湖南保靖区块海相页岩气快速钻探技术

Fast drilling technology for marine shale gas in Baojing Block, Hunan

湖南保靖页岩气勘查区块黑色页岩沉积发育,是页岩气勘探开发的有利区带。由于储层埋藏深、地层高陡、地层倾角变化大、岩石可钻性差,导致钻井周期长、成本高等问题。钻前对已有的地震、测井、岩心实验等资料的处理和分析,通过优化井身结构、钻头选型、钻具组合优选和中长筒取心等,实现了保靖区块海相页岩气快速钻探。

The main part of the Hunan Baojing shale gas exploration block is located in Baojing County of Western Hunan. It is a favorable zone for exploration and development of shale gas, but high risk and challenge are present due to complicated geological conditions, deep buried reservoir, large formation dip change, poor drillability, long drilling period and high drilling cost. Before drilling started, the formation pressure and rock compressive strength was obtained by processing and analyzing the existing data of seismic, logging and core experiments. The well structure and drill bit selection were optimized. In the drilling operation, the drilling tool assembly, mud system and cementing technology were optimized according to the characteristics of the formation. The high efficiency bit was adopted with the MWD tool and long-run core barrel to carry out compound drilling, well deviation prevention, and fast drilling. In order to improve the drilling speed and efficiency in shale gas, and reduce the drilling cost, a new 70 MPa liner hanger and liner cementing technology were adopted to ensure the overall sealing, and cementing quality of the casing string, which provided guarantee for the following fracturing treatment.