In typical cold flow heavy oil wells, only 4-8% of the original oil in place (OOIP) is recovered due to the high viscosity of oil. The tried and tested way of enhancing heavy oil recovery is by adding heat (using high pressure steam), but most heavy oil wells, particularly those outside of the Alberta Oil Sands areas, are not thermally completed. Within the Lloydminster area, it is estimated that only approximately 5% of wells are thermally completed and therefore cannot be steamed, leaving vast amounts of proven oil reserves unrecovered.
Figure: Map of wells with any type of thermal cement in Alberta (in red).
As per Directive 9, the Alberta Energy Regulator (ERA) considers thermal cement to be “a blend which does not exhibit a significant reduction in strength when subjected to temperatures greater than 360°C”. Conventional wells in designated oil sands areas must use thermal casing and cement, but only across the oil sands zone, meaning that while the target zone is thermally protected, it may still not be possible to steam the well.
However, even if a well is fully thermally completed, it is not necessarily completely immune to the effects of temperature and temperature swings. A percentage of thermally completed wells, which are actively being steamed, are prone to suffer from premature failure, either because of mechanical casing issues or cement inadequacies. There are often multiple contributing factors to casing failures but in steaming applications, big temperature swings can be a contributing factor behind such failures.
Alberta’s Directive 87 describes a casing failure as the loss of ability for any casing string in a well to contain and prevent the escape of fluids at expected operating conditions. The Alberta Energy Regulator’s Well Well Casing Failures Report, which provides a daily-updated, detailed accounting of reported casing failures, indicates that in Alberta there have been 44 reported well casing failures in thermal operations since 2022. Casing failures can result in costly remediation, at times running into millions of dollars, lost production and potentially severe environmental consequences. To illustrate the scale of potential cost, a widely publicized 2013 spill in a Cold Lake thermal operation, that is deemed to be in part due to a breach through cement, resulted in over 1,100 m3 of oil spilled and cost over $60 million to repair and investigate.
An easy-to-implement and affordable solution to protecting casing and cement from elevated temperatures and big temperature swings during thermal stimulations is GERI’s patented CasingCooler™. This technology makes steaming possible in thousands of non-thermally protected heavy oil wells and offers additional protection in existing steaming operations. The CasingCooler™ works by constantly circulating cooling water inside the annular space, packed-off between vacuum insulated tubing (VIT) and the well casing. The system provides continuous real-time temperature and pressure measurement, which can be viewed and
controlled remotely. Designed with safety in mind, automatic controls and shut-downs, ensure
safe and proper operation. To find out how the CasingCooler™ can be customized to your needs by emailing
hello@geri.com.