Linkages Between Deepwater Fold and Thrust Belt Structuring and Reservoir/Seal Nature, Deepwater, Offshore Malaysia

Abstract

Numerous deep water fold belts (DWFB) around the world show exploration potential in both their pre-kinematic and syn-kinematic strata. However the sediment fairways and fill nature differ dramatically between these two phases of foldbelt evolution. Deposits, structures and elements of both such phases are imaged in spectacular detail by 700km² of newly acquired, multi-azimuth broadband 3D seismic data, actively explored offshore Malaysia DWFB. These data enable us to develop a spatial and temporal understanding of reservoir evolution in association with pre- and multi syn- to post-deformations of this active DWFB. Detailed structural mapping and geomorphological observations applied to Middle Miocene-to-recent sediment in the study area, show that the pre-kinematic sequences are composed of two sub-facies, with the older sub-facies showing thick and spatially extensive (regionally extensive over entire structures) chaotic reflection packages, interpreted to be composed of rafted blocks and debrites (Type 1). These older sub-facies show abundant evidence of shortening (thrusts). These deposits are overlain by parallel-to-convergent, medium-to-high amplitude reflection packages, composed of low-to-highly sinuous channels lacking levees. Syn-kinematic sequences are composed of relatively smaller-scale, thinner chaotic reflections of mass transport deposits (Type 2) which fill local accommodation between structures, and are interspersed with continuous reflector packages showing both wedge and drape geometries and containing leveed channel. Sediment inputs can be identified using channel fairway mapping. Fairways and channel architecture vary in response to structuration of the DWFB. Pre-kinematic Type 1 MTCs indicate regional slope failure and may influence the occurrence and nature of post-failure turbidity flow (healing phase flows). The large extent of pre-kinematic MTCs allow them to act as regional seals in the petroleum system. Type 2 MTCs and the following successions record the active structural deformations/collapse and following fill of the local fold and thrust structure.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015