Prestack Kirchhoff depth migration of crosswell seismic data: a case study

In this paper, I describe the application of prestack Kirchhoff depth migration to a crosswell seismic dataset recorded with a piezoelectric source and a hydrophone array. The data contain compressional (P) and shear (S) waves, with a bandwidth from 200 to 1200 Hz. Data preprocessing consists of transmission traveltime tomography, tube wave attenuation, amplitude correction, and attenuation of the direct arrivals. The elastic wave modes, P-P and S-S, are used in separate migrations. Migration is performed in common-shot gather (CSG) and common-receiver gather (CRG) domains. The two images of CSG and CRG migration where the common source and common receiver are at the same depth are stacked to create a single-fold image. After migration of all the CSGs and CRGs, a volume of images is produced. Image events at common-surface-location gathers sliced from the volume are generally flat, suggesting that the tomogram, velocity model used in migration is correct. Geological structures of dipping beds, an unconformity and a reef less than 60 m thick are clearly imaged.