Log Interpretation And Evaluation Of Tight Sandstone Gas Reservoir In H Area Of Central Henan Province

In order to tap the potential of coalfield logging data and serve for the evaluation of unconventional natural gas in the coal measure strata of central Henan Province,it is necessary to carry out tight sandstone gas logging evaluation based on Coalfield logging data.Therefore,this paper carries out the interpretation and evaluation of tight sandstone gas logging in H area of central Henan Province.In this paper,the tight sandstone reservoir of Shanxi Formation in H area of central Henan Province is taken as the research object.Firstly,the geographical location and structural background of the study area are introduced.Secondly,the original coal field logging data are corrected for environmental impact,normalized processing of coal field logging data and depth homing of core data,and the stratigraphic division and correlation of the block are completed according to the logging response characteristics based on the marker layer and auxiliary marker layer.Thirdly,the existing coal field test in the study area is combined Data,the relationship among lithology,physical property,electrical property and gas bearing property of the reservoir is analyzed;then,the logging qualitative identification of tight sandstone gas reservoir is carried out;then,based on the study of"four properties"relationship,the calculation model of shale content,porosity,permeability and gas saturation of the target interval in the study area is established,and the thickness,shale content,permeability and gas saturation of the target interval are summarized Finally,the comprehensive logging evaluation of tight sandstone gas reservoir in coal measures is completed by using the mathematical method of fuzzy comprehensive evaluation.The results show that the Xiangtan sandstone and Dachan sandstone in Shanxi formation of H area in the middle of Henan Province provide favorable conditions for tight sandstone gas reservoir in coal measure strata.The study of"four properties"relationship shows that Xiangtan sandstone and Dachan sandstone are mainly medium to fine grained sandstone,the rock is dense and hard,which directly leads to poor correlation between porosity and permeability.Through studying the distribution range of reservoir logging curve value,the gas bearing performance of the reservoir is obvious.Based on the data of coal field logging curve,rock electricity experiment parameter,formation water and electricity resistance rate and formation mineralization degree,the empirical model and regression statistical model are used to optimize and calculate the shale content,porosity,permeability and gas saturation in this area.The results show that the calculation method based on logging is applicable.The plane distribution rule of reservoir parameters in this block is summarized from the plane contour map:the distribution range of shale content is 2%³2%,the distribution range of porosity is2.29%³.36%,the distribution range of permeability is 0.008×10^-3?m²⁰.02×10^-3?m²,and the distribution range of gas saturation is 26.4%⁴4.0%.Combined with the plane isoline map drawn by reservoir parameters,the fuzzy mathematics comprehensive evaluation method is used to divide the reservoir I,II and III areas and complete the comprehensive evaluation of logging.