Analysis of 4D seismic timeshifts overburden and its relation with the geomechanical model of reservoirs in a Campos Basin field

Abstract

This paper seeks to interpret the 4D seismic timeshifts in the overburden of a conventional turbidite sandstone reservoir in the Campos Basin and to calculate an empirical factor of sensitivity between these 4D data and the geomechanical deformations.  Gaining information on how the production of the reservoir affects the surrounding rocks is of great interest for the management of oil fields, with impacts ranging from optimization of production to the safety of operations and workers. The study of timeshift anomalies are common in chalk fields and unconventional fields of high temperature or pressure. We used two techniques for timeshift calculations, cross-correlation and DTW, as well as structural attributes that are calculated to assist in interpretations. Then, we estimate the sensitivity factor, which allows the construction of synthetic 4D timeshifts from the deformations simulated by the geomechanical model. In most of the field regions there was agreement between simulated deformations and 4D anomalies, showing that it is possible to extract useful information for reservoir management. The estimate of the sensitivity factor indicates that the overburden studied is sensitive to deformations in the rocks, allowing that small deformations can be detected by the given 4D seismic.