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ABSTRACT

A number of highly deviated gas producing wells in the

southern area of the Ghawar field in Saudi Arabia were

recently perforated using coiled tubing (CT) conveyed guns,

and after performing several jobs, it was found that the cost

of using the coiled tubing conveyed perforating (CT-TCP)

approach was significantly higher than anticipated. Therefore,

it became apparent that more cost-effective options were

required. The decision was then made to trial test the CT

abrasive hydrajetting perforating (AHP) technique.

A well with a gross pay thickness of 130 ft was selected

for the first trial. Consideration was given to the fact that the

chance of achieving the job objective is higher if the selected

intervals to perforate and the number of slots that can be

made in the formation in one run are not excessive.

Therefore, it was decided to create slots in 12 different

sections along the wellbore. Given this constraint, it was

important to achieve an optimum depth correlation, which

was done by using a wireless real-time casing collar locator

(CCL) tool, the first time for its use in this type of operationin Saudi Arabia. A procedure was designed to optimize

implementation time and chemical volumes, and the job was

successfully performed with better than expected results.

The objective of this article is to share results, lessons

learned, and solutions used to overcome problems and achieve

the successful implementation of a technique offering a valid,

low-cost alternative to conventional perforating in a highly

deviated well. Full details of the planning and design of the job,

operational procedures and data collected are also provided.

INTRODUCTION

As shown in several technical manuals and papers dating back

to the late 1950s, the abrasive hydrajetting perforating (AHP)

technique was tested and proven to be an approach to connect

the reservoir that induced zero damage, in contrast with

conven tional perforating techniques using explosives1-3.

Unfortunately, the AHP technique has not been widely used

until recently, due to concerns about longer operating times and

its perceived overall inferior operational practicality; however,

use of the technique has gained momentum in certain areas

around the world, in large part because of its cost effectiveness

and excellent results.

The technique has been widely used to increase the fluid

entry area in wells scheduled for hydraulic fracturing

stimulation as described in various publications1, 2. The

technique has also been used as a way to overcome logistic

difficulties in regions where permits to store and transport

explosives are difficult to obtain.

One of the distinctive advantages of using AHP for

stimulation applications is the reduction of near wellbore

tortuosity due to the large hole sizes created in the casingand in the formation rock. As mentioned3, tortuosity will

often restrict the flow of hydrocarbons from the formation

to the wellbore and restrict fluid entry during hydraulic

fracturing treatments. Another distinct advantage of AHP is

that the crushed rock and metal debris generated from the

use of shaped charges during conventional perforating does

not occur, thereby eliminating the usual reduction in the

overall production potential. Only minimal skin is created

when using AHP, because the formation rock is removed

with the abrasive slurry instead of being crushed by an

explosive charge3.

These advantages, and the results of a cost comparison

study, which showed that AHP was 20% more cost-effective

than the traditional coiled tubing (CT) perforating approach

being used, provided the necessary incentive to proceed with a

field trial in Well A, a highly deviated cased well that is a high-

pressure/high temperature (HP/HT) gas producer.

SAUDI ARAMCO JOURNAL OF TECHNOLOGY SPRING 2011 9

First Successful Low-Cost AbrasivePerforation with Wireless Assisted CoiledTubing in a Deviated High-Pressure/HighTemperature Gas WellAuthors: Walter Nez-Garcia, J. Ricardo Solares, Jairo A. Leal Jauregui, Jorge E. Duarte, Alejandro Chacn, Robert Heidorn

and Guillermo A. Izquierdo

Fig. 1. Selected perforating zones (14,770 ft to 14,900 ft) in Well A.


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JOB DESIGN

Based on the experience gained from selective stimulation

treatments performed in packerless open hole wells in the

same field, the maximum number of abrasive slurry stages

that can be carried out before washing out the hydrajetting

tool was determined to be 12 to 14. Consequently, 12 high

porosity zones were selected for perforation in a 130 ft

10 SPRING 2011 SAUDI ARAMCO JOURNAL OF TECHNOLOGY

Fig. 3. The average calculated total penetration of AHP beyond cement and pipe

wall thickness.

Fig. 4. Abrasive perforation average length.

Fig. 5. Abrasive perforation average diameter.

Fig. 6. Abrasive perforation average diameter.

Fig. 7. Jetting tool with three 316" nozzles.

(14,770 ft to 14,900 ft) gross interval with a 73 deviation in

Well A. Figure 1 shows the 12 selected zones.

