鄂尔多斯盆地富黄地区延长组长6储层成岩作用

根据砂岩薄片、铸体薄片、扫描电镜、X衍射等研究表明,富黄探区延长组长6储层砂岩为低孔低渗储集岩,其岩石类型为长石砂岩和岩屑长石砂岩,磨圆以次棱—次圆为主,颗粒间以线性接触和点—线接触为主,孔隙式和孔隙—薄膜式胶结为主,砂岩具有成分成熟度低,结构成熟度高的特点.储集砂岩经历的主要成岩作用为压实作用、胶结作用、溶蚀作用和破裂作用.压实作用是导致孔隙度丧失的主要原因,造成的平均孔隙度丧失为30.89%,胶结作用造成的平均孔隙度丧失为6.98%,碳酸盐胶结物和次生加大是造成储层物性降低的主要胶结物.而溶解作用对砂岩平均孔隙度的增加为1.22%,是改善砂岩物性的重要途径.

Diagenesis of Chang 6 reservoir of Yanchang formation in Fuhuang exploration area of the Ordos basin

On the basis of analysis of thin section observation,casting lamella,scan electron microscope and X-ray diffractions etc,the study area was determined to be a the low porosity and low permeability reservoir, whose sandstone types are arkose sandstone and lithic arkose sandstone.They are mainly in re-angular and re-round round forms,line and point-line contact forms with pore and pore-thin film cementation between rock grains.The study reservoir is mainly characterized by low compositional maturity and high textual maturity. The diagenetic factors of Chang 6 reservoir include compaction,cementation,corrosion and disruption.The compaction in the early diagenetic phase,which resulted in 30.89%porosity loss,is the main factor causing the loss of porosity for the sandstone.Cementation resulted in 6.98%average porosity loss,and carbonate and quartz overgrowth are the main cements that have reduced the reservoir quality.But the solution has added an extra 1.22%porosity to the reservoir,which is an important way to improve the reservoir quality for the sandstone.