致密砂岩气藏压裂缝耦合损害机理研究

发布时间：2018-06-16 16:50

本文选题：致密气藏 + 压裂损害　；参考：《西南石油大学》2017年硕士论文

【摘要】：压裂改造是一种有效开发致密砂岩气藏的手段,由于致密砂岩自身的低孔、低渗、孔隙结构复杂等特征,储层改造过程中不可避免的会发生地层敏感性、水锁、裂缝导流二次损害等,严重阻碍致密气藏的气体产出。致密砂岩中的损害包括基块以及裂缝两部分,本文基于室内实验、数值模拟和理论研究分析了致密砂岩裂缝-基块协同损害机理及其评价方法,主要得到以下研究成果:(1)根据室内实验以及地质特征分析,研究了致密砂岩储层的岩性、物性、裂缝发育等特征,并对储层压裂过程中基块、裂缝中存在的潜在损害因素进行了损害机理分析,实验显示致密砂岩存在较强的水锁损害,裂缝对于裂缝-基块系统水锁损害率有较大影响。不同体系压裂液胍胶含量不同,对裂缝导流能力损害影响较大;(2)通过数值模拟研究了人工裂缝与天然缝沟通下的水锁损害机理,致密砂岩微裂缝与压裂缝的沟通增强了气体的流通能力,但也导致液相沿着相互沟通的天然缝进入储层深部造成更为严重的水锁损害,损害程度主要取决于天然缝密度、宽度、产状及井底压力等;(3)压裂缝内的损害是多因素共同作用的结果,包括支撑剂层的压缩嵌入、压裂液破胶返排率低造成的残渣堵塞、滤饼等因素,基于Hertz弹性变形以及Kozeny-Carman方程等建立了综合考虑多因素损害的解析模型并给出了算例,影响人工裂缝二次损害的因素主要有:闭合压力、支撑剂直径、弹性模量、压裂液残渣含量、铺砂浓度等;(4)建立了同时考虑基块内应力敏感、水锁损害以及裂缝内压缩嵌入、聚合物残渣损害的评价模型,实现对裂缝以及基块协同损害的数值模拟,评价的指标为产气量,基于某小型压裂施工压力曲线图给出了算例,并进行了水锁损害率、临界侵入深度、支撑剂直径残渣含量等因素对产气量的敏感性分析,结果表明,致密砂岩压裂缝内的二次损害对于产气量的影响大于基块水锁损害及应力敏感性对产气量的影响。
[Abstract]:Fracturing is an effective way to develop tight sandstone gas reservoir. Due to the characteristics of low porosity, low permeability and complex pore structure, the formation sensitivity and water lock will inevitably occur in the process of reservoir reconstruction. The secondary damage of fracture diversion seriously hinders the gas production of tight gas reservoir. The damage in tight sandstone consists of two parts: base block and fracture. Based on laboratory experiment, numerical simulation and theoretical study, the mechanism and evaluation method of synergistic damage of tight sandstone fracture and base block are analyzed in this paper. According to the laboratory experiments and the analysis of geological characteristics, the lithology, physical properties, fracture development and other characteristics of tight sandstone reservoirs are studied, and the base blocks during reservoir fracturing are also studied. The damage mechanism of the potential damage factors in the fracture is analyzed. The experimental results show that the tight sandstone has strong water lock damage and the fracture has a great influence on the water lock damage rate of the fission-base block system. The content of guanidine glue in different fracturing fluid is different, which has a great influence on the damage of fracture conductivity. (2) the mechanism of water lock damage under the communication between artificial fracture and natural fracture is studied by numerical simulation. The communication between compact sandstone microfractures and compressive fractures enhances the gas flow ability, but it also results in more serious water lock damage caused by the liquid phase entering the deep reservoir along the natural fractures communicated with each other. The damage degree mainly depends on the density and width of the natural fractures. The damage in fracturing is the result of multiple factors, including the compression and embedding of proppant layer, the residue blockage caused by the low rate of gel breaking back of fracturing fluid, the filter cake and so on. Based on Hertz elastic deformation and Kozeny-Carman equation, an analytical model considering multi-factor damage is established and an example is given. The main factors affecting the secondary damage of artificial crack are: closing pressure, proppant diameter, elastic modulus, etc. The evaluation model of fracturing fluid residue content, sand spreading concentration and so on is established, which considers the stress sensitivity of base block, water lock damage, compression embedded in fracture and polymer residue damage simultaneously, and realizes the numerical simulation of fracture and cooperative damage of base block. An example is given based on the pressure curve of a small scale fracturing operation, and the sensitivity of water lock damage rate, critical invasion depth and residual content of proppant diameter to gas production is analyzed. The effect of secondary damage on gas production in tight sandstone fracture is greater than that of block water lock damage and stress sensitivity.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE258.1

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