Design for the Setting Depth of Jetting Conductors Based on Non-Probabilistic Reliability

In the design of deep water exploration wells, soil parameters tend to be insufficient when designing the setting depth of conductors, since it is costly to take soil samples by drilling holes. Moreover, there are significant uncertainties in the seabed soil parameters, so there are certain difficulties and the risks in designing conductor setting depths with deterministic methods. Based on the interval analysis method and the structure reliability theory, an available function for jetting conductor installation was built by analyzing the working load, and the design method of conductor setting depth based on non-probabilistic reliability was developed. By comparing the result of this design with that of the deterministic design method of the conductor setting, it was found that the result designed with this method is better than that of the deterministic method. It indicated that designing the conductor setting depth with this method can keep the safety and reliability for conductor systems, and it possesses a margin of safety. In the absence of soil parameters, this method can compensate for the disadvantages of the deterministic method, reduce demands for soil parameters, lower the cost and maintain the safety of deepwater drilling operations.