A New Method of Bidirectional Displacement to Enhance Oil Recovery in Fault-block Reservoirs at High Water Cut Stage

Fong, Kuo; Jiang, Haimei; Li, J.J.; Chang, You-Im; Zhao, Li; Yang, Huan; Yan, Qiushi

doi:10.3997/2214-4609.201700246

Cited by 1 publication

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“…Fault-block reservoirs are widely distributed in eastern China and the reservoir characteristics are generally expressed in terms of the large dip angle, small oil-bearing area, good sealing ability, and complex fault structure [1][2][3][4]. In order to ensure the fault sealing ability, the production well is generally drilled 50-80 m away from the top fault boundary [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…During the water flooding process, the gravity and viscous force also cause the water transport along the bottom of the structure and the bypassed oil forms along the top of the water flooded area [10][11][12]. The reservoir statistics show that the attic oil and the bypassed oil are the main types of remaining oil in the fault block reservoir [4]. The high drilling cost and complexity of drilling a horizontal well to recover the attic oil hinders the economic benefit [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

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

Jiang

et al. 2020

Energies

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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.

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