Research of the Locating-Sub Hanging Technology for Velocity String

After workover of low-yield gas wells in Qinghai, the existing velocity string snubbing technology has such problems as requiring additional special hanger, the main valve failed, and the wellhead and operation process needing reconstruction. To address the problems, by means of the zero pressure condition of the workover wellhead, and referring to the mandrel-type velocity string hanging technology similar to the conventional tubing hanging technique, the locating sub hanging velocity string technology and its low cost supporting tool are developed. The technology has the features of good operation connection, less operation support, high controllability of operation risk, and quick production after operation. The application in 2 wells in the Dongping gas field verified the feasibility of the process and the reliability of the supporting tools. The technology was proved to be adaptable, and had a great performance in reducing the labor intensity, speeding up the operation and lowering the cost. This technology provides an ideal method for running velocity string after low-yield gas well workover.