Converted-wave processing in a complex area: near surface and depth imaging challenges

Saúl Ernesto Guevara, Gary F. Margrave, Babatunde Arenrin, John C. Bancroft, William M. Agudelo

Converted waves (C-waves) could have a more extended application if some processing challenges were overcome. This study focuses on such issues like the near surface heterogeneity and the complex geological structure, and their effect on C-wave imaging. This work is inspired by a zone with such characteristics from Colombia.

For analysis purposes, this study separates the near surface and the depth imaging issues. Thus, the near surface is studied with real data using tomography, and depth reflectors imaging is investigated in a synthetic model without near surface problems. Only preliminary analyses have been carried out in the last topic.

S-wave velocity models of the near surface from surface seismic and from uphole data agree, in their main features. However, the uphole shows slower velocities in the very shallow part, which appears more reliable. Synthetic data generated reasonable good images with conventional methods. More complicated models will be investigated in the future, focused on velocity analysis and filtering methods.