A project study has been performed in reservoir saturation monitoring of carbonate reservoir on-shore Abu Dhabi. An integrated three phase fluid approach of pulsed neutron capture (PNC) in miscible gas and water alternating gas (WAG) injection of complex carbonate reservoir is presented. It has utilized open hole logs, production logs, production test, fluid sampling/PVT and core data in workflow analysis. It has been a challenge to get accurate and reliable reservoir saturation during production phase with gas and WAG wells injection in this carbonate reservoir. It's complex reservoir conditions has added the challenge for reservoir saturation monitoring program, evaluation and management.
Standard logs data quality check and correction need to be performed to ensure of consistency in analysis. PNC-Sigma (Σ), reliable lithology and porosity were used in three phase fluid model approach by optimizing simultaneous equation. It optimizes relationship among tools, parameters and formation component volumes. End point PNC-Sigma gas, oil and water have been determined in analysis to get an accurate gas, oil and water saturation. Openhole sigma, resistivity log and special core analysis (Special Core Analysis-SCAL/Digital Rock Physic-DRP) data have been used to evaluate and validate the changing of reservoir saturation. Furthermore multi spinner/probes production logs, water flow log (WFL) would be recommended in horizontal/high deviation production or injection wells along with surface production test to get an accurate of recent fluid contribution of reservoir. Validated well production profile in logged or nearby area has been used for comparison and calibration for the results.
The integration approach of logs, well production/test and core data in particular carbonate reservoir has been used to provide accurate and reliable reservoir saturation results. It has been observed that the identification of miscible gas and water saturation using three phase fluid approach in reservoir has provided a lot of benefit for reservoir monitoring and management in this field. The integration of formation evaluation in this case study has provided improvement, reliability in reservoir saturation results for carbonate reservoir monitoring and management.