ABSTRACT: An integrated
petroleum
system
study, northern Gulf of Thailand:
applications to the Block B8/32 area
Teerman, Stan C.1, Leah N. Smith2, Christopher,
N. Denison3, and Roger W. Marzi4
(1) Chevron Research Technology
Company, San Ramon, CA
(2) Pogo Producing Company, Houston, TX
(3) Chevron Overseas
Petroleum
, San Ramon, CA
(4) Hydrocarbon
System
Associates, Katy, TX
Tantawan and Benchamas fields (Miocene) are located in Block B8/32 in the northern Gulf
of Thailand. Tantawan field, to the south, produces primarily gas with associated oil and
condensate; Benchamas field, to the north, produces primarily light oil. Post-rift
faulting has compartmentalized the reservoirs, requiring a continuous in-fill and
exploration drilling program to maintain production levels. Successful exploration for
additional reserves in adjacent areas of the Gulf of Thailand requires a full
understanding of the regional
petroleum
systems.
The main source rock area is in the deeper graben areas to the
east
of the fields, in
the Pattani Trough. A regional decrease in thermal gradient from concession areas to the
south puts Block B8/32 in a favorable location for both gas and liquids generation.
Faulting strongly controls migration pathways and seals.
Restricted penetration of potential source rock intervals and lateral facies changes limits interpretation of source rock occurrence. Both oils and condensates display variations in isotopic composition and their capillary gas-chromatography character, suggesting differences in source input. Characterization of Type II and II/III kerogens by pyrolysis and organic petrology indicate the occurrence of several different source facies and depositional environments.
New source rock data have been generated in collaboration with biostratigraphic data, to understand the control of depositional environments on source rock distribution and their age. This information is integrated with stratigraphic and depositional models developed from wireline logs and 3-D seismic data to produce a predictive source facies model and to define variations in organic facies. This source model is calibrated with biomarker data.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia