Logging Evaluation Of Coalbed Methane Of Shanxi Formation In LJ Area,Southern Qinshui Basin

In order to serve the exploration and development of coalbed methane in LJ block of southern Qinshui Basin,this paper takes 3#coal of Shanxi Formation as the main research object to carry out fine evaluation of coalbed methane logging.Based on a large number of literature research and geological data,well logging data and test data in the study area,this paper carries out research on data preprocessing of coalbed methane Wells,research on logging response characteristics of coalbed methane reservoirs,formation division and correlation,research on industrial components of coalbed methane reservoirs,research on interpretation methods of physical property parameters of coalbed methane reservoirs,calculation of gas content of coalbed methane reservoirs,research on rock mechanics characteristics of coal seam roof and favorable zoning and classification of coalbed methane reservoir in the study area.The results show that the gamma-acoustic time difference cross plot has the best lithology identification effect based on logging response.The stratum thickness is stable,and the microstructure is low in the northwest and high in the east and northeast.The logging response intersection method is not effective in distinguishing coal body structure,so the Extra Trees method is used to divide coal body structure,and the identification effect is better.It can be seen that the study area is mainly composed of block pulverized coal and pulverized coal,but less lump coal.Based on the coal and rock test data,regression method and volume model method are used to carry out modeling analysis of the industrial components of coal in the study area No.3,and the regression analysis method is preferred to predict the industrial component content.The total porosity of the study area was calculated by the inverse skeleton density and the fracture porosity was estimated by the simplified Archie formula,and the overall distribution of porosity was between 3%-5%.The permeability of the study area was predicted based on the F-S method,Darcy’s law and KNN method.The KNN regression method was preferred to predict the permeability,and the predicted permeability distribution was between 0.5-1.2×10^-3μm².Kim method regression analysis and BP neural network technology were used to predict the gas content in the study area.The results showed that BP neural network method had a high prediction degree.Based on acoustic logging data and density logging data,the prediction model of elastic parameters and strength parameters of the roof of No.3 coal seam in the study area is obtained by Extra Trees regression method.By optimizing the comprehensive evaluation parameters of coal reservoirs,the coal reservoirs in the study area are divided intoⅠ,Ⅱ and Ⅲclasses by fuzzy mathematics method.The research results of this paper provide a certain result support for the design of coalbed methane reservoir development scheme in the study area,and the relevant methods have a certain reference significance for related logging geological research.