Responsible Offshore Drilling

  • Wellesley Petroleum's HSE principles in action:

    Proving a fast-track approach to environmental protection.

  • The drilling operations challenge

    Drilling Exploration wells is a complex task that carries inherent risks

    •  Macondo 2010 brought those risks sharply into focus.

    •  Key learnings from Macondo:

    • Failure in HSE culture lay at the core of the incident.
    • Always plan for a problem well.

    •  Current industry plans for accident / problem well: 50-100 days

    •  Focus on risk prevention:

    • Securing the safety of personnel on the rig.
    • Minimising the environmental impact. 
  • Wellesley's initiative to shake up the way in which the industry responds to an accident

    • The Challenge

      Going further to safeguard environment

      Wellesley set about reducing the time it takes to isolate the well.

    • Why

      To mitigate potential human and environmental risk -

      With speed, effectiveness and safety as the defining principles.

    • How

      A "capping stack" (50-100 tons) was placed over a blown-out well to stop or redirect the flow of hydrocarbons

  • The Outcome

    Wellesley's trials capped the well safely in just 72 hours.

    Watch a brief video of the trails here

    •  The programme:

    • Two full scale mobilisation exercises offshore Norway
    • Oil wells
    • Gas wells

    Demonstrated mobilisation outcomes in 72 hours:

    • Technology
    • Equipment 
    • Trained personnel

    A first in Norway, Wellesley are leading the way in Health, Safety and Environmental risk reduction in drilling operations.

Responsible Offshore Drilling

HSE principles in action: proving a fast-track approach to environmental protection

At Wellesley Petroleum, prevention is our primary focus when it comes to meeting our health, safety and environmental (HSE) objectives. However, we also understand that the drilling of exploration wells is a complex task that carries inherent risks. The Macondo incident of 2010 brought those risks sharply into focus. One of the key learnings from Macondo – often not discussed – was that a failure in HSE culture lay at the core of the incident. We must always plan for a problem well.

We believe a robust HSE culture provides the foundation for stopping minor incidents escalating into major accidents.

Our HSE culture is built on three core values:

  • Humility: our suppliers have experience that we actively use
  • Ownership: we expect all to own the operation – ‘it’s my well’
  • Teamwork: a team performs better than the best individual.

We recognise that unwanted or unplanned events can occur during drilling operations; to imagine all incidents and accidents are avoidable is naïve. We prepare and train accordingly, with one prime goal in mind: preventing escalation. It was with this priority in mind that we chose to explore ways to mitigate a potential environmental risk – with speed and effectiveness as the defining principles.


Well control is one of the key risks we manage during drilling operations.

To cite one plausible scenario: on a problem well, it is decided to disconnect the drilling rig from the well head and move off-location. Subsea blowout preventers (BOPs) enable such a disconnection to occur safely, after the BOP has been closed. The BOP, however, may not seal the well; from an environmental perspective, the worst-case scenario is that the BOP is leaking, and the well flows directly into the sea. This may not be very likely but, as Macondo and other well blowouts have demonstrated, it can happen.

In such circumstances, our focus would be on minimising the environmental impact of any spill after first securing the safety of personnel on the rig. If an incident occurs with a problem well, current industry plans typically take 50-100 days and a lot of oil can be spilt over such a period.


Seeing real merit in pursuing a much faster response rate, Wellesley set about reducing the time it takes to isolate the well using a capping stack. A “capping stack” is placed over a blown-out well to stop or redirect the flow of hydrocarbons, giving engineers time to permanently seal the well. Weighing as much as 50 to 100 tons, it can present logistical challenges in emergency situations.

That is why we decided to set our Well Incident Team the challenge of formulating a plan to cap a well within a set timescale: 72 hours. This programme culminated in a full-scale mobilisation exercise being conducted offshore Norway to demonstrate the required equipment and trained personnel could be mobilised and deployed within the target time period.


The trial involved simulating a blow-out incident offshore, with the rig disconnecting from the well above the BOP and our Well Incident Team being called upon to perform the capping work.

High quality plans and well-specific procedures are prepared for each well that Wellesley drills, and these plans were tested during the trial. For the simulated scenario, the Well Incident and Capping Teams were mobilised with two subsea vessels. The capping stack was loaded onto one of the vessels and sailed out into the fjord; the capping stack was deployed and function tested in accordance with the prepared procedures.

All physical activities were performed on time and, allowing for sailing durations and mobilisation times, it enabled us to lay claim – with confidence – to a 72-hour capping capability.



There are particular challenges associated with the location of the deployment vessel when a capping stack is being applied over a blowing gas well.

A further trial was therefore completed to test an alternative deployment concept and the associated equipment. Instead of being lowered from a single vessel, the stack was floated into place using a ballast arrangement, with the stack slung between two boats. This allowed the boats to be 1km apart, and away from any gas plume emanating from a blowing gas well.

The trial proved the system design and demonstrated our ability to cap a problematic gas well within 72 hours.

Operationally, it creates fresh confidence in Wellesley’s ability to respond to an incident on any gas well we might drill.



Oil spill contingency plans in Norway typically assume:

  • A blowout has occurred with drill pipe out of the hole (largest flow potential)
  • A capping stack must be available and used if possible
  • A relief well should be ready within as short a time as possible. There are requirements to:
  • Have mature relief well plans (two locations)

  • Identify what rigs can be used

  • Have access to relevant equipment.


Oil spill recovery plans in Norway are based on certain assumptions, and are dimensioned around the volume of oil that could be spilt while a relief well is drilled. For a typical exploration well, the spill duration is estimated to be between 50 and 100 days. We have shown, through our trials programme, that we can cap an oil or gas well within 72 hours.

Wellesley’s 72-hour capping plan is a ‘first’ in Norway and demonstrates exceptional environmental readiness in the event of such a serious incident.

Watch a video of the 72-hour well capping below: