基于多因素耦合的井筒完整性风险评价

Risk evaluation of wellbore integrity based on multi-factor coupling

为了合理开展井筒完整性评价,提出合理的管理措施,综合考虑管柱力学、管柱腐蚀、管柱及附件密封、水泥环力学、地层以及油气井管理等关键节点及因素的相互耦合协同作用,分析多因素耦合协同作用对井筒完整性的影响。对于管柱力学等具有比较明确物理意义且可以量化的因素,采用定量分析评价;对于操作管理等难以量化的因素采用定性评价,对于腐蚀环境因素采用定量与定性相结合的方法进行评价;在定性及定量评价的基础之上,对关键节点进行风险概率和风险影响程度的划分及量化,再基于层次分析及风险矩阵的方法建立井筒完整性评价模型;基于模型编制了相应的计算程序,并对某高腐蚀性气井开展了井筒完整性评价。评价结果表明,在影响该井井筒完整性的风险因素中,高酸性气体腐蚀是造成该井井筒完整性失效的主要因素。

In order to carry out the wellbore integrity evaluation reasonably,and put forward the reasonable management measures,the influence of multi-factor coupling synergistic effect on the wellbore integrity was analyzed by comprehensively considering the interactive coupling synergistic effect of the key nodes and factors,such as the pipe string mechanics,the pipe string corrosion,the pipe string and accessories sealing,the cement sheath mechanics,the strata and oil and gas well management,etc. The quantitative analysis and evaluation were adopted for the factors with relatively clear physical meaning and being quantizable,such as the pipe string mechanics etc.,while the qualitative evaluation was applied for the factors being difficult to quantify,such as the operation and management etc.,and the combination of qualitative and quantitative method was used for the corrosion environmental factors. On the basis of qualitative and quantitative evaluation,the risk probability and risk influence degree of key nodes were divided and quantified,then the evaluation model of wellbore integrity was established based on the analytic hierarchy process（ AHP） and risk matrix method. The corresponding calculation program was compiled based on the evaluation model,and the wellbore integrity evaluation on a certain highly corrosive gas well was carried out. The results showed that in the risk factors affecting the wellbore integrity of this well,the corrosion of high acid gas was the main factor to cause the wellbore integrity failure.