Project showcase

Elgin Gas Blowout – Surface Intervention and Relief Well Drilling

Project goal

Add Energy provided multiphase flow modelling and well control supervision throughout the entire project.

Why we were contracted

On March 25th 2012, hydrocarbons started to flow uncontrolled up between the 20" casing and 30" conductor in Elgin G4 well to wellhead deck. The platform is located in the UK sector of the North Sea in water depth of 92 m.
The blowout occurred during plugging and abandonment of the well. This high pressure / high temperature production well flowed gas and condensate to the platform deck due to mechanical failure of casing strings after a pressure build-up. All personnel were safely evacuated.
Highly experienced specialists from Add Energy were engaged to provide support, planning and recommendations for the upcoming kill operation.

What we did

Blowout analysis

Simulations were immediately initiated by Add Energy specialists to evaluate the actual reservoir, well and flow conditions. The main focus was to confirm the blowout rate and potential flow paths in order to provide recommendations for the upcoming kill operation.

Kill analysis

With intact wellhead, the plan was to stop the flow by surface intervention and pumping kill fluid down the production tubing.

The OLGA-WELL-KILL software, tailor made by Add Energy, was used to establish the likely leak path and match the actual flow conditions. Well kill simulations showed that a dynamic kill was possible due to low flow rate of gas and condensate. A detailed kill plan was prepared to assist the operator during the planning and execution process. The plan included recommendations with respect to pump rate, volumes and kill mud properties.

The Result

The G4 well was successfully killed May 15th, 51 days after the incident. The West Phoenix jack-up rig was used to perform the kill operation through flexible lines connected to the wellhead.

Two relief wells were drilled in parallel for contingency reasons.

"The choice of Add Energy to assist in the simulation of the Elgin well kill operations were one of the best decisions made during the project. Their expertise during the preparation and execution of the job was instrumental in helping to bring the situation back under control."

Blowout Task Force Leader