对用渗透率贡献值法求原始含油饱和度的讨论

DISCUSSION OF ESTIMATING ORIGINAL OIL SATURATION WITH THE PERMEABILITY BUTION VALUES METHOD

用沃尔公式求各级孔喉为渗透率所作出的贡献值累计至99.9％时,常出现粗孔喉而原始含油饱和度低的现象,本文通过车排子2号井区的实际资料和假想的两条毛管压力曲线都证实了这一现象。为此建议在应用时采用引进油水界面张力(σ_(ow)、油水密度差(△d)和油柱高度(h)等参数的公式,其结果较为真实,用r_(nmin)=σ_(ow)/[(σ_(ow)/rk)+4.9h.△d]求出r_(nmin)后,其对应的汞饱和度为原始含油饱和度。

When one accumulates the permeability contribution values for ranges of pore sizes, derived from Wall's Equation. to 99.9%, it often occures that the pore throat is still large but the corresponding oil saturation is low. This is explained with one field example from Well No. 2 District, Chepaizi, and one theoretical capillary pressure curve. It is therefor sugsested that Qu's Equation, which takes into account the interfacial tension between oil and water (σ_(ow)) the difference between oil and water densities (△d), and the height of the oil column, be used to estimate the original oil saturation. When rnmin is calculated from rnmin=Bow/(?)ow/ Tk)+4.9b.△d], the corresponding mercury saturation is the original oil saturation. This results in a more reasonable value.