Alternate Sealants to Restore Barrier Integrity

Failure of cement integrity is one of the main issues in the O&G during the life cycle of a well but also on P&A, that results in loss of production, safety, environmental and regulatory concerns. Primary cement might fail to deliver zonal isolation due to several reasons such as cement contamination, exposure to corrosive fluids, influxes, in-situ stress variations, etc. that can cause leaks, cracks and even micro annuli on the cement and casing. When such failures are observed and occur during the lifetime of the well, then remedial job must be performed in order to restore the barrier and well integrity by sealing those failures with the use of various sealant materials that can also heal the cement.
This master thesis focuses on resin for remediation by using epoxy resin mixed with conventional and ultrafine cement, due to resins several advantages over Portland cement such as higher compressive strength, lower shrinkage, better mechanical properties, adhesive bond strength and so on. Each slurry tests were conducted by following the API standards to evaluate the rheological behavior, shrinkage, mechanical properties of the new sealant as well as its injectivity was tested, by using the Inhouse Sealant Injectivity Setup that was also used in the previous project. After each completion of the API and injectivity tests for one of the compositions, the data was analyzed before moving on the next composition. The injectivity tests were conducted by pumping the sealants through three various tubing diameters, which are 1/4”, 1/8” and 1/16”, in order to show the new sealants pumpability and the effectiveness of ultrafine cement and solid-free materials.
The results of the experiments proved that, epoxy resin enhances the properties of the cement in terms of compressive strength, rheology, consistency, bond strength and so on as well as the injectivity of the new sealant, where both the conventional and ultrafine cement mixed with epoxy showed that the sealant flowed successfully from the 1/4” section without any issues. The tests for the 1/8” section started to show the effect of particle-granular size of the conventional cement, where some pressure peaks were observed in high flow rates but both fluids passed through. Lastly, on the injectivity tests for the 1/16”, for both sealants pipe blocking was observed when applying higher flow rates but the ultrafine showed best results in low flow rates unlike the conventional cement where few high-pressure peaks were observed reaching the pumps pressure limit.