CT1井膏盐层埋藏深度在7 106~7 806.5 m,层位为寒武系,无任何邻井钻井液资料可借鉴,井底温度170℃,钻进过程中出现掉块、垮塌、井漏、流变性复杂等问题.针对井底高温与井下复杂情况,对传统的欠饱和盐水磺化体系进行优化,引入磺化褐煤SMC替代稀释剂进行流型改善,解决深井后期因使用稀释剂致强分散、强依赖性而出现"加-放-加"难题;引入功能型纳米乳液TYRF-1,利用纳米乳液的特点改变胶体颗粒界面性质,解决高温起泡问题,同时增强体系润滑性能,与高软化点的复合沥青结合增强封堵能力,控制高温高压滤失量,解决井壁失稳及其破碎带掉块难题;在易漏井段使用酸容性堵漏剂SQD-98、刚性堵漏剂KGD-1/2/3/4、纤维复配避免恶性井漏的发生.经优化后的钻井液体系保障了CT 1井膏盐层的钻探.%The buried depth of the salt layer of well CT 1 is 7 106~7 806.5 m, and the layer is Cambrian.No drilling fluid can be used for reference.The bottom hole temperature is 170℃, and fall-off, well leakage, rheological complexity will appear during the drilling process will.In this paper, the sulfonated lignite SMC substitution thinner is used to improve the flow pattern of the traditional unsaturated salt water under the conditions of high temperature and complexity in downhole, and the issue of"to add and to discharge"caused by strong dispersion and strong dependency resulted from dilution to deep well at later stage is solved.The functional nanoemulsion TYRF-1 is introduced.With the use of nanoemulsion characteristics, the nature of the interface of colloidal particles is changed so as to solve the problem of high temperature foaming, while enhancing the system lubrication performance.Then enhanced sealing is achieved by combining with composite asphalt at high softening point.The filter loss at high temperature and high pressure shall be controlled to solve the issue of borehole instability and fall-off;acid-soluble plugging agent SQD-98, rigid plugging agent KGD-1/2/3/4 are used at leakage section to avoid severe well leakage.The optimized drilling fluid system guarantees the drilling at salt layer of well CT 1.
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