gas Giant Below the

Marcellus” There are two challenges when it comes to developing the Utica shale, its depth and

lack of information. When comparing Marcellus and Utica development decision, Marcellus

shale is less expensive to develop because operators has sufficient information to make sound

decision based on economic consideration, unlike, the Utica Shale operator who thought that it

was deeper target with uncertain payoff. In view of the latter, it became very clear that it is a

very hard decision for the operator to make in view of the prevailing economy situation that has

brought the price of natural gas to a record low while other supporting services remained steady.

However, this article suggests that the Utica shale development can take place in areas where

Marcellus has been developed, and the operator have sufficient information about the formation

lithology, pipelines, gathering system, and most importantly landowner relationship. The article

was optimistic about offshore drilling in Utica shale and went on to underline parts of Lake Erie

and Lake Ontario.

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Figure 1: Utica Shale USGS "sweet spots (USGS).

This geographic distribution of wet and dry gas in the Utica is shown in Figure 2 below while

Figure 3 illustrates the isobaths map for the Utica.

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Figure 2: Distribution of dry and wet gas in the Utica shale play (Utica Shale Blog

! Figure 3: Utica shale Isobath map (Utica Shale Blog)

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Gravel Packing

According to Saucier, a gravel pack is a downhole filter designed and used to prevent or

block the production of unwanted formation sand and solid. Saucier added the formation sand

is normally being held properly in a place by gravel pack sand which is held in place with a

sized screen. In order to determine the needed gravel pack size, a core sample from the

formation and sand formation must be examined with a view to determine the median grain size

diameter and grain size distribution (Saucier, 1974) There have been a number of publications

detailing the best possible option to be used in selecting gravel pack size to control the

production of sand formation.

One of the commonly used criteria provides that sand control, as Gurley pointed out

“when the median grain size of the gravel-pack sand, D50, is no more than six times larger than

the median grain size of the formation sand, D50. The upper case D refers to the gravel, while

the lower case refers to the formation sand. The basis for this relationship was a series of core

flow experiments in which half the core consisted of gravel-pack sand and the other half was

formation sand. The ratio of median grain size of the gravel-pack sand and median grain size of

the formation sand was changed over a range from 2 to 10 to determine when optimum sand

control was achieved.”

In carrying through this experiment, the procedure provides measuring the pack permeability with

each change in gravel size and comparing it to the formation’s initial permeability. In this, if the

final permeability is equal to the initial permeability was the same as the initial permeability, we

could say that effective sand control achieved. On the other hand, if the final permeability was less

than the initial permeability, it suggests that the sand formation was invading and plugging the

gravel pack permeability. This provides that sand control could be achieved under this condition. But

at the same time, it would decrease the well productivity (Penberthyet.al., 1992).

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Frac- Pack

Frac-Pack is a mixture of hydraulic fracturing, and gravels packing, that is why it is

called frac-pack stimulation. Roger and Chu briefly described the frac pack treatment by saying

“the frac pack treatment pumped down the tubing and into the crossover tools. The crossover

tools direct the flow into the space between the casing and the pipe, called the annulus. The

slurry flow down the screens and the casing into the perforated zone, this treatment fit the

conventional high permeable treatment, with the exceptions that the treatment is designed to

screenout at the end of the stage to ensure the maximum re-stressing of the formation.” Frac-

pack completion components are illustrated in Figure 4 Below.

Figure 4: Typical components of a frac completion (Michael J, 2007)

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!!History of Gravel Pack

It is important to trace, briefly the history of gravel pack and its application. The gravel

pack’s first frac-pack projects were conducted in the Gulf of Mexico in the early 1980s, Ray &

Mariano (2007). These treatments of the gravel pack were similar to hydraulic fracturing in its

design and execution. The gravel pack result longer, narrower fracture, which not similar to the

wider shorter fracture off frac pack treatment. This method was not accepted by the operators

because of the fact that the initial production result was not encouraging or economically viable.

