油藏流体特征参数变化规律及其在储量评估中的意义

油藏流体特征参数研究是储量研究工作的基础。根据探井测得的原始地层压力与高压物性分析资料确定的饱和压力间的相互关系,将油藏划分为饱和油藏与未饱和油藏两大类。饱和油藏与未饱和油藏流体特征参数变化规律的差异在于原始溶解气油比和地层原油体积系数随深度的变化规律是相反的,二者相同之处在于地层压力、地层温度及地层原油密度随深度的增加而增大。当PVT样品点分布不均匀时,储量评估中应选取油藏几何中心点对应的参数值;对于目标油藏,至少应获取两个以上合格的PVT资料,并结合流体分布特征合理确定油藏流体特征参数。

Variations in fluid flow parameters of reservoirs and their implications in reserves estimation

Studies on fluid flow parameters of reservoirs are a foundation of reserves estimation.Based on the relationship between original pressure measured in wells and bubble-point pressure determined by petrophysical data from high-pressure analyses,reservoirs can be divided into two types,(i.e.) saturated reservoir and undersaturated reservoir.The original gas-oil ratio in solution and oil volume factor in formation have reverse variations with increasing depth in the two types of reservoir,but the formation pressure,temperature and oil density all increase with depth in both the types.When PVT sample points are not uniform in distribution,the parameters of geometric center in a reservoir should be selected to estimate reserves.For each reservoir evaluated,at least two PVT samples should be obtained,by which the fluid flow parameters can be determined in combination with fluid distribution patterns.