ARTICLE

Time-lapse seismic interpretation in t-p space using pre-stack data

YAN-XIAO HE1 DOUG A. ANGUS1 SAN-YI YUAN2 THOMAS D. BLANCHARD3 ROGER A. CLARK1 MARK W. HILDYARD1
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1 School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, U.K.,
2 Department of Geophysics and Information Engineering, China University of Petroleum, Beijing, P.R. China.,
3 Total E&P UK Ltd., Geoscience Research Centre, Aberdeen, U.K.,
JSE 2015, 24(5), 475–496;
Submitted: 4 March 2015 | Accepted: 13 September 2015 | Published: 1 November 2015
© 2015 by the Authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution -Noncommercial 4.0 International License (CC-by the license) ( https://creativecommons.org/licenses/by-nc/4.0/ )
Abstract

He, Y.-X., Angus, D.A., Yuan, S.-Y., Blanchard, T.D., Clark, R.A. and Hildyard, M.W., 2015. Time-lapse seismic interpretation in 7-p space using pre-stack data. Journal of Seismic Exploration, 24: 475-496. We present a new algorithm to measure time-lapse vertical traveltime shifts in seismic pre-stack shot and CMP gathers by tracking traces having constant horizontal slowness in 7-p space. Unlike other methods for measuring these attributes from stacked volumes, our use of pre-stack data avoids errors and uncertainties inevitably introduced in conventional time-lapse processing, such as choosing a suitable migration velocity model and cross-correlation time-window size. Results are localised to a given interval and thus free from overburden effects. This approach is used to estimate layer vertical traveltime shifts, a reservoir compaction-dilation coefficient, and hence calculate both velocity and thickness changes within a reservoir and the overburden. We demonstrate the method using synthetic reflection data generated using both a ray-based and a finite-difference full-waveform algorithms on two suites of models: a simple four-layer reservoir model; and a hydro-mechanical simulation model. We compare our estimates of layer interval vertical time-lapse traveltime shifts and velocity and thickness changes with those of the input model. The results indicate that the new T-p time-lapse method produces sufficiently accurate results compared to conventional methods.

Keywords
time-lapse seismic
7-p domain
hydro-mechanical model
rock physics
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Journal of Seismic Exploration, Electronic ISSN: 0963-0651 Print ISSN: 0963-0651, Published by AccScience Publishing