致密储层人工裂缝导流能力及影响因素实验研究

发布时间：2018-09-11 14:02

【摘要】：致密储层开发一般需进行储层压裂改造,压后主裂缝和次级裂缝的导流能力是增产效果的关键,所以对裂缝导流能力研究具有重要意义。本文主要以长庆HQ青海ZP致密储层为研究区,在分析了体积压裂剪切滑移裂缝形成机理的基础上,采用室内实验的方法对主支撑裂缝和次级裂缝导流能力及其影响因素进行了较为系统的实验研究,并结合实验数据对研究区块进行了产能分析,验证了实验方法的可行性,主要取得了以下成果和认识:1.结合前人研究对长庆HQ区块储层裂缝分布及裂缝特征进行了描述。其裂缝系统特征为“切深小、开度小、间距小”,的小—微裂缝系统,裂缝发育的优势方位为北80°~90°西,南60°~70°东。2.采用力学方法分析了剪切裂缝形成及滑移机理,影响裂缝面滑移的主要影响因素有缝长、弹性模量和应力差,并计算研究区储层当次级缝长8~10m时,最大滑移量可达6~8mm;采用分形维数的方法进行了裂缝粗糙面定量计算,实现了裂缝面的模拟。3.采用API标准对不同人工裂缝状态下导流能力进行了研究。导流能力与闭合压力关系遵循指数递减规律;粗糙面错位不铺置支撑剂导流能力比裂缝整合形态下高一个数量级;陶粒和石英砂长期导流能力都遵循初期递减迅速,后期下降平缓的特点。4.进行了长庆HQ区块储层和青海ZP区块常规岩心人工裂缝导流实验,模拟了体积压裂次级裂缝在各种状态下导流能力与闭合应力之间关系及其影响因素。得出:闭合人工裂缝对储层渗流有一定的改善,但裂缝无弹性恢复,受压闭合后恢复率很低;多层铺砂下导流能力与缝宽成正比,单层局部铺砂条件下导流能力与铺砂浓度间符合单“单驼峰”状关系曲线;裂缝错位后导流能力与粗糙面及岩性有关,粗糙面分形维数越大,错位导流能力越高,岩石硬度越大,错位后导流能力受压力影响越小;压裂液和液相存在均会对气体导流能力造成一定的伤害。5.研究区长庆HQ储层压裂改造无因次导流能力短期在1.2~1.5之间,长期在0.2~0.25之间。采用Mcguire-Sikora型半对数增产图版和无因次支撑剂数法计算倍数分别为1.9~3.8倍和1.65~3.66倍,验证了导流能力实验的可行性,其实验数据对现场有一定的指导作用。
[Abstract]:The development of tight reservoirs usually needs to be reformed by fracturing. The conductivity of main fractures and secondary fractures after compression is the key to increase production, so it is of great significance to study the conductivity of fractures. In this paper, the formation mechanism of volume fracturing shear slip fractures is analyzed based on the study area of ZP tight reservoir in Changqing HQ Qinghai Province. A systematic experimental study on the conductivity of main and secondary cracks and its influencing factors is carried out by using the method of laboratory experiments. The productivity analysis of the study block is carried out in combination with experimental data, and the feasibility of the experimental method is verified. Mainly achieved the following results and understanding of 1. 1. Combined with previous studies, the fracture distribution and fracture characteristics of Changqing HQ block reservoir are described. The fracture system is characterized by "small cutting depth, small opening and small spacing". The dominant orientation of fracture development is north 80 掳90 掳west, south 60 掳70 掳east .2. The mechanism of shear fracture formation and slip is analyzed by means of mechanical method. The main factors influencing the slip of fracture surface are fracture length, modulus of elasticity and stress difference. The reservoir in the study area is calculated when the secondary fracture length is 8 ~ 10 m. The maximum slip value can reach 6 ~ 8 mm, and the fractal dimension method is used to calculate the crack rough surface quantitatively, and the simulation of fracture surface is realized. 3. The diversion capacity under different artificial cracks was studied by API standard. The relationship between diversion capacity and closed pressure follows the law of exponential decline; the conductivity of misaligned proppant on rough surface is one order of magnitude higher than that under the form of fracture integration; the long-term conductivity of ceramsite and quartz sand both follow the initial decline rapidly. Features of gentle decline in late stage. The artificial fracture diversion experiments of conventional core in Changqing HQ block and Qinghai ZP block were carried out, and the relationship between conductivity and closing stress of secondary fracture in volume fracturing and its influencing factors were simulated. It is concluded that the closed artificial fracture can improve the percolation of reservoir to some extent, but the fracture has no elastic recovery, and the recovery rate is very low after closed under the pressure, and the conductivity under the multi-layer sand spreading is proportional to the width of the fracture. Under the condition of single layer local sand laying, the relation curve between diversion capacity and sand spreading concentration accords with the single "single hump" curve, the conductivity after fracture dislocation is related to rough surface and lithology, the larger the fractal dimension of rough surface is, the higher the misplaced diversion capacity is. The greater the rock hardness, the less the influence of pressure on the flow conductivity after dislocation, and the existence of fracturing fluid and liquid phase will cause certain damage to the gas conductivity. The dimensionless conductivity of HQ reservoir fracturing in Changqing study area is between 1. 2 ~ 1. 5 and 0. 22 ~ 0. 25 in short term. The multiples calculated by using Mcguire-Sikora type semi-logarithmic pattern plate and dimensionless proppant number method are 1.9 ~ 3.8 times and 1.65 ~ 3.66 times, respectively. The feasibility of flow conductivity experiment is verified, and the experimental data can guide the field to a certain extent.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE357.1

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