It was decided to generate three perforations per interval,

for a total of 36 perforations, which was less than the

traditional six shots per foot perforation density designed to

maximize well productivity when using conventional

perforating guns. Several studies1, 3 have shown that because

of the reduction in tortuosity and crushing damage, the lower

AHP density is equivalent to the higher perforating density of

conventional guns. The pictures in Fig. 2 show the average

shape of abrasive hydrajetting generated perforations, which

achieve a much larger contact area than conventional

perforation tunnels without any crush zone.

The average calculated total penetration of AHP beyond

the cement and pipe wall thickness is 3.72, Fig. 3. This value

corresponds to the minimum expected penetration based on

Fig. 2. The average shape of abrasive jetting generated perforations.


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empirical correlations from surface tests. At downhole

conditions, this figure is highly likely to increase due to the

effect of hydrostatic pressure and the hydrajetting stagnation

pressure that microfractures generate4-6, making the abrasive

jet go deeper than expected into the formation.

From empirical data and yard tests, it was possible to

estimate that at surface conditions the average penetration

length in Well A would be approximately 5, or even deeper

after pumping for approximately nine minutes with a P of ~

2,500 psi. The abrasive slurry used during the yard tests was

the same that was used during the actual operation. Figures 4

to 6 show the results obtained during the yard test performed

ahead of the main job.

The jetting tool for the planned job in Well A was configured

so as to obtain the desired pressure drop across the nozzles,

taking into account the restrictions imposed by the 2 CT to be

used. The previous experience in open hole stimulation

treatments in the area suggested that the best approach was to

install three coplanar 316 nozzles set 120 apart. This is the

maximum number of nozzles that can be installed in the tool to

be able to generate between 2,000 psi to 3,000 psi with the

flow restriction imposed by a 2 CT. Figure 7 shows the jetting

tool with the aforementioned nozzle configuration.

Given that only 12 zones were selected for perforating with

a total of 36 holes, it was deemed necessary to achieve high

depth precision at the moment of positioning the jetting tool.

Installing memory gauges was first considered, but having

real-time correlation was determined to be important, so the

decision was made to use a 3 wireless casing collar locator

(CCL) tool that could tolerate the abrasive slurry while


Fig. 8a. Decision Tree.

Start

Rig up 2 conventionalHPCT, pumping unit

and N2 unit

Clean the wellbore allthe way to TD and

perform bottoms -up

RIH with GR/CCL memorygauges to perform

correlation passes (withand without pressure to

verify CT stretch)

Perform dedicatedrun for wellbore

cleanout

Is there accesstothe perforating

zone?

Rig down and cancelthe job

Is there access tothe perforating

zone?

Yes

RIH CT with jetting tooland wireless CCL (depthcorrelation) for abrasive

jetting perforation

No


zone?


zone?

Executehydrajetting

perforations asplanned

Yes

No

Perform necessary runs tocomplete 12 abrasive

jetting perforation stages

POOH CT and rigdown equipment Flow back

No

No

Yes

Go toPage 2

Circulate 50-100 bbls ofCT drag friction reducer

Circulate 50-100 bbls ofCT drag friction reducer


zone?

Yes

POOH CT breakdownBHA and install memory

gauges

Execute correlationrun (memory gauges+ wireless CCL) andPOOH CT to surface

to change BHA

Yes

Make up motor andmill and RIH to mill

out obstructionNo


zone?Yes

Rig down and cancelthe job

No

POOH CT to13,800 ft and waitfor sand to settle

(3 hours)

RIH with jetting tooland tag the top of

the fill.

Sand coveringperforations?

Yes

No

POOH, M/U SCOBHA and flow

cleanoutprocedure as perAttachment #13

Run 3 GC down tomax depth


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providing a sufficiently large flow path to allow pumping at

~3.0 barrels per minute (bpm).

Then, the operational decision tree, Figs. 8a and 8b, was

developed to prepare for a wide spectrum of possible

scenarios. The main decision tree branch included a required

wellbore cleanout to ensure full access to the perforating zone,

and to try to minimize potential sticking problems when

running in hole (RIH) with the final bottom-hole assembly

(BHA), Fig. 9. The cleanout procedure included a nitrified

fluid combined with linear gel to have excess annular velocity

in case a large amount of debris was found in the wellbore. A

nitrogen (N2) kickoff contingency was included in the plan in

case the well could not flow by itself. A contingent acid

matrix treatment was also included in case the well did not

achieve its production target.

JOB IMPLEMENTATION

A base cased hole log was not available for Well A, so gamma

ray/CCL memory gauges were run in tandem with the wireless

CCL as a backup in case something went wrong. Logging

Fig. 8b. Decision Tree.

Does the well flowby itself?

