依据密度测井资料评估煤层的含气量

煤层甲烷长期以来认为是对采煤工作的危害，只是近十多年来才被认为是一种潜在的能源。煤层不仅是甲烷的储层，而且是甲烷的源岩。煤的物理结构是一种双重孔隙结构，即煤层中含有由基质孔隙和裂缝孔隙组成的孔隙系统。煤层中的气（甲烷）主要吸附在基质孔隙的内表面，是吸附气，而不是存在于骨架粒间的孔隙空间内，因而传统的评价天然气储层含气量的方法虽然不能适合于评估煤层的气含量。本文利用密度测井资料和煤样煤质化验资料确定

EVALUATING GAS CONTENT OF COALBEDS FROM DENICTY LOG DATA

Coal Methane have long been known to be risky for exploiting a coal mine, it is considered to be a viable source of energy in recent ten years or more. The coal seam not only serves as a reservoir for methane but also serve as its own source rock. The structure of coal is generally considered to be dual porosity structure. The dual porosity system made up of primary porosity and cleat porosity in the coal foimation. Methane molecules are physically attached to the micropore walls of the coal matrix and not stored in the micropore space The Project Supported by National Natural Science Foundation of China (49474235) of the coal matrix .Coal Methane is adsorption gas,So the convertional method of evaluating gas reservoir isn't suitable for evaluating gas content of coalkeds. This paper determines coal ash content, fixed carbon content and coal pore pressure from density log data (these paramters are relation to the gas content of coalbeds). Combined these paramterswith core-measure gas content, The evaluating equation of coalbed gas content is established. Last, compared the evaluatied gas content with the core-measure gas content, the evaluated degree of accuracy is deteimined. The effectiveness of the evaluatied methad and the agreement between predicted and measured gas concent can be seen clearly by this example.