榆林南-子洲地区山2气藏水层特征及识别

Feature and identification of water zone of Shan2 gas reservoir in South Yulin-Zizhou Area

榆林南-子洲地区山2气藏具有低孔、低渗、非均质性强、开发中普遍见水的特点。为此,开展了生产井产水层特征研究,并提出了识别方法。在对山2气藏水层进行地质与测井特征系统分析的基础上,根据测试井段产水量的大小,将产水井划分为5类,以此建立了气水层识别的地质-测井标准。利用判别分析方法,建立了山2气藏气层、气水层、水层、干层的判别方程。回判结果表明,模型对气层的精度达到93.8%,气水层90.2%,水层93.4%,干层90.1%。利用未参加建模的出水井射孔段对模型进行验证,判识结果符合实际情况。该模型具有较高的精度,所建立的方法可用于未知层段的属性识别。

Shan2 gas reservoir is characterized by low porosity, low permeability, strong heterogeneity and general water breakthrough during development in South Yulin-Zizhou Area. This paper analyzes the features of water yield formation of production well and proposes the identification method. On the basis of systematic analysis of geologic and logging features for water zone in the gas reservoir, water yield wells can be divided into five types according to the water production rate of tested interval. The geology-logging standards of identifying gas zone and water zone have been established. The discriminant quations of gas zone, gas-water zone, water zone and dry zone in Shan2 gas pool have been set up through the use of identification method. Regression analysis shows that the accuracy of model is up to 93.8% for gas zone, 90.2% for gas-water zone, 93.4% for water zone and 90.1% for dry zone. After verifying this model by using the data of perforated interval of discharging well that is not used in model building, we find that the identification result is essentially in accord with the practice. The model has a high precision, and the built method can be used to identify the properties of unknown intervals.