N2 lifting

No

YesPage 2

Is formationwater beingproduced?

End JobRig down and prepare a

program for PLT,surveillance and water

shut-off

Does the well flowby itself?

Yes Yes

NoNo

Bullheading matrixacidizing

Flow back and testthe well

Is the wellproducing asexpected?

No

End Job

Yes

Fig. 9. CT BHA.


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final AHP run. The CT was run down to the perforating

interval and a final correlation pass was made before

positioning the jetting tool in front of the lowermost zone to be

perforated. Figure 10 shows the comparison between the two

CCL correlations, one using memory gauges and the other one

using the CT run wireless CCL, which performed very well.

A 2,000 gallon abrasive slurry mixture of 40#/Mgal linear

gel and 100 mesh sand with a 0.5 ppa concentration was

pumped at an average rate of 2.5 bbl/min to 3.0 bbl/min for

each perforating stage. The maximum pumping rate was

driven by the maximum allowable circulation pressure, which

was set at 9,000 psi due to safety considerations. A hydrogen

sulfide corrosion inhibitor pill was pumped after each stage to

protect the CT and BHA.

Figure 11 shows data details of the operation to complete

all 12 scheduled stages. Each stage can be clearly distinguished


Fig. 11. Acquisition graph from abrasive jetting perforation stages.

Fig. 12. Data recorded during injection test and acid wash operations.

Fig. 10. Compararison between the two CCL correlations, one using memory

gauges and the other one using the CT run wireless CCL.

passes were made at the speed required for the wireless CCL

tool to work properly, while pumping at a minimum rate, and

then the pumping rate was increased to determine the CT

stretch. A different set of logging passes at a higher speed were

made at different pump rates to determine the CT stretch

during the AHP operation. This logging run was equivalent to

running a base cased hole log, which could then be used for

future interventions requiring depth correlation. After

completing the correlation logging run, the jetting tool was

made up and run in tandem with the wireless CCL during the

Table 1. Production data pre- and post-stimulation

Choke FWHP BS&W Estimated TCA

Size (psi) (%) Gas Rate (psi)

(MMscfd)

Post-

stimulation 46/64 2,695 4 22 2,831

Pre-

stimulation 26/64 985 10 3 900


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CONCLUSIONS

1. The successful implementation of the field trial demonstrated

that hydrajetting perforating is a viable and safe alternative

to conventional perforating techniques. The post-stimulation

gas rates from Well A exceeded all expectations.

2. The use of a wireless CCL tool proved to be a key to the

successful outcome of the operation. The depth correlation

performed was accurate, and the tool worked well under

abrasive conditions.

3. The 100 mesh sand worked well as the abrasive material

needed for the hydrajetting perforating operation; however,

the small size of the material created a low permeability

pack around the perforations, which reduced injectivity

and required an acid wash. Similar jobs performed in other

wells after this one have been carried out using 20/40

proppant as the abrasive material with much better results

and no operational complications.

4. Due to concerns about the back splash effect that the

abrasive material could have on the jetting tool, thenumber of stages was limited to 12, which proved to be

conservative. The jetting tool withstood the abrasive effect

of 12,000 lbs of 100 mesh sand without any problems or

apparent damage, thereby indicating that future jobs can

be designed with a larger number of stages.

5. The data obtained from the downhole pressure/temperature

gauges set below the jetting tool, which were configured to

measure data from inside the CT and from the CT casing

annulus, were very valuable. The collected data helped

analyze the effective pressure drop across the nozzle, which

is the main point in achieving penetration through the

formation. Figure 13 shows surface and downhole pressure

data recorded throughout the operation.

6. The acid wash performed right after completing the hydra -

jetting perforating operation was useful in increasing

conductivity and helping the well flow back on its own.

7. A wellbore cleanout ahead of the hydrajetting perforating

operation is highly recommended.

ACKNOWLEDGMENTS

The authors would like to thank the management of Saudi

Aramco and Halliburton for their support and permission topublish this article.

This article was prepared for presentation at the Abu Dhabi

International Petroleum Exhibition and Conference, Abu

Dhabi, U.A.E., November 1-4, 2010.

by observing the pressure spike recorded every time abrasive

slurry was pumped through the CT. The CT pressure at the

surface was ~6,300 psi throughout the operation while

pumping at 3 bpm. The flowing wellhead pressure when the

choke was fully open, which was done to circulate abrasivesand out of the wellbore and avoid clogging the BHA, was

around 600 psi.

