Abstract: Offshore heavy oil thermal production wells are often directional or horizontal wells with large inclination angles. Under the influence of gravity, the steam injection string may contact the inner wall of the casing, leading to a decrease in the thermal insulation effect, especially at the thermal insulation coupling positions, and resulting in significant heat loss. To address this issue, a new type of insulated tubing centralizer was developed, and its thermal insulation and temperature-pressure resistance performance were tested. The centralizer mainly consists of a thermal insulation mechanism, a centralizing mechanism, and a fixing mechanism. The thermal insulation mechanism is provided with a composite thermal insulation structure designed to ensure thermal insulation functionality. The centralizing mechanism is designed with multiple centralizing blocks and combined cylindrical springs evenly distributed circumferentially, ensuring elastic centralizing functionality and guaranteeing the centralization effect of the string. Indoor performance tests indicate that the centralizer can withstand temperatures of 350 ℃ and pressures of 21 MPa, with a thermal insulation rating of Class D, and it also has good resistance to contraction when encountering obstacles. The site application results show that the new insulated centralizer ensures the seating and sealing effect of the packer, solves the problem of the steam injection string "lying against the wall" in offshore thermal production horizontal wells, effectively reduces the heat loss in the wellbore, and protects the casing and cement sheath. This technology can provide strong technical support and assurance for the safe and efficient thermal production development of offshore heavy oil oilfields.

Key words: thermal production, horizontal well, thermal insulation, tubing centralizer, heavy oil, offshore oilfield