叠前弹性阻抗在储层气水识别中的应用

APPLICATION OF PRESTACK ELASTIC IMPEDANCE INVERSION IN GAS AND WATER RECOGNITION OF THE RESERVOIR

弹性阻抗是声阻抗的概念延伸和推广,它建立在非零偏移距的基础上,是纵波速度、横波速度、密度及入射角的函数。弹性阻抗反演属于叠前反演技术,相对叠后声阻抗而言,它包含了更为丰富的储层岩性和含流体信息,并逐步发展成为一种有效的流体检测与识别技术。在简介纵波弹性阻抗的概念、方法原理及其所揭示的新的流体性质和反演过程基础上,建立了储层流体检测的基本流程。通过对研究区已知井(含气和含水)目的层段的扩展弹性阻抗的实际计算和对其随入射角变化趋势的分析,建立了一种针对碳酸盐岩储层含流体性质的有效判别依据。实际应用效果表明,该方法在储层流体识别,特别是对碳酸盐岩储层的气水判别具有良好的效果。

Elastic impedance(EI),the extension and generalization of acoustic impedance(AI),is based on the assumption of non-zero offset,and is a function of P-wave velocity,S-wave velocity,density,and incidence angle.EI inversion,as a pre-stack inversion technique,compared with poststack AI inversion,includes such more information about fluids and lithology that EI inversion has developed as an effective technique for the fluid detection and recognition.The paper briefly presented the concept,method and principle of P wave EI,analyzed the new liquid features revealed by EI,and introduced the inversion process of EI,then,the paper established basic flow for the reservoir fluid detection by using EI.An effective discriminating evidence for the fluid-filled properties in the carbonate reservoir is established by calculating the real extension elastic impedance and analyzing the change trends of EI with the changes of the incidence angle of the target horizon from several known wells(both gas and water wells).The application effects show that prestack elastic impedance inversion is favorable for the reservoir fluid identification,especially for the gas and water detection in carbonate reservoirs.Moreover,the idea has some reference values and application potentials for the study of the clastic rock reservoir.