常规与致密砂岩泊松比宽频段岩石物理特征和建模方法研究

泊松比是重要的岩石物理参数，在砂岩储层地震数据解释中，泊松比可以更加准确地获取含油气特征。泊松比地震数据解释通常基于测井纵横波速度或参考超声纵横波速度获取的泊松比信息。然而，当砂岩饱和流体时，频散效应使得测井或超声频段获取的泊松比失真，无法直接用于地震数据解释，制约着砂岩储层含油气特征的准确获取；且目前泊松比地震频段实验数据较少，尚未对泊松比开展系统的实验和建模研究。为此，本项目开展宽频段(地震、超声频段)实验系统研究常规与致密砂岩泊松比随流体类型、饱和度及频率的变化，深入分析气、水、油饱和、气水或油水部分饱和及频率等对泊松比的影响，归纳总结常规与致密砂岩泊松比在地震、超声频段的特征、规律及异同，然后分析主导泊松比变化的物理机制，构建岩石物理模型定量解释泊松比变化，有效表征泊松比参数，为常规与致密砂岩储层地震数据解释提供准确的岩石物理基础，准确获取常规与致密砂岩储层含油气特征。

Poisson’s ratio is an important rock physics parameter, which can more accurately acquire hydrocarbon-bearing characteristics in sandstone reservoirs. The basis of seismic data interpretation related to Poisson’s ratio is usually obtained by logging P-/S- wave velocities, or referred to ultrasonic P-/S- wave velocities. When the sandstone is saturated with fluid, however, the effect of dispersion makes Poisson’s ratio measured in the logging and ultrasonic frequency bands loses its accuracy, which cannot be directly applied to seismic data interpretation and restrict the accurate acquisition of the hydrocarbon characterization in the sandstone reservoir. Furthermore, the data of Poisson’s ratio measured in the seismic band is scarce, and relevant experimental and modeling studies have not been conducted systematically at present. To this end, this project firstly conducts broad frequency band (seismic and ultrasonic) experiments systematically to measure the Poisson’s ratio of conventional and tight sandstones under different pore fluid types, saturation, and frequencies. Secondly, it summarizes the characteristics, the rules, the similarities and the differences of Poisson’s ratio of conventional and tight sandstones in seismic and ultrasonic frequency bands, and analyze thoroughly the effects of gas，water, oil saturation, gas-water partial saturation, and oil-water partial saturation on the variation of Poisson’s ratio. Finally, the dominant internal physical mechanism causing the variation is analyzed, and rock physics model is developed to explain the variation of Poisson’s ratio in the broad frequency band quantitatively and characterize Poisson’s ratio effectively, thus providing accurate rock physics basis for seismic data interpretation and then accurately obtain the hydrocarbon-bearing characteristics of conventional and tight sandstone reservoirs.