Abstract

Bacab field is located offshore in the Bay of Campeche approximately 100 km north of Ciudad del Carmen, Campeche, Mexico. The main producing reservoir in the field is the BKS reservoir, a Cretaceous age naturally-fractured reservoir with aquifer support. Most producers were completed near the formation top to avoid water encroachment through channeling or coning, however several producers had early water breakthrough, which impacts well performance and shortens well life. Pressure transient tests and production data were analyzed to identify various flow regimes present in Bacab wells. It was done to explain the early water breakthrough, determine appropriate operating conditions to control water production in wells near faulted areas, and better design future field development strategy. Using static reservoir characterization and dynamic reservoir simulation, we iterated and validated these elements to match the history of the wells.

Numerical simulation results and pressure transient analysis (PTA) from a BKS well completed around the fault indicated the fault is conductive, which explains that the well's rapid water production was caused by water channeling through the fault. On the other hand, PTA results from several other wells suggested a constant pressure boundary, validated by the fact that the reservoir pressure drop is insignificant throughout the entire production history (approximately 22 years). This confirmed the primary reservoir drive mechanism in BKS is a strong aquifer drive. The strong energy could be beneficial to oil production or could be risky in channeling water to producers. Therefore, it is crucial to characterize the aquifer and reservoir vertical connectivity to enhance the field development plan.

Through integrated dynamic characterization, we successfully identified and validated several important reservoir features impacting well performance. These include reservoir dynamic properties in the vicinity of wells and faults, degree of reservoir connectivity, flow boundaries and the presence of a strong aquifer. With these inputs, we were able to successfully model the wells and reservoir and optimize BKS future exploitation designs. Furthermore, we established guidance of operating wells near conductive faults to maximize the oil recovery. An enhanced BKS field development plan based on this study is being implemented that includes well interventions and sidetracking. Accompanying reservoir management best practices in mitigating water coning and channeling while optimizing well production rates, preliminary results are promising.

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