CHARACTERIZATION OF THE PLEISTOCENE FLUVIAL SYSTEM IN SEPAT FIELD, MALAY BASIN USING SEISMIC ATTRIBUTES ANALYSIS

Abstract

This study is focusing on the characterisation of Pleistocene to present day fluvial system found in Sepat Field in the offshore of Terengganu. It aims to characterise the fluvial system in Sepat Field and correlate the fluvial systems found in Sepat Field with the larger scale fluvial system of the Malay Basin. The methodological approach used for this subsurface study includes geological interpretation of 3-dimensional seismic data and wireline logs interpretation. Frequency spectral decomposition combined with variance and relative acoustic impedance attributes had provided a precise prediction on the dimensions, flow orientation and type of the fluvial systems in this field. This study shows that the fluvial system in this field is dominated by meandering channels that flow from northwest to southeast. Points bars, straight channels, channels boundaries and the evolution of the channels can be imaged and interpreted in this study through frequency spectral decomposition technique. A “hook” shape point bar stands out clearly in the data with depth up to 1.5km and is interpreted to be related to the Malay basin fluvial system. The fluvial system in Sepat Field is interpreted to deposit in the midstream river system and highly associated with the Chao Phraya-Johore River, with sediment sources come through this drainage basin and distributed to the tributaries fluvial channels including those in Sepat Field. Keywords: seismic attributes, fluvial characterisation, Malay Basin, spectral decomposition, meandering river