广安地区须家河组气藏气水分布特征

广安地区是四川盆地中部上三叠统须家河组天然气最具勘探潜力的区块之一,其复杂的气水关系一直制约着气藏的高效开发,弄清气水分布情况成为当前气藏开发过程中的首要任务。运用气水分异理论、水蒸气含量计算、试气试采分析等研究手段,分析了气藏的气水分布情况以及产水特征。研究表明,广安气藏气水分布特征仍遵循上气下水特征,气水过渡带纵向范围较宽;通过经验公式确定地层条件下天然气水蒸气含量为0.052 1~0.092 7 m³/10⁴ m³,如果生产中水气比大于该值,气井很可能产地层水;试气试采分析认为：产水量较高的井主要集中在须六段气藏A区构造北北东部和B区,以及须四段气藏部分区域。

Features of gas and water distribution in the Xujiahe formation gas reservoir of Guang'an area

The Guang'an area in the central Sichuan basin of the Upper Triassic Xujiahe formation is the most prospective target for gas exploration. The complex gas water relationship is a key constraint for its highly effective development, thus study of gas and water distributions has become the first priority of gas development at present. Various methods, such as gas water differentiation theory, vapor content calculation, formation test and gas production test, are used to analyze the gas/water distribution and the water production features. The gas/water distribution in Guang'an gas field still accord with the pattern of "upper gas lower water", i.e. gas layers are located above water layers, and the vertical gas water transitional zone is relatively wide. Calculation with empirical formula shows that the vapor content of gas under reservoir conditions is 0.0521 0.0927 m3/104m3. If the vapor content of the produced gas is larger than this value, it is possible that the well produces formation water. Analyses of the formation test and production test results show that gas wells with a relatively high water production are mainly located in the north northeast parts of Zone A and Zone B in Xu 6 gas reservoir, as well as parts of Xu 4 gas reservoir.