Numerical study on CO₂ leakage detection using electrical streaming potential data

Abstract

We study the feasibility of detecting carbon dioxide (CO2) movement in the overburden of a storage reservoir due to CO2 leakage through an abandoned well by self‐potential (SP) measurements at the surface. This is achieved with three‐dimensional numerical (SP) modeling of two‐phase fluid flow and electrokinetic coupling between flow and streaming potential. We find that, in typical leakage scenarios, for leaky and/or injection wells with conductive metal casing, self‐potential signals originating from injection can be identified at the surface. As the injection signal is also observed at the leaky well with metal casing, SP monitoring can be applied for detecting abandoned wells. However, leakage signals are much smaller than the injection signal and thus masked by the latter. We present three alternatives to overcome this problem: (i) simulate the streaming potential of the nonleaky scenario and subtract the result from the measured streaming potential data; (ii) exploit the symmetry of the injection signal by analyzing the potential difference of dipoles with the dipole center at the injection well; or (iii) measure SP during periods where the injection is interrupted. In our judgement, the most promising approach for detecting a real‐world CO2 leakage is by combining methods (i) and (ii), because this would give the highest signal from the leakage and omit signals originating from the injection well. Consequently, we recommend SP as monitoring method for subsurface CO2 storage, especially because a leakage can be detected shortly after the injection started even before CO2 arrives at the leaky well.

An analytical effective excess charge density model to predict the streaming potential generated by unsaturated flow

“…The analytical closed-form expression of this new model is easy to evaluate and its numerical implementation is straightforward. These observations may have practical implications for opening up to the use of the SP method to study physical phenomena occurring in the unsaturated zone such as infiltration [e.g., Jougnot et al, 2015], evaporation, CO 2 flooding [e.g., Büsing et al, 2017], or even contaminant fluxes [e.g., .…”

“…The self-potential (SP) method has gained a strong interest in reservoir and environmental studies due its sensitivity to water flow. Among many other applications of SP, one can mention its use to monitor water flow in the subsurface [e.g., Doussan et al, 2002, Darnet and Marquis, 2004, Jardani et al, 2007, Linde et al, 2011, Jougnot et al, 2015, geothermal systems [e.g., Corwin andHoover, 1979, Revil et al, 1999b], oil and gas reservoirs [e.g., Saunders et al, 2006], and CO 2 sequestration [e.g., Moore et al, 2004, Büsing et al, 2017. Although SP signals are relatively easy to measure, the recorded SP signals are a superposition of different contributions related to redox, diffusion and electrokinetic processes [for more details, see Revil and Jardani, 2013].…”

An effective excess charge model to describe hysteresis effects on streaming potential

“…The SP method was effectively used to monitor pumping and recovery tests (e.g., Rizzo et al, 2004;Straface et al, 2007;Malama et al, 2009b;Soueid Ahmed et al, 2014), and also environmental studies such as CO 2 flooding (e.g., Büsing et al, 2017), contaminant fluxes (e.g., and root-water uptake (e.g., Voytek et al, 2019). The recorded SP signals are a superposition of different contributions related to electrokinetic, redox and diffusion phenomena.…”