Sensitivity analysis from single-well ERT simulations to image CO₂ migrations along wellbores

Abstract

CO2 plume imaging is a required step in CO2 geological storage for both performance assessment and risk management purposes. This work has been performed in the frame of the CO2CARE project, and its aim is to develop tools and methodologies to monitor CO2 migration and verify the long-term well integrity after site abandonment. The timely detection of an anomaly is essential to perform a suitable remediation. For this purpose, downhole tools are permanently installed, but it is important to check the resolution and efficiency of the adopted techniques. In particular, this study investigates the possibility of using electrical resistivity tomography (ERT) to image CO2 migrations around observation boreholes through a sensitivity study.

Imaging Rainfall Infiltration Processes with the Time-Lapse Electrical Resistivity Imaging Method

“…It can also be used for monitoring the groundwater flow and river water discharge patterns (COSCIA et al 2011(COSCIA et al , 2012HAYLEY et al 2009;SUZUKI and HIGASHI 2001). In the recent years, the time-lapse ERI method has been applied to monitor the preferential flow paths within the rock/soil mass (DRAHOR et al 2011;HERMANS et al 2012b;MAITI et al 2012;MUCHINGAMI et al 2012) and the geological system of CO 2 storage for the real-time purpose (BERGMANN et al 2012;CHRISTENSEN et al 2006;PICOTTI et al 2013). Compared with other geotechnical and hydrological methods used for monitoring rainfall infiltration processes, the time-lapse ERI method can perform live, high-resolution monitoring of changes in the physical properties of a subsurface (PERRONE et al 2014) in terms of the variation of subsurface resistivity distribution.…”

Using surface‐downhole ERT for detecting contaminants in deep aquifers due to exploitation of oil reservoirs

“…The lateral resolution was limited by the electrode separation as shown in Picotti et al . (). There was a gradual decrease in sensitivity outside the electrodes volume, leading to a rather low‐resolved resistivity image some meters away from the electrodes.…”

“…In this case, the measurements did not achieve enough penetration to image successfully the plume, as shown also in Picotti et al . (). That is why it is important to use surface‐downhole measurements.…”

Cross-well seismic and electromagnetic tomography for CO2 detection and monitoring in a saline aquifer

“…To our knowledge, the only crosshole experiments somewhat related to this technique have been performed by Wilt et al (1995). The method has not to be confused with electrical resistivity tomography (ERT) (e.g., Christensen et al, 2006;Picotti et al, 2013). The integrated geological model constitutes a porous description of the geological formation, where grain properties, fluid types, porosity, clay content and permeability are explicitly considered, defining characteristic values of the electrical conductivity, seismic velocities and seismic quality factors, before and after the CO 2 injection.…”