鄂尔多斯盆地陇东地区长7段致密储层精细表征

Tight sandstone reservoirs characterization of Chang 7 member in Longdong area,Ordos Basin

鄂尔多斯盆地陇东地区长7段广泛发育致密砂岩储层,致密油资源丰富。与常规储层的研究方法不同,需要采用针对性的实验技术与分析方法对其开展研究。本文采用TRA、核磁共振实验,结合岩心观察、薄片鉴定及成像测井等资料,对陇东地区长7段致密砂岩储层进行了精细表征。研究结果表明:长7段致密储层破坏性成岩作用较强,有效孔隙度、束缚烃的含量随深度的增加而减小;根据离心实验,标定长7段致密储层可动流体孔喉下限约为0.1μm,实验结果与高压压汞数据相吻合;长7段可动流体饱和度较高,可动流体饱和度与孔隙度、渗透率相关性较差,微裂缝的存在改善了油气在长7致密储层中的运移和聚集的能力。

Tight sandstone reservoirs develop extensively in Chang 7 member in Longdong area,Ordos Basin,and tight oil is abundant.Unconventional tight sandstone reservoirs need special experimental techniques and analytical methods,which is different from the conventional reservoirs of high porosity and permeability.This paper adopted tight rock analysis,NMR,core and thin section observation,and FMI materials,in order to characterize the reservoirs precisely.The results of the experiments show that：（1）Destructive diagenesis is very strong,and effective porosity,bounded hydrocarbons（% of BV）decrease with depth;（2）According to the centrifugal experiment,this paper sets 0.1μm as the lower limit of pore throat of tight sandstone reservoirs,which is consistent with high pressure mercury data;（3）The movable fluid saturation is high and the correlation between movable fluid saturation and porosity and permeability is poor.The micro-cracks develop widely and they greatly improve the oil and gas migration and accumulation capacity.