Multi Data Fusion Method Study & Its Application Based On Rock Physics

The shear wave velocity of well log is one important parameter for mutual inversion. As lots of wells short of this data and present method can't estimate the shear velocity precisely, this thesis gives a more accurate shear velocity estimation method. The paper summarized the theories of elastic-wave propagation in fluid-saturated porous media according to the analytic mechanics, compared the differences between Biot model and BISQ model, analyzed the applicability of different effective elastic modulus estimation methods for different phase combination conditions through numerical experiments, deduced the relations between effective elastic parameters of fluid-saturated porous media and its solid and liquid phase composites. Based on elastic-wave propagation theories in fluid-saturated porous media and rock physics, the main influence factors of velocity in porous media, such as mineral components, porosity and liquid saturation has been analyzed, and the rationality of different velocity models are compared. The method estimates the solid and liquid composites effective elastic modulus using VRH model via multi-mineral analysis from conventional well logs, and then calculates the shear wave velocity using Biot-Gassmann equations controlled by compressional velocity. The method has definite physical meaning, practice results show that this method is much more facility, economy and precise compared to the famous Xu-White method, its average absolute relative error between estimated values and measured values is about 5 percents, which is only half of Xu-White method.Although above multi-mineral analysis method can obtain a more reasonable wave velocity compared with the Xu-White model in the coal bed, the error of estimated wave velocity is greater than that of non-coal zones as the coal has complex components. Therefore, through the typical coal bed log responses characteristics and recognition methods study, the regression models between density and velocity, neutron porosity and velocity, shear velocity and compressional velocity are given by multi-well logs statistical analysis, so the precision of estimated share wave velocity of coal bed is improved. Through the coal bed volume model establishment, the coal components are calculated by density and neutron well logs, the cranny porosity is calculated using iterative inversion method with dual laterologs, and the adsorbed gas content is given using temperature adsorption equation according to coal bed carbon content which is more reasonable than empirical formula. Finally, combined with the oil gas reservoir log evaluation technique and multi-mineral analysis velocity estimate method for non coal zones, a systemic quantificational evaluation procedure for coal measure strata is given, which can provide the zone components, porosity, permeability, liquid property and elastic parameters. The application results show that the coal zone has distinct low velocity, low elastic moduli and low elastic impedance aspects,which provides the rock physical foundation for coal measure strata exploration.