低渗透火山岩气藏储层评价指标刍议

A preliminary view about indexes of low permeable volcanic reservoir evaluation

低渗透火山岩气藏储层在中国发现较晚,对其储层特征进行评价还缺乏合适的标准。通过兴城气田典型低渗透火山岩气藏储层特征与火山岩油藏储层评价指标的对比,认为火山岩油藏储层评价标准中的有效渗透率、基质空气渗透率和有效厚度指标不适合对低渗透火山岩气藏储层进行评价。为此,须建立低渗透火山岩气藏储层评价标准,以便更准确地对火山岩气藏储层作出评价。笔者利用岩心、录井、测井和试油资料,在对兴城气田火山岩储层定量描述参数(有效渗透率、基质有效孔隙度、基质空气渗透率和平均孔喉半径)和定性描述参数(岩相、岩性、储集空间和储层产状)研究的基础上,结合试油成果,建立了低渗透火山岩气藏储层分类评价标准。该标准确定的有效渗透率、基质空气渗透率指标值明显较火山岩油藏储层标准低,更适用于低渗透火山岩气藏储层的评价。同时,该标准也为具有相似特征的火山岩气藏储层评价提供了借鉴。

Low permeable volcanic gas reservoirs were found later in China,so it is lack proper criterion for their reservoir characteristic evaluation. According to comparison between typically low permeable volcanic reservoirs characterizations of Xingcheng gas field and index of volcanic petroleum reservoirs evaluation,it is found that some indexes of volcanic petroleum reservoir evaluation criterion,such as effective permeability,matrix air-permeability and net thickness,do not adapt to low permeable volcanic gas reservoirs evaluation. Therefore,it is necessary to establish a new evaluation criterion to fit and more correctly evaluate the low permeable volcanic gas reservoirs. Making use of information of core,well logging,and testing for oil,the low permeable volcanic gas reservoirs classification evaluation criterion was established with quantitatively describing parameters (effective permeability,matrix effective porosity,matrix air-permeability and average throat radius)and qualitative parameters (petrologic facies,lithology,accumulating vacuity and reservoir occurrence) of volcanic rock reservoirs in Xingcheng gas field. Effective permeability and matrix air-permeability adopted by the criterion are obviously lower than those assured by volcanic petroleum reservoir criterion,and are more suitable to low permeable volcanic gas reservoirs evaluation. And the criterion is also helpful to other volcanic gas reservoirs evaluation with similar characteristics.