致密油储层微观特征及其形成机理——以鄂尔多斯盆地长6—长7段为例

发布时间：2018-03-16 15:28

本文选题：微观特征　切入点：形成机理　出处：《石油与天然气地质》2017年01期 　论文类型：期刊论文

【摘要】：鄂尔多斯盆地陇东地区长(延长组)6段和长7段富含大量致密油,但由于对其微观特征与成因缺乏深入了解,阻碍了该区致密油的有效开采。为此,根据岩石孔隙铸体薄片、场发射扫描电镜等技术,对研究区长6段和长7段致密油储层微观特征及其成因进行了深入研究。结果表明:研究区致密油储层形成于三角洲前缘远端远砂坝-席状砂及半深湖-深湖重力流沉积环境,岩石粒度细(主要为极细砂岩、粉砂岩、泥质粉砂岩及粉砂质泥岩)、杂基含量高(8%~10%),几种储集岩的孔隙均极不发育,面孔率低,平均1.8%,孔径小(平均30μm),喉道细(平均0.08μm),平均孔隙度9%,渗透率基本上都低于0.3×10~(-3)μm~2,物性差。孔隙类型主要为粒间杂基微孔、长石及岩屑溶孔、胶结物晶间微孔。不同岩石类型其微观特征存在差异。沉积环境决定了其粒度细、粘土杂基高,细粒高粘土杂基岩石抗压性差,强烈的压实作用导致大量的原生孔隙损失,孔喉变得更加细小;孔喉细小的岩石由于孔隙中各种流体离子的半渗透膜效应引起强烈的碳酸盐和粘土矿物胶结,尤其是伊利石搭桥状和丝网状胶结,使岩石孔隙度渗透率进一步变差,后期酸性流体也难以进入发生溶蚀作用;云母与水云母杂基及碳酸盐胶结物对石英的强烈交代导致岩石抗压性变差以及固体体积增加,最终导致岩石的致密化。
[Abstract]:The Chang (Yanchang formation No. 6 and Chang 7 member) in Longdong area of Ordos Basin is rich in a large amount of dense oil, but the lack of a deep understanding of its microscopic characteristics and genesis hinders the effective exploitation of dense oil in this area. Therefore, according to the thin section of rock pore casting, Field emission scanning electron microscopy, The microcosmic characteristics and genesis of dense oil reservoirs in Chang6 and Chang7 members of the study area are studied. The results show that the tight oil reservoirs in the study area were formed in the distal delta front bar sheet sand and the semi-deep lacustry-deep lake gravity flow sedimentary environment. Fine grain size of rocks (mainly very fine sandstone, siltstone, argillaceous siltstone and silty mudstone), high content of complex base 8 ~ 10 ~ 10, porosity of several types of reservoir rocks are extremely undeveloped, and the porosity of several reservoir rocks is low. The average pore size is 1.8 渭 m, the pore diameter is small (30 渭 m ~ (-1) on average, the throat is fine (0.08 渭 m ~ (-1) on average, the average porosity is 9%, the permeability is basically less than 0.3 脳 10 ~ (-3)) 渭 m ~ (-2), and the physical properties are poor. The pore types are mainly intergranular micropores, feldspar and lithic micropores, The micropores of cemented materials are intergranular. The microcosmic characteristics of different rock types are different. The sedimentary environment determines the fine grain size, the high clay heterogeneity, the poor compressive resistance of fine grained clay complex rock, and the strong compaction results in a large number of primary pore loss. The pore throat became finer; the pore throat fine rock caused strong carbonate and clay mineral cementation due to the semi-permeable membrane effect of various fluid ions in the pore, especially the Illite bridging and silk mesh cementation. The porosity and permeability of rock become worse, and it is difficult for acid fluid to dissolve in the later stage, and the strong metasomatism of mica, hydromica hetero group and carbonate cement to quartz leads to the deterioration of rock compressive resistance and the increase of solid volume. Finally, the densification of the rock.
【作者单位】：中国石油大学(北京)油气资源与探测国家重点实验室;中国石油大学(北京)地球科学学院;
【基金】：国家科技重大专项(2016ZX05002-004-009) 国家自然科学基金项目(41072104)
【分类号】：P618.13

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