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我国鄂尔多斯盆地中延长组长7段致密砂岩储层基本分布于湖盆的中心,其中储层物性的下限情况决定了油气能否充注储层。因此,通过恒速压汞以及纳米CT的扫描技术对湖盆中心的渗透情况分析,结果是渗透率在0.3×l0-3um~2,其中致密砂岩中的储层孔隙度也低于12%。结合致密油的成藏期情况分析储源压差、盆地的流体特征以及原油的物理性质,而综合确定长7段中密油的成藏期。开始进行油气充注时,它的孔喉下限是14nm,而孔隙度的下限是4.2%,此外,其渗透率的下限是0.02×10-3um~2,含油饱和度在40%以上。
The tight sandstone reservoirs in the 7th member of Yanchang Formation in Ordos Basin are basically distributed in the center of the lake basin. The lower limit of reservoir physical properties determines whether oil and gas can charge reservoirs. Therefore, the permeability of the lake basin was analyzed by constant pressure mercury intrusion and nanometer CT scanning. The result was a permeability of 0.3 × 10-3um ~ 2, of which the reservoir porosity in the tight sandstone was also lower than 12%. Based on the analysis of the reservoir source pressure, the fluid characteristics of the basin and the physical properties of the crude oil during the hydrocarbon accumulation period, the hydrocarbon accumulation period in the Chang 7 Member was determined. At the beginning of hydrocarbon filling, the lower limit of pore throat is 14nm, while the lower limit of porosity is 4.2%. In addition, the lower limit of permeability is 0.02 × 10-3um ~ 2 and the oil saturation is above 40%.