Deviation Control and Fast Drilling Technologies in the Carboniferous Strata of Junggar Basin

The Carboniferous strata deep in Junggar basin have great exploration potential. The previous drilling practice showed that its geological conditions are very complicated, such as poor drillability and difficult deviation control, which severely influence drilling speed and increase downhole risk, so research on deviation control and fast drilling technologies was conducted to accelerate the exploration and development of Carboniferous strata. Technical difficulties and deviation causes of Carboniferous strata in Junggar basin were analyzed and summarized. Through analyzing their technical advantages and adaptability, it was presented that gas drilling, compound drilling with impregnated diamond bit and turbodrill and automatic vertical drilling were three effective drilling technologies for deviation control and fast drilling in the Carboniferous strata. Through comparatively analyzing the deviation correction ability of tapered drill string assembly, single stabilizer pendulum assembly and double stabilizer pendulum assembly with trend angle of deviation, the deviation correction ability of three assemblies were significantly decreased along with WOB increasing, and the deviation control ability of single stabilizer pendulum assembly was best when WOB was bigger, while the deviation correction ability of double stabilizer pendulum assembly was best when WOB was smaller. All the technical solutions have important guiding for drilling in the Carboniferous strata of Junggar basin.