基于自然电位曲线的含烃砂岩地层水矿化度反演方法

Inversion Method of Formation Water Salinity in Hydrocarbon-Bearing Sandstone Based on Spontaneous Potential

地层水矿化度是重要的储层参数,也是进行储层精细评价的基础。当储层含烃后,自然电位曲线的异常幅度变小,将影响反演地层水矿化度的精度。基于公开发表文章中的实验数据,定量表征了纯砂岩储层中含水饱和度、地层水矿化度、泥浆滤液矿化度和自然电位异常幅度之间的关系,并将该关系与饱和度模型联立,构建了基于自然电位曲线的含烃砂岩地层水矿化度的反演模型。将反演模型在目标井中进行了应用,并开展了岩心束缚水矿化度实验,来验证模型反演结果。结果表明,反演结果与实验结果基本一致,该反演模型定量表征了烃类对自然电位曲线的抑制作用,能准确计算地层水矿化度,为流体识别和油藏定量评价提供了依据。

The formation water salinity is an important reservoir parameter,which is also the basis for reservoir fine evaluation.When the reservoir contains hydrocarbons,the abnormal amplitude of the spontaneous potential curve decreases,which affects the accuracy of inverting the formation water salinity.Based on experimental data from publicly published articles,the relationship between water saturation,formation water salinity,mud filtrate salinity,and spontaneous potential reduction in pure sandstone reservoirs is quantitatively characterized.This relationship is combined with a saturation model to construct an inversion model for water salinity in hydrocarbon bearing sandstone reservoirs based on spontaneous potential curves.The inversion model is applied in the target well and an experiment of measuring bound water salinity is carried out to verify the inverse method.It shows that the inversion results are basically consistent with the experimental results.The method accurately characterizes the suppression effect of hydrocarbons on the spontaneous potential curve,and can accurately calculate the formation water salinity,providing a basis for fluid identification and reservoir evaluation.