Large-diameter three-barrel coring technology on semi-submersible platforms

When the coring operation is performed on a semi-submersible platform, not only the coring results are influenced by traditional factors, but the heave of the platform brings great challenges to the control of the coring parameters, especially the weight on bit. In addition, the core is also easily broken in the process of coring due to the platform' s heave, and consequently the coring footage is affected. A successful application case of large-diameter three-barrel coring technology on semi-submersible platforms was introduced. In this case, two large-diameter three-barrel coring operations are completed by controlling tool selection and process measures strictly. Its cumulative coring footage is 55.3 m and average coring rate is 100%. Then the difficulties of coring technology and the implementation of on-site processes during coring on the semi-submersible platform were analyzed systematically, and the large-diameter three-barrel coring technology highly suitable for semi-submersible platform was formed. This technology is mainly composed of the control of process parameters in the process of coring, the selection of core cutting methods, and the choice of core tripping out methods. In this way, the large-diameter three-barrel coring technology is successfully applied on the semi-submersible platform. And its successful application accumulates the experience for the coring operations in this block.