After completing the perforating stages, the CT was pulled

up to 14,000 ft to allow for settling time, and after three

hours the CT was rigged in hole again to verify that the

perforations were not plugged. The CT did not tag hard, so it

was concluded that the perforations were free of obstruction

in the wellbore. The CT was then pulled out of the hole and a

nitrogen lift was performed to kickoff the well. The well

flowed on its own at below target rate so an injectivity test

ahead of bullheading a matrix stimulation treatment was

attempted, but it was unsuccessful as the injection pressure

built up quickly and no fluid intake was observed. It was

assumed then that the most likely cause of the problem was

that the perforations had been plugged up, either with the 100

mesh sand used in the abrasive slurry during perforating

operations or with some other solid material. An acid wash

was successfully performed using a high-pressure CT to pump

organic and 15% hydrochloric acid blends. A new injectivity

test was then attempted, and the injectivity rate significantly

increased from 0.8 bpm to 6 bpm. Figure 12 shows details of

the operation.

Finally, a matrix acid treatment was bullheaded down thetubing at an initial maximum treating pressure and rate of

6,000 psi and 5 bpm, respectively. The well was opened for

flow back at an initial shut-in wellhead pressure of 3,580 psi,

and it performed in an excellent manner, Table 1.

This job was the first successful utilization of hydrajetting

technology as a cost-effective alternative to perforating with

CT in a high angle Saudi Aramco gas producer. The results

from this highly successful field trial were very encouraging,

and the technology has since been used with equal positive

results in other wells.

Fig. 13. Merged surface and downhole pressure data from gauges.


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REFERENCES

1. McDaniel, B.W., Surjaatmadja, J.B. and East Jr., L.E.: Use

of Hydrajet Perforating to Improve Fracturing Success Sees

Global Expansion, SPE paper 114695, presented at the

CIPC/SPE Gas Technology Symposium 2008 Joint

Conference, Calgary, Alberta, Canada, June 16-19, 2008.

2. Rees, M.J., Khallad, A., Cheng, A., Rispler, K.A.,

Surjaatmadja, J.B. and McDaniel, B.W.: Successful

Hydrajet Acid Squeeze and Multifracture Acid Treatments

in Horizontal Open Holes Using Dynamic Diversion

Process and/or Downhole Mixing, SPE paper 71692,

presented at the SPE Annual Technical Conference and

Exhibition, New Orleans, Louisiana, October 1-3, 2001.

3. Surjaatmadja, J.B., Abass, H.H. and Brumley, J.L.:

Elimination of Near-Wellbore Tortuosities by Means of

Hydrojetting, SPE paper 28761, presented at the Asia

Pacific Oil & Gas Conference, Melbourne, Australia,

November 7-10, 1994.

4. Surjaatmadja, J.B. and Sierra, L.: New Alternative toSelectively Fracture Stimulate Extended Reach, Horizontal

Wells, SPE paper 119475, presented at the SPE Middle

East Oil & Gas Show and Conference, Manama, Bahrain,

March 15-18, 2009.

5. Garzon, F.O., Franco, C.A., Ginest, N.H., Sierra, L.,

Surjaatmadja, J.B. and Izquierdo, G.: First Successful

Selective Stimulation with Coiled Tubing, Hydrajetting

Tool, and New Isolation Sleeve in an Open Hole Dual

Lateral Well Completed in a Saudi Arabia Carbonate

Formation: A Case History, SPE paper 130512, presented

at the SPE/ICoTA Coiled Tubing and Well Intervention

Conference and Exhibition, The Woodlands, Texas, March

23-24, 2010.

6. Garzon, F.O., Franco, C.A., Al-Saeed, H.A., Al-Omair,

W.M. and Ginest, N.H.: Successful Selective Stimulation

of Open Hole Dual Lateral Gas-Condensate Producers

with a Coiled Tubing, Hydra Jetting Tool and New

Isolation Sleeve in Saudi Arabia, SPE paper KSA-0138,

presented at the SPE/DGS Annual Technical Symposium

and Exhibition, al-Khobar, Saudi Arabia, April 4-7, 2010.



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Jairo A. Leal Jauregui is a Senior

Petroleum Engineer in the Gas

Production Engineering Division of the

Southern Area Production Engineering

Department (SAPED). He has 19 years

of experience in the oil and gas

industry in areas like workovers, acid

stimulation, and perforating and fracturing, with operations

in Colombia, Venezuela, Argentina and Saudi Arabia. Jairo

has authored several Society of Petroleum Engineers (SPE)papers on field technology applications, fluids and

stimulation results.

In 1990, Jairo received his B.S. degree in Petroleum

Engineering from the Universidad Industrial de Santander,

Bucaramanga, Colombia, and a Specialization in Project

Management from Pontifica Universidad Javeriana, Bogot,

Colombia, in 2005.