The first and successful tip-screeout (TSO) gravel pack pumped in the late 1980s, this

pumping was done in sandstone formation. Ray and Marion opined that “These early TSO

treatments placed short, wide fractures. Further advances by companies including BP and

Pennzoil led to equipment and technique innovations that helped to extend the length and width

of the fractures to give much higher sustained production rates than were typically seen in gravel-

packed wells.” Ray and Mario added that “Early frac packs were pumped at about 10 bbls/min

with proppant concentrations up to12 lbm/gal to give total proppant quantities up to 40,000 lbm.

However, industry demands for increased pump rates, higher proppant volumes, and the move to

the more-abrasive ceramic proppant materials led to increased erosional forces on downhole

crossover tools.”

Service companies and scholars has over the years came up wit significant technical progress

and tools that can comfortably carry through and cope with the gravel pack technology.

Presently, drilling industries do places frac packs at 50 bbl/min, with 12 lbm/galUS proppant

concentrations and a total proppant quantities in excess of 200,000 lbm Ray & Mariano (2007).

Initially candidates selected to be treated by frac pack technique were screened using different

qualifiers to help ensure that success is achieved in carrying through the job. There are

advantages associated with the Net Present Value (NPV), reservoir management, time period for

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commercial production, reduced intervention, and lower operating costs which quickly became

clearly seen to operators to accepted to use this technology (Ray & Mariano (2007). Operator

commonly use frac pack as their completion case and in doing this, they must have arrived at a

certain conclusion that using the sand control technique is significant in this frac pack process

(Ray & Mariano (2007). Part of the advantage of the later opinion of the operators was that the

frac-pack technique helps to solve some of the problems and risk associated with the stability of

a formation and near-wellbore positive skin or damage, water production and water injection for

pressure maintenance (Ray & Mariano (2007).

Figure 5 shows the relative sand face areas for gravel packing, high-rate water packing, and frac

packing.

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Figure 5: Relative Sand Face Areas for Gravel Packing, High-Rate Water Packing, and Frac Packing (SLB, 2007)

Sand Control

In this process, the first step to be taken in completion design in an unconsolidated or weak

sand formation is the necessity to have knowledge of the formation’s strength. The sand grains in

general could move due a number of factors especially forces due to coupled drag. There are

other factors that could influence formation strength, which could amount to six different phases.

For example, pressure, and drag forces, which are commonly believed that they could influence

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formation strength, such as drilling and completion; clean up; initial production at maximum

rates; shutdown, start-up and production at pressure depletion (Vaziri, and Nouri, 2006).

Normally gas well operations is known and used in minimizing sand movement that focused on

the prevention of flux rates so as to control erosion, thereby limiting the chance of high

production in the initial production rate loads at a startup to reduce the invasion of screen or

gravel pack by fines or formation solids (Vaziri, and Nouri, 2006).

The need for gas control for gas wells is important concern that would over time grow as the

exploration is gradually moving into complex formation especially coal and shale. Gas control

for gas wells is a critical concern that will grow as the exploration is increasingly driven into

more complex formation such as coal and shales. King and O’Connell suggested that the best

way to effect sand control is to achieve the sand control without introducing any mechanical

obstruction such as gravel and screens. King and O’Connell added that production skins in sand

control completions range as low as 0-3 for open hole gravel pack and frac-pack, to skin of 10 to

15 for cased hole gravel packs with gravel interface outside the casing. Figure 6 illustrates the

type of sand control completion methods being used in the industry, such as external or open hole

gravel pack, cased hole gravel pack, screen only, internal, and frac-pack (King, 2000). Also,

figure 7 shows the reliability of sand control completions for gas well (King, 2000)

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Figure 6:!Sand control completions methods: A. Screen only External C. Open hole gravel pack internal or cased hole gravel pack D. High-Rate gravel pack E. Frac-pack. (Modern Fracturing, 2007).

Figure 7: Reliability of sand control completions for gas well (after King, 2000).

