Report to be shared as below.

This alert was submitted by an IOGP member. It shows how multiple small changes to a project (including organizational ones), without proper reassessment and communication of the risks, can decrease the awareness and vigilance of the rig crew. A problematic drilling situation such as total losses and BHA pack off drove the focus away from the necessity to maintain well control, and a kick was unnoticed until it was released at the surface. 

Decreased geologic awareness combined with hole problems leads to an unnoticed well kick

While drilling the 12-¼” hole section of an onshore exploration well at 1910m MDRT into a highly permeable formation (most likely fractured basement) total losses were encountered. During attempts to cure total losses, the string was pulled back 3 stands and became packed off. While attempting to free pipe the well kicked. The kick was not promptly identified and finally a well release occurred with for a period of 26 seconds. The annular BOP was closed, and the well was secured. There were no personal injuries.

What went wrong?

The immediate causes for the first release were:

• Encountering total losses in the fractured formation.
• Insufficient contingency plans in place to cure losses.
• Allowing the hydrostatic column in the wellbore to reduce below the reservoir pressure.
• Not recognizing the kick and failing to close the BOP before the release.

The root cause of the incident was the following:

• Decreasing integrated team risk awareness during the planning process regarding entering the basement: combined risk of total losses, hole instability and kick.
• Management oversight and wellsite supervision.
• Rig qualification, selection/acceptance and competence.
• Organizational changes prior to the event.

Corrective actions and recommendations

An integrated offset wells review would have clearly highlighted the main risks (combined total losses and kick, H2S.) and would have promoted more prudent mitigations to be put in place in the planning phase.

• Communication of the risks had broken down throughout the project and the project team. Ensure continuous integrated risk assessment takes place throughout the project. Detailed contingency plans to be developed and documented for entering the basement prior to operations.
• Competency of rig supervision and rig crew to be clearly assessed and documented in relation to the expected well conditions prior to commencing operations. The relevant gaps identified and the appropriate training has to be provided to close gaps for operator, rig site and service company personnel.
• Well risks, geological objectives and contingency plans have to be considered and risks have to be assessed for the BHA selection.
• Share lessons with all drilling, completion, subsurface and HSE teams: When faced with a well control situation or stuck pipe, we have to focus on the well control.
• Drilling Management handover period should be sufficient to transfer clear understanding and responsibility.
• Risk Assessment and review of project schedule should take place with Senior Leadership prior to committing to change the rig strategy. Option to delay the project should be given greater consideration if for a suboptimal rig.
• In complex rig acceptance projects, the rig survey should be repeated by the independent survey company prior to acceptance and a second condition report generated. All punch list items shall be witnessed prior to closeout.
• Risk Assessment and Management of Change training to be further developed and delivered to key personnel in the well planning and execution phase.
• Introduce a project management system that ensures that documentation for all drilling projects is effectively controlled and communicated.
• Ensure clear accountability for discipline Peer Reviews Recommendations and ensure follow up and closure of findings within the disciplines involved in the Project while also ensuring a system is set up to be able to document all the discussions in the Peer Reviews.