页岩气井压后返排制度优化

发布时间：2018-03-04 02:09

本文选题：页岩气　切入点：强制闭合　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,由于常规油气资源越来越紧缺,页岩气作为一种潜能巨大且清洁高效的非常规能源成为了世人们关注的重点。为了获得具有经济效益的产气速度和总产气量,需要对页岩气藏压裂改造,以增大地层渗透率,达到工业化产气规模。压裂时,返排工作是尤为重要的一个过程,这直接影响到压裂液对地层的伤害程度及裂缝的导流能力,继而影响压裂效果。本文对压裂液的返排开展了深入且系统的研究工作,重点研究了返排过程中压裂液的二维滤失模型、支撑剂的回流模型、裂缝强制闭合的拟三维模型,并对返排率的影响因素进行了分析与计算。研究成果可以用于引导页岩气井的压后返排工作。本论文的研究工作体现在以下几点:首先,依据渗流力学理论对裂缝闭合过程中压裂液向地层的渗透过程进行了详尽而又系统的分析,并根据相关原理建立了滤失模型。该模型可以较为准确的预测裂缝闭合时间,因此可以为更换油嘴的时机选择提供合理可信的科学参考。其次,详尽的探讨了支撑剂在裂缝中回流的时间与位移,建立了支撑剂的回流模型,分析了井口停泵压力、支撑剂颗粒粒径、支撑剂密度以及压裂液的破胶粘度对放喷油嘴和临界流速的影响,并计算得出了避免支撑剂发生回流效应的最大放喷油嘴。再次,综合考虑压裂液返排与压后产能,鉴于压裂液返排过程中的复杂情况,建立了与其相对应的强制闭合情况下的渗流模型,并对其进行数值差分求解。之后,对返排率的影响因素进行了分析与计算。最后,根据前面的研究成果,得出了进行返排控制方案设计的原则和方法,并编制了裂缝强制闭合过程中压裂液返排计算软件,利用页岩气井压后返排优化软件计算临界油嘴大小与其更换时间,从而更加科学化的指导现场的返排工作。
[Abstract]:In recent years, because of the increasing shortage of conventional oil and gas resources, shale gas, as a potential and clean and efficient unconventional energy, has become the focus of attention in the world. In order to increase formation permeability and achieve industrial gas production scale, fracturing of shale gas reservoir is necessary. During fracturing, backflow is a very important process, which directly affects the damage degree of fracturing fluid to formation and the conductivity of fracture. Then the effect of fracturing is affected. In this paper, the deep and systematic research work is carried out on the backflow of fracturing fluid, focusing on the 2-D filtration model of fracturing fluid, the reflux model of proppant, and the pseudo-3D model of forced closure of fracture. The research results can be used to guide the backflow of shale gas wells. The research works in this paper are as follows: first, According to the theory of percolation mechanics, the permeation process of fracturing fluid to formation during fracture closure is analyzed in detail and systematically, and a filtration model is established according to the relevant principles. The model can accurately predict the fracture closure time. Therefore, it can provide a reasonable and reliable scientific reference for selecting the time of replacing oil nozzle. Secondly, the time and displacement of reflux of proppant in fracture are discussed in detail, the reflux model of proppant is established, and the pressure of stopping pump at wellhead is analyzed. The effects of particle size of proppant, density of proppant and viscosity of fracturing fluid on the nozzle and critical flow rate are calculated, and the maximum discharge nozzle to avoid the backflow effect of proppant is calculated. Considering the backflow and post-pressure productivity of fracturing fluid, considering the complicated situation in the process of fracturing fluid reflux, the seepage model corresponding to the forced closure of fracturing fluid is established, and the numerical difference solution is carried out. Finally, according to the previous research results, the design principles and methods of the control scheme for back drainage are obtained, and the calculation software for back discharge of fracturing fluid in the process of forced closure of fracture is developed. The critical nozzle size and its replacement time are calculated by using the software of back discharge optimization after shale gas well pressure, so as to guide the work of backflow in the field more scientifically.
【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】：TE377

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