Research on contamination-proof technique strings and supporting tools for offshore thermal recovery wells

In view of stratum contamination by kill fluid which is caused by both injection strings and production strings in offshore thermal recovery wells, the contamination-proof technique strings and supporting tools for offshore thermal recovery wells have been developed. The technique strings is mainly composed of contamination-proof packer for thermal recovery, contamination-proof down-hole switch and intubation sealer for thermal recovery. When the contamination-proof packer is set and suspended in the well, it can open or close the down-hole switch by lifting or lowering the thermal recovery intubation, hence effectively sealing the passageway between the oil reservoir and upper space and avoiding kill fluid from entering the stratum. Ground test, simulation well test and high temperature test have shown that this tool is flexible in setting, getting locked and releasing without jamming and the seal anchoring is reliable. It can withstand high pressure under multi-cycle alternative changes among high, medium and normal temperatures. The down-hole switch can open and close flexibly, and can meet the requirement of multi-cycle gas injection and oil recovery for offshore thermal recovery wells.