Difficulties and optimization of wire-line core drilling technology for broken formation in complex structure area of northwest Hunan

Taking Xiangcidi 1 Well in the complex structural area of northwest Hunan as an example, in view of the common drilling difficulties encountered during the drilling process such as low core adoption rate and stuck-drilling buried drilling, we adopted the self-developed pumpless reverse circulation advanced side spray line and optimized the drilling fluid system to effectively improve the core drilling rate of the drilling project. The new type of drilling tool can form a local reverse circulation at the bottom of the hole, and combined with the internal anti-clogging cone net of the drilling tool and the design of the advanced side jet bit can effectively improve the drilling core rate in broken formations. By applying the drilling tool in practice, the drilling core rate in the core broken formation reached 94.4%, so it has achieved good application effects.