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?
In practice the HSE would question any proposal to complete a production well without a
downhole safety valve but in some cases it might be possible for the company proposing the
well completion to argue that the inclusion of such valves was not “reasonably practicable”.
This would require a demonstration that the “sacrifice” (time, trouble and expense, including
increased risk) of installing the valve was “grossly disproportionate” to the benefit [31].
2.3 United States of America
The Minerals Management Service (MMS) manage the US's offshore mineral resources
including the oil/gas production. Regulations concerning offshore operations on the outer
continental shelf states
“Paragraph 250.800:
Production safety equipment shall be designed, installed, used, maintained, and tested
in a manner to assure the safety and protection of the human, marine, and coastal
environments.” [11]
Specific requirements of subsurface safety devices are included:
“Paragraph 250.801:
All tubing installations open to hydrocarbon-bearing zones shall be equipped with
subsurface safety devices that will shut off the flow from the well in the event of an
emergency unless, after application and justification, the well is determined by the
District Supervisor to be incapable of natural flowing. These devices may consist of a
surface-controlled subsurface safety valve (SSSV), a subsurface-controlled SSSV, an
injection valve, a tubing plug, or a tubing/annular subsurface safety device, and any
associated safety valve lock or landing nipple.” …”(c) Surface-controlled SSSV’s. All
tubing installations open to a hydrocarbon-bearing zone which is capable of natural
flow shall be equipped with a surface-controlled SSSV.” [11]
2.4 Standard organizations
The NORSOK standards (the competitive standing of the Norwegian offshore sector) and are
approved as in force regulations of the NPD and state:
“During production activities at least two independent and tested barriers shall be
normally available between reservoir and environment in order to prevent an
unintentional flow from the well. The barriers shall be designed for rapid
reestablishment of a lost barrier. The position status of the barriers shall be known at
all times.”[17]
Standards issued from the American Petroleum Institute (API) and the International
Organization for Standardization (ISO) refers to the DHSV as if the presence in an oil/gas well
is obvious. The standards include descriptions of design, installation, repair and operation of
the DHSV. The existing standards are more of technical character. None of the current API and
ISO standards, however, includes a demand for a DHSV in a subsea well.
2.5 Regulatory challenges
The regulations from the concerning authorities are clear. A downhole safety valve (DHSV) is
required in both the Norwegian and U.S. regulations. In the U.K. the HSE states that they will
Diploma thesis, NTNU 2002
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