Integration of Geological & Reservoir Dynamic Pressure Data to Characterize Hydraulic Flow Barriers in the Greater Burgan Field

Abstract The study aims at collating the entire dynamic pressure test history of the Greater Burgan field and integrating with latest Geological and Petrophysical description of the various hydraulic flow units for field development planning. The analysis is deemed critical for understanding the fluid flow behavior, hydraulic communication of marginal low-quality sands with the underlying reservoirs and develop a strategy for comprehensive waterflood scheme based on the integrated view of the multiple stacked reservoirs. The complete field data comprises of wireline formation pressure tests, static bottom hole pressures and petrophysical log evaluation results for all wells across the entire field were collated. Later, a 15×15km sector in the field was selected for a detailed integrated analysis. The wireline pressure test measurements were converted to pressure potentials to determine permeability flow barriers across various reservoirs. These pressure breaks were integrated with petrophysical rock types in selected wells. Pressure tomography maps were prepared for each stratigraphic interval which were integrated with regional geological depositional environments and facies description. The integration of pressure data with geological and petrophysical information helped to visualize the degree of reservoir connectivity both in vertical as well as spatial dimension. The intra reservoir shale barriers were characterized by their thickness, lateral extent and the magnitude of pressure potential breaks across. The static bottom hole pressure data for the wells were integrated to see the impact of pressure depletion for the completion intervals in the wells. The pressure tomography maps highlighted areas where fluid transmissibility was high and other areas where the sand intervals were hydraulically in isolation. The analysis identified causes of low productivity in wells completed in marginal sands having poor vertical connectivity. The work also facilitated in understanding the areas which require immediate pressure maintenance for Burgan Upper Sands through waterflood which might not have been supported from bottom aquifer otherwise. The RFT mobility data was also used to calibrate and improve the log-based permeability estimates as the data available for fluid viscosities was comprehensive. The RFT data was also used to mark fluid gradients in wells with secondary gas cap considering the depletion and reservoir heterogeneity effects masking the fluid gradient interpretations. The work became an integral part of the life of field plan to target areas which require immediate focus for waterflood implementation and execution. The pressure data has been integrated at the field level for the very first time at such a scale. The process of visualizing and validating has now been streamlined in KOC which has resulted in a substantial manual effort reduction.