Is it necessary to install a downhole safety valve in a subsea ... - NTNU

Is it necessary to install a downhole safety valve in a subsea oil/gas well?
2 Rules and regulations
This chapter will give an overview of the requirements related to safety barriers and having a
downhole safety valve (DHSV), in Norway, the United Kingdom and the United States of
America.
2.1 Norway
In Norway, the following requirements to well barriers are included in the regulations from the
Norwegian Petroleum Directorate (NPD):
“Section 76:
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, cf. also the Facilities
Regulations Section 47 on well barriers.
If a barrier fails, no other activities shall take place in the well than those
intended to restore the barrier.”[29]
“Section 47:
Well barriers shall be designed so that unintentional influx, crossflow to shallow
formation layers and outflow to the external environment is prevented, and so that they
do not obstruct ordinary well activities.” [30]
The NPD has also issued specific requirements related to the use of downhole safety valves
(DHSV):
“Section 53:
Completion strings shall be equipped with downhole safety valves (SCSSV). If the
production annulus is used for gas injection, this equipment shall also be equipped with
downhole safety valve (SCSSV) to provide for annulus barrier testing.” [30]
2.2 United Kingdom
In the United Kingdom (UK), the offshore safety regulations are issued and followed up by the
Health and Safety Executive (HSE).
There are no specific requirements in the UK regulations for the installation of any type of
downhole valve in any type of well. The regulations, which do apply to this situation, are; The
Offshore Installations and Wells (Design and Construction etc,) regulations 1996, regulation
13.1:
“The well-operator shall ensure that a well is so designed, modified, commissioned,
constructed, equipped, operated, maintained, suspended and abandoned that—
(a) so far as is reasonably practicable, there can be no unplanned escape of
fluids from the well;”[31]
and The Offshore Installations (Prevention of Fire and Explosion and Emergency Response)
regulations 1995, regulation 9.1 which requires installation owners to take appropriate
measures to prevent the uncontrolled release of flammable fluids. This regulation applies in
principle to subsea wells [31].
Diploma thesis, NTNU 2002
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