Geomorphological evolution of the Group I fluvial system, AX field, Malay Basin

Abstract

The AX Field is located 167km off NNE Kerteh, Terengganu of Peninsular Malaysia, southwest of Malay Basin. This study is focused on the 3D seismic analysis of the Lower Miocene fluvio-deltaic Group I. The objective of the study is to evaluate the geomorphological evolution of fluvial succession and interpret the possible intra-basinal and extra-basinal controls on the fluvial evolution. One hundred strata slices were generated in order to evaluate the evolution of the fluvial systems within the Group I interval. Seismic attributes such as Root Mean Square (RMS), sweetness and spectral decomposition were computed to map channel geomorphology. Different fluvial styles were identified in the different parts of the study area. Variation of fluvial style were identified within the Group I interval including the low sinuosity system with tributary channels, high sinuosity system with broad meander belt and braided system. Fluvial channel imaged within the studied interval can be divided into six (6) stages based on the channel morphology. Stage 1 (1875 – 1810 ms), the oldest stage, displays high sinuosity channels. Braided system associated with coal deposition were imaged in Stage 2 (1810 – 1765 ms). During stage 3 (1765 – 1710 ms), the fluvial system is characterized by low to moderate sinuosity channel features that varies in scale and geometry. Stage 4 (1710 – 1675 ms) display fluvial style characterized by low sinuosity-to-straight system with tributary channels. Stage 5 (1675 – 1615 ms) is represented by high sinuosity fluvial system with broad meander belt and point bar. During Stage 6 (1615-1536 ms) the fluvial system displays moderate-to-high sinuosity. The high sinuosity system in period 6 exhibit well-defined meander scroll bar morphology that reveals the extension and translation course of the fluvial system.