【作者】 高杰；

【导师】 侯冰；

【作者基本信息】 中国石油大学(北京) ， 油气井工程， 2018， 硕士

【摘要】 临兴-神府地区位于鄂尔多斯盆地东缘,区块在地质上具有煤系气多层叠置发育,各种非常规气藏在垂向上重置分布的特点。当硬脆性砂岩与塑性煤层组合开发时,层间地应力差、岩石力学性质、界面胶结性、井斜、方位、压裂施工参数等都对人工裂缝的穿层扩展产生较大影响,产层组压裂裂缝扩展规律存在认识不清的难点,给产层组储层改造方案的合理设计提出挑战。本文通过选取砂岩和煤岩露头进行纵向叠置组合,模拟产层组地层特征,开展了砂煤产层组室内真三轴穿层压裂物理模拟实验,研究了压裂选层、层间胶结强度、煤层厚度、压裂施工参数等对水力裂缝穿层扩展的影响,为定性表征层间胶结强度这一影响因素,深化开展了层状介质物理模拟实验。实验结果表明:1、水力裂缝在煤岩中起裂时,受煤岩节理和天然裂缝的影响,水力裂缝在扩展过程中,容易发生转向,使得裂缝形态复杂多样,不利于裂缝穿层;在砂岩层中起裂时,砂岩中水力裂缝形态简单,易形成水力主缝,穿透砂岩产层,沟通煤层。2、层间弱胶结能够能够有效控缝高,使得水力裂缝发生转向,沿界面扩展。3、煤层越厚越容易耗散水力能量,使得水力裂缝难以穿层扩展。4、胶液的造缝能力优于活性水,但其对储层伤害较重,压裂液类型的选取需根据现场压裂所需进行甄选。针对射孔参数对产层组水力裂缝穿层扩展的影响,结合岩石力学参数室内实验与测井资料,对目的区块储层的力学参数、地应力进行计算,并根据储层力学性质、地应力参数、施工参数等,基于3D网格算法,建立产层组水力裂缝起裂扩展模型,研究了射孔参数对水力裂缝穿层扩展的影响。模拟结果表明:1、在煤层中上部射孔有利于水力裂缝的扩展。2、随着射孔长度的增加,裂缝的有效改造面积减小。3、间接压裂能够实现水力裂缝的穿层扩展,有利于产层组的综合改造。基于上述物理模拟实验以及数值模拟结果,本文提出产层组压裂裂缝穿层扩展机制,为提高现场产层组压裂改造效果提供理论指导。更多还原

【Abstract】 Lin Xing-Shenfu area is located in the eastern margin of the Ordos Basin.The blocks are characterized by multi-layer superimposed development of the coal measure gas,and all kinds of unconventional gas reservoirs are vertically distributed.When the hard brittle sandstone and plastic coal were developed together,it is hard to predict hydraulic fracture morphology because of stress difference between layers,rock mechanical properties,interfacial bonding,hole deviation and azimuth,fracturing parameters and other factors.It is a challenge to design rational reservoir stimulation scheme.In this paper,the natural sandstone and coal outcrop rocks were mutually combined to carry out hydraulic fracturing simulation experiments with a true tri-axial pressure machine,and a study was conducted on the natural fracture,different stratum,interface bonding strength,thickness of coal seam,fracturing operation parameters which affected the expansion of the hydraulic fracture.In order to qualitatively characterize the influence factors of interlayer cementation strength,the further physical simulation experiment of layered media has been developed.The experiment result showed natural fracture and bedding in coal rock would change the propagation direction of hydraulic fracture and cause complex fracture morphology,which is bad for hydraulic fracture to propagate across the interface.However,when the target fractured formation was sandstone,the hydraulic fracture morphology was simple and easier to connect interlayers.When hydraulic fracture approached the weak bonding interface between layers,hydraulic fracture could turn to propagate along the interface.Thick coal seams can easily dissipate hydraulic energy,which makes hydraulic fractures difficult to penetrate formation.Although the gel had a better ability to generate fracture than the active water,the gel is damage to reservoir.So it is necessary to consider select the fracturing fluid on the basis of the field requirement.In order to study the effect of perforation parameters on hydraulic fracture,according to the rock mechanics parameters of indoor experiment and logging data,the paper calculated mechanical parameters and stress of reservoir which were used to establish 3D lattice method hydraulic fracture extension model.The model study the influence of perforation parameters on hydraulic crack propagation.The simulation results show that perforation in the upper part of the coal seam is conducive to the expansion of hydraulic fractures.With the increase of the perforation length,the effective reconstruction area of the crack is reduced.The indirect fracturing can realize hydraulic fracture through multilayer,which is beneficial to the comprehensive development of the layer group.On the basis of physical simulation experiments and numerical results,the paper put forward a mechanism for determining fracture propagation,especially in multi-layers combined with tight gas and coal bed gas.The study provided theoretical guidance for improving the fracturing effect in the field production.更多还原