Research On Comprehensive Evaluation Methods Of Tight Sandstone Gas Reservoirs

Tight sandstone gas fields are widely distributed in Chinese major basins,and its reserves are very rich,which is important for the future of Chinese exploration and development in unconventional natural gas resources.In this thesis,the tight sandstone gas reservoirs in Daning-Jixian area as the target block,taking into account both the commonness of tight sandstone gas reservoirs,and also highlight the personality of the target block.During the master through a lot of research work,the following results were obtained:(1)Based on well logging data,and according to the study of block reservoir mineral characteristics,the block reservoir of tight sandstone layer of clay content and porosity are analyzed and calculated.In the meantime,according to the calculation formula of penneability in the physical reservoir,the suitable calculation formula of penetration in the block in tight sandstone gas reservoir are established;(2)Using calculation model of reservoir permeability by pressure after the pressure drop,the effective penneability of the reservoir are analyzed and calculated,then contrasting and correcting the permeability by formula and the permeability by the model pressure after the pressure drop,the final prediction model of reservoir permeability is gotten;(3)By using the logging response characteristics of reservoir,the gas content of tight sandstone in the target block is analyzed qualitatively in this study,and the simple and intuitive judgment can be made in the field construction to improve the construction efficiency by using this method.In addition,by using the equivalent elastic modulus method and triple porosity difference ratio method,the tight sandstone gas reservoir is analyzed quantitatively too.The model needs less data,easily to be calculated,and has a high rate of correct judgment,also it will be able to meet the actual needs of the project;(4)By using grey correlation degree model to identify the gas content of tight sandstone gas reservoir,five kinds characteristic parameters which have a high correlation with the gas bearing reservoir,and comparing the grey correlation model with the standard model of reservoir fluid,based on this method,identifying reservoir fluid are identified.The result can meet the actual needs of the project and the accuracy rate of judgment is high;(5)By analyzing on the gas content of the tight sandstone gas reservoir,the gas content of the gas reservoirs in the target block are identified,then regarding the reservoir permeability and gas saturation as the input layer,using a neural network model to analyze the stable gas production of each well layer,meanwhile selecting the layer whose gas content is more than 1000m3/d.