吉木萨尔凹陷芦草沟组层理页岩渗吸置换规律  

Imbibition Replacement Rules of Bedding Shale in Lucaogou Formation in Jimsar Sag,Junggar Basin

作　　者：田刚 祝健 蒲平凡 夏安 董卓 吴嘉仪 王飞[2] TIAN Gang;ZHU Jian;PU Pingfan;XIA An;DONG Zhuo;WU Jiayi;WANG Fei(Research Institute of Engineering Technology,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang 834000,China;School of Petroleum Engineering,China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国石油新疆油田分公司工程技术研究院(监理公司),新疆克拉玛依834000 [2]中国石油大学(北京)石油工程学院,北京102249

出　　处：《新疆石油地质》2024年第3期346-354,共9页Xinjiang Petroleum Geology

基　　金：国家自然科学基金(51974332)。

摘　　要：为研究吉木萨尔凹陷二叠系芦草沟组层理页岩储集层压裂后渗吸期间原油的动用规律,采用岩心渗吸置换实验结合核磁共振技术,定量描述不同孔隙内原油的相对含量。采用吉木萨尔地区上甜点的岩心开展渗吸实验,研究重力作用、各向异性、重力分异和水力压裂裂缝宽度对渗吸置换影响,并进行定量表征。结果表明:层理页岩自发渗吸的过程中,重力作用在渗吸中起到了动力作用,顶部渗吸的采收率高于水平渗吸;各向异性对层理页岩渗吸的影响较大,压裂液进入平行于层理的渗吸置换量大,达到渗吸平衡的时间较垂直于层理短,平行于层理渗吸采收率高于垂直于层理;重力分异是指在岩心底部渗吸时,渗吸置换出原油而停留在岩层表面形成油膜,阻止压裂液继续进入基质,导致渗吸效果变差,底部渗吸采收率与顶部渗吸采收率相差14.12%;模拟水力压裂裂缝宽度为2 mm的条件下发生渗吸置换的液量有限,导致模拟裂缝内含水饱和度下降快,限制了渗吸的进一步进行。因此,裂缝的缝高方向应尽量穿过平行层理,增大裂缝宽度,增加裂缝改造体积。In order to investigate the production of crude oil during the imbibition period after hydraulic fracturing of the bedding shale in the Permian Lucaogou formation in the Jimsar sag,core imbibition replacement experiments and nuclear magnetic resonance(NMR)technology were combined to quantitatively describe the relative content of crude oil in different pores.Cores from the upper sweet spot in Jimsar sag were used in the experiments to identify the impacts of gravity,anisotropy,gravity differentiation,and hydraulic fracture width on imbibition replacement and quantitative characterization was conducted.The results show that during the spontaneous imbibition process of bedding shale,gravity plays a dynamic role,and the recovery of top imbibition is higher than that of horizontal imbibition.Anisotropy has a significant impact on imbibition of bedding shale,with a larger imbibition displacement of fracturing fluid into parallel bedding and a shorter period to reach imbibition equilibrium compared to vertical bedding,and imbibition recovery of parallel bedding is higher than that of vertical bedding.Gravity differentiation means that during the imbibition at the bottom of the core,the crude oil is displaced by imbibition and stays on the surface of the core to form an oil film,which prevents the fracturing fluid from further entering the matrix,deteriorating the imbibition effect.The recovery of imbibition at the bottom differs by 14.12%from the recovery of imbibition at the top.Given a simulated hydraulic fracture width of 2 mm,the volume of liquid involved in imbibition replacement is limited,causing a rapid decline of water saturation within the simulated fracture,which restricts further imbibition.Therefore,the fracture height should be oriented to pass through parallel bedding,so that the fracture width and the stimulated reservoir volume can be increased.

关 键 词：吉木萨尔凹陷 芦草沟组 页岩 渗吸置换 层理缝 储集层改造 水力压裂裂缝 

分 类 号：TE122.23[石油与天然气工程—油气勘探]