4D Seismic Inversion on Continuous Land Seismic Reservoir Monitoring of Thermal EOR

Abstract

A permanent reservoir monitoring system has been installed for Shell at the end of 2010, on a medium heavy-oil onshore field situated in the north-east of The Netherlands, in the context of re-development of oil production by Gravity Assisted Steam Flood. The first challenge was to continuously monitor, with seismic reflection, the lateral and vertical expansion of the steam chest injected in the reservoir during production over more than a year. As the 4D seismic attributes obtained from monitoring fit the measurements made at observation, production and injector wells, the 2D monitoring system was extended to 3D in April 2012. The second challenge was quantify seismic amplitude variations in terms of petro-acoustic parameters. For that purpose 4D inversion was performed on continuous 2D and 3D seismic monitoring data in order to quantify the lateral and vertical expansion of the steam chest on a daily basis. The 4D inversion results not only point out that the inversion enables to quantify the 4D effects in terms of P-impedance variations, but also greatly improves the vertical location of these events. Moreover, the percentage of maximum impedance variations and the thickness where these variations are observed are in good agreement with the petro-elastic model.

Sensitivity of the near-surface vertical electric field in land controlled-source electromagnetic monitoring

“…This method has recently been successfully applied for steam injection monitoring (Michou et al, 2013). However, this requires substantial experimental effort; developing less expensive monitoring techniques is thus desirable.…”

Intra‐survey reservoir fluctuations – implications for quantitative 4D seismic analysis

“…For example, depending on the mobility (relative permeability divided by viscosity), a waterfront may move typically at a velocity of 0.3–1.5 m/day (Tjetland, Kristiansen and Buer ), whereas hydrocarbon gas, steam or CO 2 fronts can propagate at up to 5 m/day (Michou et al . ). It is observed that in some cases CO 2 propagation can exceed 13 m/day (Lu et al .…”

Updating the low-frequency model in time-lapse seismic inversion: A case study from a heavy-oil steam-injection project

“…The most common 4D inversion workflows known to the industry include either a separate inversion of the base and monitor surveys (e.g., Sarkar et al, 2003) or a simultaneous inversion of the base and monitor, as illustrated, for instance, by Michou et al (2013) in the framework of an onshore permanent reservoir monitoring.…”