Design and Results of a Shallow, Light Oilfield-Wide Application of CO2 Huff 'n' Puff Process

Abstract

SPE Member Abstract A C02 huff and puff process has shown to be economic at current oil prices in a shallow oil field in the Pappalachian Basin. Design and field results are reviewed. The project shows excellent results for a tight, light oil reservoir at immiscible conditions. The results of 200 treatments (340 to 4130 Mscf (9630 to 116,900 m3 each) over a four year period are investigated. The results of a second treatment on wells that had been treated over three years prior are also shown. Mechanical failures have teen published as attributing to partial failure of other huff and puff projects; thus, prescreening and small treatments have been used to minimize this problem. The mechanics of the treatment will be reviewed with an emphasis on simplicity and safety. The production response from the treatments have been from one to four years. The response developed from field tests of different sizes will be reviewed and correlated with reservoir parameters. The complex relationships among these factors leads to the need for modeling that will not only predict the ultimate recovery efficiency but also the response curve for specific wells for project optimization. The optimum treatment or combination of treatments for a well is not where the 002 utilization efficiency for the total treatment is maximized but where the net revenue is maximized. With the high cash turnover rate, a project can be designed to minimize the working capital exposed and maximize the project cash flow. The primary project area covers over 400 wells in the same reservoir with varying reservoir and production parameters. Initial treatments have been set up to test all the wells. Information from these treatments are helping to supply data for modeling and multiple linear regression analysis. Introduction CO2 huff and puff or cyclic CO2 injection has recently undergone a transition from the initial use for heavy oil 2 stemming from the steam huff and puff to light oil near miscible. This case study relates only to immiscible and light oil project. Laboratory investigations for this project have shown the immiscible more favorable to the near-miscible or miscible case.' Research grants, oil pricing incentives, tax incentive and special C02 availability supported many of the early C02 huff and puff field tests. Most of the results of puff field tests. Most of the results of these tests on a straight up economic basis were not profitable. Discouraged by the results, activity in this process waned. However, as with any new method, a learning process is necessary to define the best process is necessary to define the best application. C02 huff and puff treatments are in the early stages of development and will continue to be refined. This field case study reviews a project that is currently economic and is one of primary contributors of revenue for a small primary contributors of revenue for a small independent oil company. The task has been to identify areas of improvement and continually upgrade the technology for this project area. project area. P. 925