页岩水平井应力—应变场分析及数值模拟

发布时间：2018-03-10 17:01

本文选题：页岩水平井　切入点：扩展有限元　出处：《西安石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：采用水平井对页岩储层开发时井壁失稳现象频发,严重影响了钻井周期,增加了钻井成本,而失稳的根本原因是钻井过程中井眼应力的重新分布。因此,对于页岩气井壁的应力场的研究是解决井壁失稳的关键。本文以某页岩气区块为研究对象进行了以下内容研究:(1)综合分析工区的地质资料、测井资料以及现场钻井数据,对工区储层特征进行描述。结果表明:工区储层岩石硬度大、可钻性低,地质构造相对复杂;目的层五峰-龙马溪组地层裂缝发育,且多为张性裂缝;页岩气层渗透率、孔隙度低,是典型低孔低渗储层。(2)开展室内岩石力学实验和测井解释,获取工区储层岩石参数和地应力剖面并分析地应力分布规律。结果表明:目的层岩石力学参数具有明显的各向异性;工区地应力差较大,区块构造运动剧烈,造成页岩井壁失稳的主导原因为应力垮塌。(3)基于扩展有限元理论利用ABAQUS软件对井壁围岩的裂缝扩展过程进行模拟,分析影响裂缝扩展的因素。结果表明:裂缝的起裂、扩展、走向以及裂缝长度和宽度受水平地应力差、钻井液性能、孔隙压力等因素影响较为明显。(4)针对工区的井壁失稳问题,在分析井壁围岩应力状态的基础上,建立相应的直井段和水平井段应力几何分析模型,利用ABAQUS有限元软件对工区钻井情况进行模拟,得出井壁应力应变分布规律;分析了井斜角、方位角、裂缝产状以及地应力等因素与坍塌压力的关系,制定针对工区稳定钻进的有效措施。研究表明:工区水平井段沿最小地应力方向钻进,坍塌压力最低;宜选取高粘度油基钻井液和采用结构简单、尺寸尽量小的钻具组合。
[Abstract]:When horizontal wells are used to develop shale reservoirs, the phenomenon of wellbore instability occurs frequently, which seriously affects the drilling cycle and increases drilling cost. The fundamental cause of instability is the redistribution of borehole stress during drilling. The research on stress field of shale gas wellbore is the key to solve the wellbore instability. In this paper, a shale gas block is studied as follows: 1) Comprehensive analysis of geological data, logging data and field drilling data. The results show that the rock hardness, low drillability, relatively complicated geological structure, the formation fractures in Wufeng Longmaxi formation, the permeability of shale gas reservoir, the formation fractures of Wufeng Longmaxi formation, the target layer, the permeability of shale gas reservoir, the formation fracture of the target layer, the formation fracture of the Longmaxi formation, the permeability of shale gas reservoir, Low porosity is a typical low porosity and low permeability reservoir. The rock parameters and stress profile of reservoir are obtained and the distribution of in-situ stress is analyzed. The results show that the rock mechanics parameters of the target layer have obvious anisotropy, the difference of ground stress is great, and the tectonic movement of the block is violent. The main cause of shale wall instability is stress collapse. 3) based on the extended finite element theory, the fracture propagation process of wall rock is simulated by ABAQUS software, and the factors influencing fracture propagation are analyzed. Strike and fracture length and width are affected by horizontal stress difference, drilling fluid performance, pore pressure and other factors. The stress geometric analysis model of vertical well and horizontal well is established, the drilling condition in working area is simulated by ABAQUS finite element software, the distribution law of wellbore stress and strain is obtained, the inclined angle, azimuth angle, azimuth angle of shaft wall are analyzed, According to the relationship between fracture occurrence and in-situ stress and collapse pressure, the effective measures for steady drilling in the working area are established. The results show that the horizontal well section in the working area is drilling along the direction of minimum in-situ stress, and the collapse pressure is the lowest; High viscosity oil-based drilling fluid and drilling tool combination with simple structure and as small size as possible should be selected.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE243

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