Present-Day Stress Field of Southeast Asia

Tingay, Mark¹; Morley, Chris K.²; King, Rosalind³; Coblentz, David⁴
¹Australian School of Petroleum, Univ Adelaide, Adelaide, SA, Australia.
²PTT Exploration and Production, Bangkok, Thailand.
³School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA, Australia.
⁴Los Alamos National Laboratories, Los Alamos, NM.

Present-day stress information is particularly valuable for petroleum geomechanics applications in Southeast Asia. The region contains 31 basins, the majority of which host active petroleum producing fields, with Indonesia, Malaysia, Vietnam and Thailand having a combined production of over 2.4 million barrels of oil per day. The Cenozoic tectonic evolution of the Sunda region of SE Asia is usually considered to be controlled by escape tectonics associated with India-Eurasia collision. However, SE Asia is bounded by a poorly understood and complex range of convergent and strike-slip zones and little is known about the effect of these other plate boundaries on the intraplate stress field in the region. We compile the first extensive stress dataset for Southeast Asia, containing 275 A-D quality (177 A-C) horizontal stress orientations, consisting of 72 stress indicators from earthquakes (located mostly on the periphery of the plate), 202 stress indicators from breakouts and drilling-induced fractures and one hydraulic fracture test within 14 provinces in the plate interior. This data reveals that a variable stress pattern exists throughout Southeast Asia that is largely inconsistent with the region's approximately ESE absolute motion direction. The present-day maximum horizontal stress in Thailand, Vietnam and the Malay Basin is predominately north-south, consistent with the radiating stress patterns arising from the eastern Himalayan syntaxis. However, the present-day maximum horizontal stress is primarily oriented NW-SE in Borneo, a direction that may reflect plate-boundary forces or topographic stresses exerted by the central Borneo highlands. Furthermore, the South and Central Sumatra Basins exhibit a NE-SW maximum horizontal stress direction that is perpendicular to the Indo-Australian subduction front. Hence, the plate-scale stress field in Southeast Asia appears to be controlled by a combination of Himalayan orogeny-related deformation, forces related to subduction (primarily trench suction and collision) and intraplate sources of stress such as topography and basin geometry.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012