Nanomodified Polymers for the Long-Term Repair and Remediation of CO2 Wellbores

Wellbores that intersect CO2 storage formations represent a potential leakage pathway that can lead to subsurface migration of stored CO2 and/or subsequent venting of stored CO2 to the surface; consequently, repair and remediation of these wellbore is critical for ensuring the permanent storage of CO2 in geologic formations. Repair and remediation operations are particularly challenging for these wellbores because of the range of types and conditions of wells; the widely varying leakage pathways encountered; the harsh environmental conditions that degrade most conventional materials; and the need to be effective for a very long time. A system is being proposed for repair and remediation of wellbores associated with CO2 storage facilities. The cornerstone of the proposed system is an extremely durable nano-modified polymer that will penetrate and seal very small but problematic leakage pathways as well as bond to and protect steel casing. In Phase I, the polymer will be modified to decrease its viscosity and extend its gel time to extend its utility for repair and remediation operations such as squeeze jobs and casing repair for wells associated with CO2 storage facilities. Using this polymer, a polymer modified cement with superior durability, flexibility and strength will also be developed in Phase I to replace the use of conventional cements in repair and remediation operation. In addition, the technical feasibility of an alternative delivery system for the polymer sealant using environmentally sensitive microcapsules will be established in Phase I. This delivery system can be used to engineer effective repair and remediation applications. A commercialization plan for the new repair system will be executed to aid in bringing the technology to the market. The key components of the system will be developed in Phase I. Phase II will include accelerated longevity testing of the system components under extreme environmental conditions, scaling of the microcapsule fabrication process to a commercial scale, and lab and field verification of the system effectiveness. The system will be available to be deployed in the increasing number of CO2 sequestration demonstrations, pilot operations, and commercial projects throughout the US and the world. There will be many wells associated with these facilities as many potential locations are located in formations that have numerous wellbores from previous oil and gas production – so-called legacy wells. It is in the best interest of the public and owners/operators of the wells to use a repair and remediation system that has been developed specifically for the challenges of these wells. In addition, a system that addresses the range of issues and conditions that may be encountered translates to more efficient and less costly field operations.