Technique Research On The Imaging Of The Cross-well Seismic Reflected Wave

The cross-hole seismic is an important component of seismic,It is a new seismic geophysical methods that the source and receivers are placed in the well.As it avoid the absorption of high-frequency seismic signal by the surface low velocity layer.Therefore,we can obtain the high resolution seismic information for fine describing the geological objective such as the cross-hole geological structure,reservoir and so on.Synthesizing and studying the rich ultra-high frequency longitudinal and shear wave data from the cross-hole seismic and other relative information,we can solve the thin layer,reservoir connectivity,fluid distribution,gas injection effect,fracturing effects of complex reservoir geology and engineering problems.Cross-hole seismic observation form are different from surface seismic,VSP seismic survey.Because of the form of special geometry between the holes caused the complexity of the cross-hole seismic wave field.So cross-hole seismic wave field difficult to identify and Wave field separation more difficult.The new seismic imaging technology is remain to be developed.Cross-hole seismic reflection imaging is one of the most critical step of cross-hole seismic data processing technology and an effective means of Geological model inversion.In this paper,It discussed and researched cross-hole seismic reflection imaging technology in-depth,Analyzed the advantages and disadvantages of various imaging methods,selected a simple and practical cost-effective imaging method-common-lateral point sort imaging method. This method is proposed in the horizontal layered medium condition,we can achieve good result and higher imaging quality in the area that have less complex subsurface and less changed in lateral velocity.The first step of the imaging method is:To velocity scanning,Velocity spectrum produced by using the superposition principle and extracted the stacking velocity.The second step is:Base on the hyperbolic theory of reflected wave,using the stacking velocity for vertical moveout correction of original common-shot gathers or common-receiver gathers,correct the reflected wave phase axis to the horizontal position.The third step is:Calculate the spatial position of each reflection point for doing coordinate conversion and correct the reflection point to the true position and then form the common-lateral gathers.Finally,doing the horizontal stacking imaging in the common-lateral gathers.Paper complete the computing method programs based on the step of the CLP sort imaging by using Visual C++ 6.0.Achieved the modularization and visualization of the program by QT3.3.2.In this paper,analyzing the imaging of cross-hole seismic theoretical models and actual databy CLP sort imaging method,got good result.So this reflection imaging method has certain practical and effectiveness.