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Results from the figure above show a failure rate of less than 0.010 per year.

Proppant Strength Knowing the proppant strength before designing any hydraulic fracture treatment is very important

because if the proppant strength is inadequate the formation closure stress will crush the proppant,

resulting fines that will plug the proppant pack.

Below are the common type of proppant and their relevant maximum closure pressure:

• Sand Pc < 6000 psi

• Resin Coted Sand Pc < 8000 psi

• Intermediate Strength 5000 psi < Pc < 10000 psi

• High Strength Proppant Pc > 10000 psi

In general, the largest grain size provides more permeable pack. However, their use increases

difficulties in proppant transport and placement. In addition, as grain size increases, it becomes

more fragile structure, reducing its strength.

Conductivity Conductivity is the measure of how well the propped fracture is able to transport fluids. There are

many factors effecting the fracture conductivity and these are as follows:

• High closure pressure, Crush proopant, and generate fines that reduce the permeability.

• Cycling of stress, occur during the well shut-in, decreases conductivity.

• Largest grain size.

• Fracture width.

• Proppant strength, grain shape (Palisch et al., 2007).

Fracture conductivity is calculated from Darcy’s equation. Fracture conductivity is the

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product of the fracture permeability and the width according to Equation 1 (Gidley and others,

1989).!! = !"!!/!∆!!………………………………………………………..(Eq.1)

D r y, W e t a n d R e t r o g r a d e - G a s C o n d e n s a t e R e s e r v o i r s

Dake’s The Practice of Reservoir Engineering gave a brief description to dry gas, wet gas

and retrograde condensate reservoir in order to understand the major differences between them. The

types of hydrocarbon system described below are illustrated by the phase envelope and have initial

states at points A and B (Figure 8). As both lie to the right of the critical point (CP), they are

initially in the gaseous phase in the reservoir. During reservoir pressure depletion which is normally

assumed to occur under isothermal conditions, the gas initially at point A will remain as a single

phase gas in the reservoir since its depletion path lies to the right of the cricondentherm and the

maximum temperature on the phase envelope. Thus it never crosses into the two-phase region.

Nevertheless, in producing the gas to the surface, there will be a reduction in both pressure and

temperature so that some liquid hydrocarbons will be collected in the surface separator operating at

pressure and temperature represented by point X within the two-phase envelope, (Dake, 2013).

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Figure 8: Phase Envelopes

! The hydrocarbon mixture of interest for this study has initial condition at point B (Figure 8).

Point B lays between the critical points and the circondentherm, that is why hydrocarbon at point B

a retrograde-gas condensate. During the reservoir pressure depletion at constant temperature, at the

dew point (DP), the path crosses into the two–phase region and liquid hydrocarbons (condensate)

will be deposited in the reservoir, (Dake, 2013). (Figure 9) represents the condensate recovered by

the surface separators: r, (stb/ MMscf of dry gas).

Above the dew point, all the liquid hydrocarbons contained in each MMscf of gas are recovered

but below the dew point, since liquid is deposited in the reservoir, there is a growing deficiency in

the volume of condensate recovered at the surface, as the reservoir pressure continues to decline.

Eventually, as the reservoir pressure decreases as it approaches the base of the two-phase region

some condensate in the reservoir will evaporate thus increasing the surface yield but in the field this

is not always observed since abandonment might occur at a higher pressure, (Dake, 2013).

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!Figure 9: Condensate Yield !

Dake added that there are two effective means to maintain the reservoir pressure; first, by recycling

the dry gas, after removal of the liquid condensate by the surface separator, the dry gas is re-

injected into the reservoir to help maintain pressure and displace the liquid condensate towards the

wellbore for production. Second means, to maintain pressure is water injection, but considering the

potential wastage of gas when choosing this process, it is not usually considered as a recovery

method, (Dake, 2013).

