1.Key Laboratory of Coal Resources Exploration and Comprehensive Utilization，Ministry of Land and Resources，Xi’an ,China;2 .Shaanxi Coalfield Geology Investigation Institute Co.,Ltd.,Xi’an ,China;3.Shaanxi Coalfield Geology Co.,Ltd.,Xi’an ,China

黄陇侏罗纪煤田属于典型的低阶煤含煤层气区带,煤炭勘查结果显示其西部具有一定的煤层气开发潜力,为了弄清该煤层气成藏条件,以黄陇煤田永陇矿区麟北区为例,从煤层气地质、煤储层特征、气藏保存条件3个方面研究了黄陇煤田西部地区的煤层气成藏条件及主控因素。研究结果表明:黄陇煤田西部地区延安组煤变质程度低,煤层厚度大,埋深适中,含气性较好,但煤储层渗透性较差;煤层气富集主要受水动力条件影响,埋深其次,构造和盖层影响较小,埋深500~700 m是该区煤层气成藏的最佳深度;因受成煤后期燕山运动等多期次构造运动的影响,原生生物气和热成因气大量逸散,新生代以来煤层接受浅部地表水和大气降水的补给,接受次生生物气的补充,是煤层气成藏的关键,属典型的盆缘缓坡晚期生物成藏模式。

Huanglong Jurassic coal field belongs to the typical low-rank CBM-bearing zone.Coal exploration data shows that there are certain exploration potentials of CBM in the west,but the condition of CBM reservoir formation is not clear.Based on the above,this paper studied the CBM reservoir forming conditions in the western area of Huanglong Coalfield from three aspects:CBM geology,coal reservoir characteristics and gas reserving condition,taking Linbei area of Yonglong Mining Area in the west of Huanglong Coalfield as an example.The main controlling factors of CBM reservoir formation in the study area were analyzed.The results showed that the Yan’an Group in western area of Huanglong Coalfield was characterized by low coal metamorphism,thick coal seam,moderate burial depth and good gas bearing property,but the permeability of coal reservoir was poor.The CBM enrichment was mainly affected by the depth of burial and hydrodynamic conditions,and the influence of structure and cap layer was small.The depth of 500～700 m was the best depth of coalbed formation in the study area.In the late period of coal formation,the Yanshan movement was affected by many stages of tectonic movement.The original biogenic gas and thermogenic gas were dissipated.Since the Cenozoic,the coalbed had received shallow surface water and atmospheric precipitation,and received secondary biogas was the key to CBM accumulation.The formation of CBM reservoirs in the study area was typical of the late-stage biotallogenetic accumulation model of basin-margin.

国土资源部煤炭资源勘查与综合利用重点实验室资助项目(ZP2013-3)；陕西省科学技术研究发展计划资助项目(2016GY-187)；