3D Seismic Interpretation and Development of Sequence Stratigraphic Model of a Carbonate Buildup in Central Luconia, Offshore Sarawak

The calibrated 3D seismic data were studied to characterize the carbonate
facies in a carbonate buildup located in southeast Central Luconia Province. The
sequence stratigraphy and seismic attributes analyses were carried on the carbonate
bearing intervals to characterize the facies, understand the evolution and map-out their
distribution. The carbonate bearing intervals, which is defined by Top Carbonate and
Base Carbonate horizons were accumulated in Early Miocene to Middle Miocene
time in two major sequences. These sequences were developed in response to the
changes of relative sea level, with well defined associated system tracts. The stacking
pattern of the system tracts and stratigraphic unit reveal the growth architecture and
the evolution of the buildup. Three main factors have been identified in controlling
the growth, evolution and architecture of the buildup; which are tectonics (faulting
and subsidence), relative sea level and also paleowind direction in addition to the rate
of carbonate production. Using seismic facies approach, the mounded reefal and
progradational facies are potentially associated with good reservoir properties. They
are extensive in peripheral area of the buildups, whereas the tight lagoonal facies is
commonly found in the central of the buildup. The porosity and permeability
enhancement through secondary processes such as karstification and late leaching has
been identified as one of the main contribution to the reservoir formation. These
facies is distributed in association with the formation of the sequence boundaries
during lowstand sea levels. The findings from the study could contribute in lowering
the future exploration and development risks and also to maximize the returns.