June 22, 2018 Incident Bulletin Update: Unauthorized Discharge of Drilling Mud


The Canada-Nova Scotia Offshore Petroleum Board (CNSOPB) has completed its review and investigation of the unauthorized discharge of synthetic based drilling mud (drilling mud) that was reported by BP Canada Energy Group ULC (BP Canada) on June 22, 2018, and has determined the following:

  • The incident occurred as a result of a failed connection in the mud boost line that is fastened to the marine riser, approximately seven metres below the water surface. The volume of drilling mud discharged was determined to be a maximum of 136 cubic metres.
  • The discharge of the drilling mud into the marine environment is, in itself, a non-compliance with the section of the Accord Acts legislation that prohibits spills. The investigation determined that BP Canada was duly diligent in complying with other sections of the Accord Acts legislation that would be relevant to this incident.
  • BP Canada completed the necessary investigation into the incident, and implemented appropriate corrective actions to prevent reoccurrence of such an incident, to the satisfaction of the CNSOPB, prior to being allowed to resume drilling operations. These actions included repairs and operational improvements to the involved equipment, and improved inspection and monitoring procedures.
  • The fate and effects analyses of the drilling mud discharge concluded that there were no significant adverse environmental effects as a result of the incident.

A Notice of Non-Compliance with respect to the unauthorized discharge of drilling mud was issued to BP Canada by the CNSOPB’s Chief Safety Officer and Chief Conservation Officer on October 15, 2019.

The Notice of Non-Compliance was issued in reference to S.166(1) of the Canada-Nova Scotia Offshore Petroleum Resources Accord Implementation Act:

Spills Prohibited

166(1) No person shall cause or permit a spill on or from any portion of the offshore area.

The CNSOPB contemplated whether additional enforcement action is required as a result of this incident. A number of factors were taken into account when making the decision, including:

  • The CNSOPB, based on the results of the fate and effects analyses, available advice and information (including comparison to pre-activity conditions), determined that there were no significant adverse environmental effects as a result of the incident.
  • There were no known previous incidents of similar failure of the mud boost line within the industry globally, and the CNSOPB accepted that the design, installation, testing, inspection and monitoring practices used by BP Canada and its contractors for the mud boost line equipment aligned with accepted industry practice at the time of the incident.
  • The incident learnings in terms of improved equipment practices have been shared within BP globally and the contractors involved in the drilling program, and have also been shared with the global oil and gas industry to help prevent future such incidents.

The CNSOPB also considered the appropriateness of BP Canada’s corrective and preventative actions, along with BP Canada’s cooperation with the CNSOPB in response to this incident, recognizing the following:

  • BP Canada reported the incident to the CNSOPB in a timely manner. The CNSOPB directed BP Canada to halt drilling operations, and BP Canada did not resume drilling until authorized by the CNSOPB.
  • The CNSOPB visited the rig on a number of occasions following the incident to gather information relating to the incident, to verify regulatory compliance and implementation of corrective and preventative actions, and to provide enhanced regulatory oversight.
  • BP Canada conducted its own investigation into the incident in accordance with regulatory requirements and their company management systems.
  • The CNSOPB reviewed and followed up on BP Canada’s investigation report and other information submitted as required following the incident, ensuring that appropriate actions were being taken by BP Canada, and that these measures were aligned with the CNSOPB’s own information and expectations.
  • ​On July 22, 2018, after drilling operations had been suspended for 31 days, the CNSOPB was satisfied that the necessary investigation along with the implementation of appropriate corrective and preventative actions had been completed by BP Canada. These actions included repairs and operational improvements to the involved equipment, and the implementation of improved inspection and monitoring procedures. Only then did the CNSOPB authorize drilling operations to resume.

The CNSOPB concluded that the facilitated compliance measures taken following the unauthorized discharge of drilling mud are appropriate for preventing reoccurrence, and that further enforcement action on this matter is not necessary to ensure ongoing regulatory compliance.

The Notice of Non-Compliance will be taken into account should BP Canada have an incident in relation to any future activity in the Canada-Nova Scotia offshore area.

To read CNSOPB’s incident summary click here.

Additional information:

Media Contact:

Stacy O’Rourke

BP Canada Energy Group ULC
Maureen Herchak
​BP Media Line: 1-403-233-1033