A Delineation of Multi-Formation Fluid Components Using Cased Hole Logs for Offshore Malaysia Gas-Condensate Reservoir

Gas reservoir fluid properties vary during the production phase as the reservoir pressure declines below the dew point. The evaluation of formation saturation across such reservoirs may become more complicated when water saturation increases due to water influx from the aquifer.

Formation saturation analysis using conventional pulsed neutron carbon/oxygen and thermal neutron capture cross section (sigma) logs do not provide a clear sensitivity between gas and condensate. A combination of a multi-detector pulse neutron tool with an improved analysis capability has been the key to unlocking some of the challenges faced by an operator of a gas-condensate field located off the coast of Sarawak, offshore Malaysia.

Pulsed neutron logging was performed for three-phase saturation evaluation as part of a multi-well logging campaign. Production logging was also conducted in a flowing condition in one of the wells to determine the contribution from perforated intervals.

The saturation results will provide a reference to determine if there are changes required to be made on the inputs to calculate the fluid saturations (particularly water saturation, Sw) for the initial condition. This update on the inputs will improve the reservoir dynamic modelling in part with delivering actual production vs modelling.