CHALLENGEReduce skin and improve the productivity index (PI) in new wells to increase overall field productivity for Petronas Carigali Sendirian Berhad (PCSB).

SOLUTIONUse the PURE* clean perforations system to achieve greater productivity than is possible with conventional static under-balance perforating.

RESULTSCompared with other wells in the region that had been perforated conventionally, the well perforated using the PURE system enabled additional production and significantly reduced the production payback period.

PCSB wanted to improve the PI in new off-shore wells to increase field productivityA field in the PMO region was put into comm-ercial operation with initial total production rates of 15,000 bbl/d oil and 60 MMcf/d gas.

Because the field is one of the biggest oil producers in Malaysia—contributing one- sixth of the total national oil production— its development is considered essential to meeting the nation’s rapidly increasing need for hydrocarbons.

Previously, all the region’s wells had been perforated using conventional static under-balance to clean damage and debris from the perforations. The results had been high skin values and, therefore, lower-than-desired PIs.

PCSB sought to maximize field recovery and meet production forecasts by improving the deliverability of new expansion wells.

Schlumberger proposed PURE system to maximize productivityFor the second expansion phase in the field, Schlumberger proposed using the PURE system. Unlike conventional perforating, which relies on a large static pressure differential between the wellbore and the formation to remove perforation debris and crushed-zone damage, the PURE system fully exploits the transient underbalance that occurs immediately after perforating. It creates a large dynamic underbalance, then absorbs perforation debris into the gun chambers, minimizing skin and leaving an obstruction-free path for flow from the reservoir to the wellbore.

The PURE system planner software was used to specify the unique perforating system based on full consideration of the completions geometry, reservoir fluids, and formation characteristics SPAN* Schlumberger perforating analysis was used to select the most suitable gun configura-tion, shot density, and charges and to simulate operation performance. A tubing-conveyed perfo-rating system was used to perforate the well, allowing perforating and testing in a single trip.

CASE STUDY

Perforating

Recovery Optimized with Dynamic Underbalance PerforatingPURE system for underbalance perforating helps PCSB achieve targeted production in offshore field

Manado

Samarinda

Rabaul

Iloilo

Nong Khai

Lhasa

Imphal

Banjarmasin

Jayapura

Kupang

Pontianak

Mandalay

Sittwe

Lae

Madang

Wewak

Bacolod

Baguio

Cagayan De Oro

Laoag

Zamboanga

Chiang Mai

Chumphon

Khon Kaen

Songkhla

Can Tho

Da Nang

Vinh

Monywa

Chittagong

Changsha

Chongqing

Dukou

Fuzhou

Guangzhou

Guiyang

Jingdezhen

Kunming

Nanning

Ningbo

Pingxiang

Shang Rao

Shantou

Shaoguan

Wenzhou

Xiamen

Zhanjiang

Medan

Surabaya

Kaohsiung

Taipei

Hai Phong

Ho Chi Minh City

Nanchang

YueyangZigong

Bandung

Palembang

Semarang

Ujungpandang

Davao

Quezon City

Dhaka

Agana

Hong Kong

Jakarta

Phnom Penh

Vientiane

Kuala Lumpur

Rangoon

Saipan

Kokor

ManilaBangkok

Bandar Seri Begawan

Port Moresby Honaira

Hanoi

Darwin

CHINA

MYANMAR

THAILAND

KAMPUCHEA

BHUTAN

VIETNAM

LAOS

BANGLADESH

WEST MALAYSIA

PAPUANEW GUINEA

BRUNEI

SINGAPORE

PHILIPPINES

TAIWAN

MALAYSIA

INDONESIA

AUSTRALIA

Bay of Bengal

Andaman Sea

Gulf of Thailand

Indian Ocean

Java Sea

South China Sea

Timor Sea

Philippine Sea

Arafura Sea

Gulfof

Carpentaria

North Pacific Ocean

Coral Sea

Pacific Ocean

PMO region

The field offshore West Malaysia.

PCSB was able to be certain its expansion wells would have higher PIs than previous wells in the regionA pressure buildup survey was conducted shortly after Well A was put into production. The calculated skin of 0.3 was significantly lower than skins measured in earlier field wells perforated using conventional tech-niques. No acid treatments or perforation washes were required.

Production from the layer perforated with the PURE system was significantly higher than production from neighboring wells. No water was produced for almost two years after startup.

The production payback period was only three days, and the total incremental value was determined to be USD 2.5 MM/month. This economic impact convinced PCSB to use the PURE system dynamic underbalance perforating in other fields it operates.

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CASE STUDY: PURE system dynamic underbalance enables higher PIs and production, Malaysia

Closed chamber with 3,965 psi trapped pressure

Gun detonated

Transient pressure,

psi

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

0

Time, ms

PURE system creates dynamic underbalance of 1,662 psi

0 400 800 1,200 1,600 2,000 2,400 2,800

Reservoir pressure: 2,137 psi

Oil rate, bbl/d

Gas rate, Mcf/d

Tubing-headpressure, psi

Tubing-head pressure

Oil �ow

Gas �ow

Choke size

Water cut

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

0

160

140

120

100

80

60

40

20

0

Choke size, 1/64 in

Water cut, %

Date

Jan. 1, 2007 Jan. 1, 2008 Jan. 1, 2009

Fast gauge measurement showing the large dynamic underbalance created by the PURE system.

Optimized production history for Well A.