Reservoir Simulation of Primary and Enhanced Oil Recovery by Huff and Puff Gas Injection, and COStorage in la Luna Shale of Colombia

La Luna Shale in Colombia has significant oil and gas potential in the Middle Magdalena Valley andCatatumbo Basins that can be developed with the use of hydraulically fractured horizontal wells. Thispotential, however, has not been fully evaluated. Thus, this paper concentrates on estimating La Luna'sprimary and enhanced oil recovery, as well as the potential for COstorage with the use of reservoirsimulation. Simulation of enhanced oil recovery is conducted in this study using CH4 and COas injected gasesduring huff and puff (huff 'n' puff) operations. Simultaneously, the study simulates the viability of usingLa Luna Shale as a safe place for storing COwith negligible possibilities of unwanted leaks. The selectionof La Luna Shale for this purpose stems from the observation of geologic containment in La Luna. Geologic containment is a concept developed by our research group at the University of Calgary. Ourstudy concludes that geologic containment occurs in La Luna Shale, where natural gas, condensate and oilare upside down or in an inverted position in the structure. The paper demonstrates that if the hydrocarbonsremain in the same position where they were generated, then the possibilities that the injected gases willleak beyond the volume that is hydraulically fractured are nil. Simulation results reveal that primary recovery from La Luna Shale for the investigated areas rangebetween 23 to 25%. These recoveries are much larger than those reported for the Eagle Ford Shale ofTexas, which range between 5 and 10%. Higher quality of La Luna shale is associated with these significantrecoveries, which are supported by production data from La Luna and Eagle Ford shales. Simulation resultsshow that these recoveries can be improved by huff 'n' puff gas COinjection. The simulation further shows that during successive cycles of huff 'n' puff with CO, the volume of COretained in La Luna is progressively larger. Once huff 'n' puff reaches its economic limit, COcan beinjected continuously until reaching a maximum pressure equal to the initial reservoir pressure. COinjectedis thus stored safely and permanently in La Luna Shale. The novelty of the paper is demonstrating that geologic containment exists in La Luna Shale in both theMiddle Magdalena Valley and Catatumbo basins of Colombia. Under these conditions, and given the quality of La Luna Shale, reservoir simulation shows that La Luna primary oil recoveries can be significant and canbe improved by huff 'n' puff COinjection. Furthermore, the advantage of using COis that it can be storedsafely and permanently with negligible possibilities of unwanted leaks. Thus, La Luna shale can contributewith two important segments of CCUS: (1) Utilization of COfor Enhanced Oil Recovery (EOR) and (2)Storage of COas shown in this paper. The segment associated with Capture of COcan be accomplishedfrom refineries and large industrial complexes. This, however, is beyond the purpose of the present study.