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岩石从干燥状态下到饱和流体后纵波速度的变化情况对于地震速度预测、AVO分析以及流体识别具有重要意义,而有关泥质砂岩在干燥与饱和流体状态下纵波速度之间关系的研究甚少.因此本文利用三组实验数据研究了泥质砂岩在干燥与饱和流体状态下纵波速度之间关系的影响因素,并通过多元线性回归分析方法建立泥质砂岩饱和流体后的纵波速度与干燥状态下的纵波速度、孔隙度以及黏土含量之间的关系.研究表明:泥质砂岩在干燥与饱和流体状态下纵波速度之间的简单线性关系容易受到固结程度、孔隙流体性质以及围压的影响,而多元线性回归分析与简单线性分析相比,其拟合结果的判定系数明显提高,标准误差明显减小.此外,本文首次提出黏土含量与孔隙度比的概念(CPR),发现CPR与泥质砂岩饱和流体前后纵波速度差之间有很好的正相关性,随着CPR的增加,纵波速度差也表现出增大的趋势,CPR的提出为解释流体替换过程中岩石物理属性的变化情况提供了新的思路.
The variation of P-wave velocity from dry to saturated fluid is of great significance for the prediction of seismic velocity, AVO analysis and fluid identification. However, little is known about the relationship between the velocity of P-wave and dry-saturated fluid. In this paper, three sets of experimental data are used to study the influencing factors of the relationship between the P-wave velocity and the P-wave velocity under the condition of dry and saturated fluids. The P-wave velocity and dry state of the saturated sandstone fluid are established by multivariate linear regression analysis P-wave velocity, porosity and clay content.The results show that the simple linear relationship between the P-wave velocities of muddy sandstone under dry and saturated fluid conditions is easily influenced by the degree of consolidation, the property of pore fluid and the confining pressure Compared with simple linear analysis, multivariate linear regression analysis showed that the coefficient of determination of fitting results was significantly improved and the standard error was significantly reduced.In addition, the concept of clay content and porosity ratio (CPR) was first proposed in this paper, and it was found that CPR and shaly sandstone There is a good positive correlation between the longitudinal wave velocity differences before and after saturated fluid. With the increase of CPR, the longitudinal wave Poor also showed a tendency to increase, CPR is proposed to provide a new idea to explain the changes in the physical properties of the fluid replacement process of the rock.