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

shut-in, well barriers were established, i.e. with a plug directly above the reservoir section,
and the well was filled with brine. 5
The well was considered to be "complex". This was related to (see Figure 2):
- Factors which give the well reduced integrity (corrosion, leaks).
- Unconventional well completion with a great many small completion elements.
- Additional completion elements installed in the well in connection with repairs (Scabliner
and straddle)
- Downhole well control valves
Figure 2. Well sketch reflecting status <strong>of</strong> well integrity prior to start-up <strong>of</strong> the well operation.
3 COURSE OF EVENTS
This chapter describes the actual course <strong>of</strong> events, based on information obtained in the
investigation. The activities are described in chronological order. The description <strong>of</strong>
assessments refers to the evaluations that were made by the personnel involved during the
course <strong>of</strong> events. This chapter is divided into three main parts.
The first part focuses primarily on the planning <strong>of</strong> the well operation, and relates to the time
period from the spring <strong>of</strong> 2004 until start-up <strong>of</strong> SNA on 16 November 2004. The second part
mainly deals with start-up <strong>of</strong> the well operation and up to when the well went out <strong>of</strong> control
on 28 November 2004. The third part largely describes measures implemented to handle the
situation when the well ran out <strong>of</strong> control.
5 CaCl2/CaBr2 brine with 1.47 s.g.
11