页岩气井产能评价及数值模拟研究

发布时间：2018-08-30 13:34

【摘要】：页岩气在双重介质中的流动是一个复杂的多尺度流动过程,运移产出机理特殊,对渗流过程的数学表征也更为复杂。目前国内外所建立的渗流模型对页岩气的渗流过程表征不够完善和准确,大多数两相流模型都没同时考虑气体滑脱效应和页岩气吸附对流体渗流规律的影响,这在很大程度上都降低了模型在描述流体渗流过程上的准确性。大量实验和理论研究也证实了,气体滑脱效应和页岩气吸附对储层中流体的运移过程有着重要影响。因此,建立考虑解吸、扩散、渗流和滑脱效应全过程的页岩气藏单井渗流数值模型,对指导单井产能影响因素分析和气藏数值模拟研究具有重要意义。本文通过大量文献调研,认识分析了页岩气的储层特征、赋存方式和运移产出机理,建立了页岩储层三维气—水两相渗流数学模型,并利用数值模拟方法求解建立了水平井开采页岩气的数值模型；利用商业数值模拟软件Eclipse2011对页岩气井的生产动态进行了模拟和分析,在此基础上研究了滑脱效应和吸附气对页岩气藏水平井产量的影响,并对影响页岩气井产量的参数进行了敏感性分析。通过以上研究工作,本文主要取得了如下几点研究成果： (1)通过对页岩气的储层特征、赋存方式和运移产出机理等方面的认识,基于数值模拟和多相流体渗流理论,建立了考虑解吸、扩散、渗流和气体滑脱效应的双重介质页岩储层三维气—水两相渗流数学模型,利用数值模拟方法得到了水平井开采页岩气的数值模型,并对数值模型进行了迭代编程求解； (2)在对数值模型进行编程求解的基础上,研究了滑脱效应对渗透率的影响,渗流过程中滑脱效应的强弱很大程度上取决于储层孔隙压力的大小,储层孔隙压力越小,滑脱效应越明显,页岩储层裂缝孔隙中存在明显的滑脱效应；并对天然裂缝渗透率、Langmui3压力常数Langmuir体积常数和水平井水平段长度等参数进行了敏感性分析； (3)利用商业数值模拟软件Eclipse2011建立了考虑滑脱效应和气体吸附—解吸的页岩气分段压裂水平井模型,并对气井的生产动态进行了模拟和分析；滑脱效应有利于页岩气水平井中后期产量的提高,页岩气井的产量是游离气运移和吸附气解吸共同作用的结果,在页岩气的开发生产过程中不能忽略滑脱效应和吸附气的影响； (4)在商业数值模拟软件Eclipse2011所建模型的基础上,对影响页岩气井产量的多种参数进行了敏感性分析；页岩储层的岩石压缩系数的变化对气井产气量的敏感性很弱；基质系统内气体的扩散、等温吸附规律和吸附气含量对气井中后期的产量影响较大；天然裂缝渗透率、压裂裂缝导流能力、裂缝间距和裂缝半长的变化对页岩气藏水平井的产气量影响很大,敏感性很强。
[Abstract]:The flow of shale gas in dual media is a complex multi-scale flow process with special mechanism of migration and production and more complicated mathematical characterization of the seepage process. The influence of shale gas adsorption on fluid percolation law greatly reduces the accuracy of the model in describing fluid percolation process. A large number of experimental and theoretical studies have also confirmed that gas slippage effect and shale gas adsorption have important influence on fluid migration process in reservoir. The numerical model of single well seepage in shale gas reservoir with the whole process of flow and slippage effect is of great significance to the analysis of influencing factors of single well productivity and numerical simulation of gas reservoir.
In this paper, the reservoir characteristics, occurrence mode, migration and production mechanism of shale gas are analyzed through a large number of literature research. A three-dimensional gas-water two-phase seepage mathematical model of shale gas reservoir is established, and a numerical model for horizontal well production of shale gas is established by numerical simulation method. The production performance of rock gas wells is simulated and analyzed. On this basis, the effects of slippage effect and adsorbed gas on horizontal well production in shale gas reservoirs are studied, and the sensitivity of parameters affecting production of shale gas wells is analyzed.
Through the above research work, the following research results are obtained.
(1) Based on numerical simulation and multiphase fluid percolation theory, a three-dimensional gas-water two-phase percolation mathematical model for shale gas reservoirs with dual media including desorption, diffusion, percolation and gas slippage effects is established by understanding the reservoir characteristics, occurrence mode, migration and production mechanism of shale gas. The level is obtained by numerical simulation method. The numerical model of shale gas is developed and the numerical model is solved by iterative programming.
(2) Based on the numerical model, the influence of slippage effect on permeability is studied. The strength of slippage effect in the process of seepage depends largely on the pore pressure of reservoir. The smaller the pore pressure of reservoir, the more obvious the slippage effect, and the obvious slippage effect exists in the fracture and pore of shale reservoir. Sensitivity analysis of fracture permeability, Langmui 3 pressure constant Langmuir volume constant and horizontal section length of horizontal wells was carried out.
(3) Using commercial numerical simulation software Eclipse 2011, a shale gas fracturing horizontal well model with slippage effect and gas adsorption-desorption is established, and the production performance of the gas well is simulated and analyzed; slippage effect is conducive to the increase of production of shale gas horizontal wells in the middle and late stages, and the production of shale gas wells is free gas migration and absorption. As a result of the combined action of adsorbed gas and desorption, the slippage effect and the influence of adsorbed gas can not be neglected in the development and production of shale gas.
(4) Based on the model established by commercial numerical simulation software Eclipse 2011, the sensitivity of various parameters affecting the production of shale gas wells is analyzed; the change of rock compressibility coefficient of shale reservoir is very weak in sensitivity to gas production of gas wells; the diffusion of gas in matrix system, isothermal adsorption law and the content of adsorbed gas in gas wells are later. Natural fracture permeability, fracture conductivity, fracture spacing and fracture half-length have a great influence on gas production of horizontal wells in shale gas reservoirs.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE328

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