Study and application of a new mechanical anti-contamination tool in offshore oilfields

The mechanical anti-contamination tools existing in offshore oilfields are faced with inaccurate opening pressure of acid injection channel, difficult releasing in high-angle deviated wells and other difficulties. A new type of mechanical anti-contamination tool and its dedicated releasing tool were developed based on the characteristics of offshore oilfields. In this way, the tool can be released hydraulically. In addition, a centralizer was added, the spring adjustment mechanism was optimized and stress analysis was conducted on compression spring and elastic claw. And as a result, its anti-corrosion performance and pressure regulation performance are improved, the construction is simple, and its application is beyond the restriction of well deviation. The field application indicates that when the new mechanical anti-contamination tool combined with the dedicated hydraulic releasing tool is applied in the oil wells with the well deviation of 86°, the release of the new mechanical anti-contamination tool can be realized by putting Ø57 mm steel balls and pressurizing to 10 MPa through the tubing, and the acid injection channel can be opened by increasing the pressure to 8 MPa on the ground. The research results provide the technical support for the reservoir anti-contamination measures of offshore oilfields.