Abstract:Fuling Shale Gas Field was the first marine shale gas field put into commercial exploitation. It went through the development evaluation test phase in 2013 years, and the Phase I productivity construction from 2013 to 2015 with development of a series of drilling and completion technology ideal for Fuling Shale Gas Field exploration and exploitation through field test and application. In the second phase, greater buried depth, and formation uncertainty led to great obstacles in increasing the drilling speed; particularly the bit type selection was difficult for some complex formation. It was mainly reflected in the low drilling rate per round trip with conventional bits, multiple times of tripping, and difficult orientation. With the analysis of drillability and directional difficulties, 121/4in high abrasive hybrid drill bits were selected for strong abrasive and alternating sand and mudstone in the Xiaoheba Formation of Pingqiao Block. In order to solve the serious problem of directional drag force in drilling of the second section in long reach three-dimensional wells, 121/4in high-efficiency directional hybrid bits were optimized. In view of the characteristics of high formation deflection rate and strong abrasiveness in the build section of Longmaxi Formation (containing turbidite sandstone), the 81/2in hard formation directional hybrid bit was optimized. Up to now, the three types of hybrid drill bits have been used in the Fuling work area for more than 200 times totally, with an average reduction of 4 to 5 trips and cutting short of the drilling duration by 6～7 days. The selection of the hybrid bit has provided technical guarantee for the drilling acceleration and efficiency improvement in the second construction phase, and also provides the bit selection scheme for the efficient development of the following shale gas fields.
