In mid-2012 Winterhawk was made aware that a large and growing number of wells that had reached the end of their commercial life. These wells had been suspended by the operator but had not been abandoned. At that time the number of wells awaiting abandonment was in the range of 75,000.
When Winterhawk asked operators why they had not been abandoning wells, they replied that the process prescribed by the Energy Resources Conservation Board [(ERCB]; now the Alberta Energy Regulator [AER]) was problematic. The accepted technology was to utilize neat Class G cement, which was known to experience volume decreased over time. This volume decrease (of ½% to 1% over 20 years) led to the formation of micro-annular leak paths inside and outside of the well casing. Many operators chose to continue to pay the annual suspension fee rather than abandon wells using technology that was likely to fail at some point in the future.
Winterhawk had been developing technology for use in cyclic steam stimulation (CSS) wells that used a eutectic salt as the sealing mechanism. One of the unique characteristics of eutectic salt is that it increases in volume when it changes phase from liquid to solid. Winterhawk presented this CSS technology to the ERCB. During that meeting, questions were posed about the possible utility of the eutectic salt as a replacement for cement in well abandonments.
To address this possibility, Winterhawk proposed that a study be undertaken to determine if the eutectic salt would be a suitable replacement for cement in well abandonment. Interest and support was encouraging and Winterhawk was able to raise funds for research and development from private investors, the National Research Council – Industrial Research Assistance Program (NRC-IRAP) and the Petroleum Technology Alliance of Canada (PTAC).
The purpose of the study was to address four issues:
- The mechanical-seal potential of the solid eutectic salt
- The thermal expansion of the casing potential for damaging casing or primary cement column
- The water solubility of the eutectic salt
- The corrosivity of the eutectic salt
The study began in the second quarter of 2014 in the SAIT Applied Research and Innovation Services (ARIS) laboratory. In August 2014 the R&D was moved to a private facility due to incompatibility of SAIT protocol and commercial R&D requirements. The testing continues to be operated in this private facility.