鄂尔多斯盆地西部长6砂岩致密化过程分析  

ANALYSIS ON DENSIFICATION PROCESS OF CHANG 6 SANDSTONES IN WESTERN ORDOS BASIN

作　　者：沈崇辉 周晓峰[2] 郭伟[3] SHEN Chonghui;ZHOU Xiaofeng;GUO Wei(China University of Geoscience,Beijing 100083,China;China University of Petroleum,Beijing 102249,China;Langfang Branch of Research Institute of Petroleum Exploration and Development,Petro China,Langfang 065007,Hebei,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国石油大学(北京)石油工程学院,北京102249 [3]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出　　处：《地质力学学报》2018年第6期776-784,共9页Journal of Geomechanics

基　　金：国家科技重大专项(2011ZX05013-006);国家级矿产资源综合利用示范基地项目(国土资厅发[2011]88号文件)

摘　　要：通过储层物性、铸体薄片和带能谱仪的扫描电镜,对鄂尔多斯盆地西部长6砂岩的致密化过程进行定量研究。研究表明,鄂尔多斯盆地西部长6超低渗透砂岩的原始沉积物孔隙度为39.3%,渗透率为22400×10^(-3)μm^2,其致密化过程分为2个阶段;早成岩阶段的压实作用和方解石及绿泥石膜胶结作用,导致砂岩的孔隙度和渗透率急剧下降到8.0%和0.17×10^(-3)μm^2,砂岩转化为超低渗透储层;中成岩阶段A期的油气充注成藏过程中,油气携带有机酸性流体进入超低渗透储层,长石与有机酸性流体发生反应,产生长石溶蚀孔隙,使孔隙度和渗透率提高到11.6%和0.61×10^(-3)μm^2;鄂尔多斯盆地西部长6超低渗透砂岩致密与成藏的配置关系为"先致密后成藏,边成藏边扩容增渗"。By core physical property,casting slice,scanning electron microscope analysis with energy disperse spectroscopy,the densification process of Chang 6 sandstones in western Ordos Basin was studied quantitatively. The study showed that the initial porosity and permeability of sandstones in the area were 39.3% and 22400×10 -3 μm 2 respectively,and its densification process was divided into two stages. In the course of early diagenesis stage,both calcite and chlorite coat cements and mechanical compaction caused the sandstones into ultra-low permeability reservoir whose porosity and permeability were 8.0% and 0.17×10 -3 μm 2 apart. During hydrocarbon accumulation in middle diagenesis stage A,hydrocarbon with organic acid came into this ultra-low permeability sandstones,and under organic acid circumstance feldspar dissolution formed secondary pore,which made porosity and permeability up to 11.6% and 0.61×10 -3 μm 2 individually. So the relationship between the densification process of Chang 6 sandstone and hydrocarbon accumulation is first densification then accumulation and accumulation with increased porosity and permeability.

关 键 词：先致密后成藏 边成藏边扩容增渗 超低渗透砂岩 长6 鄂尔多斯盆地 

分 类 号：P618.13[天文地球—矿床学]