Geosteering technology and CBM horizontal well drilling without pilot hole

Aiming at the difficulties of hole-forming of the horizontal interval in a soft coal seam, low drilling ratio of coal seam and need of pilot hole during deflecting drilling, the key technologies such as drilling parameter optimization, anti-collapse drilling were put forward in the paper. Geosteering technology with multi-markers was used to realize timely layer identification, to search suitable targeting angle, to be adaptive to the stratum dip so as to realize one time direct landing at the target. Geosteering and geometric steering were combined to control finely the wellbore trajectory of the horizontal interval, to make the wellbore trajectory smooth. Three horizontal wells were drilled in Chengzhuang coal mine, the accumulative footage in coal seam was 1 604.72 m, drilling ratio of coal seam was 100%, and the final horizontal section into the PE screen had a total length of 1 366 m. The study can improve drilling and completion technology of CBM horizontal wells, provided a new approach for low cost and efficient CBM development.