Study on mechanism of spontaneous imbibition and pressurized imbibition in shale oil reservoirs
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ORIGINAL PAPER- PRODUCTION ENGINEERING
Study on mechanism of spontaneous imbibition and pressurized imbibition in shale oil reservoirs Lanlan Yao1,2 · Zhengming Yang1,2 · Haibo Li2 · Bo Cai3 · Chunming He3 · Debin Xia1,2 Received: 13 October 2020 / Accepted: 21 November 2020 © The Author(s) 2020
Abstract Imbibition is one of the important methods of oil recovery in shale oil reservoirs. At present, more in-depth studies have been carried out on the fracture system and matrix system, and there are few studies on the effect of energy enhancement on imbibition in shale oil reservoirs. Therefore, based on the study of pressurized imbibition and spontaneous imbibition of shale oil reservoirs in Qianjiang Sag, Jianghan Basin, nuclear magnetic resonance technology was used to quantitatively characterize the production degree of shale and pore recovery contribution under different imbibition modes, and analyze the imbibition mechanism of shale oil reservoirs under the condition of energy enhancement. The experimental results showed that with the increase in shale permeability, the recovery ratio of pressurized imbibition also increased. The rate of pressurized imbibition was higher than spontaneous imbibition, and pressurized imbibition can increase the recovery ratio of fractured shale. Spontaneous imbibition can improve the ultimate recovery ratio of matrix shale. Pressurized imbibition can increase the recovery contribution of macroporous and mesoporous. Keywords Shale oil · Nuclear magnetic resonance · Spontaneous imbibition · Pressurized imbibition
Introduction The inter-salt shale oil reservoirs in the Jianghan Basin are thin in thickness, with well-developed upper and lower salt layers, complicated reservoir lithology, high soluble salt content, poor technical effects of conventional measures, and short stable production periods, affecting the effective production of shale reservoirs. Volume fracturing and water injection huff and puff are the ways to effectively supplement formation energy. After volume reformation of shale oil reservoirs, a complex fracture network system is formed in a large area near the wellbore, the oil–water contact area is greatly increased, and the imbibition is sharp. Strengthening, which provides favorable conditions * Debin Xia [email protected] 1
College of Engineering Science, University of Chinese Academy of Sciences, Beijing 101400, China
2
Institute of Percolation and Fluid Mechanics, China Petroleum Exploration and Development Research Institute, Langfang 065007, China
3
Fracture Acidification Center of China Petroleum Exploration and Development Research Institute, Langfang 065007, China
for shale oil to improve recovery and profitable development. In recent years, imbibition oil production has been highly valued by oilfield development technicians due to its simple injection technology and lower operating costs and better oilincreasing effects. A large number of research results have been reported (Li et al. 2017, 2019; Zhou et al. 2017; Wang et al.
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