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Chapter 3 Methodology

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This study utilizes real-life data in the investigation of gravel-pack parameters on

retrograde gas condensate production from shale. For this work, a horizontal well with a

lateral length of 3000 ft is investigated. The well has a TVD (True Vertical Depth) of 8,500ft

and an MD (Measured Depth) of 11,500 ft as shown in Figure 10 below. The reservoir

has a temperature of 155 oF as shown in the diagram.

Figure 10: 3000 ft. Lateral well

!The parameter for the well in Figure 10 investigates their effects on maximum retrograde gas

condensate production on a newly drilled well. This investigation will be pursued via the

use of Petroleum Experts’ PROSPER Software. PROSPER is a well performance, design and

optimization software. Table 2 shows the investigated parameters, such as, mesh size,

GP permeability, GP Type (Ottawa, Carbolite and Isopac), GP length.

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Table 2: Input and Investigated Parameters!

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Sensitivity analysis will be performed on the aforementioned parameters to assess their effects

on gas/condensate well performance from the well design in Figure 10. Figure 11 illustrates

the reservoir pressure distribution after 30 days, without gravel packing or hydraulic fracturing

when the well is designed with REVEAL which is a dynamic numerical reservoir simulator by

Petroleum Experts. Most of the work contained herein, is done on Well Performance Software

“PROSPER” rather than numerical reservoir simulation software.

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Figure 11: Reservoir Pressure Distribution after 30 days (No Gravel Packing or Hydraulic Fracturing)

GP

Gravel(Type Mesh/SizeGP(Perm

Length

md inOttawa%Sand 12/20. 500000 1

Carbolite 20/40 150000 2

Isopac 30/50 90000 3

40/60 60000 450/70 30000 516/20 350000

500000110000

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!

Figures below depict the building of the well performance model, w h i c h has been

incorporated in this study. Figure 12 shows the input of reservoir fluid description,

calculation type, well type/flow type and well completion information. For this work, no

attempt is being made to investigate artificial lift.

Figure 12: Model System Summary

!Figure 13 and 14 illustrates the input of PVT data, composition, separator data, reservoir

temperature, pressure and impurities among others. Gas gravity and separator GOR are also

entered on the screen.

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Figure 13: PVT data Input.

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!Figure 14: Separator Train Input

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Figure 15 illustrates the PROSPER interface when modeling a compositional well.

Figure 15: PROSPER interface

Figure 16 illustrates the deviation survey for the horizontal well of interest. The well consists of a 3000 ft lateral, 11500 ft MD and 8500 ft TVD.

Figure 16: Well Deviation Survey

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Figure 17 depicts a deviation plot for the horizontal well.

Figure 17: Well Deviation Survey Plot.

The Figure below illustrates a list of downhole casings and tubings from surface to MD.

Figure 18: Downhole Equipment

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Figure 19: Geothermal Gradient

Figure 19 illustrates the thermal gradient survey from surface to TVD/MD. Figure 20 confirms that

all required equipment data for the well have been entered.

Figure 20: Equipment Data

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25!!

This figure allows for the input of IPR data such as reservoir pressure and temperature,

WGR, Tank GOR and reservoir model type. For this study a Dual Porosity & Hydraulically

Fractured Well models have been selected for this study as shown in Figure 21.

Figure 21: Inflow Performance Input

!

26!!

Figure 22: Gun Type and Perforation database in PROSPER

Figure 22 displays some of the hundreds of available gun type and perforation

database on PROSPER from which we can select; from several servicing companies as shown in

Figure 22. While Figure 23 displays compositional data input into the model.

27!!

Figure 23: PVT Compositional Input

Figure 24: Dual Porosity Model

28!!

!Figure 25: Hydraulically Fractured Well Model

Figure 24 and 25 display the dual porosity/ hydraulic fracturing data interface while Figure 26

displays the gravel-packing interface. Finally Figure 27 displays the heat capacity interface for

the reservoir fluids.

29!!

Figure 26: Gravel Pack Modelling

Figure 27: Average Heat Capac.

29!!

