The feasibility of asynchronous injection alternating production for multistage fractured horizontal wells in a tight oil reservoir
YU Haiyang, YANG Zhonglin, MA Tian, LEI Zhengdong, CHENG Shiqing, CHEN Hao
1 State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum-Beijing, Beijing 102249, China 2 Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
In order to solve the problem of water injection and low recovery rate of traditional EOR methods in tight oil reservoirs, we first investigated asynchronous injection alternating production (AIAP) for a multistage fractured horizontal well. AIAP is a new method in which zigzag hydraulic fractures are arranged between two parallel horizontal wells or in a pattern of the foregoing units. With help of volume fracturing of a multi-stage horizontal well, this method can not only evenly maintain the tight oil reservoir pressure, but also can develop crude oil through dialysis replacement. In this paper, the sensitivity of the L tight oil reservoir in the Changqing Oilfield is analyzed by numerical simulation. The optimal parameters are as follows: the spacing of fracture is 80 m, the length of the fracture is 160 m, the injection volume is 3000 m3, the injection rate is 300 m/d, the stewing time is 35 d and the cumulative increase in oil production is 1449 t. The results show that the traditional water injection alternating production can only increase the cumulative oil recovery in the short term and its recovery rate is not significantly improved; direct water flooding between fractures achieves a high yield quickly but it does not last long; AIAP has a longer production period and achieves a 6.0 % higher recovery rate than that of natural depletion. The development method of the AIAP can overcome the problem of water injection and of low sweep efficiency in tight oil reservoirs, which currently inhibits the feasible exploitation of tight oil.
asynchronous injection alternating production tight oil reservoir multistage fractured well imbibition development mode
于海洋，杨中林，马恬，雷征东，程时清，陈浩. 致密油藏多级压裂井异井异步注采可行性研究[J]. 石油科学通报, 2018, 3(1): 32-44. YU Haiyang, YANG Zhonglin, MA Tian, LEI Zhengdong, CHENG Shiqing, CHEN Hao. The feasibility of asynchronous injection alternating production for multistage fractured horizontal wells in a tight oil reservoir. Petroleum Science Bulletin, 2018, 3(1): 32-44.