Reflection Of Acoustic Logging The Migration Stack Method Research And The Effect Of Different Contrast

Conventional sonic logging methods have the disadvantages of small detection range.Therefore,it is difficult to understand the lateral variation rules of out-of-well reservoirs or the extension and development of fractures.Seismic exploration methods including three-dimensional seismic exploration and cross-hole seismic exploration with low resolution are difficult to describe smaller geological formations and reservoir changes.In terms of resolution and measurement range,the emerging reflected acoustic imaging logs are exactly between the above two measurement methods,helping to fill in the gap between the two.Reflection Acoustic Imaging Logging uses sound field energy that is radiated into the formation outside the well as an incident wave to detect the sound field that is reflected back from a crack or a small structure near the well.By analyzing the full-wave array signal received by the detector,the construction information of the well-side medium can be understood.Offset superposition is a key step in the processing of analyzing the reflected acoustic logging data.Offset superposition can image the geologic structure out of the well,so that the position,size,and inclination of the structure can be obtained from the image map.Seismic migration technology is one of the three basic technologies for modern seismic exploration data processing,and it has been developed relatively well.These mature technologies can be fully used in the offset superposition processing of reflected acoustic logging.The purpose of this paper is to provide three imaging offset stacking methods and comparisons: Kirchhoff migration,F-K migration,and reverse time migration.The imaging effects of the three methods under the four models are discussed.Firstly,the finite-difference algorithm in two-dimensional rectangular coordinate system is used to simulate the propagation process of acoustic waves in the stratum,and the infinite boundary is simulated using the absorption boundary to provide forward data for subsequent migration imaging.Three migration methods are used to image the same set of forward data from the same set of models.In the homogeneous media layer,a single horizontal interface,a double horizontal interface,a double-layer inclined interface,and a single-layer fault interface contrast different offset methods.Furthermore,concentrate on the differences of imaging effect and calculation efficiency with the same model.Reverse time migration can accurately present the interface morphology,and it has better imaging effects for tilted interfaces and faults,but the computational efficiency is low,and there are certain requirements for the storage strategy.The F-K migration method used in this paper is more sensitive to the velocity model than the inverse time migration method used in the paper,and the imaging is vulnerable to ghost images due to poor absorption boundary effects.The calculation speed is about five times that of the reverse time migration imaging.Compared with the inverse time migration method used in the paper,the Kirchhoff migration has poor imaging performance for the second interface and the calculation speed is about three times that of the reverse time migration imaging.