页岩气流动特性的数值模拟

发布时间：2018-11-15 07:14

【摘要】：随着人类社会对能源需求量的持续增长,常规油气的资源量逐年减少,页岩气等非常规油气资源的开发利用变得尤为重要。由于页岩气在赋存方式及运移方式方面的特殊性,研究页岩气的流动特性,对页岩气的开发开采具有重要意义。本文采用数值模拟方法,开发了页岩气流动过程的计算程序,研究了页岩气的流动特性。对于页岩基质中的流动,研究了定压力出口边界条件下基质中的压力分布及流量变化规律,获得了解吸附作用对基质中压力及流量的影响；通过对各参数模量的定义,对比了渗透率压缩系数、孔隙率压缩系数以及甲烷动力粘度压缩系数对流量的影响。对于页岩整体的开发过程,利用“基质——天然裂缝—水力裂缝”三重介质流动模型,建立了页岩气流动数学模型,数值求解了耦合三重介质的页岩气流动过程的数学方程,分析了不同井底流压、水力裂缝长度、水力裂缝数目以及Langmuir体积等因素对气体产量的影响规律。研究结果表明,解吸附作用的存在会维持储层的压力,提高页岩气的产能；孔隙率压缩系数越大,初始产气量越大,产气速率下降的也越快,低孔隙率压缩系数储层的稳产能力强于高孔隙率压缩系数储层。出口压力对页岩气会造成很大的影响,出口压力越低,页岩气产量下降速度越快；水力裂缝越长,流量越大,但随着水力裂缝长度的增加,流量增长速度下降；水力裂缝数目越多,总流量越大,但随着裂缝条数的增加,增产效果下降；在前期生产过程,Langmuir体积对产量的影响效果可以忽略不计,生产一定时间之后,Langmuir体积越高,储层的稳产能力越强。
[Abstract]:With the continuous growth of energy demand in human society, the amount of conventional oil and gas resources decreases year by year, and the exploitation and utilization of unconventional oil and gas resources such as shale gas become particularly important. Because of the particularity of shale gas in storage mode and migration mode, it is of great significance to study the flow characteristics of shale gas for the development and exploitation of shale gas. In this paper, a numerical simulation program for shale gas flow process is developed, and the flow characteristics of shale gas are studied. For the flow in shale matrix, the pressure distribution and flow rate variation in the matrix under the condition of constant pressure outlet boundary are studied, and the influence of adsorption on the pressure and flow rate in the matrix is understood. The effects of permeability compression coefficient porosity compression coefficient and methane dynamic viscosity compression coefficient on the flow rate are compared by defining the modulus of each parameter. For the whole development process of shale, the mathematical model of shale gas flow is established by using the "matrix natural fissure hydraulic fracture" triple medium flow model, and the mathematical equation of shale gas flow process in coupled triplet medium is solved numerically. The effects of different bottom hole pressure, hydraulic fracture length, number of hydraulic fractures and Langmuir volume on gas production are analyzed. The results show that the existence of desorption can maintain the reservoir pressure and increase the productivity of shale gas. The larger the porosity compression coefficient is, the greater the initial gas production is, and the faster the gas production rate decreases, the more stable the production capacity of the low porosity compression coefficient reservoir is than that of the high porosity compression coefficient reservoir. The lower the export pressure, the faster the shale gas production decline, the longer the hydraulic fracture, the larger the flow rate, but the lower the hydraulic crack length, the lower the flow rate. The more the number of hydraulic cracks, the larger the total discharge, but with the increase of the number of cracks, the effect of increasing production decreased. In the early production process, the effect of Langmuir volume on production can be ignored. After a certain time of production, the higher the volume of Langmuir, the stronger the stable production capacity of reservoir.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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