Chapter 4

Results and Discussion

The analysis below shows effects of various gravel-packing parameters, gravel pack

activities, on Well Performance of wet gas bearing shale horizontal wells. As shown in table 3,

parameters that will be evaluated and their range of interest includes mesh size, GP permeability,

GP Type (Ottawa, Carbolite and Isopac), GP length.

Also, below are results obtained for the evaluation of each parameter. Figure 28 illustrates

the input parameters for gravel pack length. Results for gas well performance, and condensate

well performance shown in figures (Figure 29, 30) respectively, shows as the gravel pack length

increases from 1 inch to 5 inches, in increments of 1 inch, the well’s maximum capability to

produce gas, and condensate decreases.

Figure 31 illustrates the input parameters for gravel pack permeability. The results for gas

well performance (Figure 32) shows that, as the gravel pack permeability increases, the well’s

maximum capability to produce gas also increases, but at a diminishing rate. The results for

condensate well performance (Figure 33) shows that, as the gravel pack permeability increases,

the well’s maximum capability to produce condensate also increases, but at a diminishing rate.

30!!

Effect of Gravel Pack Length on Well Performance. !!

! Figure 28 Gravel Pack Length Input

!

31!!

! Figure 29: Gravel Pack Length Gas VLP/IPR

!

! Figure 30: Gravel Pack Length Condensate VLP/IPR

!!

32!!

Effect of Gravel Pack Permeability on Well Performance !

! Figure 31 Gravel pack permeability Input

!

33!!

! Figure 32 : Gravel pack permeability Gas VLP/IPR

!!

Figure 33: Gravel Pack Permeability Condensate VLP/IPR

34!!

Effect of Gravel Pack Type on Well Performance For this analysis, a comparison is made of the well performance of the horizontal well used

in this study against three different types of gravel packs (Carbolite, Ottawa, Isopac) of

similar mesh size as shown in the table below.

Table 3: Gravel Pack Type, Mesh Sizes.

!

For this analysis, a c o m p a r i s o n i s m a d e w i t h Ottawa 20/40, Carbolite 20/40 and

Isopac 20/40 on well performance. Figure 34 shows that the well can produce as much as 32.156

MMscf/d of gas and 7842.9 stb/d of condensate when the Isopac 20/40 gravel pack is used. Figure

35 shows that the well can produce as much as 32.398 MMscf/d of gas and 7910.8 stb/d of

condensate when the Ottawa 20/40 gravel pack is used. Figure 37 shows that the well can

produce as much as 32.884 MMscf/d of gas and 8020.5 stb/d of condensate when the Carbolite

20/40 gravel pack is used. The overall trend is that Carbolite is the most effective gravel pack

followed by Ottawa and finally Isopac. However, the difference in production (gas and

condensate) is not much, between the three types of gravel packs, as can be seen in Table 4

below. The differences in production can be attributed to the different lab permeability as shown

in Table 3.

35!!

Figure 34: Isopac Gravel Pack Type Result

!

! Figure 35: Ottawa Gravel Pack Type Result !

36!!

! Figure 36: Carbolite Gravel Pack Type Result

Table 4: Gravel Pack Type Result Summary

! Gravel!Pack!Types!

! Isopac! Ottawa! Carbolite!

Mesh!Size! 20/40! 20/40! 20/40!

Gas!Production,!MMscf/d! 32.156! 32.398! 32.884!

Condensate!Production,!STB/d! 7842.9! 7910.8! 8020.5!

Lab!Permeability! 110000! 150000! 350000!

!

37!!

Effect of Gravel Pack Type on Fracture Width

For this analysis, a comparison of many types of gravel packs to investigate their effect on fracture

width is being made. Table 5 shows the different type of gravel packs used for the frac and pack

treatment design.

Table 5: Gravel Pack Type.

Prop!Type!Avg!Hydrulic!Frac!Width(in)!

20/40!Jordan!Sand!! 0.785!

20/40!Econoprop!! 0.728!

