煤层气损失气量计算的全脱分析法

A new method for calculation of lost coalbed methane

针对目前煤层气损失气量无法计算煤层的溶解气和游离气含量问题,根据烃类气体进入钻井液的方式和分布状态理论,基于气测录井资料,提出了计算煤层气损失气量的新方法——全脱分析法。通过沁水盆地枣园区块3号煤层的实际应用,发现该方法计算的损失气量明显高于常规煤心样品的回归结果,前者一般为后者的1.5-4.5倍。该方法不仅能有效地解决煤层气损失气量计算中忽视的溶解气和游离气问题,而且还能消除损失时间的影响,同时也可以按不同部位计算煤层气损失气量。该方法适用于不同煤级、各种结构的煤岩,数据易采集,计算过程简单,有很好的应用前景。

Aiming at the problem that dissolved gas content and free gas content can not be calculatd by lost gas content,based on gas logging data,a new method,named total degassed hydrocarbon analysis,was proposed for computing lost coalbed methane.In the practical application of the method for the No.3 coal seam in Qinshui basin,it was found that the lost gas content obtained by this method was significantly higher than that by conventional coal core sample regression method,and the former is generally 1.5 to 4.5 times higher than the later.In one hand this method can not only effectively solve the problem ignoring of dissolved gas and free gas in coalbed gas content calculations,but also eliminate the impact of lost time.In addition this method is able to calculate the lost gas for different coal seam parts.This method is promising in lost gas calculation because it is easy to collect data,has simple calculation process and is widely applicable in coal with different rank and various structures.