Subsurface Reflection and Transmission Response Estimation by Seismic Interferometry Using Deep Borehole Data at Groningen

Abstract

Seismic interferometry reconstructs the impulse response between two receivers. In this study, we use deconvolution interferometry to estimate the subsurface reflection and transmission response using active and passive borehole data in the Groningen gas reservoir at ~3 km depth. Assuming the medium is approximately laterally homogeneous, recorded up- and downgoing P- and S-wave are separated using f-k filtering based on wavenumber and velocity. We validate the wavefield separation and deconvolution interferometry process using synthetic data of a 1D elastic model built from field P-wave velocity logging. The estimated full-waveform reflection response using a virtual source at the top geophone is consistent with the actual response from synthetic data with a corresponding active source. For the virtual source at the bottom geophone, the reflection response appears to be phase delayed, though its arrivals are consistent with the local subsurface geology. Using the same principle, a first-order estimated local transmission response successfully approximates the P-wave velocity in the reservoir. We show that seismic interferometry in a deep borehole setting can retrieve the physical reflection response and velocity structure in the reservoir. Reliable subsurface information obtained from borehole interferometry can be of use for reservoir imaging without requiring knowledge of the medium parameters, and for reservoir monitoring by detecting velocity and/or interface time-lapse variations with negligible cost and effort compared to conventional approaches.