A Research On Inverse Gaussian Beam Stack Imaging In 3d Crosswell Seismic Of Deviated Well And Its Application

In crosswell seismic, imaging section produced by migration employed with wave equation has a serious arc phenomenon at its edge and small effective range due to the restriction of geometry. Another imaging section produced by VSP-CDP stack imaging employed with ray-tracing theory is amplitude-preserved but has difficulty in imaging 3D complex lithological structure accurately. Therefore, the paper proposes inverse Gaussian beam stack imaging in 3D crosswell seismic of deviated well based on the Gaussian beam ray-tracing theory. Through employing Gaussian beam ray-tracing theory into 3D crosswell seismic, the energy relationship between the seismic wave field and its effective rays is analyzed. Then the author converts the single channel seismic wave field data in the common shot point (CSP) gather into multiple effective wave fields in common reflection point (CRP) gather by inverse Gaussian beam when imaging and thus produces more intensive reflection points fold number. Finally, the wave fields of the effective reflection points in the same stack bin, selected from horizontal and vertical direction of the 2D measuring line, are projected onto the 2D measuring line, chosen according to the distribution characteristics of the reflection points, and stacked into an imaging section. The method is applied in X oilfield to identify the internal structure of offshore gas cloud area. The result provides positive support for inverse Gaussian beam stack imaging in producing accurate imaging in 3D complex lithological structure and make it a powerful imaging tool for 3D crosswell seismic data processing.