Pore type classification scheme for continental Yanchang shale in Ordos Basin and its geological significance

Wang Xiangzeng; Zhang Lixia; Li Zongtian; Fu Haijiao

doi:10.11743/ogg20160101

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Pore type classification scheme for continental Yanchang shale in Ordos Basin and its geological significance
Vol. 37, Issue 1, Pages: 1-7(2016)
Online First：08 February 2016，

Published：2016
DOI： 10.11743/ogg20160101
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DOI：

Wang Xiangzeng, Zhang Lixia, Li Zongtian, et al. Pore type classification scheme for continental Yanchang shale in Ordos Basin and its geological significance[J]. 2016, 37(1): 1-7. DOI： 10.11743/ogg20160101.

摘要

鄂尔多斯盆地延长组陆相页岩储层作为一种非常规储集体，对于其孔隙类型划分，当前国内尚无针对性的划分方案。为此，充分调研了国内外页岩储层孔隙类型分类方案，并从中优选出Loucks和于炳松的分类方案，结合延长组陆相页岩孔隙类型扫描电镜观察结果，对Loucks和于炳松的分类方案适当修改，提出了针对性更强的延长组陆相页岩孔隙类型划分方案，以期为延长石油陆相页岩气的发展提供理论支撑。此外，通过氩离子抛光扫描电镜观察，分析了延长组陆相页岩储层孔隙类型发育特征，系统研究了各类孔隙的形成机制、发育规模及油气地质意义。实验结果表明，延长组陆相页岩中粘土集合体内矿物片间孔隙油气地质意义最大；其次为黄铁矿晶间孔隙、有机质孔隙、裂缝孔隙和粘土矿物片间孔隙；再次为刚性颗粒粒间孔隙及边缘孔；石英颗粒溶孔孔径小、连通性差，油气地质意义最小。

Abstract

The continental Yangchang shale reservoirs in Ordos Basin are unconventional reservoirs

for which no specific pore classification scheme is available.Based on an investigation of pore type classifications of both abroad and domestic

we selected two classification schemes suggested by Loucks and Yubingsong and proposed a new classification upon modification of the previous two by combining the actual observation data of samples taken from the Formation.Argon ion milling scanning electron microscope was employed to characterize and systematically probe into pore development(including forming mechanisms

scale and geological bearings)of the reservoirs.The results show that pores in between congregated mineral lamellae contribute most to oil and gas poolings and followed by pyrite intergranular pores

organic pores

microfractures and pores in clay mineral lamellae.Intergranular pores and edge pores of rigid particles are still less meaningful in terms of geological indication.Solution pores among quartz grains are believed to be the least important among all types of pores found in the reservoirs.