Review and Analysis of Autonomous Inflow Control Devices for Gas Production Regularization in an Offshore Carbonate Reservoir

Autonomous inflow control devices (AICDs) have been piloted/deployed as one of well lower completions to regulate gas production from the target giant carbonate oil field located offshore Abu Dhabi. The AICDs were introduced to industry for autonomous regularization of gas/water production as well as achievement of uniformly distributed inflow profiles. However, because their performance depends on reservoir/fluid characteristics, further implementation of this technology in the subject field requires review and analysis of actual performance of the piloted/deployed AICDs. This study presents a series of reviews/analyses on the performances of multiple pilot wells completed with the AICDs. The reviews evaluated well inflow performance and AICDs’ nozzle performance (by integrating results of flow tests, pressure build-up tests, and production logging tool (PLT) surveys), which enabled us to calibrate key parameters of the published AICD models via history-matching with numerical well/reservoir models. Subsequently, reservoir simulation studies investigated expected future performance of the AICDs under i) gas breakthrough from horizontal direction and ii) gas coning from overlaying gas cap with the calibrated parameters and a multi-segment well capability prepared in commercial reservoir simulators. The data review of pilot wells showed existence of induced pressure drop through the AICD nozzles as evidenced by time-lapse PLTs in one of the wells though the pressure drop seems lower than designed one. The inflow/pressure matching against PLT data suggested sets of values for the parameters in the AICD model although the parameter related with gas/water contribution has higher uncertainty because of no gas/water breakthrough in the subject well. A hypothetical horizontal gas breakthrough scenario with a refined single well reservoir simulation suggests that AICD installation makes the well life longer by couple of months even with 6-10 times larger drawdown than base case. Subsequently, the full-field simulations (for gas coning scenarios) in planning of future wells demonstrated equalized inflow distribution along the horizontal drain by delaying the gas coning but it highly depends on depth/distance from the gas cap. Selective regulation of the gas production was not anticipated with the parameters used under reasonable range of the gas-oil ratio in the subject field. It should be noted that nozzle leakage scenario was also a reasonable hypothesis to reproduce the observed PLT data, but it led to massive inflow from these nozzles causing acceleration of gas coning even worse than no AICD case. It should be noted that limited number of works has been presented focusing on actual long-term AICD performance and its integration for future forecasting. Therefore, this work is intended to serve as a reference to provide diagnostic results of such an advanced lower completion device with remaining challenges and potential risk-mitigation plans.