Logging evaluation of the transformability potential for deep coalbed methane reservoir:a case study of SN Block
Deep coalbed methane is a new hot spot in China,and the transformability evaluation is an im-portant technical guarantee for its effective development.By taking SN Block as an example,combined with the geological and fracturing construction data,the logging interpretation of key compressible parameters such as porosity,gas content,coal structure and ground stress has been carried out to make clear the com-prehensive evaluation parameters and methods.The results indicate that①SN block is mainly composed of medium and low ash coal,which has great resource potential and a transformable material basis.②Based on GSI and combined spring models,a coal structure and rock mechanics interpretation model is established,which has strong applicability.The calculation show that the coal structure in this area is complex,and the intact coal,the cataclastic coal and the granulated coal are developed.The average maximum horizontal principal stress is 32.21 MPa,the minimum is 20.31 MPa,and the stress difference coefficient is 0.32～1.26,with big differences exists.③A comprehensive weight method is used to establish the evaluation model of deep coalbed methane transformability parameters,and it is pointed out that coal structure,stress difference coefficient,gas content and porosity are the key factors restricting the transformability.Based on the parameters,it is divided into four model types,which can provide theoretical basis for the effective de-velopment of deep coalbed methane.
deep coalbed methanetransformabilitylogging evaluation
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