关键词: 地层条件, 砂岩储层, AVO模板, 岩石物理模型, 正演分析

Abstract: The reservoir sandstone core samples from W3 formation of WXS depression were measured for density, porosity and acoustic velocity under pressure and temperature of formation condition in laboratory. A method based on core result and rock physics model was proposed to produce an advanced AVO response template capably showing integrated information of reservoir character (porosity and thickness) and saturation fluid. This method used the sandstone porosity as the key factor to construct the rock physics model based on the linear relationships of porosity-density and porosity-impedances in dry condition. Using Gassmann fluid replacement technique, the forwarding modeling results of AVO responses for different reservoir conditions were obtained, and then the AVO template was made by analyzing the distribution and shape characteristics of AVO clusters on intercept-gradient crossplots. Through this template the porosity, thickness and fluid type of reservoir could be estimated directly, and thus the non-uniqueness of AVO inversion due to complex geology was greatly reduced and the accuracy of direct hydrocarbon prediction could also be improved.

Key words: formation condition, sandstone reservoir, AVO template, rock physics model, forwarding analysis