考虑启动压力梯度和应力敏感的页岩油井产能分析

The Effect of Threshold Pressure Gradient and Stress Sensitivity on Shale Oil Reservoir Productivity

刘礼军 姚军 孙海 白玉湖 徐兵祥 陈岭

LIU Lijun YAO Jun SUN Hai BAI Yuhu XU Bingxiang CHEN Ling

中国石油大学(华东)油气渗流研究中心, 青岛 266580; 中海油研究总院, 北京 100028

Research Centre of Multiphase Flow in Porous Media, China University of Petroleum(East China), Qingdao, Shandong, 266580, China; CNOOC Research Institute, Beijing, 100028, China

为研究启动压力梯度及应力敏感效应对页岩油井产能的影响规律，基于油气水三相渗流模型，建立了考虑启动压力梯度和应力敏感效应的页岩油渗流数学模型，给出了数值求解方法，并编制了页岩油藏数值模拟器。利用页岩油藏数值模拟器分析了启动压力梯度和应力敏感效应对多级压裂页岩油水平井产能的影响规律。页岩油藏数值模拟器退化计算结果与Eclipse软件的计算结果基本吻合，验证了模拟器的准确性。数值模拟结果表明：当启动压力梯度达到0.5 MPa/m时，生产10 000 d的累计产油量为无启动压力梯度时的24.7%；当应力敏感系数由0.1 MPa-1升至0.5 MPa-1时，生产10 000 d时储层近井地带的渗透率降低近一个数量级，累计产油量为无应力敏感效应时的36.2%；同时考虑启动压力梯度和应力敏感效应时，累计产油量更低。研究结果表明，启动压力梯度和应力敏感效应对页岩油井的产能均有较大的抑制作用，如不考虑启动压力梯度和应力敏感效应会过高估计页岩油井的产能，页岩油藏数值模拟器可为页岩油藏的开发提供指导。

In order to research on the effect of threshold pressure gradient and stress sensitivity on shale oil well productivity,a mathematical model that takes into consideration of the threshold pressure gradient and stress sensitivity for shale oil seepage was developed on the basis of oil-gas-water three-phase seepage model.A numerical solution method was offered and numerical simulator of shale oil reservoir was compiled.Patterns and mathematical rules for threshold pressure gradient and stress sensitivity on horizontal well productivity of multistage fracturing shale oil reservoir were analyzed by using a shale oil reservoir numerical simulator.The calculation results on the degradation of the simulator were basically identical with Eclipse software calculation results,which validated the correctness of the simulator.The numerical simulation results showed that the cumulative oil production rate for 10 000 days was 24.7% of that where there was no threshold pressure gradient when threshold pressure gradient reached 0.5 MPa/m. When the stress sensitivity coefficient rose from 0.1 MPa-1 to 0.5 MPa-1,the reservoir permeability near borehole zones dropped approximately one order of magnitude and the cumulative oil production rate was 36.2% that of no stress sensitivity effect after 10 000 days’ production.Moreover,the cumulative oil production was lower while simultaneously considering threshold pressure gradient and stress sensitivity effect.The results showed that the threshold pressure gradient and stress sensitivity effect both greatly inhibited shale oil productivity and the shale oil productivity might be overestimated without consideration of the threshold pressure gradient and stress sensitivity effect.Therefore a shale oil reservoir numerical simulator can provide guidance for the development of shale oil reservoirs.

国家自然科学"页岩油气多尺度渗流特征与开采理论"（编号：51490654）、中海石油（中国）有限公司综合科研项目"海外页岩油气产能评价技术与方法研究"（编号：YXKY-2016-ZY-03）、中央高校基本科研业务费专项资金"页岩油储层多尺度数字岩心构建及流动机制研究"（编号：17CX02008A）及国家科技重大专项"基于数字岩心的页岩气藏微观流动模拟及产能评价方法研究"（编号：2016ZX05061-14）联合资助。

https://doi.org/10.11911/syztjs.201705015