块状致密砂岩的非均质性及对致密油勘探开发的启示  

HETEROGENEITY OF THE MASSIVE TIGHT SANDSTONES AND ITS INSPIRATIONS FOR THE EXPLORATION AND DEVELOPMENT OF THE TIGHT OIL

作　　者：尤源[1,2] 刘建平 冯胜斌[1,2] 贺静[1,2] 梁晓伟[1,2] 牛小兵[1,2] 

机构地区：[1]低渗透油气田勘探开发国家工程实验室,陕西西安710018 [2]中国石油长庆油田分公司勘探开发研究院,陕西西安710018 [3]中国石油长庆油田分公司油田开发处,陕西西安710018

出　　处：《大庆石油地质与开发》2015年第4期168-174,共7页Petroleum Geology & Oilfield Development in Daqing

基　　金：中国石油天然气股份有限公司重大科技专项"鄂尔多斯盆地致密油勘探开发关键技术研究"(2011E-2602)资助

摘　　要：应用CT技术对鄂尔多斯盆地延长组长7油层组块状致密砂岩样品进行扫描,发现外观均质的块状砂岩内部表现出明显的CT响应差异,并且由样品顶端至底端CT吸收值呈现出逐渐变低的递变趋势。据此对该砂岩样品不同部位取样,并进行铸体薄片分析。结果显示,该致密砂岩样品具有微观非均质性,在整体致密、可见孔隙少,压实和胶结作用明显的背景下,不同部位孔隙特征有差异。最显著的差异是样品底端广泛发育微裂缝,以条状延伸和顺层展布为主,并多见有机质充填。分析认为长7块状砂岩重力流滑塌成因机制造成微裂缝广泛分布,差异溶蚀造成孔隙分布不均匀。这种块状致密砂岩内部的微观非均质性,尤其是广泛发育的微裂缝对致密油勘探及开发具有重要意义,说明了储层微"甜点"的存在,也指出了储层改造潜在的有利部位。CT is adopted to scan the massive tight sandstone samples from Oil Group Chang 7 of Yanchang Formation of Ordos Basin, CT differential response is obviously presented in the inner part of the sandstones, although their appearances are pretty homogeneous, and moreover the CT absorption value of the samples shows a trend of variation from top to bottom. Just because of the above, the sampling from different parts of the sandstones is conducted and so does the analysis on the cast thin. The results show that the sandstone samples are characterized by microscopic heterogeneity, under the background of the overall tightness; few visible pores, obvious compaction and cementation, the characteristics of different parts of the pores are various. The most obvious difference is the micro-fractures at the bottom of the samples are well-developed, these micro-fractures are belt like and spread as bed parallel, and moreover the filled organic materials are often found. The analyses show that the wide-spread mi- cro-fractures are resulted from the slumping mechanism of the gravity flow of Chang 7 massive sandstones, and moreover so done the heterogeneous distribution of the pores from differential solution and corrosion. The micro-heterogeneity within the sandstones, especially the wide-distributed and well-developed mircofractures possess important significances for the exploration and development of the tight oil. All the achievements show that there are small ＂ sweet spots＇＂ in the reservoirs, and furthermore the favorable parts of the potential reservoirs to stimulate and eonstruet are presented as well.

关 键 词：鄂尔多斯盆地 致密油 长7油层组 块状砂岩 CT技术 微裂缝 

分 类 号：TE311[石油与天然气工程—油气田开发工程]