砂岩油藏水平井压裂返排理论研究

发布时间：2018-02-05 19:49

本文关键词： 水力压裂压裂液返排强制闭合返排临界流量模型水电模拟实验　出处：《长江大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着石油行业的发展,常规油藏的开发大多已经进入了开发末期,为了石油工业的持续性发展,勘探开发和科学研究的重点逐渐转移到了低渗油藏(渗透率小于10mD)的开采上。对于低渗透砂岩油藏,一般采用水平井水力压裂进行开采。压裂液的返排是水力压裂施工的重要组成部分,其对压裂效果有着重要的影响。针对现场压裂返排施工中的压裂液返排临界流量的确定问题,本文以砂岩油藏为研究对象,基于压裂液在砂岩油藏中的渗流机理,建立了压裂液滤失方程;结合建立的压裂液滤失方程,利用物质平衡原理和流体力学相关理论建立砂岩油藏水力压裂裂缝闭合模型,分析了放喷油嘴尺寸和裂缝闭合时间的关系;借助动力学和流体力学的相关理论推导了临界返排流量模型,结合吉林油田相关基础数据验证该模型的准确性。通过对砂岩油藏临界返排理论的研究,本文得到了以下认识。(1)基于裂缝闭合模型分析了裂缝闭合时间的影响因素,得出放喷油嘴直径越大,裂缝闭合时间越短。(2)通过裂缝闭合前的临界返排流量模型,计算支撑剂的横向位移,将此位移和裂缝半长对比,分析得出裂缝闭合前支撑剂不会回流。(3)基于吉林油田某区块基础数据验证了临界返排流量模型的准确性,得出实际施工中应该采用一个略大于理论临界返排流量的返排量进行施工。(4)基于临界返排流量模型分析了支撑剂粒径和压裂液粘度对压裂临界返排流量的影响,在裂缝闭合条件下,其他条件相同时,临界返排流量随支撑剂粒径的增大而增大,随着返排液粘度的增加而增加。(5)利用水电模拟实验,考虑了在不同的裂缝条数、裂缝间距和裂缝长度条件下,借助渗流场图,分析了返排过程中的裂缝内返排量的干扰情况,得出其他条件相同时,随着裂缝条数的增加,单条裂缝上的返排流量会略微减少,但是返排总量增加,同时每条裂缝上的返排流量是相同的。通过对于砂岩油藏水平井压裂返排理论进行研究,为现场压裂返排施工提供了一定的理论指导。
[Abstract]:With the development of petroleum industry, most of the conventional reservoir development has entered the end of development, for the sustainable development of the petroleum industry. The emphasis of exploration and development and scientific research has gradually shifted to the production of low permeability reservoirs (permeability less than 10mD.) for low permeability sandstone reservoirs. Hydraulic fracturing is generally used in horizontal wells, and the back discharge of fracturing fluid is an important part of hydraulic fracturing operation. It has an important impact on the fracturing effect. In order to determine the critical flow rate of the fracturing fluid in the field fracturing backflow operation, this paper takes sandstone reservoir as the research object. Based on the percolation mechanism of fracturing fluid in sandstone reservoir, the filtration equation of fracturing fluid is established. Combined with the established fluid filtration equation, the fracture closure model of hydraulic fracturing in sandstone reservoir is established by using the principle of material balance and the relevant theory of fluid mechanics, and the relationship between the size of the nozzle and the time of fracture closure is analyzed. Based on the relevant theories of dynamics and fluid mechanics, the critical flow back flow model is deduced, and the accuracy of the model is verified by combining with the relevant basic data of Jilin Oilfield. Based on the fracture closure model, the influence factors of fracture closure time are analyzed, and the bigger the diameter of the nozzle is obtained. The shorter the crack closure time is, the more the lateral displacement of proppant is calculated through the critical flow back flow model before fracture closure, and the displacement is compared with the half length of fracture. The analysis shows that the proppant will not reflow before the fracture closure.) based on the basic data of a certain block in Jilin Oilfield, the accuracy of the critical flow back flow model is verified. It is concluded that a backflow volume slightly larger than the theoretical critical backflow rate should be used in actual construction. Based on the critical flow back flow model, the effects of the particle size of proppant and the viscosity of fracturing fluid on the critical flow back flow of fracturing are analyzed. Under the condition of crack closure and other conditions, the critical flow rate increases with the increase of the particle size of proppant, and increases with the increase of the viscosity of the fluid. Considering the different fracture number, crack spacing and fracture length, with the aid of seepage field diagram, the disturbance of internal displacement in the process of back discharge is analyzed, and other conditions are obtained. With the increase of the number of cracks, the flow back flow on a single crack will be slightly reduced, but the total amount of back discharge will increase. At the same time, the flow rate on each fracture is the same. Through the research on the theory of fracturing and drainage in horizontal well of sandstone reservoir, this paper provides some theoretical guidance for the field fracturing backflow operation.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.1

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