Time-lapse seismic forward modeling method for CO2 geological storage in sand-mud interbed without shear wave velocity logging

Abstract

The invention discloses a forward simulation method for a sand-mud interbed CO2 geology sealing time-shifting earthquake without shear wave velocity logging. The method comprises the following steps: collecting data; extracting the data layer by layer; using logging information to calculate a sandstone mineral composition curve, calibrating the longitudinal and shear wave velocity under the pressure condition after the CO2 injection, and forecasting the shear wave velocity; executing the mixed fluid to replace the longitudinal and shear wave velocity curve after the injection; reserving the logging information time-depth conversion of the thin-layer information and using a Zoeppritz equation to calculate the reflection coefficient; executing the convolution with Ricker wavelet to obtain a synthetic seismogram; and using the time-shifting forward artificial synthetic seismogram of the different injection stages and different basic frequencies before and after the CO2 injection to subtract, to obtain the difference forward earthquake response. The method is capable of, in allusion to the feature of the complicated sand-mud thin interbed, solving the mixed fluid saturation replacement problem of the different reservoir features in the CO2 oil flooding and geology sealing process better and forecasting the longitudinal and shear wave velocities of the pressure change in the CO2 injection stage.

Description

technical field

[0001] The invention relates to greenhouse gas emission reduction technology, CO 2 4D Seismic Monitoring of Geological Storage and CO 2 Oil displacement technology monitoring technology, geophysical monitoring technology for oil and gas field development. Specifically, it involves the prediction of compressional and shear wave velocities under different pressures using Digby formula, the use of Gassmann theory for mixed fluid replacement and the use of non-uniform sampling methods that retain thin layer information to perform deep-time conversion of well data, and then perform time-lapse seismic Methods for Response Modeling and Differential Earthquake Modeling. Background technique

[0002] In the process of making time-lapse seismic forward modeling with logging data, P-wave velocity, S-wave velocity and density are needed. However, due to the cost of measurement and the limitations of early technology, in most cases there is no shear wave velocity loggi...

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