Development and application of hydraulic releasing device for screen pipe

Natural gas in Changbei Gasfield is developed using dual branch horizontal wells in cooperation with open hole completion. In order to prevent wellbore collapse when drilling mudstone layer and coal bed, the pre-bored screen pipe is run to the horizontal open hole section to support the wellbore side wall. Due to complexity of wellbore conditions, a number of technical difficulties have been met in horizontal well operations in Changbei Gasfield such as difficulties in running long screen pipe, that short screen pipe is too light to effect smooth release, that conventional release tools cannot be freed by rotation at tight hole, and that the conventional ball seat needs to be drilled out by tripping in separately, etc. A hydraulic releasing device for screen pipe has been developed, which has rotation function, allowing the screen pipe to pass the tight hole by rotating when it is run. There are two release methods: hydraulic releasing and mechanical release. The designed retrievable ball seat mechanism can be lifted out as a whole with the running tool after the job is finished and does not need to be drilled out. This hydraulic releasing device for screen pipe has passed a series of surface performance experiments and utilized in two horizontal branch wells CB23-2 and CB23-3 in Changbei Gasfield; four runs of screen pipe were conducted, which successfully addressed the field difficulties.