--> Abstract: 4-D Petroleum Systems Modeling on the Vietnam Side of the North Malay Basin—High Heat Flow Effect on Fault-Flow Properties, by Marek Kacewicz, Greg Cable, Joe Curiale, Russel Davies, Art Trevena, and Clark Weaver; #90039 (2005)

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4-D Petroleum Systems Modeling on the Vietnam Side of the North Malay Basin—High Heat Flow Effect on Fault-Flow Properties

Marek Kacewicz1, Greg Cable2, Joe Curiale3, Russel Davies4, Art Trevena3, and Clark Weaver5
1 Unocal Corporation, Sugar Land, TX
2 Unocal Vietnam Exploration, Ho Chi Minh City, Vietnam
3 Unocal Exploration and Exploitation Technology, 77478 Sugar Land, TX
4 Rock Deformation Research USA, McKinney, TX
5 Unocal Thailand, Sugar Land, TX

A long history of Vietnam exploration in or on the flank of a mature basin, with hundreds of drilled wells and with existing production, has proved that the North Malay basin is not fully understood. In addition to such typical issues as migration directions and fault/seal/flow through time, heat flow and heat flow history pose interesting problems that might affect future exploration decisions. It is documented that heat flow in the basin is very high, and cannot be explained by rifting alone. The passage of 35-45 Ma since rifting, along with heat flow values in the 55- 100 mW/m2 range, suggest that there must be significant vertical thermal exchange within the system at present day.

Several 4D basin models were developed to study thermal processes in the basin and to test how faults and caprock properties affect hydrocarbon migration directions. Our “CV-2X dryhole” example demonstrates the importance of understanding fault and caprock properties at different temperature and pressure conditions. Depending on regional and local stress, fault juxtaposition, and clay smear, faults might serve as seals and/or conduits. Fault flow properties vary over time as a result of effective stress, temperature, and diagenesis. Analysis of present day conditions is not sufficient, and past fault behavior and modeling of fault permeability through time is critical. Very high North Malay Basin heat flows result in shallow quartz diagenetic effects and brittle-ductile-brittle transitions, which can be used to calculate fault zone permeability for the basin model. This paper discusses how various fault history scenarios and associated fault and diagenetic processes have affected present day hydrocarbon distributions.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005