Release-type BOP string for oil wells with high gas-oil ratio

In view of the oil/gas flowing out of the wellhead during pipe tripping in wells in high gas-oil ratio block of Changqing Oilfield, research was conducted on blowout prevention technology for wells with high gas-oil ratio and optimization design was made to the pipe string based on the principle of down-hole switch valve. This pipe string used key tools like suspended packer, vane switch and uniflow sealing intubation. The vane switch is closed during pump inspection, which blocks off the formation oil/gas below the packer, hence solving the difficulty of oil/gas flowing out of the wellhead during pipe tripping. Lab tests and field application show that this pipe string realizes the function of preventing oil/gas from blowing out of surface and achieves the goal of blowout prevention during pump inspection.