黄陵二号煤矿油型气赋存微观特征及富集规律

Microscopic Characteristics and Enrichment Law of Oil-type Gas Storage in Huangling No.2 Coal Mine

明确岩体微观结构特征是研究油型气赋存规律的基础。矿物颗粒通过特定的排列和结合形成了主要由孔隙组成的储集空间,孔隙性的好坏直接决定岩层储存油气的数量。针对黄陵二号煤矿岩样,本文分析了油型气储集空间类型及孔隙微观结构,研究了砂岩的成岩作用对油型气的影响,并得出了试验工作面的油型气富集规律。研究表明黄陵二号煤矿延安组岩心孔隙度在0.5%~23.8%之间,渗透率在(0.1~2979.3)×10^(-3)μm^(2)之间,总体物性较好,油型气赋存岩石类型以中-细粒岩屑长石砂岩、长石岩屑砂岩为主。油型气储集空间与油、气运移,聚集关系密切。通过油型气成藏要素分析发现黄陵二号煤矿的主要生储盖组合是下生上储的组合类型。煤层顶板油型气赋存受到构造、储集层厚度、储集层岩性、封盖条件、烃源岩条件等因素共同控制,预测217工作面煤层顶板垂深35m处油型气出现富集。

Defining the microstructural characteristics of the rock body is the basis for the study of oil-type gas accumulation law.Mineral particles form reservoir spaces mainly composed of pores through specific arrangements and combinations,and the quality of porosity directly determines the amount of oil and gas stored in rock formations.For the rock samples of Huangling No.2 Coal Mine,this paper analyzes the type of oil-type gas storage space and pore microstructure,studies the effect of diagenesis of sandstone on oil-type gas,and derives the oil-type gas enrichment law of the test workings.The study shows that the porosity of the core of Yan’an Formation in Huangling No.2 Coal Mine ranges from 0.5%to 23.8%,and the permeability is between(0.1~2979.3)×10^(-3)μm^(2),with good physical properties in general,and the rock type of the oil-type gas storage is dominated by the medium-fine grained clastic feldspathic sandstones and feldspathic clastic sandstones.The oil and gas storage space is closely related to oil and gas transportation and aggregation.Through the analysis of oil and gas formation and storage elements,it is found that the main storage cover combination of Huangling No.2 Coal Mine is the combination type of lower and upper storage.The oil-type gas storage in the top plate of coal seam is controlled by the tectonic structure,thickness of reservoir layer,lithology of reservoir layer,capping condition and hydrocarbon rock condition,etc.It is predicted that the oil-type gas will be enriched in the top plate of the coal seam at the depth of 35 m in the working face of No.217 mine.