Tukau Field: Finding New Oil in Matured And Complex Field After 20 Years of Production

Mohd Ridza MD Shariff, Peter Majid, and Samsudin Mohd Yusoff

The Tukau Field is located some 30 km offshore Sarawak, Malaysia, in water depth of about 160 ft. The field, discovered by TK-2 in 1966 found 235 ft net oil sand and 16 ft wet gas sand. After further seismic data acquisition and interpretation, six (6) appraisal wells were drilled from 1973 to 1975 before the field could be commercially developed.

The Tukau structure is a structurally complex feature formed as a domal anticlinal uplift, located along the Tukau / Bakau / Baram trend. It is dissected at the shallow level by normal synthetic and antithetic faults. These fault system divide the field into seven (7) fault blocks. The major hydrocarbon accumulations are between 2400 ftss and 7500 ftss and the main prospective sequence consists of fine to very fine grained sand of the upper cycle V of lated miocene age and deposited in a deltaic, fluriomarine, coastal to near shore environment.

Development drilling commenced in 1975 with a total of 23 wells. To date a total of nine (9) rounds of development activities were carried out resulting in 55 wells being drilled and nine (9) well jackets installed.

In 1975, based on the seismic and well data, the field is estimated to contain some 300 MMSTB of oil. Following subsequent field reviews incorporating some 50 odd well data and seismic reinterpretation in 1987, the field STOIIP increased to 500 MMSTB. 3D seismic was acquired in 1992 and field review carried out in 1995 resulted in some development potential and appraisal / exploration opportunities.

The appraisal well drilled in October 1995, increased the field STOIIP by some 50 MMSTB. Preliminary evaluation based on geological, engineering and economic information indicated that Tukau field will be further developed with additional well jacket and this will boost the field production by about 50%.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California