Reservoir Characterization and Modeling of the Glorieta and the Clearfork Formations, Monahans Field, Permian Basin, Texas

Monahans Field of the Permian Basin in West Texas is a complex carbonate reservoir due to the lateral heterogeneity caused by facies changes throughout the Lower Guadalupian Glorieta Formation and the Upper Leonardian Upper Clearfork Formation. A facies model, porosity model, and a siltstone model were generated in Petrel to better characterize the Monahans Field reservoir. Interbedded impermeable siltstone beds in Monahans Field partition the reservoir making oil production and water injection difficult. The facies model indicates that during deposition, a tectonically uplifted area (island) influenced sedimentation and also shows that the Upper Clearfork Formation is mainly subtidal facies and the Glorieta Formation consists mainly of tidal flat facies. The porosity model shows the greatest porosity to be in the diagenetically altered supratidal deposits. The siltstone model identified siltstone barriers that prograded across the platform when sea level was low. 4th-order sequences occur within the larger 3rd-order sequence. The models identified multiple flow units in Monahans Field. Preferential injection of water within the reservoir compartments, horizontal drilling, and hydraulic fracture stimulation may all provide mechanisms to more efficiently sweep the remaining reserves from the reservoir.