APPLICATION OF WATER FLOODING AND WATER ALTERNATIVE GAS (WAG) FLOODING TECHNIQUES IN A CARBONATE RESERVOIR: INTEGRATION OF RESERVOIR AND PRODUCTION SYSTEMS FOR DECISION MAKING

The objective of this work is to evaluate the impact of integration between reservoir and production systems on the decision making for field production development. The authors demonstrated, in a benchmark case, the applicability of water injection (WI) and water alternating gas injection (WAG) techniques for various production systems by proposing a novel methodology. This work explores three optimization approaches: (1) based on the complete model considering integrated systems, (2) for production system based solely on reservoir model and followed by the integration and optimization of production system, and (3) derived from (2) considering subsequent integration and optimization for complete model. In the implementation step, production strategies are applied in a reference model. This work compares production strategies, reservoir performance forecast, and the net present value (NPV) objective function. The integrated models yeild similar objective-function values by utilizing a production system that does not alter the bottom-hole conditions significantly, thereby replicating the behavior observed in the non-integrated model. The results of non-integrated reservoir optimizations should be used with caution for decision-making purposes, as the subsequent integration may cause the changes to the the production forecasts. The differences in reservoir behaviors can be attributed to the changes in the dynamics (movement) of fluids from the reservoir to the wells and the type of recovery mechanism affected by well positioning. The implementation of production strategies in the reference model resulted in lower values of NPV (20% for WI and 60% for WAG) than those obtained in the optimization step. The findings demand caution in the application of closed-loop procedures to prevent biased or inaccurate assessments of decisions made solely based on reservoir models. The application of this work can be considered an import study for Carbon Capture Utilization and Storage (CCUS), as well as for energy transition based on WAG optimization.