针对钻井基础信息参数存在不确定性的问题,以区间分析方法和可靠性理论为基础,通过分析钻井过程中井下故障发生的力学致险机理,建立了钻井工程风险的非概率可靠性评价方法。该方法只需根据先验信息确定出井下故障的风险评价函数和风险因素的上下界,即可进行风险系数计算。确定了几种常见井下故障的风险评价函数,根据区间变量运算法则推导出了风险系数表达式。以西部某区块的W井为例进行了验证分析,结果表明,该方法计算简便、实用,能够满足工程实际需要。
In view of the uncertainty in basic drilling parameters, through the analysis of mechanical risk mechanism of downhole accidents in drilling,non-probabilistic reliability evaluation method was estab- lished for drilling engineering risk based on interval analysis method and reliability theory. This method could calculate risk factor after risk evaluation function and the upper and lower bounds of risk factors were established according to prior information. Risk evaluation functions for several common downhole complexities were set up in the paper while the formulas of risk factors were derived from interval variable al- gorithm. Taking Well W in some western region as an example, the evaluation results indicated that the method, simple and practical, could satisfy the needs of engineering practice.