页岩气水平井分段压裂产能分析研究

发布时间：2018-04-27 23:32

本文选题：页岩气 + 水平井　；参考：《西安石油大学》2015年硕士论文

【摘要】：页岩气藏具有孔隙度极小、渗透率极低、埋藏深度一般较深,物性较差等特点,因此页岩气藏必须经过水力压裂才能获得较高的产能。水平井辅以分段压裂措施开发页岩气已成为世界趋势,但由于页岩气在储层中存在解吸、扩散和渗流相互作用,且具有独特的渗流特性,其产能分析较为复杂。本文调研了页岩气的基本特征及页岩气井产能分析的研究进展,介绍了页岩气藏的储层特征和性质,页岩气的储集以及运移产出机理,针对页岩气藏中吸附气与游离气共存的储集方式,基于双重介质模型建立了考虑吸附解吸作用的页岩气藏不稳定渗流数学模型,利用Laplace变换计算页岩气藏的点源解,通过势的叠加原理得到定产量生产时分段压裂改造后的井底压力解,结果表明在页岩气开采中吸附解吸气量所占比例较大,且考虑吸附解吸后,定产量生产所需压差小,压力波传播到边界时间晚,压力导数曲线凹槽更加明显,同时定井底流压生产时压裂水平井产量更大,稳产时间更长;Langmuir吸附体积越大,压力波传播越慢,所需压差越小,压力导数曲线凹槽越深,Langmuir吸附压力须结合地层压力共同进行分析。同时依据文献中分析的四川威远—长宁地区下志留统龙马溪组页岩气藏特征,建立页岩气藏和压裂带的组合模型,推导了考虑等温吸附、Knudsen扩散以及滑脱效应多种渗流机制共同作用下的气藏气体渗流模型,对于压裂带,通过源汇反映原理,推导了考虑缝间干扰时的水平井压裂带气体渗流模型,得到了页岩气藏压裂水平井的产能预测模型,并对该区进行了模拟计算,得到了该区水平井裂缝优化参数。最后从地质物性方面与开发方面分析总结了页岩气井产能影响因素,再者运用正交试验法,选取四个因素进行25组正交试验,极差计算表明,基质渗透率与裂缝半长权重较大,裂缝间距与吸附比权重较小,与美国A.Kalantari-Dahaghi做对影响页岩气生产状况的敏感参数分析表中的影响次序相吻合,验证了产能预测模型的可靠性,对页岩气的开发具有一定的指导意义。
[Abstract]:Shale gas reservoirs are characterized by very small porosity, extremely low permeability, deep burial depth and poor physical properties. Therefore, shale gas reservoirs must be hydraulic fracturing in order to obtain higher productivity. It has become a trend in the world to develop shale gas with fracturing in horizontal wells, but the productivity analysis of shale gas is complicated because of the interaction of gas desorption, diffusion and percolation in the reservoir, and its unique percolation characteristics. In this paper, the basic characteristics of shale gas and the research progress of shale gas well productivity analysis are investigated, and the reservoir characteristics and properties of shale gas reservoir, the reservoir and migration mechanism of shale gas reservoir are introduced. Aiming at the coexistence of adsorption gas and free gas in shale gas reservoir, a mathematical model of unsteady percolation of shale gas reservoir considering adsorption and desorption is established based on dual medium model. The point source solution of shale gas reservoir is calculated by Laplace transform. According to the superposition principle of potential, the bottom hole pressure solution after fracturing and revamping at constant production rate is obtained. The results show that the proportion of adsorption and desorption amount in shale gas production is large, and the pressure difference required for constant production is small after considering adsorption desorption. When the pressure wave propagates to the boundary, the grooves of the pressure derivative curve become more obvious. At the same time, the production of the fracturing horizontal well is larger and the longer the stable production time is, the larger the adsorption volume of Langmuir is, the slower the pressure wave propagation is, and the smaller the pressure difference is. The deeper the grooves of the pressure derivative curve, the more the Langmuir adsorption pressure must be analyzed in conjunction with the formation pressure. At the same time, according to the characteristics of shale gas reservoirs of Lower Silurian Longmaxi formation in Weiyuan-Changning area, Sichuan Province, a combined model of shale gas reservoirs and fracturing zones is established. The gas seepage model of gas reservoir under the combined effect of Knudsen diffusion of isothermal adsorption and slippage effect is derived. For the fracturing zone, the principle of source and sink reaction is adopted. The gas percolation model of horizontal well fracturing zone considering interfracturing interference is derived, and the productivity prediction model of fractured horizontal well in shale gas reservoir is obtained, and the simulation calculation is carried out in this area, and the fracture optimization parameters of horizontal well in this area are obtained. Finally, the factors affecting shale gas well productivity are analyzed and summarized from the aspects of geological physical properties and development. Furthermore, by using orthogonal test method, 25 groups of orthogonal experiments are carried out by selecting four factors. The results of range calculation show that the matrix permeability and fracture half-length weight is large. The weight of fracture spacing and adsorption ratio is small, which coincides with the order of influence in the sensitive parameter analysis table of American A.Kalantari-Dahaghi on shale gas production, which verifies the reliability of productivity prediction model and has certain guiding significance for shale gas development.
【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

【参考文献】