Microscopic pore structure of shale oil reservoirs in the Lower 3<sup>rd</sup>Member of Shahejie Formation in Zhanhua Sag, Bohai Bay Basin

Zhang Leilei; Lu Zhengyuan; Wang Jun; Tian Tonghui; Wang Xingjian

doi:10.11743/ogg20160111

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Microscopic pore structure of shale oil reservoirs in the Lower 3^rdMember of Shahejie Formation in Zhanhua Sag, Bohai Bay Basin
Vol. 37, Issue 1, Pages: 80-86(2016)
Online First：08 February 2016，

Published：2016
DOI： 10.11743/ogg20160111
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DOI：

Zhang Leilei, Lu Zhengyuan, Wang Jun, et al. Microscopic pore structure of shale oil reservoirs in the Lower 3^rdMember of Shahejie Formation in Zhanhua Sag, Bohai Bay Basin[J]. 2016, 37(1): 80-86. DOI: 10.11743/ogg20160111. DOI：

摘要

通过岩心观察、薄片鉴定、X-衍射、物性和有机质等分析测试工作，揭示了页岩油储层矿物成分、物性、有机质和岩性等地质特征，并在此基础上利用氩离子抛光-扫描电镜技术，分析研究了页岩油储层孔隙类型、结构等特征及其对储集性的影响。测试和研究表明，渤海湾盆地沾化凹陷沙河街组三段下亚段（沙三下亚段）矿物成分主要为粘土矿物、碳酸盐矿物和陆源碎屑，孔隙度和渗透率均很低，有机碳含量为0.52%～9.32%，干酪根类型为Ⅰ型，镜质体反射率（R

）为0.7%～0.93%，岩性主要为泥质灰岩、灰质泥岩和含泥质灰岩，含少量灰质白云岩。通过氩离子抛光-扫描电镜实验，对罗69井10块钻井岩心样品进行了定性观察和定量统计。根据孔隙特征将孔隙分为微孔隙和微裂缝，微孔隙包括粒间孔、晶间孔、溶蚀孔和晶内孔。微裂缝、溶蚀孔、大孔径晶间孔和粒间孔是页岩油储层的主要储集空间。因主要孔隙类型和发育情况不同，不同岩性的岩石储集性存在差异，灰质白云岩储集性最好，灰质泥岩、泥质灰岩和含泥质灰岩依次变差，灰岩最差。

Abstract

Core observation

thin section identification

X-ray diffraction

physical property and organic matter testing are integrated to reveal the mineral composition

physical properties

organic matter and lithology of the shale oil reservoirs in the Lower 3

Member of Shahejie Formation in Zhanhua Sag

the Bohai Bay Basin.And the characteristics of pore types and structure and their influences on reservoir property are analyzed by using Argon-ion milling and scanning electron microscope (SEM) technique.The mineral compositions of the target strata are dominated by clay

carbonate and terrigenous clastics.Both the porosity and permeability are low.The kerogen belongs to type I with high total organic carbon (TOC) content in the range of 0.52%~9.32% and vitrinite reflectance (R

) in the range of 0.7%~0.93%.The lithologies are dominated by argillaceous limestone

limy mudstone and mud bearing limestone

with minor limy dolomite.With Argon-ion milling and SEM method

we studied 10 core samples from Well Luo 69 via qualitative analysis and quantitative statistics.According to the pore characteristics

pores can be divided into micropores and microcracks.The micropores can be further subdivided into intergranular pore

intercrystalline pore

dissolved pore and intracrystalline pore.The microcracks

dissolved pores

large intercrystalline pores and intergranular pores provide the main reservoir space for the shale oil reservoir.Pore types and distribution vary with different reservoir lithologies

which control the reservoir storage capacity.The limy dolomite is the best in storage capacity

followed by limy mudstone

argillaceous limestone and mud bearing limestone

and the limestone is the least.