摘要
The determination of shale gas content is of great significance to the assessment of shale gas reserves and the identification of play fairway.Under the guidance of geologic theory,we performed a correlative analysis of factors that may influence shale gas content.In the Lower Silurian Longmaxi Fm shales in southeastern Chongqing,shale gas content may be influenced by various factors such as porosity,permeability,water saturation,TOC,Ro,clay content,quartz content,carbonate content and pyrite content.The effects of these potential factors are evaluated through normalized factors analysis,providing the criteria for eliminating the factors with minor effects on gas content from the initial set.Fast iterative clustering with Euclid distance and correlation was adopted to obtain the major controlling factors including TOC,porosity,quartz content and pyrite content.On this basis,a stepwise regression method was used to formulate the fitting equation for the correlation between gas content and these determined major controlling factors,which was also validated and found to be in consistent with the data from other well cores and outcrop samples.With this proposed correlation method,the shale gas in place in this study area is calculated to be 1.77 trillion m3,indicating that the study area is prosperous for future shale gas exploration and development.