【摘要】 在地震资料的AVO分析以及储层预测的流体识别分析等中需要横波速度信息,然而目前多数地区缺少横波速度测井,既没有岩石物理测试也没有VSP提供的横波速度信息.以往AVO和储层反演中的横波速度通常依靠经验公式或从纵横波波速度比为常数的假设中得到.这些经验公式往往精度很低,对于AVO特性包括弹性阻抗等特性描述不准确.特别是对储层中流体变化引起的AVO异常无法准确描述.为了获得准确的横波速度信息,我们采用Gassmann方程为基础的孔隙介质理论以及Lee提出来的方法建立了孔隙介质的横波速度模型.以此模型为基础,利用Thomsen的裂隙介质理论建立更加符合实际的含有裂隙的孔隙砂岩模型.预测的横波速度与实际的横波速度的对比证明了本文方法的有效性.更多还原

【Abstract】 S-wave velocity is necessary in AVO analysis,reservoir prediction and fluid discrimination.However, there is often lack of S-wave velocity which either from dipole sonic or VSP.There is also lack of rock physics measurements in oil field.S-wave velocity is often obtained from unrealistic empirical equation or constant Vp/Vs ratio assumption in AVO analysis and reservoir parameter inversion.These S-wave velocity statistical relations are usually inaccurate and lead to unreliable AVO attributes or elastic impedance in AVO inversion.In order to get more accurate S-wave velocites,we develop a method based on rock physics theory in which Gassmann’s equation and Lee’ s method are used to calculate elastic modulus of dry rock in porous sandstones.Furthermore,we construct a more realistic model in which cracks and fractures are included in porous model by using Thomsen’s theory.The accuracy of our method is proved by comparing predicted S-wave velocity and measured S-wave log in a coal mine.更多还原