盖层封闭天然气有效性定量评价方法及应用

Quantitative Evaluation Method of Sealing Gas Efficiency of Caprock and Its Application

为研究盖层在含油气盆地或凹陷内天然气聚集中的作用,在盖层封闭有效性及其与天然气富集关系研究的基础上,选取主要影响因素作为评价参数,利用模糊评价方法,建立了一套同时考虑盖层封闭天然气能力和时间有效性的盖层封闭天然气有效性定量评价方法,并将其应用于定量评价大港油田21个气藏盖层封闭天然气有效性,结果表明:大港油田21个气藏中有16个气藏盖层封闭天然气有效性定量评价权值大于零,封闭天然气有效性相对较好,有利于天然气聚集与保存;有5个气藏盖层封闭天然气有效性定量评价权值小于零,封闭天然气有效性相对较差,不利于天然气聚集与保存;有盖层封闭的天然气有效性越好,气藏储量丰度越高,反之则越低。这一评价结果与目前气藏储量丰度具有一定的正相关关系,表明该方法用于定量研究盖层封闭天然气有效性是可行的。

To study the role of caprock in gas accumulation in oil gas-bearing basin or depression,and on the basis of researches on sealing gas efficiency of caprock and its relation with gas accumulation, the main influence factors were selected as evaluation parameters and fuzzy mathematics evaluation method was used to establish a set of comprehensive quantitative evaluation method of sealing gas efficiency of caprock, considering both sealing gas ability efficiency and sealing gas time efficiency of caprock. This method was applied to the quantitative evaluation of sealing gas efficiency of caprock in 21 gas reservoirs of Dagang Oilfield. The results indicate that among 21 gas reservoirs of Dagang Oilfield, the comprehensive quantitative evaluation weight of sealing gas efficiency of eaprock in 16 gas reservoirs are greater than zero,and the sealing gas efficiency of caprock is relatively good, which is favorable for gas accumulation and preservation,while those in 5 gas reservoirs are less than zero and the sealing gas efficiency of caprock is relatively bad, which is not favorable for gas accumulation and preservation. The better the sealing gas efficiency of caprock is, the higher the reserve ahundanee is,and vice versa. There is some positive correlation between this evalua tion result and the current abundance of gas reservoir, indicating that this method used to quantify the sealing gas efficiency of caprock is feasible.