枯竭气藏改建储气库盖层封闭能力综合评价研究——以兴9枯竭气藏为例

COMPREHENSIVE EVALUATION OF SEALING ABILITY OF MUDSTONE CAP ROCK FOR XING 9 DEPLETED GAS RESERVOIR IN RECONSTRUCTING UNDERGROUND GAS STORAGE

盖层质量是决定枯竭气藏能够改建地下储气库的关键因素。在室内试验的基础上,建立基于全应力–应变特征的盖层岩石脆性评价模型,综合盖层常规物性封闭和岩石力学2种评价方法,提出一种改进的储气库盖层质量综合评价方法。在对枯竭气藏储气库盖层影响因素进行详细分类和分析的基础上,提出了各评价指标的等级划分标准,建立枯竭气藏储气库盖层质量评价体系的目标层次结构模型,应用层次分析法确定模型中12项基本指标在评价体系中所占的权重,建立盖层质量评价的适宜度计算公式。将该方法应用于兴9枯竭气藏储气库盖层评价,评价结果与专家论证结果一致,表明该方法的有效性。

Quality of cap rock is a critical factor controlling the effective accumulation of natural gas for underground gas storages. In view of this,the brittleness evaluation model of cap rock is set up based on the complete stress-strain curves through lab tests. In combination with physical sealing method and rock mechanics method,a modified sealing evaluation method of cap rock is proposed. Based on the classification of the influence factors and the analysis of cap rock for gas storage of depleted gas reservoir,the index suitability standards of cap rock evaluation for gas storage are put forward. Then taking the analytic hierarchy process,a layer structural model of sealing evaluation is built and the importance weights of 12 influence factors are calculated. Combined with the importance weights of influence factors,a formula is developed to calculate the synthetical appropriate value of cap rock. This method is used to evaluate the suitability of Xing 9 gas reservoir and evaluation result of cap rock is consistent with the expert opinions,which shows that this method is reasonable.