CNSOPB Incident Prevention and Spill Response

This section includes information on the following:

1.   Types of spills and releases from a blowout

2.    Probability of a blowout

3.    Spill trajectory modelling

4.    Managing hazards

         i). Introduction

         ii). Increased Regulatory Expectations Post -Macondo

 1) Types of spills and releases from a blowout

In the unlikely event of a blowout occurring while drilling a well, a release of water, brine, natural gas or oil could occur. By its very nature, the probability of encountering hydrocarbons in an exploratory well is not high. Should a blowout event occur, the environmental response techniques would depend strictly upon whether hydrocarbons are released and, if so, the type of hydrocarbon that is released. A blowout involving natural gas would have relatively minor environmental impact. Should it be light oil, similar to that which was discovered and produced in the Cohasset Panuke project, the oil would float on the ocean surface in a thin layer and breakup / evaporate naturally within hours to days depending on the sea state. Response techniques to be employed would need to be more robust and varied should medium or heavy grade oil be spilled.  

2) Probability of a Blowout

An analysis of the probability of potential blowouts from offshore exploration wells was completed as part of the Environmental Impact Statement filed by BP Canada pursuant to the CEAA 2012 environmental assessment process. 

Historical data indicates that the probability of a blowout incident is extremely low. It is estimated that for wells with a subsea blowout preventer (BOP) installed, including shear rams and following the two-barrier principle, the frequency of a blowout incident is 0.031% per exploration well drilled (please note that a blowout may or may not contain hydrocarbons, and each blowout event would differ in terms of the rate of flow and volume released). This probability estimate is based on data from the Gulf of Mexico, United Kingdom (UK) and Norway between 1980 and 2004, prior to the implementation of additional controls and mitigation measures that are now used for well control such as improved BOP designs with additional redundancies and controls (safeguards) to ensure operability under all anticipated conditions, enhanced BOP testing, third party verification of BOPs, onshore remote monitoring of well operations, and enhanced industry training and competency.

There have been more than 50,000 offshore exploration wells drilled worldwide. There have been two instances, both in the Gulf of Mexico (in 1979 in Mexican waters and in 2010 in U.S. waters), where a blowout of an exploration well resulted in a major spill of oil (millions of barrels) into the ocean. Other past exploratory well blowout events spilled less than 250,000 barrels (39,750 cubic metres) of oil. 

3) Spill Trajectory Modelling 

Oil spill fate and trajectory modelling and analyses were performed to help evaluate potential environmental effects of accidental spills and to enable oil spill response planning. Worst-case spill scenarios were conservatively modeled using local historical meteorological and oceanographic conditions and by assuming that no response measures are put in place to minimize or reduce effects.  In the unlikely event of a major spill, oil spill response measures would be used to reduce adverse effects on the environment.  Oil spill containment and recovery and shoreline protection (if oil was to flow towards a shoreline) operations would be undertaken to reduce adverse effects to marine and coastal resources and to mitigate the spill’s impacts.  

BP Canada modelled a worst credible case scenario of a 30-day unmitigated spill (with no response measures in place) over a period of 120 days. BP Canada has demonstrated that a well would be capped and contained in a shorter time period than 30 days, and as such this modeling is considered to be conservative. This resulted in the following findings: 

  1. Following an unmitigated release, the majority of oil will remain in offshore waters.

  2. Seasonal variation in the movement of oil following a release is expected:

           a.    during winter conditions, oil was more likely to be  transported to the south and southwest due to the stronger southwesterly surface currents in winter;

           b.    during summer conditions, movement is more uniform with multi-directional transport patterns and a higher frequency of transport towards the south and east, farther offshore, due to prevailing winds from the west;

           c.    higher percentages of the oil were found within the water column during winter months as a result of increased wind and wave action which draws surface oil into the water column; and

           d.    the greatest surface oiling occurred during summer months, with calmer conditions wind and wave conditions compared to winter.

       3.   The likelihood of oil reaching the mainland shore was demonstrated to be very low, with a <20% probability that a surface oil sheen will enter nearshore waters of mainland Nova Scotia:

           a.    oil would need to remain on the surface for 30 to 50 days to be transported to mainland Nova Scotia nearshore waters;

           b.    in-water oil concentrations above the established threshold are not predicted to reach the nearshore waters of mainland Nova Scotia;

           c.    the possibility of shoreline oiling would be low (0 to 10%) along mainland Nova Scotia with the probability of reaching most predicted contact locations being less than 1%; and

       4.    The probability of shoreline oiling of Sable Island would be up to 50% and could occur within 3.8 days in the summer and 5.8 days in the winter.  


