Abstract: Well Jinzi-1 is drilled to provide data for the underground gas storage project used for west to east gas transportation. It is difficult to accomplish the required technical requirements by using the conventional hydraulic expanding packer in this well, thus modification was conducted to the K344-190 hydraulic packer, enlarging the central pipe from 73 mm to 127 mm and this improved its tension strength from 600 kN to 1200 kN. Field operation proved its reliability, and this is an innovation in long open hole zonal high pressure test and ensures reliable data for accurate evaluation of the underground gas storage project.