Canadian Natural submitted its comprehensive Final Report to the Alberta Energy Regulator (“AER”) on April 1, 2015 related to the Q2 2013 seepage to surface at our Primrose operations. The Final Report replaces the interim Causation Report submitted to the AER on June 27, 2014, providing the technical data and interpretation to support the Causation Report’s conclusions. The conclusions of both reports, which remained unchanged, identify the enabling conditions that led to the seepage to surface events. The results of both the Causation and Final Reports were reviewed by an independent technical panel who submitted its Independent Expert Panel report to the AER on May 19, 2015.
Please click here for the Executive Summary of Canadian Natural’s Final Report submitted to the Alberta Energy Regulator (AER) on April 1, 2015.
Canadian Natural's Final Report Conclustions
The Final Report, consistent with the Causation Report, identifies both the cause of the seepage to surface and the pathways from the Clearwater formation to surface. In essence, four contributing factors must sufficiently overlap to cause seepage to surface:
- A large volume of fluid was released into the Grand Rapids formation from the Clearwater formation (producing zone)
- To have seepage to surface, this volume must continue at both a sufficient rate and duration to move to the top of the Grand Rapids formation
- In addition, the volume must be in close proximity to a pathway (most likely being a mechanical failure of a wellbore) to bypass the Lower Colorado shale
- Steaming volumes, if sufficiently large, can change the stress states of the Upper Colorado shale allowing continuation of an upward flow to surface
As a result of extensive data gathering, investigation, analytical analysis and interpretation, Canadian Natural and the industry’s understanding of cyclic steam processes has been enhanced. These learnings have been applied, and our operational practices and strategies have been modified to mitigate the risk of future seepages.
Mitigation plans include:
- Proactively remediating wells with unconfirmed cement across the Colorado group of shales, thereby eliminating wellbore pathways through the Lower Colorado shales
- Modifying steaming strategies to minimize changes in the capping shales and limit the potential for fluid releases into the Grand Rapids formation
- Enhanced pressure monitoring of the Grand Rapids formation
- Heightened response to signals from the sub surface monitoring system to prevent the contributing factors (1&2 above) from occurring
Canadian Natural takes every incident seriously and we proactively work to deliver continuous improvement in safety and environmental performance. Canadian Natural is committed to developing resources using the most effective, efficient and environmentally responsible operations and does not expect significant changes to the targeted recovery of crude oil at Primrose.