Enhanced Gas Recovery, Challenges Shown at the Example of three Gas Fields

Abstract

CO 2 -EOR has been used successfully to recover incremental oil after water flooding. In the USA, more than 260,000 bbl/d are produced by using this EOR method. CO 2 Enhanced Gas Recovery (CO 2 -EGR) has also been proposed, however, only small scale projects have been performed until know.In this paper, the challenges of CO 2 -EGR are addressed at the example of three fields.The Hoeflein Field (Austria) contains gas condensate with a maximum liquid drop out of 4 %. The simulation results show that CO 2 injection can recover incremental condensate. However, owing to the shape of the reservoir, CO 2 will break through early. Hence, gas recovery will be reduced compared with conventional gas production.The second field which was investigated is located in Pakistan. This field is an elongated field. The production wells are distributed over the full length of the field. CO 2 injection can increase recovery (0.2 % maximum) only, if the surface facilities are able to handle high CO 2 contents in the produced gas (more than 50 %).The Schoenkirchen Uebertief Field (Austria) is a deep (5700 mSS), elongated structure. The production wells are located at one end of the structure. To recover incremental gas, good well placement and gas injection later in the lifetime of the field is required, about 1.5 % additional gas compared with depletion drive can be expected.The example cases of CO 2 -EGR show that even for almost ideal reservoir structures (elongated with wells at one end and injection at the other end), limited potential for CO 2 -EGR exists. To increase gas production compared with depletion, a good well placement and knowledge of the structure accordingly is required, the production facilities have to be able to handle high CO 2 contents and CO 2 injection should commence later in the life-time of the field to avoid trapping of hydrocarbon gas in unswept areas at high pressures.

Current Progress and Development Trend of Gas Injection to Enhance Gas Recovery in Gas Reservoirs

“…The numerical simulation study results showed that the best development effect was achieved when the injection well was located on the side of the structure. The recovery could be increased to about 1.6%, but the output resulted in about 32% CO 2 [15].…”

“…However, these technologies still have limitations; so, the gas injection method has been developed. By injecting CO 2 , N 2 and their mixtures, recovery efficiency in gas reservoirs can be effectively enhanced, and the long-term stable production of gas fields can be supported [15]. Specifically, CO 2 injection can not only help to enhance gas recovery but also allow for the capture and storage of CO 2 to deal with the current greenhouse effect.…”

“…Specifically, CO 2 injection can not only help to enhance gas recovery but also allow for the capture and storage of CO 2 to deal with the current greenhouse effect. Field tests have shown that CO 2 storage in depleted gas reservoirs is effective and can enhance gas recovery [15][16][17][18][19][20][21][22]. At the same time, N 2 plays an outstanding role in enhanced gas recovery [8,23], due to its abundant resources, sufficient gas source and low cost.…”

Worldwide Status of CCUS Technologies and Their Development and Challenges in China

“…Its efficiency is highly dependent on reservoir type, temperature and pressure conditions, heterogeneity, production strategy, and so on [55][56][57][58][59][60]. For some CO 2 -EGR projects, the gas recovered can reach 10%, while other projects have seen less or no enhancement [61][62][63]. The rapid breakthrough of CO 2 in a production well, resulting in a high concentration of CO 2 , restricts the production of pure natural gas [64].…”

A Techno-Economic Analysis of Coupling Enhanced Hydrocarbon Recovery and CO2 Storage in Gas Condensate Reservoirs

“…The literature tends to focus either on maximising incremental production or on CO 2 storage capacity. However, simultaneous enhanced gas recovery (EGR), enhanced condensate recovery (ECR) and CO 2 storage may be feasible (Oldenburg, 2003;Oldenburg et al, 2004;Ramharack et al, 2010;Clemens et al, 2010). Following the European Trading Scheme, commercialising simultaneous EGR, EGR and CO 2 storage for all gas reservoirs is now being considered.…”