2016年2期

湘中地区邵阳凹陷二叠系页岩储集物性特征研究

发布时间:2016-09-05阅读次数:

【期数】2016-2

【作者】张国涛,陈孝红,张保民,李 海

【机构】中国地质调查局武汉地质调查中心,武汉 430205

【关键词】邵阳凹陷;二叠系;岩矿特征;微观孔隙特征;比表面积;控制因素

【中文摘要】基于全岩、粘土矿物X射线衍射、低温氮气吸附实验等手段,结合有机地球化学等参数对邵阳凹陷二叠系页岩储层物性特征进行了深入的研究,并探讨了页岩储集物性的控制因素。分析结果表明:1)页岩矿物成分中普遍具较高的脆性矿物含量,这能提高页岩孔隙度,并有利于储层开发过程中的压裂,然而相对低的粘土矿物含量可能会降低页岩储层吸附性;2)页岩孔隙大小以微孔、中孔为主,两者贡献了绝大部分的比表面积、总孔体积,仅存在的少量大孔对于比表面积与总孔体积的影响较小。孔隙形态普遍为具平行板壁的狭缝形,且开放性良好。3)有机碳含量与粘土矿物含量是页岩比表面积、总孔体积的主要控制因素,平均孔径的分布特征与比表面积、总孔体积之间呈现一定反相关性,即越小平均孔径的页岩,能够提供的比表面积与总孔体积越大。热演化程度对于页岩孔隙发育的影响具正反两面性,在相关性分析并没有发现它们之间具明显的规律性。

【英文摘要】In an attempt to elucidate the physical properties of the Permian shale reservoirs in the Shaoyang sag, we have investigated mineral composition and content of shales by using X-ray diffraction method, and measuring surface area and pore volume of shales by the method of BET ( low temperature nitrogen adsorption method), then discussed the controlling factors of the physical properties of reservoir through combing with the organic geochemistry of shale reservoir. The analysis result shows that: 1) the Permian shales generally have a high content of brittle mineral composition, which may improve the shale porosity, and facilitate fracturing for shale gas reservoir in the process of development, but it can be reducing adsorption for shale reservoirs due to low level of clay minerals; 2) shale pore size is characterized mainly by micropore and mesopore, which both contribute vast majority of specific surface area, total pore volume, only a few large pore were less affected for the specific surface area and total pore volume. The morphology of pore is generally narrow with parallel plate, good openness. (3) the content of organic carbon and clay minerals dominate mainly shale specific surface area and total pore volume of shale, the correlation between average pore size and surface area, total pore volume are negative, it means that the shales with smaller average pore size can provide larger specific surface area and total pore volume. In addition, due to two sides of the influence of thermal evolution degree on the development of shale pore, there is no obvious regularity between thermal maturity and surface area, total pore volume.

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