“煤岩气”概念的探讨与辨析  

Discussion and analysis on the concept of"coal-rock gas"

作　　者：傅雪海[1,2] 张宝鑫 康俊强 FU Xuehai;ZHANG Baoxin;KANG Junqiang(MOE Key Laboratory of Coalbed Methane Resource&Reservoir Formation Process,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)

机构地区：[1]中国矿业大学煤层气资源与成藏过程教育部重点实验室 [2]中国矿业大学资源与地球科学学院

出　　处：《天然气工业》2025年第3期46-53,共8页Natural Gas Industry

基　　金：国家自然科学基金项目“准南急倾斜储层深部孔渗与含气量随埋深非线性变化的机理研究”(编号:42072190)。

摘　　要：深部煤层气中游离气占比高导致其产出特征与浅部煤层气呈现出差异,部分学者提出“煤岩气”概念来表征深部煤层气,但煤层气与“煤岩气”的赋存载体均为煤层,“煤岩气”是否具有独立于煤层气的特殊特征有待商榷。为此,通过对比分析煤层气与“煤岩气”的气源特征、赋存相态、资源量/储量计算参数等地质和开发特征,探讨了是否有必要提出“煤岩气”的概念。研究结果表明:(1)“煤岩气”存在外源气混入是其与煤层气的区分标志之一,但煤层气定义本身未强调气源,煤层气由生成至保存普遍经历了运移过程,准噶尔盆地南缘地区、鄂尔多斯盆地黄陵矿区浅部的侏罗系煤层气亦有外源气混入;(2)深部温度对煤储层吸附负效应影响下,游离气比例增大已是煤层气领域研究的共识,吸附气临界深度等概念已得到业界认可;(3)煤层气研究对吸附态、游离态及水溶态含气量关注已久,含气量及地质储量计算已考虑了三相态含气量;(4)“煤岩气”排水期较短,开井较快产气等特征是因为深部游离气含量高占据水相空间,一方面导致深部煤储层含水量低,另一方面游离气产出后储层压力下降导致吸附气解吸,只是降压方式发生了变化,但仍遵循煤层气降压解吸机理,产出过程符合先游离气产出、稳产期依赖吸附气接替的规律,无水煤层、受次生生物气和气水分异影响的浅部煤储层压裂后也快速产气。结论认为,“煤岩气”地质与开发特征尚未脱离煤层气的范畴,提出“煤岩气”概念反而会导致语义重复、同一煤层浅、中、深部“煤岩气”与煤层气存在转换等问题,现阶段分析成果未体现定义“煤岩气”的必要性。The high proportion of free gas in deep coalbed methane(CBM)leads to differences in production characteristics from shallow CBM.Some scholars have proposed the concept of"coal-rock gas"to represent the deep CBM.However,"coal-rock gas"and CBM are both reserved in coal seams,and it is debatable whether the"coal-rock gas"has special characteristics independent of CBM.In this paper,whether it is necessary to propose the concept of"coal-rock gas"is discussed by comparatively analyzing CBM and"coal-rock gas"from the aspects of gas source,occurrence phase state,resource/reserve calculation parameters and other geological and exploitation characteristics.The following results are obtained.First,the exogenous gas introduced in"coal-rock gas"is one of the signs that distinguish"coal-rock gas"from CBM.However,the definition of CBM does not emphasize the gas source,and CBM generally undergoes a migration process during its generation to preservation.For example,there is also exogenous gas in shallow Jurassic CBM in the southern margin of the Junggar Basin and the Huangling Mining Area of the Ordos Basin.Second,a consensus that the negative effect of high temperature on coal reservoir adsorption in the deep part leads to the increasing proportion of free gas has been reached in the field of CBM research,and the concepts such as critical depth of adsorbed gas have been widely recognized in the industry.Third,CBM research has paid attention to the content of adsorbed gas,free gas,and water soluble gas,which have been included in the calculation of gas content and geological reserves.Fourth,the reasons for the characteristics of"coal-rock gas"such as short drainage period and fast gas production after well startup are that the high free gas content occupies the water space,leading to a low water content in deep coal reservoirs,and the decreasing reservoir pressure after the production of free gas results in the desorption of adsorbed gas.The pressure drop pattern changes,but it still follows the mechanism of CBM depressurization

关 键 词：煤层气 “煤岩气” 地质特征 开发特征 游离气 吸附气 水溶态含气量 必要性 

分 类 号：P168.11[天文地球—天文学]