河北省煤系天然气资源及其成藏作用

为摸清河北省煤系天然气资源潜力,揭示其耦合成藏作用,采用等温吸附、TOC含量测试、X衍射、岩石热解、高压压汞、液氮吸附、显微组分镜鉴、脉冲渗透率等试验测试,对源-储地化和物性特征进行研究,结合各赋煤构造区煤系沉积-构造演化史,进行煤系天然气资源评价并揭示其成藏作用。结果显示:河北省煤系天然气资源丰富,煤层气资源量39 015×108m3,页岩气资源量33 447×108m3,致密砂岩气资源量24 000×108m3,石炭二叠系占绝对优势;烃源岩有机质以Ⅲ型为主,成熟度Ro介于0.5%~3.0%,以成熟—过成熟阶段为主;煤对煤系天然气藏起决定作用,富有机质泥页岩起关键作用,泥页岩的厚度优势弥补了有机质"欠缺";煤系储层连通性较好,属低孔低渗型,二次生烃作用是煤系天然气成藏的关键;共生调节机制煤层气表现为层间调节,页岩气为层内调节,砂岩气为协调调节;基于共生调节机制和空间叠置关系,将煤系天然气藏分为"远源"致密砂岩气藏、"自源"页岩气/煤层气藏和"自源+他源"叠合气藏3类,后者包括3种成藏模式。

Resources and reservoir formation of unconventional gas in coal measure,Hebei Province

In order to find out the potential of the unconventional gas resources in coal measure and reveal its effect of coupling reservoir in Hebei Province,the geochemical and physical characteristics of coal measure reservoir were investigated by adsorption isotherm experiment,total organic (TOC) measurement,X-ray diffraction experiment,Rock-Eval experiment,high-pressure mercury intrusion experiment,low temperature N2 adsorption experiment,macerals identification and pulse permeability,et al.The unconventional gas resources in coal measure were evaluated and its reservoir formation was revealed combining with the evolution history of coal measure sedimentation-tectonic.The results show that the unconventional gas in coal measure is abundant in Hebei Province,with 39 015×108 m3 coalbed methane (CBM),33 447×108 m3 shale gas and 24 000×108 m3 tight sandstone gas,which is dominated by the Permo-Carboniferous.The organic types are mainly type Ⅲ,and the Ro between 0.5% to 3.0%,which are mainly at the mature to over mature stage.Coal plays a decisive role and organic-rich mud-shale plays a key role on coal measure reservoir,while the thickness of the mud-shale makes up the deficiency of organic matter.The connectivity of coal measure reservoir is good and overall is low porosity and permeability,the second hydrocarbon-generation is the key to coal measure reservoir.In terms of symbiotic regulation mechanism,CBM behaves as a layer adjustment,shale gas behaves as a layer of regulation and tight sandstone gas behaves as a coordination adjustment.Three types of coal measure reservoirs were distinguished by symbiotic regulation mechanism and spatial overlap,including the “far-source” tight sandstone gas reservoir,the “self-source” shale gas/CBM reservoir and the “self-source and other-source” superimposed gas reservoir,three patterns were introduced to clarify the characteristics of the latter type reservoir.