Reservoir Simulation and Evaluation of the Upper Jurassic Smackover Microbial Carbonate and Grainstone-Packstone Reservoirs in Little Cedar Creek Field, Conecuh County, Alabama



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This thesis presents an integrated study of mature carbonate oil reservoirs (Upper Jurassic Smackover Formation) undergoing gas injection in the Little Cedar Creek Field located in Conecuh County, Alabama. This field produces from two reservoirs, one grainstone-packstone and the other microbial boundstone. The main objective of the study is to determine a potential redevelopment plan to increase oil recovery from the field by targeting the remaining oil saturation. This study involves using numerical reservoir simulation to identify the remaining recoverable oil distribution throughout the field. The 3-D geological model, which served as input for the dynamic reservoir simulation performed in this study, was provided by another author.

Reservoir simulation indicates that potentially high recoverable oil saturation remains in the unitized area in the southwestern part of the field. Also, the simulation studies show that the following redevelopment plan investigated in this study has the potential to recover up to 5 MMSTB of oil by January 2017: converting 3 wells to inject water into the microbial boundstone reservoir, converting one more well to inject recycled gas into the grainstone-packstone reservoir performing work-over operations on 18 wells, sidetracking a plugged and abandoned well 10560, already completed in the grainstone-packstone reservoir, to another location in the same reservoir, and drilling 7 new wells in the grainstone-packstone reservoir and 5 new wells in the microbial boundstone reservoir. All these 12 new wells should be drilled on 160-acre unit size according to the field rules. Moreover, reservoir simulation showed that drilling additional 6 wells on a unit size less than160-acre (infill drilling) could result in additional recovery of up to 0.7 MMSTB of oil from the grainstone-packstone reservoir. No cost-benefit analysis studies have been performed in this thesis. Thus, the redevelopment plan investigated cannot be recommended for implementation until such analyses have been conducted.