致密储层压裂缝网渗透性变异的影响因素分析

发布时间：2018-01-10 21:18

本文关键词：致密储层压裂缝网渗透性变异的影响因素分析　出处：《桂林理工大学学报》2017年03期 　论文类型：期刊论文

【摘要】：页岩储层的渗透性是页岩气开发过程中的最为重要的指标之一。在页岩气储层压裂后的排采过程中,储层渗透性会随储层压力、孔隙压力等的降低而发生变化。本文从微观层次上对储层基质微纳孔隙收缩效应、气体滑脱效应对页岩储层渗透性影响的力学机制进行了分析,从宏观层次上分析了储层岩体蠕变、裂缝缝面闭合蠕变、储层衰减应力变化对压裂缝网渗透性影响的力学机制。结果表明:在压裂排采期,基质微纳孔隙页岩吸附气体解吸造成的基质收缩效应和气体滑脱效应会在一定程度上增大压裂储层的渗透率,但基质收缩效应对储层岩体渗透性的影响十分微弱,气体滑脱效应在低压条件下会增加储层岩体的渗透性。由于储层水力改造增加了岩体破碎程度,提高了岩体含水率,水力改造区内储层岩体长期蠕变会极大的压缩缝网空间,降低导流裂缝的渗透性。此外,与储层压力减小有关的裂缝壁面闭合蠕变、地层压实变形会致使水力裂隙开度和渗透性进一步降低。
[Abstract]:The permeability of shale reservoir is one of the most important indexes in the process of shale gas development. The effect of pore pressure on the permeability of shale reservoir is analyzed in this paper from the microcosmic level of the micropore shrinkage effect of reservoir matrix and gas slippage effect on the permeability of shale reservoir. The mechanical mechanism of rock mass creep, fracture surface closed creep and reservoir attenuation stress change on the permeability of pressure fracture network is analyzed from the macro level. The results show that: during the period of fracturing and production discharge. The matrix shrinkage effect and gas slippage effect caused by gas desorption of matrix microporous shale will increase the permeability of fracturing reservoir to some extent. However, the effect of matrix shrinkage on the permeability of reservoir rock mass is very weak. The gas slippage effect will increase the permeability of reservoir rock mass under the condition of low pressure. With the increase of water content of rock mass, the long-term creep of reservoir rock mass in hydraulic reconstruction area will greatly compress the space of fracture mesh and reduce the permeability of diversion fracture. In addition, the closed creep of fracture wall is related to the decrease of reservoir pressure. The formation compaction deformation will further reduce the hydraulic fracture opening and permeability.
【作者单位】：中国科学院地质与地球物理研究所中国科学院页岩气与地质工程重点实验室;中国科学院大学;
【基金】：国家自然科学基金项目(41372325;41372323;41402280) 中国科学院战略性先导科技专项(B类)(XDB10030602)
【分类号】：TE311
【正文快照】： 由于页岩气储层的非均质性和致密性,压裂改造后的储层岩体可视为典型的双重介质(裂隙系统和 0引言页岩气是指以吸附和游离状态存在于泥页岩基质系统)(图1、图2)。经典的双重孔隙介质模地层中的非常规天然气[1]。含气页岩储层分布广型主要有Warren-Root模型[6]、De Swann模

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