页岩气藏自然返排缓解水相圈闭损害实验研究

发布时间：2018-12-11 20:03

【摘要】：水平井分段压裂是页岩气藏开发的主要技术手段。然而,页岩纳米孔与微裂缝的毛管自吸作用往往导致压裂液返排困难,滞留压裂液对页岩气解吸—扩散—渗流过程潜在损害严重。为深化页岩气藏压裂液返排与及其水相圈闭损害动态变化的认识,利用川东龙马溪组页岩样品,在岩心柱尺度上实验模拟增产改造时压裂液自吸—返排过程,讨论了孔隙结构、裂缝发育情况、返排压差及时间影响自吸—返排效果的机理。结果表明:孔隙半径越小,毛管力越大,页岩自吸速率越大,水相返排效果越差;自吸诱发页岩产生裂缝,增大了气相渗流通道,促进了滞留水相返排;返排压差、返排时间与水相返排效果呈正相关关系,在返排压差0.2MPa和1.0MPa条件下先后各返排12h,水相最大返排率约为46%,最大渗透率恢复率约为67%。分析表明:页岩气藏潜在水相圈闭损害严重,滞留水相的返排有利于增强页岩气渗流能力。
[Abstract]:Horizontal well fracturing is the main technique for shale gas reservoir development. However, the capillary self-suction of shale nano-pore and micro-fracture often leads to the difficulty of fracturing fluid backflow, and the potential damage to shale gas desorption, diffusion-percolation process caused by retained fracturing fluid is serious. In order to deepen the understanding of back drainage of fracturing fluid in shale gas reservoir and the dynamic change of its water phase trap damage, using shale samples of Longmaxi formation in eastern Sichuan, the self-suction and backflow process of fracturing fluid during stimulation and reconstruction was simulated on the scale of core column, and the pore structure was discussed. The development of fracture, the mechanism of pressure difference and time influencing the effect of self-priming and reflux. The results show that the smaller the pore radius, the greater the capillary force, the greater the self-priming rate of shale, and the worse the backflow effect of water phase, the more fissures are produced by self-priming shale, the larger the gas phase seepage channel is, and the other is that the reflux of retained water phase is promoted. There is a positive correlation between the back discharge pressure difference, the back discharge time and the back discharge effect of water phase. Under the condition of 0.2MPa and 1.0MPa pressure difference, the maximum rate of water phase back discharge is about 46 and the maximum permeability recovery rate is about 67% under the condition of back discharge pressure difference 0.2MPa and 1.0MPa respectively. The analysis shows that the potential water phase trap damage in shale gas reservoir is serious, and the backflow of retained water phase is beneficial to enhance the permeability of shale gas.
【作者单位】：西南石油大学油气藏地质及开发工程国家重点实验室;富象油气有限公司;
【基金】：国家自然科学基金项目(编号:51674209) 国家科技重大专项“彭水地区常压页岩气开发技术与政策研究”(编号:2016ZX05061003) 非常规油气层保护四川省青年科技创新研究团队项目(编号:2016TD0016)联合资助
【分类号】：TE377

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