A Novel Assisted Gas–Oil Countercurrent EOR Technique for Attic Oil in Fault-Block Reservoirs

Kang Ma, Hanqiao Jiang, Junjian Li, Rongda Zhang, Kangqi Shen and Yu Zhou
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Kang Ma: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
Hanqiao Jiang: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
Junjian Li: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
Rongda Zhang: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
Kangqi Shen: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
Yu Zhou: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China

Energies, 2020, vol. 13, issue 2, 1-15

Abstract: As the mature oil fields have stepped into the high water cut stage, the remaining oil is considered as potential reserves, especially the attic oil in the inclined fault-block reservoirs. A novel assisted gas–oil countercurrent technique utilizing gas oil countercurrent (GOC) and water flooding assistance (WFA) is proposed in this study to enhance the remaining oil recovery in sealed fault-block reservoirs. WFA is applied in our model to accelerate the countercurrent process and inhibit the gas channeling during the production process. Four comparative experiments are conducted to illustrate enhanced oil recovery (EOR) mechanisms and compare the production efficiency of assisted GOC under different assistance conditions. The results show that WFA has different functions at different stages of the development process. In the gas injection process, WFA forces the injected gas to migrate upward and shortens the shut-in time by approximately 50% and the production efficiency improves accordingly. Compared with the basic GOC process, the attic oil swept area is extended 60% at the same shut-in time condition and secondary gas cap forms under the influence of WFA. At the production stage, the WFA and secondary gas cap expansion form the bi-directional flooding. The bi-directional flooding also displaces the bypassed oil and replaced attic oil located below the production well, which cannot be swept by the gas cap expansion. WFA inhibits the gas channeling effectively and increases the sweep factor by 26.14% in the production stage. The oil production increases nearly nine times compared with the basic GOC production process. The proposed technique is significant for the development of attic oil in the mature oil field at the high water cut stage.

Keywords: gas–oil countercurrent; attic oil; secondary gas cap; double displacement process; fault block reservoirs (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
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