The continuously popularized technology for the development and exploitation of deep wells and horizontal wells and the large scale development of gas have raised the higher and higher requirements for tightness of tubing and casing;
    To minimize the potential risk of incidents caused by  thread leak, special-thread casing and tubing are mandatorily required for leak detection in most  oilfields in North America, Mexico and South America.
 

    The factors of machining tolerance, transportation damage and microcorrosion and especially the inappropriate torque-up or breakout and repeated use for tubing/casing running work in high pressure gas wells may cause seal failure, so leak detection for tubing/casing in time is a necessary mean to avoid potential safety hazards.
    The dual seal detection packer is delivered to thread connection of strings when strings are putting down into the hole, then it is setting to seal. Lately, the high pressure helium is injected into the packer tool and high sensitivity detector works outside of tubing thread and indicates whether it leaks or not according to the detected helium leakage value.