| 摘要: |
| 水平井分段压裂形成的裂缝网络使页岩气藏经济开发，但也为压裂液大量滤失和进入页岩基块深部提供了通道和途径，削弱了压裂改造效果。开展页岩基块、单裂缝、"T"型裂缝网络水相自吸试验，并与致密砂岩水相自吸试验进行对比分析。结果表明：与单基块、裂缝相比，页岩裂缝网络在增大水相赋存空间的同时，也为裂缝-基块间自吸创造有利供给条件，增加了水相自吸侵入深度；致密砂岩水相自吸呈现活塞式均匀推进，且未产生新裂缝，而页岩水相自吸优先沿页理发生，因侵入流体与页岩发生水-岩作用萌生页理缝，进步增加页岩缝网密度，扩大水相自吸范围。通过优选压裂液配方，利用滞留压裂液与页岩相互作用，发挥滞留压裂液对储层缝网的积极改造作用，可以达到改善页岩储层渗流通道、强化页岩气解吸-扩散-渗流传质能力的目的。 |
| 关键词: 页岩气藏 裂缝网络 压裂液 毛管自吸 水-岩作用 |
| DOI：10.3969/j.issn.1673-5005.2018.01.010 |
| 分类号:TE258 |
| 文献标识码:A |
| 基金项目:国家自然科学基金项目（51674209）；四川省青年科技创新研究团队项目（2016TD0016）；四川省高校科技成果转化重大培育项目（17CZ0040） |
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| Experimental study on spontaneous water imbibition in fracture networks of shale rocks |
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YOU Lijun, CHENG Qiuyang, KANG Yili, TIAN Jian, YANG Bin
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(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation in Southwest Petroleum University, Chengdu 610500, China)
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| Abstract: |
| The fracture networks generated by multi-stage hydraulic fracturing of a horizontal well make the economic development of shale gas reservoirs becoming a reality. But they also can provide channels and paths for a great quantity of fracturing fluid to imbibe into the shale matrix deeply, and weaken the fracturing effect. In this study, spontaneous water imbibition experiments using shale matrix, single fracture and a fracture network of "T" type were carried out and compared with those using tight sandstones. The experimental results show that the fracture networks not only can increase the storage space of water phase, but also create favorable conditions for the spontaneous water imbibition from cracks to rock matrix, significantly increasing the invasion depth of water imbibed. The spontaneous water imbibition in tight sandstones behaves like a piston propulsion and no new cracks can be created. However, in shale rocks, water imbibes preferentially along the shale bedding, and then can generate new cracks due to the incompatibility between the fluid and shale, which can lead to the initiation of new cracks, further expanding the imbibition. By optimizing the composition of the fracturing fluid to enhance the interactions between the fracturing fluid and shale rocks fully, the fracture networks can be reformed to improve the seepage channels in shale reservoir and strengthen the desorption and diffusion of shale gas. |
| Key words: shale gas reservoirs fracture network fracturing fluid capillary imbibition water-rock interaction |
