Cyclic Miscible Stimulation Doubles Estimated Ultimate Recovery from Mature Shale Wells

Abstract Application of Enhanced Oil Recovery methods in shale has met limited commercial success to date. The target for improved recovery is huge with typical primary recovery factors in the range of 5% - 20% for most of the shale plays in the US. Cyclic Miscible Stimulation (CMS) is a "Huff and Puff" miscible process which overcomes the two critical challenges faced by Operators through dramatically reduced surface facility costs and dramatically reduced solvent requirements using NGL which is a much more effective solvent than alternative methods. CMS applies Natural Gas Liquids (NGL) in a cyclic process to mobilize residual oil in shale wells. NGL is a superior solvent to other solvents employed to date in the industry because of their lower minimum miscibility pressure. NGL is injected into wells as a liquid, allowing the use of simple low pressure, low rate surface pumping equipment compared to very high pressure, high rate gas injection compressors required for cyclic gas Huff and Puff. Model results backed up by a series of field trials demonstrate that the reservoir physics are robust. Injected NGL effectively mobilizes oil in mature shale wells. History matched models indicate that cyclic injection of NGL over a number of years will result in a doubling or more of EUR for most shale reservoirs. NGL is a valuable commodity, so the CMS process employs a novel surface facility process flow to capture reproduced NGL and recycle it to make up the majority of the injectant used over the life of a CMS project. The surface facility used for processing produced fluids from the project is standard oilfield equipment configured in a novel process flow that allows the recapture of the majority of the solvent produced from the wells on the "Puff" or production cycle, returning it to the reservoir on the "Huff" or injection cycle. The combination of higher reservoir efficiency with NGL, low-cost facilities, and recycle of solvent allows CMS to deliver better economics than processes using alternative injectants and makes CMS projects competitive with new wells for scarce capital. CMS has the potential to more than double EUR from existing shale wells. The application of CMS provides huge upside to Operators facing abandonment of mature wells, a dwindling inventory of drilling locations, shrinking proved reserves, and shrinking economic margins on their leases. CMS boosts energy reserves with a fraction of the carbon footprint of alternative sources, greatly enhances the outlook for US energy independence, and delivers tremendous incremental value from the use of relatively low value NGL. Capturing the benefits from CMS requires access to proprietary methods and facility designs which are covered under a range of US patents.