海上低渗透油藏非线性渗流机理表征与数值模拟  

Characterization and numerical simulation of nonlinear flow mechanism in offshore low-permeability reservoir

作　　者：张利军 赵林 谭先红 徐世乾 卢聪[2] ZHANG Lijun;ZHAO Lin;TAN Xianhong;XU Shiqian;LU Cong(CNOOC Research Institute Ltd.,Beijing 100028,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028 [2]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500

出　　处：《中国海上油气》2024年第6期68-79,共12页China Offshore Oil and Gas

基　　金：中国海洋石油有限公司“十四五”重大科技项目“海上低渗及潜山油气田有效开发技术”课题“海上低渗透油藏压裂开发地质工程一体化技术研究(编号:KJGG2022-0701)”部分研究成果。

摘　　要：与陆上相比,海上低渗油藏开发井距更大,低压力梯度区范围更广,基质非达西渗流现象更加显著;另一方面,海上压裂规模相对较小,裂缝应力敏感现象对产能影响更大。建立了考虑残余边界层效应的基质非达西渗流模型及考虑支撑剂参数的裂缝应力敏感模型,并将其应用至可精细刻画压裂裂缝形态的嵌入式离散裂缝模型中,研究非线性渗流对低渗压裂油藏流场及开发指标的影响。结果表明,基质非达西渗流对衰竭开采油井的高峰年产油量和累产油量均有显著降低作用,其中无因次初始边界层厚度较残余边界层厚度的影响更为突出;裂缝应力敏感对高峰年产油量的影响比对累产油量的影响更为显著。支撑剂铺砂浓度对累产油量影响幅度较大,支撑剂直径对累产油量影响幅度较小。非线性渗流在压裂井水驱开发中使波及面积减小和见水时间延缓。不考虑非线性渗流时,见水后的含水率上升更快。本文方法为海上低渗透油藏产能预测和开发优化提供了高效工具。Compared to onshore low-permeability reservoirs,offshore low-permeability reservoirs have larger well spacing,which results in a wider range of low-pressure gradient areas and thus more significant non-Darcy flow phenomena in matrix.For another,the fracturing scales of offshore low-permeability reservoirs are relatively smaller,and fracture stress sensitivity has a greater impact on production capacity.This paper establishes a non-Darcy flow model for matrix which considers the effect of residual boundary layers and a fracture stress sensitivity model considering proppant parameters.The models are then applied to the embedded discrete fracture model that can finely depict the morphology of fracturing fractures.The study investigates the impact of nonlinear flow on the flow field and development indicators of low-permeability fractured oil reservoirs.The results show that non-Darcy flow in matrix significantly reduces the peak annual oil production and cumulative oil production of oil wells under depletion development.The effect of dimensionless initial boundary layer thickness is more prominent than that of residual boundary layer thickness.Fracture stress sensitivity has a more significant effect on the peak annual oil production than on the cumulative oil production.The proppant sand concentration has a great impact on the cumulative oil production,while the proppant diameter has a small impact on the cumulative oil production.Nonlinear flow has a significant effect in reducing the swept area and delaying the water breakthrough time in the water flooding development of fractured wells.If nonlinear flow is not considered,the water cut rises faster after water breakthrough.The method in this paper provides an efficient tool for productivity prediction and development optimization of offshore low-permeability reservoirs.

关 键 词：海上低渗透油藏 非达西渗流 裂缝应力敏感 三维嵌入离散裂缝 生产动态 

分 类 号：TE349[石油与天然气工程—油气田开发工程]