Mechanical and Chemical Removal

of Organic Bridge Deposits and

Acid Stimulation of Extended

Reach Offshore Wells

Presented By: Syed Danish

Account Representatives – Halliburton Coiled Tubing

Coauthors: Jose Noguera, Halliburton Saudi Arabia; James Arukhe and Hussain Al-Saiood, Saudi Aramco

© Copyright 2014, Saudi Aramco. All rights reserved.

2

▌ Abstract

▌ Manifa Field – Introduction

▌ Objective

▌ Downhole Challenges

▌ Execution Challenges

▌ Stimstar (Stimulation Vessel) and Kinoa (CT Barge)

▌ PWI – Generic Stimulation Procedure

▌ OP – Generic Stimulation Procedure

▌ Case Studies

▌ Conclusion

Contents

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▌ The Manifa field – Saudi Arabia:

Peripheral matrix water injection as a pressure maintenance scheme.

Unique placement of both onshore and offshore PWI and OP.

Wells are extended reach, highly deviated, with deep open holes.

▌ Stimulation is a required to restore reservoir productivity or injectivity with multiple challenges:

A heavy tar mat zone characterizes the field.

Hardened mixed sludge results in stable bridges.

▌ The scope of this presentation is to review:

Remedial coiled tubing stimulations performed during this campaign.

Interventions executed for removing wellbore organic obstruction by both chemical and mechanical means.

▌ Two case histories in an offshore PWI candidates are offered.

Abstract

4

Manifa Field – Introduction

▌ Largest offshore carbonate project of the region with target production:

900 MBPD heavy crude oil.

90 MMSCFD sour gas.

65 MBPD condensate.

▌ Unique engineering design:

Water drive mechanism.

Unique placement of both power water injector and oil producer wells.

Onshore footprint on artificial man-made islands.

Offshore footprint on shallow platforms with ~10 m water depth.

5

Objective

▌ Main objective is to acid stimulate and/or nitrogen lift every offshore and onshore newly drilled/ workover well.

▌ Formation has limited injectivity and productivity indices:

Post-drilling and workover operations residual mud damages/loads up the OPs.

PWI wells drilled in heavy oil mat zones have hardened sludge and tar bridges.

Mixed deposits limit production due to commingled inorganic scale and tar generation.

6

Downhole Challenges

▌ 80% of these wells are extended reach, with measure depth (MD) to total vertical depth (TVD) ratio exceeding 2.

Need to utilize hydraulic tractor and agitator assemblies to reach TD.

▌ 90% of the wells are highly deviated, with maximum deviation angle reaching 90° for more than 50% of the open hole region.

Excessive wash out regions in the open hole cause multiple tags, need to utilize hydraulic indexing and knuckle joint assemblies to jump over wash outs.

▌ 30% of the measured depth coverage is for open hole production or injection:

Open hole results in excessive drag while RIH, slick friction reducer is placed in the 45° deviated zone.

▌ 2% of the wells have multilateral profiles:

Lateral finding technology is required like MWD assembly or live downhole CCL telemetry.

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Execution Challenges

▌ Offshore Wells (Assigned to HAL):

Barge Deck Loading/Capacity:

− Limited in terms of CT string length.

− Limited to use other services, including full surface testing package, stimulation package, slick line or wireline.

− Without flare booms small equipment off loading is not possible.

Crane Capacity and Length – 45 ton port side and 25 ton starboard side:

− Limited in terms of lubricator height, tool deployment is restricted.

Barge Technology:

− Self-propelled barge without dynamic positioning, weather plays a important role during barge positioning.

Barge Leg Lengths – 52 m and Barge Draft – 4.5 m:

− Cannot perform deep water or shallow water operations in nearby fields.

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Stimstar (Stimulation Vessel) and Kinoa (CT Barge)

Exp

osive

Carg

o

2.3

02.4

0

538

554

Mean

Dra

ft

2.4

8

trans. P

um

ps

iso. T

anks

ch. In

j. Pum

ps

569

585

2.5

52.6

6

1716

1514

1312

1110

-9-8

-7-6

-5-4

-3-2

-10

12

34

56

78

910

1112

1314

1516

17

Min

us

"-"P

lus

"+"

1

43

21

Dry

Store

10

Chill

er 12

Free

zer

Muste

r

№2

89

H2

S

№1

H2S

№2

2

Muste

r

№ 1

24

7 Paint

Store

Bosun store

9

Stimstar (Stimulation Vessel) and Kinoa (CT Barge)

10

PWI – Generic Stimulation Procedure

▌ Power Water Injectors:

