摘要
为深入认识页岩油储集层孔隙结构特征和渗流特性,以吉木萨尔凹陷二叠系芦草沟组页岩油储集层为研究对象,利用微CT扫描技术和聚焦离子束电镜扫描技术,构建三维数字岩心模型,获得孔喉结构参数,并基于该结构特征建立多孔介质微尺度渗流物模装置,研究流体在微通道内的低速流动规律,同时利用该物模装置测量不同压裂液的流动特性和伤害程度。研究结果表明:页岩油储集层的孔隙结构具有非均质性强、孔隙连通性差等特点,储集空间主要为纳米级孔隙,储集层的流动能力取决于微米级孔隙的数量和大小;流体在微观尺度下的低速流动为非达西流,有启动压力梯度,且随着驱动压差增加,边界流体才能不断流出;胍胶破胶液的残渣和大分子结构的凝聚物易对储集层孔隙产生堵塞,建议页岩油储集层压裂时减少胍胶的用量,提高滑溜水比例,减少储集层伤害。
To make clear pore structures and flow characteristics of shale oil reservoir, taking the shale oil reservoir of Permian Lucaogou formation in Jimsar sag as the study object, the paper uses Micro-CT and FIB-SEM scanning technologies to establish a 3D digital core model and to obtain parameters of pore throat structures. Based on which a microscale physical simulation instrument for porous media is established to study the low-velocity flow laws of fluids in micro paths. Meanwhile, the physical simulation model is used to measure flow characteristics and damage degree of different fracturing fluids. The study results show that the pore structure of the shale oil reservoir is featured with strong heterogeneity and poor connectivity, the main reservoir space is dominated by nanoscale pores and the fluidity depends on the amount and sizes of the micron-scale pores;the low-velocity flow of fluid at micro scale is non-darcy flow with a threshold pressure gradient, and with the increase of driving differential pressure, the fluid in more pores will continue to flow;the residue of guar gel breaker and the aggregates of macromolecular structure are easy to block pores. It is suggested that less guar gel and more slick water should be used to reduce reservoir damage during shale oil reservoir fracturing.
作者
李佳琦
陈蓓蓓
孔明炜
吕蓓
孟雪
LI Jiaqi;CHEN Beibei;KONG Mingwei;LYU Bei;MENG Xue(Research Institute of Engineering Technology,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang 834000,China)
出处
《新疆石油地质》
CAS
CSCD
北大核心
2019年第3期319-327,共9页
Xinjiang Petroleum Geology
基金
国家油气重大专项(2016ZX05046-004)