【摘要】 基于岩心、测井资料及普通薄片、铸体薄片、扫描电镜、X衍射、物性和压汞等化验分析资料,研究了柴达木盆地马北8号构造下干柴沟组下段砂岩储层特征。结果表明:该套储层的储集空间以原生粒间孔为主,夹少量次生粒间孔,储层物性好,排驱压力和饱和度中值压力较低,孔喉半径较大且分选性中等,歪度粗,孔隙结构参数总体较好。储层质量受沉积相和成岩作用的综合影响,其中,辫状河河床及滩坝沉积区为最有利储层发育区,加之压实作用较弱、成岩早期的中等胶结作用和比较普遍的溶蚀作用有利于原生孔隙和喉道的保存及部分次生孔隙和喉道的发育。利用储层物性及压汞等参数,将马北8号构造下干柴沟组下段储层划分为Ⅰ、Ⅱ、Ⅲ类储层,其中Ⅰ、Ⅱ类储层在目前的技术条件下是增储上产的首选储层。更多还原

【Abstract】 Characteristics of the lower part of the Xiaganchaigou Formation in the Mabei-Ⅷ structure in the northern margin of the Qaidam Basin were investigated based on analytical data of cores,logging,scanning electron microscope,X-ray diffraction,physical property,common thin sections,casting thin sections,and mercury injection test.The results show that the reservoir pore space includes mainly primary residual intergranular pores with partial secondary intergranular pores,indicating a good reservoir property,and the reservoir has low displacement and saturation median-point pressures,big pore-throat radius,good pore-throat sorting and rough skewness,the parameters of pore structure are wholly better.Generally,the quality of a reservoir is affected jointly by depositional facies and diagenesis,among which the riverbed and the beach-bar of a braided river are the most favorable zones for reservoir development,in addition,weaker compaction,medium cementation in early diagenesis and universal corrosion are also favorable for the protection of primary pores as well as the development of partial secondary pores and throats in a sandstone reservoir.According to petrophysical properties and pore structure parameters of reservoirs,the lower part of the Xiaganchaigou Formation in the Mabei-Ⅷ structure could be divided into typeⅠ,type Ⅱ and type Ⅲ pools,among which the type Ⅰ and type Ⅱ pools were proposed as preferred target zones for increasing reserves under current technical conditions.更多还原