考虑流固耦合影响的页岩力学性质和渗流规律

发布时间：2018-10-20 07:16

【摘要】：为了研究页岩气藏在生产过程中外来水对页岩力学和渗流规律的影响,以四川盆地宜宾地区的下志留统龙马溪组黑色页岩露头及页岩岩心为样本进行了分析。首先,利用VHX-5000超景深显微镜观察了饱和水后岩心裂缝的发育情况;其次,通过单轴压力试验机、应变测试分析系统,研究了水、地层水及滑溜水与饱和水岩心、未饱和水岩心压裂后的破坏形式和抗压强度的变化;最后,通过DYQ-1型多功能驱替装置,研究不同含水条件下流固耦合对页岩气渗流特征影响。岩心成分分析结果表明:龙马溪组页岩脆性矿物含量高,属于可压性较高的储层,有利于压裂改造。页岩抗压强度实验结果表明:去离子水、地层水和滑溜水对页岩的作用效果不同,导致页岩饱和前后的抗压强度差距较大,水的存在会降低页岩的抗压强度,更容易被压裂,产生更多的裂缝,从而提高页岩的渗流能力。含水条件对页岩气渗流特征实验结果表明:流固耦合条件下,含水饱和度越大,页岩微裂缝在压力作用下,扩展发育效果和渗流能力越好,水的存在有助于页岩气藏压裂改造,达到了增加产量的目的。
[Abstract]:In order to study the influence of foreign water on shale mechanics and percolation during the production of shale gas reservoir, the black shale outcrop and shale core of Lower Silurian Longmaxi formation in Yibin area of Sichuan Basin were analyzed. Firstly, the development of core fractures after saturated water is observed by VHX-5000 hyper-depth microscope, and secondly, the water, formation water, slippery water and saturated water core are studied by uniaxial pressure testing machine and strain test analysis system. The change of failure form and compressive strength of unsaturated core after fracturing. Finally, the influence of fluid-solid coupling on shale gas percolation characteristics under different water cut conditions was studied by DYQ-1 multifunctional displacement device. The results of core composition analysis show that the shale brittle minerals in Longmaxi formation are of high content and high compressibility, which is beneficial to fracturing. The experimental results of shale compressive strength show that the effect of deionized water, formation water and slippery water on shale is different, which leads to a large difference in compressive strength before and after shale saturation, and the existence of water will reduce the compressive strength of shale and be more easily fracturing. More fractures are produced, thus increasing the seepage capacity of shale. The experimental results show that under the condition of fluid-solid coupling, the greater the water saturation is, the better the expansion and percolation ability of shale microfractures is under pressure, and the existence of water is helpful to the fracturing reconstruction of shale gas reservoir. The goal of increasing output has been achieved.
【作者单位】：浙江海洋大学石化与能源工程学院;
【基金】：国家重点基础研究发展计划(973计划)项目“页岩气多场耦合非线性渗流理论研究”(编号:2013CB228002)
【分类号】：TE31

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