4) Managing Hazards

i)..    Introduction

The regulatory system enforced by the CNSOPB requires operators to identify hazards, to eliminate them where possible, and to properly manage those that remain. Risks are required to be reduced to as low as reasonably practicable. This is achieved through the selection of appropriate designs, and through the implementation of appropriate controls (or safeguards). The primary focus of the CNSOPB’s efforts is to ensure that operators take all reasonable precautions to prevent the occurrence of incidents that may pose a threat to safety of personnel or to the environment. 

In addition, operators are required to identify and understand the potential consequences of each hazard, and develop appropriate recovery strategies, to the satisfaction of the CNSOPB, that would be implemented should an unwanted incident occur.

This approach is displayed pictorially in Figure 1 for a potential spill event. In this example, a threat could be a loss of well control event (which could result in a blowout). There are a number of controls and safeguards that must be in place to prevent a spill incident from occurring, some of the key ones being listed under the left side of the ‘bow tie’.  Some of the key recovery strategies that would be implemented should a spill incident actually occur are detailed in the right side of the ‘bow tie’. Since the Macondo incident that occurred in 2010, significantly increased regulatory expectations have been introduced to further reduce the probability of a well control event, and to reduce the consequences of a blowout should it occur. 

Multiple Drilling Safeguards

Regulations enforced by the CNSOPB require many systems to be in place to prevent accidental releases or blowouts during a drilling program. These systems include proper drilling unit selection, hazard identification and risk assessments, the mud system and the steel (casing) design, downhole measurements of pressure and temperature real time, and finally Blowout Preventers (BOPs). The information generated by the downhole measurements enables appropriate personnel to make proper decisions while a well is being drilled.

ii)..    Increased Regulatory Expectations – Post Macondo

Regulators worldwide have increased their expectations of operators since the Macondo incident. The CNSOPB is no exception. Key improvements that are now required by the CNSOPB, and that are being applied to BP Canada’s proposed drilling program, include both additional preventative control and recovery measures, as detailed in Figure 1, and as discussed below.

Additional Preventive Control Measures – Post-Macondo (as listed under the left side of the ‘bow tie’ in Figure 1)

a.    Independent Well Examiner

The CNSOPB now requires that the detailed design of each well that is to be drilled, which is originally prepared by an operator’s drilling team, be subsequently reviewed and verified by a qualified, independent well examiner. During the drilling of the well, if the drilling program deviates from the verified well design, operations must be stopped and corrective actions taken to bring the drilling program back into compliance. Any changes to the well design that may be proposed at any time during the execution of the drilling program also require the independent well examiner to review and sign off confirming that the change is appropriate and maintains well safety, and such information must be submitted to the CNSOPB. This provides additional layers of oversight that previously didn’t exist.

b.    Improved Blowout Preventers (BOPs)

A number of significant improvements have been made to BOPs since the Gulf of Mexico incident, some of which are as follows:

Focus on Prevention of Incidents / Spills



BOP re-certification not required

5 year re-certification required

Shearing of pipe within the BOP not always possible (preventing sealing of well in some instances)

Verification of shearing capability required at maximum anticipated pressure

One blind shear (cutting) ram required

2 blind shear rams mandatory

Remote operated vehicle (ROV) intervention at BOP not robust enough to perform all required functions in case of an emergency event

ROV functional testing must be undertaken and verified at the time BOP is installed 

c.    Real Time Monitoring

The CNSOPB now requires that data that is continuously collected from the well during the execution of a drilling program be sent to an onshore base in real time. This data must then be monitored by qualified drilling experts 24 hours a day, seven days a week, to ensure that drilling personnel on site do not overlook something that could lead to a loss of well control. The onshore personnel must be able to phone to the drilling installation and speak directly with the drilling personnel to discuss what they are observing and actions that may need to be taken. This provides an additional layer of oversight that previously didn’t exist.

d.   Increased Training and Competencies

According to regulations, and established standard practices validated by the CNSOPB, offshore operators must ensure that each worker has appropriate training specific to their position. Since the Macondo incident, the CNSOPB has significantly increased training and competency expectations, with an emphasis on greater well control training and ongoing recertification of long-serving personnel. Refer to the Atlantic Canada Offshore Petroleum Industry Standard Practice for the Training & Qualifications of Personnel for details.

e.    CNSOPB Oversight Program

This Plan details the CNSOPB’s oversight measures during the planning and execution of drilling operations that are to take place in deep water, and / or for wells that may encounter high pressure / high temperature. These oversight measures are being applied to the well to be drilled by BP Canada.  

