Evaluation of Robust Epoxy Resin Sealants for Wellbore Integrity Apllications

Abstract

During the drilling and completion phases of oil and gas wells, cement is placed in the wellbore as a barrier between the casing and the formation. All casing strings must be cemented to protect and support the casing, and to isolate production zones. The primary cement must prevent the wellbore fluids from migrating in an annular flow path so as to allow the wells to be utilized without any control problems. The primary cement may fail to deliver full zonal isolation due to several reasons such as insufficient mud removal before the cementing, casing expansion, and contraction, high fluid losses, cement free fluids, inadequate hydrostatic pressure, high-pressure tests and temperature variations across the cement causing micro-annuli and cracks that may allow fluids to migrate. In addition, if the cement is placed in zones where corrosive fluids are presented, chemical degradation could compromise the cement integrity. If any of these failures occurred during the life of the well, remedial job must be performed to restore the well integrity. Failing to restore the cement integrity may lead to unwanted severe consequences to the environment, the equipment, and personnel. This work presents the results of evaluating several epoxy resin sealants that have the potential to replace the conventional Portland cement used in remedial jobs. This study includes the rheological behavior, curing kinetics, injectivity, plugging performance against water and CO2, chemical resistance, and the mechanical properties of epoxy resin sealants. This work compares the results of epoxy resin sealants to that of the conventional Portland cement. The findings obtained from this work can be utilized in optimizing the cement remedial operations.