PP Wave And PS Wave After Stack Joint Inversion Method And Application Of Oil And Gas Forecast

Reservoir geophysics can be applied to study the physics-characteristic,space disturber,fluid attribute of reservoir by making user of seismic technology, rock-physics ,and other methods. It helps us to identify and evaluate the reservoir qualitatively or quantitatively.At present, logging and seismic joint inversion of geophysical technology as the core of research methods is the main way to predict the effective reservoir. Now some of the seismic inversion techniques such as prestack AVO inversion although it gets the pp-ps wave velocity ratio and other parameters, but the main advantage of the longitudinal wave AVO data, solving the wave equation by Zeoppritz equation, with some approximation and assumptions. Aspect of conventional post-stack inversion is usually the first wave are inverted pp and ps wave impedance, and then linked to the analysis, ignoring the intrinsic connection between them.In fact, the P-wave velocity and S-wave velocity linear contact. P-wave velocity and density of the geological body is closely linked. In view of this, the paper will use the vertical and horizontal wave stack inversion method, the lithology of these three important parameters linked to simultaneous inversion,thus improving the accuracy and reliability of the inversion, the final impact of multiwave.Forecast lithology and fluid identification advantages into full playing.Specific study is divided into the following aspects:(1) Study the vertical and horizontal wave stack at the same time the joint inversion method. Fatti and others under the P-wave seismic record expressions, and Steward and Larson's wave seismic record expressions, using the reflection coefficient, wave impedance, shear impedance and density, the relationship between the vertical and horizontal wave stack is derived after the joint inversion of seismic records expression. Based on the actual logging data, using conjugate gradient method for solving the wave impedance inversion, shear impedance and density of rocks and other important parameters, a basis for further calculated shear wave velocity ratio, Poisson's ratio and other parameters.(2) Study the PP wave and PS wave seismic data matching. PP and PS seismic wave data matching processing include: time matching ,the energy matching and waveform matching. PP and PS wave wave profiles match the quality aspect is the impact of post-stack inversion results of the reliability of wave one of the keys.(3) On the basis of the above, the completion of a new market areas Xujiahe aspect of reservoir after the joint inversion of wave stack prediction. Utilization of the vertical and horizontal wave obtained by joint inversion of compressional wave velocity, shear wave speed, wave impedance, shear impedance and shear wave velocity ratio, Poisson's ratio and density important lithology, physical parameters. Study the characteristics of these parameters, extract the corresponding petrophysical information and oil and gas information, enabling comprehensive prediction of gas reservoir distribution.Finding of this research is to achieve vertical and horizontal wave of post-stack inversion of the effective ways to complete vertical and horizontal wave layer of the well - seismic calibration, vertical and horizontal seismic data to achieve a match, and after the completion of the reservoir property inversion parameters of the integrated interpretation, the initial formation of a deep western Sichuan tight clastic reservoir prediction of vertical and horizontal wave post-stack inversion. The research is similar to other regions of dense clastic reservoirs of important guiding role.