Pre-job requirements of the Operator include demonstration of readiness for the drilling program and submission of contingency and response plans to be implemented in the case of a spill. A critical and systematic assessment of the robustness of the well design from a wellbore security, well safeguard and well control perspective is conducted by CNSOPB staff.  Particular attention is paid to: 
•    the adequacy of the casing and cementing program;
•    well suspension and abandonment plans;
•    and the need for a comprehensive risk assessment of all anticipated well hazards.  

The CNSOPB review process also includes the verification the adequacy of the well safeguards on an initial and ongoing basis and confirmation of the operator’s ability to drill a relief well and to access well containment systems such as a capping stack. 

During drilling program execution, there are daily reporting requirements and special reporting of all events such as BOP testing, casing pressure tests and cement logging that is done to confirm cement integrity. Weekly meetings with the Operator’s senior staff are held to ensure well control is being maintained at all times. Throughout the program, audits and inspections of the vessel, procedures and key activities are performed by CNSOPB staff.

Regular meetings will be held with BP Canada focusing on kick prevention, kick detection, well control and blowout prevention and anomalies or upset conditions. “Time-outs” must be called as required until an anomaly (if one has occurred) is fully understood; its impact on the execution of the program is determined; and, any necessary remedies are implemented.

A full scrutiny of any proposed drilling program changes will be undertaken by CNSOPB staff prior to being implemented by the operator.

Additional Recovery Measures – Post-Macondo (as listed under the right side of the ‘bow tie’ in Figure 1)

Operators have traditionally been, and still are, required to submit an Oil Spill Response Plan in support of any drilling program. To review BP Canada’s plan, click here. This Plan documents the procedures for responding to an oil spill. The Plan must describe spill response resources, including those on-site, in the local region, nationally and internationally and arrangements to mobilize to site. Typical spill response methods are described on the CNSOPB website here.

Additional requirements implemented by the CNSOPB include the necessity for a net environmental benefit analysis to support decision making for use of dispersants, and well containment plan(s) to address the drilling of a relief well and the deployment of a capping stack should a blowout occur.  The preparation and submission of these plans to the CNSOPB is also a condition imposed in the Decision Statement issued by the Minister of the Environment and Climate Change Canada. 

a.    Net Environmental Benefit Analysis 
Net environmental benefit analysis (NEBA), also referred to as a spill impact mitigation assessment (SIMA) is a structured approach used by the response community and stakeholders during oil spill preparedness planning and response, to compare the environmental benefits of potential response tools and develop a response strategy that will reduce the impact of an oil spill on the environment. A NEBA/SIMA is one of the considerations used to select spill response tools that will effectively remove oil and will minimize the impact of the spill on the environment. 

During the planning phase of BP Canada’s drilling project, a SIMA was prepared to inform the development of the response strategy detailed in the Oil Spill Response Plan. View the full SIMA document here. The SIMA was reviewed by the CNSOPB.  Advice was provided to the CNSOPB through Environment and Climate Change Canada’s National Environmental Emergencies Centre’s Science Table. Participants included representatives from Fisheries and Oceans Canada, Environment Canada, Canadian Wildlife Service, Canadian Coast Guard, Transport Canada and Natural Resources Canada.

Neither the acceptance of the NEBA/SIMA, nor the granting of an authorization for a drilling program (and any related approvals to drill a well), grant approval for the use of a dispersant in responding to an oil spill.

If a major incident was to occur, and an Operator was to consider the use of a dispersant, legislation requires that a specific request for approval be made at that time to the CNSOPB’s Chief Conservation Officer (CCO).  Such a request would have to be accompanied by an incident specific NEBA/SIMA.  The use of dispersants would only be considered in cases where a net environmental benefit analysis concludes that it is better for the environment to do so.  The CCO would first consult with experts of Environment and Climate Change Canada’s National Environmental Emergencies Centre’s Science Table, which brings together relevant experts in the field of environmental protection in all levels of government, other stakeholders, and the response community. Additionally, the CCO is obligated by legislation to consult with the federal Minister of Natural Resources Canada and provincial Minister of Energy before granting approval to use a dispersant.