Hydraulic barrier design and applicability for managing the risk of CO2 leakage from deep saline aquifers

Abstract

A proper risk management scheme for CO 2 storage should include an adequate monitoring plan completed with a site-specific intervention plan in order to demonstrate that any undesired consequence can be prevented, if not corrected. In the case of CO 2 escape from the storage reservoir to an overlying aquifer through a vertical conduit (representing the degraded cement of a well or a permeable fault), directly modifying the leak hydraulic properties (e.g. permeability) may be unfeasible. An appealing option is to counter the driving forces of the migration (natural CO 2 buoyancy and injection-induced over-pressure) by increasing the pressure over the leak through brine or water injection within the overlying aquifer, i.e. by creating a -hydraulic barrier‖. The present article presents and discusses the operational and strategic issues associated with this corrective technique and proposes a methodology in order to set the main design parameters (injection flow rate and duration) depending on the site specificities. The methodology is tested on a leakage scenario and three implementation cases of hydraulic barriers (brine injection 10 m away from the leak with or without delay, or 1 km away without delay) are simulated using the 3D multiphase flow transport code TOUGH2/ECO2N. We assess their effectiveness for stopping the leakage and for trapping (residual and dissolution) the CO 2 accumulated in the overlying aquifer. This example shows that the hydraulic barrier can be suited to low transmissivity overlying aquifers, and that its effectiveness will primarily depend on the distance from the leak to the brine injection well. When possible, a brine injection within the overlying aquifer formation in the vicinity of the leak ensures a rapid stop of the leakage and an effective trapping of the CO 2 .

Analytical model of leakage through fault to overlying formations

“…Such fluid interchanges may be especially important in the case of strong and widespread pressure perturbations in the connected formations, which may be caused by the production of oil, gas, and water, or the injection of fluids at high volume for waste disposal, gas storage, or geological storage of CO 2 [ Cihan et al , 2011]. Remedies such as brine extraction and reinjection into overlying aquifers and varying wells' configurations have been suggested to minimize these pressure perturbations [ Ghaderi et al , 2009; Réveillère et al , 2012; Buscheck et al , 2012; Hosseini and Nicot , 2012]. The potential for leakage of CO 2 and native fluids via fractures and faults is an area of considerable uncertainty for geological storage of CO 2 [ Benson and Cook , 2005; Nicot , 2008; Jordan et al , 2011; Stauffer et al , 2011; Selvadurai , 2012; Watson et al , 2012].…”

Induced seismicity and carbon storage: Risk assessment and mitigation strategies

“…Residual or mineral trapping, fault healing, geochemical mechanisms, or active mitigation may then be needed to limit impacts. Recent research has focused on a number of intervention strategies that can be used to stop ongoing leaks in a relatively short time frame, assuming they are detected (Réveillère, 2012).…”

Leakage Mitigation During CO2 Geological Storage Process Using CO2 Triggered Gelation

“…Some research works have been carried out to investigate methods of leakage control during CO 2 storage process. Reveillere et al 23 presented and discussed key issues associated with hydraulic barrier technology for leakage control and evaluated the applicability for blocking the CO 2 leakage from deep saline aquifers through simulation works. The results showed the suitability of hydraulic barrier for controlling CO 2 leakage in the low transmissivity overlying aquifers.…”