VSP Slit-hole Diffraction Imaging Method Based on Symmetrical Observation

Abstract

The invention provides a VSP fracture-vug diffraction imaging technical method based on symmetrical observation; the method comprises the following steps: vertically deploying multi-stage detectors atequal intervals in a well; enabling an excitation point wave field to extrapolate downwards from the ground according to a depth sampling interval; enabling a reception point wave field to extrapolate downwards from the most shallow reception point depth according to the depth sampling interval, and adding the reception point wave field into the extrapolating wave field each time certain reception point depth is reached; aiming at each depth sampling point, enabling the reception point extrapolating wave field and excitation point extrapolating wave field to carry out related imaging according to imaging conditions; respectively processing two imaging areas with separated well positions after all depth sampling points finish offset imaging, using the imaging area with no excitation pointas VSP diffraction wave imaging, and using the imaging area with excitation points as VSP reflection wave imaging. The technical method is efficient and stable in operation, flexible and convenient inprocessing, and has a higher identification ability in fracture-vug type reservoir imaging.

Description

technical field [0001] The invention relates to the technical field of oilfield development, in particular to a VSP fracture-cavity diffraction imaging technique method based on symmetrical observation. Background technique [0002] Fractures and caves generally exist in all kinds of rocks in the earth's crust, and they are favorable spaces for the migration and accumulation of underground oil and gas. Compared with rock formations, the scale of fractures and caves is smaller, and they are regarded as diffracters in seismic exploration. When the seismic wave field passes through these small-scale diffracters, it will excite the diffracted wave field, and these diffracted wave fields can be regarded as the illumination of the secondary source to the underground structure that is difficult to be illuminated by the primary wave. In this way, the weak energy diffracted wave imaging has high research and practical value. The use of diffraction wave imaging can find and identify...

AI Technical Summary

Problems solved by technology

[0003] Traditional imaging has the following unfavorable factors for diffraction target imaging: the diffraction wave field is regarded as interference noise and is filtered out; the conventional migration algorithm ignores the diffraction effect; cover

[0004] With the refinement of seismic exploration, the diffraction imaging technology of fracture-cavity reservoirs has become a research hotspot. At present, various diffraction wave imaging methods have been proposed one after another, all of which are researched on surface seismic data imaging. The research of radio wave migration imaging method is blank

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