关键词: 流体替换, 胶结砂岩模型, 孔隙度, 泥质含量, 地震数据

Abstract:

Fluid substitution is commonly used to compute elastic property parameters of rocks before and after the variation of reservoir fluids, which is a key procedure in seismic reservoir characterization and monitoring. However, fluid substitution requires the information on parameters of rock porosity and matrix, fluid properties, clay content, etc. Therefore, at present fluid substitution can be only conducted on the part of a reservoir that has available log data, and the dynamic seismic response of fluid variations is obtained through seismic numerical simulation during seismic attribute analysis and optimization. In order to expand the application of fluid substitution, we proposed to directly conduct fluid substitution by utilizing seismic data, in which a geologic model of oil reservoirs was established to simulate the amplitude peak-value correlation of seismic reflection between wet and gas reservoirs according to the determination of reservoir fluid types and petrophysical models, and to characterize variations in the amplitude correlation dynamically with the change of reservoir parameters, including porosity, thickness and clay content. The correlation was calculated by means of curve fitting to obtain a linear equation of fluid substitution capable of the direct application to seismic data, achieving the fluid substitution of in-situ seismic date. Both the simulation analysis based on the petrophysical model of cemented-sand reservoirs and the application experiment of in-situ seismic data have proved the feasibility of directly conducting fluid substitution based on seismic data.

Key words: fluid substitution, cemented-sand model, porosity, clay content, seismic date