气藏盖层封气能力评价方法的改进及应用——以我国46个大中型气田为例

通过统计我国46个大中型气田得到盖层厚度、排替压力、断裂对盖层破坏程度、气藏压力和天然气粘度是影响我国大中型气田盖层封气能力的主要因素。根据这5个主要因素与盖层封气能力作用关系，改进了气藏盖层封气能力评价方法，利用此方法对我国46个大中型气田盖层封气能力进行了评价，结果得到我国46个大中型气田盖层封气能力等级以差为主，其次是中等封盖保存能力的大中型气田，再次是好封盖保存能力的大中型气田，最少为较好封盖保存能力的大中型气田。通过我国46个大中型气田盖层封气能力与其储量丰度之间关系研究得到，二者之间为正相关关系。中等盖层封气能力的大中型气田平均储量丰度最高;其次是较好盖层封盖保存能力的大中型气田;最低的是好和差盖层封盖保存能力的大中型气田。这表明盖层封气能力并不是我国高储量丰度大中型气田形成的唯一主控因素，其储量丰度高低还要受到其它成藏条件的制约。

Improvement and Application of the Methods of Gas Reservoir Cap Sealing Ability

Through statistics,it is concluded that the thickness and displacement pressure of cap rock, destroy degree of cap rock from fault, pressure of gas reservoir and gas viscosity are the main factors that influence the gas reservoir cap sealing ability of 46 large and medium gas fields in China. According to relationship between them and sealing and preservative ability of gas reservoirs, this paper has corrected an evaluation method of sealing and preservative ability of gas reservoirs, and evaluated for sealing and preservative ability of large and medium gas fields in China by the method. Finally it is concluded that sealing and preservative ability of 46 large and medium gas fields in China were bad in the main, followed by the middle, again best, and at least were better. Through the study of the sealing and preservative ability of cap rock and gas reserves abundance of 46 large and medium gas fields in China, this paper considered that there was a direct correlation between them. The average reserves abundance of gas fields sealed and perseverated by medium cap rock is the highest, followed by better cap rock. The minimum is best and bad cap rock. It indicates that sealing and preservative ability is not the only main factors controlling formation of large and medium gas fields with high reserve abundance in China. The reserve abundance of large and medium gas fields was yet controlled by other main factors.