Milling process of long-segment casing in Tahe Oilfield

In order to obtain higher single-well output and reduce the cost in drilling, sidetrack horizontal well drilling is conducted in the old wells in Tahe Oilfield. In view of the long period of milling of which the average is 48 days and high probability of accidents during the drilling, the blocking technology of the perforation in the liner and the milling tools are developed, as well as the research on milling technologies, systematic drilling technologies, and protection technologies of casing are conducted. Based on the field application of the technologies in T415CH and TK205CH wells, it is shown that the milling rate is increased by 0.3 m/h in Tahe Oilfield by applying the long-segment casing milling process, the period is shorten by 23.5 days, and the occupation time of accidents is reduced by 7.5 d on average. This is of great significance to the construction of the old wells in the oilfield, to increase the single-well output and the oilfield output.