三相流体非均匀饱和多孔岩石声学模拟与分析

多孔岩石岩性、孔隙度、渗透率变化,导致流体饱和度在储层中非均匀分布.传统的基于流体均匀混合的双相介质模型不能用于计算流体非均匀饱和岩石的声学性质（纵、横波速度）.依据三相流体Brooks-Corey模型、Gassmann理论和边界理论提出了有效计算中观尺度下非均质多孔岩石三相流体非均匀饱和时岩石声学性质的方法,为研究三相流体非均匀分布对岩石声学性质影响提供理论与方法,并建立了在毛管压力平衡状态下非均匀饱和多孔岩石声学性质与总含水饱和度的定量关系.揭示了不同流体饱和状态下纵、横波速度随总含水饱和度的变化规律.实例模拟分析表明,多种岩性岩石组成的多孔岩石储层三相流体非均匀饱和时,纵波速度随总含水饱和度的变化趋于连续变化,而流体均匀饱和岩石,仅在接近完全含水时,纵波速度有明显变化.流体饱和度分布均匀与否对横波速度没有影响,但岩石三相流体饱和与两相流体饱和时相比,横波速度随总含水饱和度的变化特征更加复杂.

Acoustics simulation and analysis of three phase fluid patchy saturations porous rock

Fluid saturation distribution is patchy due to variation of lithology, porosity and permeability of porous rock. Traditional porous medium theory based on homogeneous saturation does not apply to acoustical signatures calculation of patchy saturation porous medium. Employing three phase fluid Brooks-Corey model, Gassmann theory and bound theory, acoustical signatures calculation method of mesoscopic-scale inhomogeneous porous rock with three phase fluid patchy saturation is proposed, in order to research the effect of fluid saturation distribution on acoustical signatures of rock. Under conditions of capillary equilibrium, the quantitative relationship between porous medium acoustical signatures and global water saturation is established, then rules of compressional wave velocity （Vp） and shear wave velocity （Vs） of different fluid saturated rock vary with different global water saturation are revealed. Numerical results demonstrate that Vp of porous rock with three phase fluid patchy saturations more continuous variation across the entire global water saturation range. It will be more suitable for quantitative interpretation of hydrocarbon saturations than the case of three phase fluid homogeneous saturations. Vs of porous rock doesn＇t depend on saturations distribution. However, the relationship between Vs and global water saturation in three phase fluid saturations porous rock is more complex than that in two phase fluid saturations porous rock.