Directional drilling technology optimization in the coal exhausted area of Zichang field

The directional drilling technology has an urgent need for optimization because the oil well drilling speed has been affected and the cost of drilling has been increased in the coal exhausted area. Being tried repeatedly in practice, the way using the small drill bit with diameter of 222.2mm to drill through the two layers of the coal exhausted area and using dynamical drilling tool assembly to replace the rotary drilling tool assembly after second section to drill to the bottom of the well, decreases the period of drilling through the two layers of the coal exhausted area from 2-3 days to 1 day. After running surface casing cementing, the problem of every well leakage is improved to some wells leakage in the process of drilling in second section, and the average well drilling cycle is shortened to 7-8 days from the initial 23 days, which is a better solution to the problem of the development of oil resources in the coal exhausted area. The optimized drilling technology is both feasible in field operation and economical benefit, and provides a new way in jointly developing a variety of mineral resources in resource overlapped areas in the future.