BHT 210 °F

BHP 3,500 psi

Average depth ~ 20,000 ft

Completion 7” tubing, 7”

liner and 6.125” open hole

Average open hole length ~

8,000 ft

Max deviation 90°

Extended reach

Single or multilaterals

Treatment Fluid Loading Placement Method

H2S Scavenger Bullheaded from surface to

push the migrated H2S

Friction Reducer Bullheaded from surface and

placed at 45° deviation

Pre-Flush

Treated Water 6 gal/ft

CT RIH, from liner shoe to

maximum depth

Main Acid

15% HCl 3 gal/ft

CT POOH from maximum

depth reached, 500 ft stages

with 36 bbl main acid

Visco Elastic Agent

in 15% HCl 3 gal/ft

CT POOH, 500 ft stages with

36 bbl diversion

Main Acid Spacer

15% HCl 3 gal/ft

CT POOH, 500 ft stages with

36 bbl main acid

Emulsified Acid

15% HCl 6 gal/ft

CT POOH, 500 ft stages with

71 bbl main acid

Post-Flush

Treated Water 3 gal/ft

CT static from liner shoe,

displace treatment

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OP – Generic Stimulation Procedure

▌ Oil Producers:

BHT 210 °F

BHP 3,500 psi

Average depth ~ 15,000 ft

ESP lift completion 4.5”

tubing, 7” liner and 6.125”

open hole

Average open hole length ~

4,500 ft

Max deviation 90°

Extended reach

Single laterals

Treatment Fluid Loading Placement Method

H2S Scavenger Bullheaded from surface to

push the migrated H2S

Friction Reducer Bullheaded from surface and

placed at 45° deviation

Pre-Flush

Treated Water 3 gal/ft

CT RIH, from liner shoe to

maximum depth

Diverter

Visco Elastic Agent

in 15% HCl

5 gal/ft CT POOH, 500 ft stages with

60 bbl diversion

Main Acid

15% HCl 10 gal/ft

CT POOH, 500 ft stages with

119 bbl main acid

Post-Flush

Treated Water 3 gal/ft

CT static from liner shoe,

displace treatment

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Case Study – Organic Bridge Deposits

▌ Well-X PWI (Newly Drilled):

High injection pressures were observed with scavenger and friction reducer.

While RIH CT experienced multiple soft tags at different depths.

Hard bridge of mixed organic deposits were accumulated just above the end of liner shoe.

After multiple attempts CT was POOH and tar deposits were observed on the BHA.

▌ Well-Y PWI:

No injection was observed with scavenger and friction reducer.

While RIH CT experienced very similar hard tag near surface.

After multiple attempts CT was POOH and tar deposits were observed on the BHA.

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Case Study – Chemical and Mechanical Solution

▌ Solution:

Acid Compatible Motor and Bit – Mechanical Milling.

Lab Test – Chemical Solubility:

− Tests showed deposits retrieved from Well-X were mixed heavy

tar with drilling mud residue.

− Tests showed deposits retrieved from Well-Y were heavy tar.

− An organic solvent emulsion in 20% HCl was proposed as

treating solvent. Treatment Fluid

Solubility for

Well-X

Solubility for

Well-Y

Organic Solvent 31.4% in 4 hrs

at 185 °F

94% in 4 hrs at

95 °F

20% HCl 54.2% in min at

95 °F N/A

Emulsified Organic

Solvent + 20% HCl Acid

84% in 4 hrs at

185 °F

94% in 4 hrs at

97 °F

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Case Study – Well-X Job Plot

7/12/201400:00 08:00 16:00

7/13/201400:00 08:00 16:00

7/14/201400:00

7/14/201408:00

Time

-5000

0

5000

10000

15000

20000

25000

30000

35000

A

0

1000

2000

3000

4000

5000

6000

7000

B

0

2500

5000

7500

10000

12500

15000

17500

EU1 Pipe Weight (lbf) U1 Pressure (psi)

U1 Tubing Depth (ft) U1 Wellhead Pressure (psi)

A B

E B

Customer: SAUDI ARAMCO Job Date: 11-Jul-2014 Sales Order #: 12345

Well Description: MNIF-746 UWI:INSITE for Well Intervention v4.6.0

08-Sep-14 20:41

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Case Study – Well-Y Job Plot

7/18/201406:00 14:00 22:00 06:00 14:00 22:00 06:00

7/20/201414:00

Time

-10000

0

10000

20000

30000

40000

50000

60000

A

0

1000

2000

3000

4000

5000

6000

7000

B

0

2500

5000

7500

10000

12500

15000

17500

EU1 Pipe Weight (lbf) U1 Pressure (psi)

U1 Tubing Depth (ft) U1 Wellhead Pressure (psi)

A B

E B

Customer: SAUDI ARAMCO Job Date: 18-Jul-2014 Sales Order #: 11112013

Well Description: UWI:INSITE for Well Intervention v4.6.0

08-Sep-14 20:54

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▌ CT intervention led to the removal of mixed deposit bridges and successful completion of large scale stimulation on the mentioned wells.

▌ Successfully completed 58 interventions and 50 stimulations. Injectivity results post-stimulation revealed 300% improvement.

▌ Execution time per well has been reduced to 1/4th of the original time.

Customized CT stack rig up reduced R/U and R/D time.

Flexibility in operations from chemicals solvents, dispersants to tool tractors, agitators, indexing/knuckle joints, acid compatible motor and mill assembly.

Jack Up Barge and Stimulation Vessel combination helped improve logistics and resource availability.

▌ Planning to introduce CT fiber optic technology for DTS – stimulation assessment on PWI and logging operations for PLT – production logs on OP.

Conclusion

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Thank You for Your Time

Questions?