Jorge E. Duarte is a Production

Engineer working in the Gas

Production Engineering Division. He

has 13 years of oil field experience.

In 1996, Jorge received his B.S.degree in Petroleum Engineering from

the Universidad America, Bogot,

Colombia.

Alejandro Chacn is the Lead

Technical Engineer for Halliburton

Coiled Tubing in Saudi Arabia. He has

held this position since January 2009.

Alejandro joined the industry in early

2006 in Colombia as a Field Engineer,

and since then he has gained

experience in the following types of operations, among

others: matrix stimulation, pinpoint stimulation, logging,

CT-TCP, conformance and general coiled tubing (CT)

extended reach applications.

He is currently focusing on new technology applications

for CT operations in Saudi Arabia.

In 2006, Alejandro received his B.S. degree in

Mechanical Engineering from the Universidad de los Andes,

Bogot, Colombia.

BIOGRAPHIES

Walter Nnez-Garcia is a Senior

Petroleum Engineer. He has worked for

the Gas Production Engineering

Division for 4 years and has 17 years

of overall experience in the oil industry.

Previously, Walter worked for

ECOPETROL (Colombian national oil

company) serving in several different technical and

administrative positions.

In 1992, he received his B.S. degree in Petroleum

Engineering from the Universidad America, Bogot,

Colombia, and in 2000, he earned a financial degree from

La Gran Colombia University, Bogot, Colombia. Walter

then earned his M.S. degree in Petroleum Engineering from

the University of Oklahoma, Norman, OK, in 2002.

He is a member of the Society of Petroleum Engineers

(SPE).

Walter has authored several SPE papers covering field

technology applicstions.

J. Ricardo Solares is a PetroleumEngineering Consultant and a

Supervisor with the Southern Area

Production Engineering Department

(SAPED) in Udhailiyah. He has 25

years of diversified oil industry

experience. Throughout his career,

Ricardo has held positions as a Reservoir and Production

Engineer with Arco Oil and Gas and BP Exploration, while

working in a variety of carbonate and sandstone reservoirs

located throughout the worlds major hydrocarbon

provinces in the Middle East, the Gulf of Mexico, Alaska

and South America.

Since joining Saudi Aramco in 1999, he has beeninvolved with a variety of technical projects and planning

activities that are part of large gas development projects.

Ricardo manages a team responsible for the introduction

and implementation of new technology, the issuing of

operating standards, stimulation and production

optimization activities, and completion design.

His areas of expertise include hydraulic fracturing and

well stimulation, all aspects of production optimization,

completions and artificial lift design, pressure transient and

inflow performance analysis, completions design and

economic evaluation.

In 1982 Ricardo received his B.S. degree in Geological

Engineering and in 1983 he received his M.S. degree in

Petroleum Engineering, both from the University of Texas at

Austin, Austin, TX. He also received an MBA in Finance

from Alaska Pacific University, Anchorage, AK, in 1990.

Ricardo received the 2006 Society of Petroleum

Engineers (SPE) Regional Award in the area of Management

and Information, and a SPE Technical Editor award for his

work on the Editorial Review Committee. He has also

published over 20 SPE papers and articles in a variety of

international technical publications.


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Robert Heidorn is the Lead Technical

Professional for Halliburton Coiled

Tubing, Saudi Arabia, and has held this

position since December 2009. He

joined Halliburton in early 2006 in

South Texas, where he received his

coiled tubing (CT) training, and then

worked for the following 3 years offshore in the Gulf of

Mexico, before transferring to Saudi Arabia. During this

time as a Field Engineer, Robert gained experience information consolidation, matrix stimulation, pinpoint

stimulation, and general CT operations for high deviation

and extended reach applications, among many others.

In 2006, he received his B.S. degree in Mechanical

Engineering from Louisiana State University, Baton Rouge, LA.

Guillermo A. Izquierdo is a Petroleum

Engineer working for Halliburton in

Saudi Arabia as a Senior Account

Representative in Production

Enhancement. He has held this position

since December 2005. Guillermo joined

Halliburton in 1997 and his experienceincludes acidizing, de-scaling, scale inhibition, coiled

tubing, conformance and fracturing technology applications

for both sandstone and carbonate formations.

He received his B.S. degree in Petroleum Engineering

from the Universidad Industrial de Santander, Bucaramanga,

Colombia, in 1996.

Guillermo has authored several papers covering

stimulation technology. He is currently focused on new

technology applications for production enhancement for

Saudi Arabian fields.

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