Carbonate reservoirs are of strong heterogeneity. Their geological features and dynamic behaviors vary significantly for different types of carbonates. Characterizing the distribution of different types of carbonates and proposing different development strategies are critical for a successful development of carbonate reservoirs. This paper focuses on a super-giant carbonate reservoir with OOIP (Original Oil in Place) of more than 20 billion barrels. However, it has been naturally depleted over the past 40 years. Its reservoir pressure is approaching the bubble point pressure. Therefore, it is critical and urgent to propose optimized water flooding plan for this reservoir.
In this paper, the dataset includes seismic data, well logs, production history, dynamic surveillance data, et al. Firstly, three reservoir types are characterized as good, medium and poor reservoirs based on static and dynamic data. Then, the stacking patterns of different reservoir types are concluded and their distributions are determined, which provide us the foundation to propose customized water flooding plan. Finally, the water flooding performances of different stacking patterns are analyzed and full-field development strategies are proposed based on fine-scale geological modeling and numerical simulation.
Results indicate that stacking pattern has intimate relationship with facies map. For example, the distribution of stacking pattern A, in which good reservoir accounts for the majority, is consistent with the distribution of favorable grainstone shore facies, indicating very good reservoir quality that resulted in higher production rate, longer stable production period, and slow decline. In addition, different offtakes, well patterns, pressure maintenance, well types of different reservoir stacking pattern are determined based on the simulation results and distribution of different stacking patterns. The EUR is increased by more than 20% compared with natural depletion.
This paper offers a reference case of grouping different types of reservoirs and proposing customized water flooding plan, which help engineers and geologists to better develop other similar fields.