柴达木盆地北缘下干柴沟组储层特征及影响因素分析

过对柴达木盆地北缘古近系下干柴沟组储层岩石学、孔隙类型、物性特征和成岩作用等的研究，指出下干柴沟组储层主要由长石砂岩、岩屑长石砂岩和长石岩屑砂岩组成，胶结物为碳酸盐；储层砂岩的成分成熟度普遍较低，结构成熟度中等—较差；不同构造带上孔隙的发育程度和储集性能存在着明显的差异，马海—南八仙地区孔隙最发育、储集性能最好，孔隙类型以原生粒间孔为主，发育中高孔—中高渗储层，冷湖构造带孔隙发育—较发育、储集性能较好，孔隙类型以原生粒间孔为主，发育中低孔—中低渗储层，鄂博梁构造带储层孔隙相对最不发育、储集性能很差，仅发育少许残余粒间孔和次生溶孔，发育特低孔特低渗储层。认为控制研究区储层性能的主要因素为储层的岩石成分和成岩作用，成岩作用主要有压实作用和胶结作用，而碳酸盐胶结和绿泥石粘土膜对储集性能的改造具有建设性和破坏性双重作用。

Characteristics and Influential Factors of Low|GanchaigouFormation Reservoir in North Edge of Qaidam Basin

By means of detailed study about the lithology, pore type, physical property and diagenesis of Paleogene Low|Ganchaigou Formation reservoir in the north edge of Qaidam Basin, this paper confirms that Low|Ganchaigou Formation reservoir sandstones consist of arkose, lithic arkose and arkose rock fragment sandstone, and the cement is carbonates. The reservoir sandstones have low compositional maturity and medium textural maturity. The development extent of pore and the accumulation property have apparent deviation in different tectonic belts. Both the development extent of pore and the accumulation property in Mahai|Nanbaxiang area are best, and produced mainly primary intergranular pores. The reservoir has high porosity and middle permeability. The development extent of pore is very good to good and the accumulation property is good in Lenghu tectonic belt, and produced mainly primary intergranular pores. The reservoir has mid|low porosity and mid|ow permeability. Reservoir porosity and accumulation property are relatively very poor in Eboliang tectonic belt, and merely has a few relict intergranular pores and secondary solution pores, and the reservoir has extremely low porosity and extremely low permeability. The rock component of sandstone reservoir and diagenesis are the main factors which control the reservoir property of Paleogene in the north edge of Qaidam Basin. The diagenesis mainly contains compaction and cementation. Carbonate cementation and clay encrustation have constructive and devastating effects to reservoir property.