天然气井水泥环封隔能力的测井评价

摘要

. It is difficult in oilfield exploration and development to evaluate sheath isolation be-tween gas intervals and wellhead pressure conditions in gas wells. Analyzed are cement bond log data, gas invasion data, historic drilling data and wellhead pressure data. Discussed are the anal-ysis method for the sheath isolation between gas intervals in gas field by using CBL, SBT and USI logging examples. Provided are methods to evaluate wellhead pressure in gas well with the length of good cement intervals , the length of mud-slurry transition intervals and the combina-tion of the above two methods. The above research shows that the log evaluation of the sheath i-solation between gas intervals is similar to the conventional cement bond evaluation of oil or water intervals. The length of good cement intervals and the length of mud-slurry transition intervals derived from log data can be used to evaluate the wellhead pressure conditions. These methods have been successfully used in some gas fields in China.%水泥环气层层间封隔和气井井口带压评价是勘探开发中亟待解决的问题.综合分析了气井固井质量测井资料、验窜资料、钻井历史和气井井口带压的有关资料.通过CBL、SBT和USI测井资料的验证实例,讨论了天然气井水泥环层问封隔能力的分析方法.提出用良好胶结累计长度法、混浆带长度法评价及2种方法交会法评价气井井口带压状况的方法.研究表明,利用测井资料评价气层之间的水泥环封隔能力与常规固井质量评价方法相似;利用固井质量测井资料显示的良好水泥胶结长度和混浆带长度,可以评价井口带压.该方法在中国海上和陆地一些气田应用,取得初步成功.