Advanced Wireline Log Acquisition and Innovative Data Processing, Along with an Integrated Petrophysical Methodology, Unleash the Full Potential Of Cycle II/III Reservoir Offshore Sarawak
Authors: Nordin T. B. , Azid A. A. , Ong L. W. , Abdullah M. Z. 
Published: February 2024

This study presents an integrated petrophysical evaluation by highlighting a practical trustworthy approach petrophysical model with advanced wireline logs for Cycle II/III reservoirs in Balingian, Sarawak and it was considered one of the most important exploration findings. Comprehensive petrophysical and fluid distribution evaluation is crucial for optimal reservoir development and management. Conventional measurements to determine the presence of movable hydrocarbons, qualitative producibility and in situ reserves estimation have proved to be inconclusive due to presence of complex lithology, thin-beds, dispersed clay and highly variable water salinity. The case study presented demonstrates that the constraints of the conventional measurements can be overcome and highlights the benefits of the following multidisciplinary integration approach: Triaxial array induction resistivity, high-resolution neutron-density and nuclear magnetic resonance data identified the potential thinly bedded hydrocarbon bearing zones.Advanced nuclear magnetic resonance log provided key measurements by continuous scanning of the formation properties to correctly identify the moveable reservoir fluids and contact levels and to reproduce variations of fluid distribution radially into the formation with multiple frequency data. NMR provides independent measurement regardless of variations in formation water salinity or low contrast resistivity pay.Optical spectroscopy coupled with fluorescence and reflectance measurement identified the full characterization of the formation fluid, both composition and phase behavior. This allowed identifying the distinct types of hydrocarbons (gas, light and dark oil), independently from their level of saturation. In combination with magnetic resonance fluid maps, this gives an insight on original fluid in place, and change of phase is properly described.Determination of the characteristic of the potential zones using borehole imager tool and allow to estimate textural heterogeneities and define thickness of reservoir zones and borehole geometry.All this information is key to defining future field development strategies.

Because of the existence of complicated lithology, thin beds, dispersed clay, and extremely variable water salinity, conventional measurements to establish the presence of mobile hydrocarbons, qualitative producibility, and in situ reserves assessment have been inconclusive. This research discussed several case studies for carbonate and clastic reservoirs with petrophysical features that may be defined utilizing advanced logs, drilling data, LWD, triple combo, and DST. For optimal reservoir development and management, comprehensive petrophysical study and fluid distribution evaluation is required. In summary, the integration of available data (advanced wireline logging and drilling data) and the application of new in-house workflow ideas and solid geoscientific knowledge will add value to our further understanding of this surrounding area.