异常高压地层的纵波速度响应特征分析

目前已经可以利用试验方法解释纵波速度在砂泥岩与碳酸盐岩异常高压地层的变化特征，但机理研究还处于探索阶段。基于Biot理论，建立了纵波速度方程，分析了纵波速度的主要组成；探讨了影响纵波速度变化的主要因素，解释了异常高压地层的纵波速度变化特征。研究结果表明，在异常高压地层，砂泥岩的骨架体积弹性模量大幅变小，基质型碳酸盐岩的骨架体积弹性模量几乎不变，裂缝性碳酸盐岩的骨架体积弹性模量小幅变小。研究表明，骨架体积弹性模量决定了砂泥岩与碳酸盐岩地层异常高压的纵波速度变化特征，可以根据骨架纵波速度分析饱和流体岩石的纵波速度变化趋势。 

Analysis of Response Characteristic of P-Wave Velocity in Abnormal Over-Pressure Formation

The response characteristics of P-wave velocity in abnormal over-pressure shale sand and carbonate rock can be interpreted by using experimental methods now,but the research on mechanism is still in the exploratory stage.Based on Biot theory, P-wave velocity equation was established and the major components of the P-wave velocity were analyzed.The main factors affecting P-wave velocity change were discussed and the variation features of P-wave velocity in abnormal over-pressure formation were explained.The results showed that in the abnormal over-pressure formation,the rock framework bulk modulus of shale sand rock became significantly smaller,that of matrix carbonate rock kept essentially constant,and that of fractured carbonate rock dropped slightly.The study showed that the response characteristics of P-wave velocity of shale sand rock and carbonate rock with abnormal over-pressure were determined by the rock framework bulk modulus,and the P-wave velocity of rock framework could be used to estimate the P-wave velocity variation trend of saturated rock.