20/40!Carbo!Lite!! 0.727!

40/70!St!Peter!Sand! 0.716!

40/70!CarboUProp! 0.541!

30/50!Econoprop!! 0.729!

30/50!Interprop!! 0.631!

Figure 37 shows that 20/40 Jordan Sand give us the highest fracture width of 0.785 in followed by

30/50 Econoprop, 20/40 Econoprop, and 20/40 Carbo lite.

!

Figure 37: Prop Type vs. Avg Frac Width

38!!

!

Chapter 5

Conclusion and Recommendation

This study investigates the effect of various gravel packing parameters, gravel pack activities,

on the Well Performance of wet gas bearing shale horizontal wells, as opposed to dry gas, from deep

Utica shale formation while utilizing reservoir PVT data, real field well data and downhole

assembly prior to parametric investigation. Parameters, which were investigated within this study

included gravel pack permeability, gravel pack length, gravel, pack type.

Results for gas well performance showed that with the increase of gravel pack length,

the well’s maximum capability to produce gas and condensate decreased. On the other hand, the

well’s maximum capability for production increases with increased in gravel pack permeability.

With respect to the effect of gravel type on well performance, the overall trend is that Carbolite is

the most effective gravel pack followed by Ottawa and finally Isopac. However, the difference in

production (gas and condensate) is not much, between the three types of gravel packs, as is shown in

Table 4. The differences in production can be attributed to the different lab permeability as shown in

Table 3.

Finally, even though the stimulation model suggested the use of 20/40 Jordan sand to achieve

the highest fracture width of 0.785in, which will ensure the highest fracture conductivity among the

tested proppant pack. But due to the fact that Utica closure stress can reach up to 10,000 psi and

sand based proppant can only be sufficient up to 6,000 psi. Therefore, It’s recommended we use

30/50 Econoprop, since the ceramic proppant pack has a higher stress tolerance, with 0.729in

fracture width, compared to 0.623in fracture width of the commonly used 30/50 Interprop pack.

!

!

39!!

Chapter 6

Reference

"Utica Shale - The Natural Gas Giant Below the Marcellus." Ohio Geological Survey. Ohio.gov. Web. 26

Mar. 2015. <http://geology.com/articles/utica-shale/>.

"Utica Shale Depth." Utica Shale Blog. Web. 26 Mar. 2015<http://www.uticashaleblog.com/p/maps.html>.

“Geology- New York Department of Environmental." Alpha Geoscience. Web. 24 Mar. 2015.

<http://www.dec.ny.gov/docs/materials_minerals_pdf/ogdsgeischap4.pdf>.

Anumele, Linda. “A Strategic Study and Economics of Optimum Well Design for the Utica,”

API RP 58, Recommended Practice for Testing Sand Used in Gravel Packing Operations, first edition,

API 1986.

Barree, R.D., Roger, B.A., and Chu, W.C.: “Use of Frac-Pack Pressure Data to Determine Breakdown

Condition and Reservoir Properties,” SPE 36423, October 1996.

Cocales, B. “Optimizing Materials for Better Gravel Packs” World Oil, 1972. Fjaer, E. "Mechanics of

hydraulic fracturing", Elsevier, 2008.

Dake, L. P. "Chapter (6) Gas Reservoir Engineering." The Practice of Reservoir Engineering. Rev. ed.

Amsterdam: Elsevier, 2001. Print.

Economides, Michael J. "Well Completions." Modern Fracturing: Enhancing Natural Gas Production.

Houston, TX: ET, 2007. Print.

Fan, Yong. "Fracture Dimensions in Fac & pack Stimulation." Login Required. One Petro, 1 Oct. 1995.

Web. 26 Mar. 2015. https://www.onepetro.org/download/journal-paper/SPE-30469-PA?id=journal-

paper/SPE-30469-PA.

