Abstract
Big attention was directed towards the deepwater fields offshore Sabah area after the discovery of commercial hydrocarbons Sabah in 2002. Hundreds of wells were drilled in up-faulted structural traps within North East trending thrust ridges which some of it are dry. The interpretation of these reservoirs was established as a series of four turbidite fans from Upper Miocene to Pleistocene. Yet, no correlation was found between the same fan in different locations with regards to geometry, thickness and mineral composition. This research studied over 50,000 sqkm of 3D seismic surveys, over 100 wells with different sets of logs including image logs, cores from two wells and bathymetric images. Normal seismic structural interpretation was conducted and seismic attribute of the turbidite fans were analysed. Seabed morphology was examined using bathymetry surveys and 3D seismic. The deepwater sediments type and depositional environment were investigated using core and log data.
The geometry of the oil prone sand reservoir bodies and heterolithic sand bodies within the deepwater fields was found to be of three types:
North East trending narrow sand channels and turbiditic channel levees in the Southwest area of deepwater offshore Sabah,
North East trending confined turbidite sand bodies bounded by elevated structural ridges south and south east of type 1,
Deepwater fan system composed of channel sand, levee turbidites and local and regional MTD to the North East of type 1
This new understanding of the source and sediment supply of the deepwater fields Northwest (NW) Sabah explains the geometry, distribution and lack of correlation within the Miocene sediments. Thus, this study will direct the future exploration in the deepwater reservoirs.
