岩体渗流—损伤耦合及其水力压裂机理数值试验研究

发布时间：2018-01-24 21:51

本文关键词： 岩体水力压裂非均匀性数值模拟裂纹扩展　出处：《东北大学》2015年博士论文　论文类型：学位论文

【摘要】：水力压裂是一种广泛应用于石油天然气开采及地应力测量的技术,其中油气开采的主要原理为通过地面高压泵组将压裂液以超过地层吸收能力的排量注入井中,从而在井底附近的地层产生裂缝,后注入带有支撑剂的携砂液,形成具有一定几何尺寸和导流能力的填砂裂缝,以达到油气开采增产增注的目的。相对比常规油气资源来说,非常规油气资源具有成藏地质条件复杂,储层非均质性强,渗透率低的特点,其开发难度更大,技术要求更高。随着常规油气资源的逐渐开采殆尽,储量丰富且分布广泛的非常规油气资源在全球能源结构中开始占领主要地位,因此在人类工程活动范围越来越广及常规油气地下有效动用储量下限不断降低的今天,非常规油气开发条件下的岩石水力压裂机理问题是众多学者探索的目标,它不仅是热点和难点问题,并且是亟需解决的问题。自上世纪90年代以来,计算机模拟方法日趋成熟,并且它相对于传统物理试验方法具有成本低、周期短、效率高的优点,可对同一模型进行不同荷载的多次模拟,所以对于岩石水力压裂机理问题的研究,通过数值方法,辅以物理试验,才是最终解决这一难题的有效手段。本文以数值模拟为研究手段,以页岩岩体为研究对象,突破传统断裂力学方法基于连续均匀介质且只能研究均匀单一岩层水力压裂问题的限制,以当前石油领域工程中面临的一些具体问题为研究背景,从宏观角度深入认识岩体水力压裂机理问题,以揭示非常规油气储层内的非均质页岩岩体在复杂条件下的水力裂纹扩展规律为研究目标,对岩体水力压裂问题展开研究,研究结果有望为现场施工及设计提供借鉴及指导,具有较高的理论意义及实际应用价值。主要工作包括以下几个方面： 1.应用RFPA2D2.0-Flow数值模拟软件,分别建立层理页岩、地应力变化页岩岩体以及定向射孔页岩岩体二维数值模型,通过岩体渗流流量、声发射、模型起裂压力、破裂压力等关键指标,研究复杂条件下的页岩岩体基本渗流-损伤特性及水力压裂机理,全面分析层理参数、地应力差值及定向射孔对水力压裂的影响规律。 2.针对裂隙页岩岩体内复杂缝网的形成及储层体积改造,对天然裂隙页岩岩体的水力压裂全过程进行数值模拟研究,全面分析单裂隙页岩岩体及多裂隙页岩岩体的井下压裂裂纹开裂扩展规律及与天然裂隙相交模式。 3.以分段压裂为研究背景,提出双阶压裂的概念,以水平井内垂直于井筒的两条平行压裂裂缝为研究对象,研究分段压裂完成后,在最大主地应力与预期裂缝方向垂直的前提下,双缝长度、间隔及暂堵材料性质对裂纹开裂扩展的影响规律及复杂缝网的形成规律。
[Abstract]:Hydraulic fracturing is a widely used measure of stress and mining oil and natural gas technology, the main principle of the exploitation of oil and gas through the ground pressure pump group of fracturing fluid to over strata absorption capacity of displacement injection well, resulting in the formation of cracks near the bottom, after injection with proppant carrying fluid, formation sand filling cracks with certain geometric dimensions and the conductivity of the oil and gas production in order to achieve the purpose of production and injection increasing.
Compared with the conventional oil and gas resources, unconventional oil and gas resources with the accumulation of complex geological conditions, strong reservoir heterogeneity, the characteristics of low permeability, its development is more difficult, higher technical requirements. With the gradual depletion of conventional oil and gas resources, unconventional oil and gas resources is abundant and widely distributed to occupy the main position in the global energy structure, so in the increasingly wide range of human engineering activities and conventional oil and gas reserves continue to lower limit of underground effective today, hydraulic fracturing mechanism of oil and gas development under the conditions of unconventional many scholars to explore the objectives, it is not only a hot and difficult problem, and it is urgent to to solve the problem.
Since the last century since 90s, the computer simulation method has become more mature, and it is compared with the traditional physical test method has the advantages of low cost, short cycle, high efficiency, the simulation can be carried out in different loads on the same model, so the problem of rock hydraulic fracturing mechanism studied by numerical methods, supplemented by physical test, it is effective the final way to solve this problem.
In this paper, by numerical simulation, using shale rock as research object, break through the traditional fracture mechanics method of continuous homogeneous medium and only homogeneous single rock hydraulic fracturing problem based on the restricted to some specific problems currently in the field of petroleum engineering as the research background, from a macro perspective, in-depth understanding of the rock hydraulic fracturing mechanism, in order to reveal unconventional oil and gas reservoirs in the heterogeneous shale rock hydraulic crack under complex conditions propagation as the research object, research on rock hydraulic fracturing, the results are expected for the construction and design field to provide reference and guidance, and practical application has a high theoretical significance value. The main work includes the following aspects:
1. application of numerical simulation software RFPA2D2.0-Flow, established bedding shale, shale rock and numerical changes of stress oriented perforating shale mass flow through the two-dimensional model, acoustic emission, seepage model, fracturing pressure, fracture pressure and other key indicators, to study the complex conditions of shale rock basic seepage damage characteristics and hydraulic fracturing mechanism, comprehensive analysis bedding parameters, effect of stress on hydraulic fracturing and perforation.
2. for the fractured shale rock complex fracture formation and reservoir volume network transformation, numerical simulation is conducted on the whole process of natural fracture shale rock hydraulic fracturing, a comprehensive analysis of downhole fracturing crack and rock fractured shale fractured shale rock crack propagation and intersect with the natural fracture mode.
In the 3. subsection fracturing as the research background, puts forward the concept of double step horizontal wells in fracturing, perpendicular to the shaft of the two parallel fracture as the research object, research fracturing, in the premise of maximum principal stress and the expected direction of crack under the vertical, double slit length, interval and temporary plugging material properties on crack influence of extended and complex fracture network formation rule.

【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE357.11

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