Abstract: Miocene-Oligocene Sequence Stratigraphy of the Malay Basin

Richard Lovell, Mohd. Rohani Elias, Rob E. Hill, Missy H. Feeley

The Malay Basin has experienced extension in the Eocene(?) through Oligocene, sag in the early Miocene, and compression in the middle Miocene through Pliocene-Pleistocene. The interaction of structurally induced and glacial-eustatic accommodation changes has resulted in complex, interrelated play elements, including multiple reservoirs, diverse nonmarine sources, discontinuous migration pathways, and thin seals.

Extensional subbasins were filled with braided streams, associated coastal plain, lacustrine deltas, and thick lake shales (groups M-K). This initial rift fill comprises an overall second order progradational cycle punctuated by 3rd-order cycles. These 3rd-order cycles are capped by thick, source-rich, lacustrine shale packages.

The lower Miocene section (groups I and J) consists of progradational to aggradational fluvial to tidally-dominated estuarine sands. Hydrocarbons are generated from interbedded coals and other coal-related lithologies.

Initiation of localized compression and associated loading coupled with an overall sea level rise resulted in increased accommodation during the middle Miocene (groups H and F). Middle Miocene deposits are dominantly marine deltaic with isolated fluvial/estuarine channels. Hydrocarbons are generated from thin coal intervals. Maximum rise in relative sea level culminated at the top of the group F, followed by an abrupt downward shift (3rd-order boundary) marking the initiation of group E deposition. A progradational stack of dominantly fluvial/estuarine channels characterizes the reservoirs at this time, with hydrocarbons generated from interbedded oil-prone and gas-prone coals. Progradational deposition continues up into group D, which culminates with an areally restricted erosional u conformity.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994