Report Investigation of gas blowout on Snorre A - Well Integrity ...

Statoil could not document that an overall assessment, review or investigation had been
implemented after repeated serious and less serious incidents on SNA.
Requirement:
• The Management Regulations, Section 19 relating to Registration, examination and
investigation <strong>of</strong> situations <strong>of</strong> hazard and accident require that situations that
frequently recur shall be examined closely through investigation.
• The Activity Regulations, Section 22 relating to Procedures requires that the
responsible party shall ensure that procedures are established and used in such a way
as to fulfill their intended functions.
• WR0015. ”Handling <strong>of</strong> undesirable incidents and HSE data in UPN”, Chapter 6.1.4
”Incidents that are repeated”.
5.1.14 Non-conformity 14. Implementation <strong>of</strong> tail pipe perforation
On 21 November 2004, the 2 7/8” tail pipe was perforated in accordance with the program.
The well was then opened to communication with the reservoir pressure <strong>of</strong> maximum 325 bar.
After testing in December 2003, the secondary barriers were rated for just 94 bar.
Evidence:
No documentation has been submitted to the PSA to confirm that measures had been
implemented to analyze and secure the secondary barrier in relation to maximum pressure,
before the tail pipe was perforated. Nor is there documentation that the secondary barriers
were tested for the anticipated pressure.
Requirement:
• The Activity Regulations, Section 76 relating to Well barriers requires that, during
drilling and well activities, there shall at all times be at least two independent and
tested well barriers after the surface casing is in place.
• The Management Regulations, Section 2 relating to Barriers requires that "it shall be
known which barriers are not functioning".
5.1.15 Non-conformity 15. Executing link does not stop the operation before
perforation <strong>of</strong> the tail pipe
When the tail pipe was perforated, the well was opened to communication with reservoir
pressure. The executing drilling crew, with the drilling operations supervisor, drilling
supervisor and toolpusher as pr<strong>of</strong>essional experts, did not demand a full halt in the operation,
for example for the reason that the situation was not sound.
Evidence:
The operation was not halted due to inadequate barrier status.
Requirement:
• The Activity Regulations, Section 76 relating to Well barriers requires that, during
drilling and well activities, there shall at all times be at least two independent and
tested well barriers after the surface casing is in place.
5.1.16 Non-conformity 16. Inadequate handling <strong>of</strong> non-conformities
The drilling supervisor - night inquired in an e-mail <strong>of</strong> 23 November 2004 to the program
engineer, with a copy to the drilling operations supervisor, ”is it OK to pull 7 5/8” scab-liner
31