Application of the Balanced Differential Pressure Method in the Downhole Operation of Bohai Oilfield

When a fishing operation is needed for a well in which the production string is stuck, the first step is cutting the string above the sticking point and then fishing the left production string in the screen. Due to the uncertainty in fishing operation, the increase in working duration will result in the increase in the cost for a well. Based on the analysis of the down-hole condition, the authors speculated the main cause was the absorption force produced by the differential pressure above and below the production packer. The fishing was successfully completed in a short time by opening the wellhole with the reservoir and releasing the differential pressure between the formation and the string, which reduced the working duration and cost and provides the valuable reference for the similar down-hole operation in the future.