Evaluation On The Economic Recovery Of CBM In Jiergalangtu Sag

In this paper,the key parameters affecting the development of CBM are discussed,and a method for evaluating the economic recoverability of CBM is put forward,that is,taking the technical recoverable resource abundance as an important evaluation index and complementing with the economic evaluation of wells to study,and finally using the technical recoverable resource abundance to demarcate the economic benefits of wells.The evaluation of recoverability is divided into four steps:resource abundance evaluation,feasible resource abundance evaluation,theoretical recovery prediction and technical recoverable resource abundance evaluation.The economic benefit evaluation of wells is to calculate the input-output of single well on the basis of the production matching and prediction of typical wells.The results show that the thickness of coal seam is large,the gas content is low,and the resource abundance is high in the Jiergalangtu sag.The resource abundance is higher than 0.5×10~8 m~3/km~2.And it is high in the middle of the sag and gradually becomes low around.The thickness proportion of simple coal structure in 3#and 4#is 72.27%and 88.9%respectively,and the coal seam has good feasibility.The most probable values of theoretical recovery of3#and 4#are 68%and 64%,respectively.Finally,the technical recoverable resource abundance is reduced to about 55%of that of resource abundance,but compared with that of resource abundance,the technical recoverable resource abundance comprehensively considers two aspects of coal structure and theoretical recovery,which is more practical for the technical development of CBM,and the accumulated abundance of technical recoverable resources is still higher than 1×10~8 m~3/km~2,which is favorable for the development of CBM.After 20 years,the IRR of Jimei 11 and 15 is10.29%and 17.33%respectively,and the accumulated after tax discounted cash flow in20 years is 3.6×10~5 yuan and 2.5×10~7 yuan respectively.There is a good corresponding relationship between the technical recoverable resource abundance and IRR.When the accumulated abundance of technical recoverable resources of the main coal seams in the study area is 1×10~8 m~3/km~2,the IRR is about 5.7%.The IRR in the middle of the sag is relatively high,with an average of 13.12%.The wells in the middle of the sag are more economically recoverable.