Compositional Simulation of CO 2 Huff-n-Puff Processes in Tight Oil Reservoirs with Complex Fractures Based on EDFM Technology Considering the Threshold Pressure Gradient

Jiayu Zheng, Tianhao Jiang, Xiaoxia Chen (), Zhengpan Cui, Shan Jiang, Fangxin Song, Zhigang Wen and Lei Wang
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Jiayu Zheng: Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan 430100, China
Tianhao Jiang: The Tenth Oil Production Plant, PetroChina Changqing Oilfield Company, Qingyang 745100, China
Xiaoxia Chen: Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan 430100, China
Zhengpan Cui: The Tenth Oil Production Plant, PetroChina Changqing Oilfield Company, Qingyang 745100, China
Shan Jiang: Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan 430100, China
Fangxin Song: The Tenth Oil Production Plant, PetroChina Changqing Oilfield Company, Qingyang 745100, China
Zhigang Wen: Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan 430100, China
Lei Wang: School of Earth Resources, China University of Geosciences, Wuhan 430074, China

Energies, 2023, vol. 16, issue 22, 1-19

Abstract: Although tight oil reservoirs have abundant resources, their recovery efficiency is generally low. In recent years, CO 2 injection huff-n-puff has become an effective method for improving oil recovery on the basis of depleted production of volume-fracturing horizontal wells in tight oil reservoirs. In order to study the effects of CO 2 huff-n-puff (CO 2 -HnP) on production, a compositional numerical simulation study of CO 2 huff-n-puff (CO 2 -HnP) was conducted in tight oil reservoirs with complex fractures. Embedded discrete fracture model technology was used in the simulations to characterize complex fractures. The process of CO 2 huff-n-puff (CO 2 -HnP) was simulated, which consists of CO 2 injection, CO 2 soaking, and CO 2 production. Taking into account the threshold pressure gradient and stress sensitivity in the model, we conducted a series of numerical simulations with different production condition parameters, such as bottom-hole pressure, CO 2 injection rate, injection time, soaking time, and the number of cycles of CO 2 huff-n-puff (CO 2 -HnP). Then, the effects of these sensitivity parameters on the cumulative oil production (COP) were studied. The results indicate that the threshold pressure gradient and rock stress sensitivity factors greatly affect the pressure field of tight reservoirs and the cumulative oil production (COP) of multistage-fracturing horizontal wells. The production parameters all have an impact on the COP. The injection rate and circulation number both have optimal values, and the injection time and soak time tend to have less significant effects on the growth of cumulative oil production over time. According to the numerical simulation, the optimal solution is 5 × 10 4 m 3 /day injection rate per cycle, 25 days of injection time, 35 days of soaking time, three cycles, and production for 5 years, which can obtain the optimal cumulative oil production.

Keywords: CO 2 huff-n-puff; compositional simulation; tight oil reservoir; EDFM (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: 2023
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