Facies and Stratigraphic Organization of the E-D-B Groups (Middle Miocene) Incised Valley Successions of the Noring Field, Malay Basin, Malaysia

Abd Rahman, Abdul Hadi¹, Mohd Rapi Mohamed Som², Moh’D. Nurein Bushara³

(1) Universiti Sains Malaysia, Penang, Malaysia (2) Petronas Research Malaysia,Bangi, Selangor, Malaysia (3) Petronas Carigali Sdn Bhd, Kuala Lumpur, Malaysia

The Noring field is located towards the northeastern margin of the Malay Basin, offshore east-coast of Peninsular Malaysia, in the South China Sea. Gas-bearing sandstones occur within the continental, coastal and marginal marine Middle Miocene sandstones, mudstones and coal successions of the E and D Groups.

Facies and stratigraphic analysis of the sections identified a total of seventeen lithofacies that are grouped into: i) a fluvial floodplain, and ii) an estuarine/tidal flat facies-assemblage. The floodplain facies-assemblage includes proximal over bank lithofacies association (fine­grained levee deposits, crevasse-channel and crevasse-splay), lacustrine-floodplain lithofa­cies association (laminated silt, shale and heterolithics) and back swamp lithofacies associ­ation (coal and paleosols). These lithofacies defines part of the E Group. Stratigraphic inter­pretation of the E Group identified a basal coal-bearing meandering fluvial and floodplain sub-interval, a middle sand-prone braided fluvial sub-interval and an upper lacustrine and meandering fluvial succession. The estuarine facies-assemblage is restricted to the D Group, which overlies the floodplain facies. This facies-assemblage is marked by the presence of Diplocraterion and Teichicnus trace fossils within the mudstones and siltstones, and the absence of coal. Thick, coarsening-upward deltaic successions of the B Group is represent­ed by a basal lowstand fluvial facies, a transgressive prodelta mud succession, and capped by a delta-front highstand deposits.

The organization of depositional facies and intervals of the E-D-B Groups represent an incised-valley fill. The westward thickening of the marine-influenced mud-dominated suc­cessions within the D and B groups indicates the axis of the paleo-valley in the NNW sea­ward direction.