基于贝叶斯网络的气井环空带压风险评价模型及应用分析

针对气井生产过程中环空带压日益严重导致井完整性失效风险上升这一问题，开展了环空带压风险评价研究。建立了基于贝叶斯网络和实际生产数据的环空带压风险预警模型，该模型将影响环空带压的因素分为油套管泄漏和水泥环失效两个单元，确定了各个单元的主要风险因素和风险失效概率，在此基础上，建立了环空带压风险量化评价指标，并进行了相应风险等级划分，形成了气井环空带压风险评价方法。统计了新疆采气一厂的191口井的失效概率，进行了实例应用，结果表明:该模型可对环空带压的潜在风险进行定量计算，可推理得出主要风险因素的逆向成因，为预防和控制环空压力提供决策依据，有助于降低气井环空带压风险的发生概率。

Risk assessment model of sustained casing pressure of gas well based on Bayesian network and its application analysis

Sustained casing pressure gets serious increasingly in the process of gas well production, which increases the risks of well integrity failure. To solve this problem, this paper assessed and studied the risks of sustained casing pressure. The early warning model of sustained casing pressure based on Bayesian network and actual production data was established. By virtue of the model, the influential factors of sustained casing pressure were divided into two units, i.e., tubing/casing leakage and cement sheath failure, and the main risk factors and risk failure probability of each unit were determined. In addition, the quantitative risk assessment indexes of sustained casing pressure were set and the risks were classified correspondingly. Thus, the risk assessment method of sustained casing pressure of gas well is developed. It was applied practically based on the statistical failure probability of 191 wells in No.1 Gas Production Plant of Xinjiang Oilfield Company. The case application indicates that this model can quantitatively calculate the potential risk of sustained casing pressure, deduce the reverse origins of main risk factors and provide decision making basis for sustained casing pressure prevention and control, which is conductive to reduce the occurrence probability of sustained casing pressure of gas well.