Gidley, J.L., Holditch, S.A., Nierode, D.E. and Veatch, R.W., 1989, Recent advances in

Gurley, D.G., Copeland, C.T., and Hendrick Jr., “Design, Plan, and Execution of Gravel-Pack Operations

40!!

for Maximum Productivity,” J Pet Technol 29 SPE-5709-PA, 1974.

“Hydraulic fracturing,” SPE Monograph, Volume 12, SPE, Richardson, TX.

King, GE. Wildt, P.J., and O’connell, E.:” Sand Control Completion Reliability and Failure Rate

Comparison With a Multi-Thousand Well Database,” SPE 84262, 2000.

Nouri, A., Vaziri, H., Belhaj, H., and Islam, R.: “Sand Production Prediction: A New Set of Criteria for

Modeling base on Large-Scale Transient Experiments and Numerical Investigation,” SPE 90273,

SPE, June 2006.

Paktinat, J., J.A. Pinkhouse, and J. Fontaine. "Investigation of Methods to Improve Utica Shale Hydraulic

Fracturing in the Appalachian Basin." Onepetro, 17 Oct. 2007. Web. 3 Apr. 2015.

<https://www.onepetro.org/conference-paper/SPE-111063-MS>.

Palisch, T., Duenckel, R., Bazan, L., Heidt, H., and Turk, G. 2007, Determining realistic fracture

Penberthy, W.L. Jr. and Shaughnessy, “Sand Control, Vol. 1, 11-17” Monograph Series, SPE, 1992.

Ray, Mariano. "FRAC PACKING: FRACTURING FOR SAND CONTROL." Slb.com. 7 Nov. 2007. Web.

24 Mar. 2015. <http://www.slb.com/~/media/Files/resources/mearr/num8/37_49.pdf>.

Saucier, R.J., “Considerations in Gravel Pack Design” J Pet Technol 26 SPE-4030-PA, 1974.

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Sparlin, D.D., “Sand and Gravel - A Study of Their Permeabilities”, SPE-4772-MS, 1974.

SPE 106301.

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Petroleum System." Ohio.gov, 1 Jan. 2008. Web. 26 Mar. 2015.

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41!!

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paper/SPE-39475-MS>.

42!!

Appendix A !

Appendix A Shows the Schlumberger MFrac software used to model the Frac-Pack treatment. Step by step procedure to run the software is shown below. !!

!Figure A-1 MFrac launcher main screen

!!!!

!Figure A-2: MFrac Data Options.

This feature allows the user to enter the general information about the reservoir, fracture, and the proppant.

43!!

!

!Figure A-3 : Wellbore Hydraulic.

! !In Figure A-3 MFrac allows the user to inter the general information about well design. In this case the injection was done through the tubing. Horizontal well and frac-pack were selected along with the screen diameter. !!!!!!!!!!!!!!!!!!

44!!

l Figure A-4: Wellbore Hydraulics, Profile.

Figure A-4 shows that the well has a TVD (True Vertical Depth) of 8,500ft and an MD (Measured Depth) of 11,500 ft.!!

!Figure A-5: Zone Selection

! !MFrac enable the user to select the zone data in this study!!

45!!

!

Figure A-6: Treatment Schedule.

As shown in the figure above, the user can enter the treatment design, change the type of fluid, change the type of proppant, and the desire concentration per unit area as desired. !!

!Figure A-7: Summary Information.

46!!

!Figure A-7 illustrate the run summary for the frac pack treatment.!!!

!Figure A-8 : Fracture Characteristic Plots.

Different type of plots can be selected and viewed from the figure above. For example, the width profile contours, and the fracture profile were shown below respectively.!!

!Figure A-9: Width Profile Contours

!

47!!

Figure A-10: Fracture Profiles.

!!!

!Figure A-11: Height &Width vs. Length.

!!!!!

48!!

!!!

!Figure A-12: Report Generation. !

! ! After running the model MFrac generate a comprehensive report allowing the user to choose the report of interest, or simply press OK for a complete report. An example of the report is show below:

49!!

!!

50!!

!!!!

51!!

!!