Key parameters identification for deep coalbed methane reservoir in Linxing block of eastern Ordos Basin

Key parameters identification for deep coalbed methane reservoir is a basis for its development. Based on the deep coalbed methane exploration and experiments in Linxing block of eastern Ordos basin,Langmuir volume increases and then decreases with vitrinite reflectance,Langmuir pressure varies like U-type with vitrinite reflectance,and the transform point of both is around 2. 5% Ro,max . Using nonlinear fitting method,a prediction model for deep coalbed methane content was established,and the correction coefficients deduced from relationship between measured gas satu- ration and burial depth were added into the model to assure the accuracy of the model. Gas contents of No. 4+5 coal in Shanxi formation vary between 6. 7 and 22. 1 m3 / t,while those of No. 8+9 coal in Benxi formation change from 12 to 20 m3 / t. The gas contents distribute as high in west and low in east. Critical desorption pressure of No. 4+5 coal vary between 1. 03 and 9. 4 MPa,and the ratios of critical desorption pressure and reservoir pressure change from 0. 11 to 0. 63,and averaged value is 0. 33. Critical desorption pressure of No. 8 +9 coal vary between 1. 27 and 10. 47 MPa, and the ratios of critical desorption pressure and reservoir pressure change from 0. 12 to 0. 64,and averaged value is 0． 334. Critical desorption pressure and ratios of critical desorption pressure and reservoir pressure of No. 4+5 coal distribute like high in west,low in east and highest in north-west,while those of No. 8+9 coal distribute as high in north and low in south.