Feasibility of Novel Techniques to Mitigate or Remedy CO2 Leakage

Abstract

New ways to decrease the level of CO2 in the atmosphere are necessary to reduce the effects of the global warmimg. Subsurface CO2 storage has been identified as one of the key methods to reduce the emissions of CO2. The most crucial requirements that must be fulfilled to obtain a license for CO2 storage are: safety, reliability and the ability to remediate unwanted leakage. Remediation or mitigation of unwanted migration from storage sites requires new approaches for which the feasibility is yet to be demonstrated. The remediation technologies are classified as passive (e.g. stop injection) or active (e.g. producing or removing CO2). If passive methods are not enough to permanently stop the leakage, they need to be coupled with active approaches. The methodologies that we present in this work were stringently risk based, to ensures that the obtained results can be adopted to improve and help the regulatory process: protocols, safety regulations and guidelines. We studied the feasibility of some promising active technologies: 1. inject a chemical mixture near the location of leakage that reacts with the CO2 or formation water, forming solid reaction products; 2. inject heavy nanoparticles (NPs) and CO2 in a homogeneous mixture to increase the density of the CO2-saturated brine and consequentially escalating the dissolution rate of the CO2; 3. divert the injected CO2 from a leaky compartment of the reservoir to an adjacent compartment, separated by a sealing fault; 4. mitigate the CO2 leakage through natural faults located far from existing wells, transporting a polymer-gel by using man induced hydraulic fractures to drastically reduce the permeability of the fault; 5. transport foam to a leakage site to block CO2 from leaking out of a point leak. The results will be published in an interactive web-based tool, to advise and inform operators and authorities on the novel options that we investigated for remediation and mitigation.

Comprehensive Review of Sealant Materials for Leakage Remediation Technology in Geological CO2 Capture and Storage Process

“…(3) Other properties, such as long-term thermal stability, easy injectivity, cost-effectiveness, strong sealant integrity, and environmental protection, are also vital for an ideal sealant. Researchers have reported various kinds of sealants to remediate or mitigate CO 2 leakage performance during the CCS process . The commonly applied sealants include Portland cement, geopolymer cement, resins, biofilms barriers, gel systems, foams, nanoparticles, and so on.…”

A Review of CO2 Storage in View of Safety and Cost-Effectiveness

“…It should be mentioned that the foam can also reduce the risk of leakage in the underground CO 2 storage unit result from the reduction of fluid mobility. For instance, due to the significant shear rates differences between the flowing in the reservoir rock and leakage pathway, the foam may become gel inside the leak and reduce the leakage through the shear-induced gelation, i.e., the particles break the interaction barrier of forming clusters in high shear stress condition [171].…”

Injection of a CO2-Reactive Solution for Wellbore Annulus Leakage Remediation

“…In the case of sustained CO 2 leakage, a corrective measures plan must be in place and appropriate remediation measures should be taken [20,21]. Intentional clogging of the near-well area with salt has been proposed as a preventative measure against CO 2 leakage [22].…”