基于非概率可靠性的喷射导管下入深度设计方法

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

在深水探井设计中,由于钻孔取土壤样的费用高,设计导管下入深度时往往缺少所需的土壤参数,而海底土壤参数又存在较大的不确定性,此时采用确定性方法进行导管下入深度设计存在一定的难度和风险。为此,以区间分析方法和结构可靠性理论为基础,通过分析喷射下入导管的载荷,建立了喷射下入导管的功能函数,形成了一种基于非概率可靠性的喷射导管下深设计方法。通过实例对比了该设计方法与确定性导管下入深度设计方法的设计结果,发现该方法的设计结果大于确定性方法的设计结果。这说明,采用该方法设计导管下入深度可以保证导管系统安全可靠,而且有一定的安全余量。该方法克服了缺少土壤参数情况下确定性方法存在的不足,降低了对土壤参数的需求,有助于降低深水钻井作业成本,同时可以保证深水钻井作业安全。

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.