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.
geologic awareness combined with hole problems leads to an unnoticed well
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.
Encountering total losses in the fractured
Insufficient contingency plans in place to cure
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
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
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
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