Elastic reverse time migration of prismatic waves for surface topography based on decoupled elastic wave equations in the curvilinear coordinates

Abstract

Steeply dipping structures bring huge challenges in high-resolution imaging. The imaging of the steeply dipping structures can be improved by incorporating the prismatic waves, which has some steeply dipping structure information where primaries cannot contain. In this paper, an elastic reverse time migration of prismatic waves (ERTM-P) is proposed to produce high-resolution multi-component images of steeply dipping structures with complete compressional (P-) and shear (S-) wave illumination of the subsurface. To avoid severe spurious diffraction caused by dramatic surface topography, the velocities are meshed into curvilinear grids and migration is conducted in curvilinear coordinates. In addition, the imaging conditions of prismatic waves in P- and S-components are derived using the decoupled curvilinear-coordinated elastic equations to suppress the imaging artefact from P- and S-wave crosstalk. In numerical examples, we use an elastic horizontal- and vertical-layer model, topographic elastic sag model and salt dome model with surface topography to demonstrate that the proposed method can accurately handle with the dramatic surface topography and obtains high-quality multi-component images by improving the images of steeply dipping structures.

KEYWORDS:

• Elastic
• imaging
• reverse-time
• migration

Acknowledgment

This research is supported by seismic wave propagation and imaging (SWPI) group of China University of Petroleum (East China). This research is supported by National Natural Science Foundation of China (41904101, 41774133, 42074133), Natural Science Foundation of Shandong Province (ZR2019QD004), Fundamental Research Funds for the Central Universities (19CX02010A), the Major Scientific and Technological Projects of CNPC (ZD2019-183-003) and the Open Funds of SINOPEC Key Laboratory of Geophysics (wtyjy-wx2018-01-06, wtyjy-wx2019-01-03).

Disclosure statement

No potential conflict of interest was reported by the author(s).