Finding out the reasons for wellbore instability in the Longmaxi Formation and Wufeng Formation and putting forward drilling fluid technical countermeasures to strengthen and stabilize the wellbore are very crucial to horizontal drilling. Based on X-ray diffraction, electron microscope scanning, linear swelling experiment, and hot-rolling dispersion experiment, the physicochemical mechanism of wellbore instability in complex strata was revealed, and thus, the coordinated wellbore stability method can be put forward, which is “strengthening plugging of micropores, inhibiting filtrate invasion, and retarding pressure transmission.” Using a sand bed filtration tester, high-temperature and high-pressure plugging simulation experimental device, and microporous membrane and other experimental devices, the oil-based drilling fluid treatment agent was researched and selected, and a set of an enhanced plugging drilling fluid system suitable for shale gas horizontal well was constructed. Its temperature resistance is 135°C and it has preferable contamination resistibility (10% NaCl, 1% CaCl₂, and 8% poor clay). The bearing capacity of a 400 μm fracture is 5 MPa, and the filtration loss of 0.22 μm and 0.45 μm microporous membranes is zero. Compared with previous field drilling fluids, the constructed oil-based drilling fluid system has a greatly improved plugging ability and excellent performance in other aspects.

中文翻译：

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油基钻井液堵漏法增强页岩气井筒稳定性

找出龙马溪组和五峰组井筒失稳的原因，并提出加强和稳定井筒的钻井液技术对策，对水平钻井至关重要。通过X射线衍射，电子显微镜扫描，线性溶胀实验和热轧分散实验，揭示了复杂地层井筒失稳的理化机理，可以提出协调的井筒稳定性方法，即“加强微孔的堵塞，抑制滤液侵入，并阻止压力传递。” 使用沙床过滤测试仪，高温高压堵漏模拟实验装置，微孔膜等实验装置，对油基钻井液处理剂进行了研究和选择，构建了一套适用于页岩气水平井的增强型堵漏钻井液系统。其耐温性为135°C，并具有较好的耐污染性（10％NaCl，1％CaCl₂和8％的劣质粘土）。400微米裂缝的承载力 为5 MPa，0.22微米和0.45 微米的微孔膜的过滤损失 为零。与以前的现场钻井液相比，该构造的油基钻井液系统具有大大提高的堵漏能力和其他方面的优异性能。