Subsea system worries by ProQuest

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									Subsea
system
worries
High integrity pressure protection systems (HIPPS) have been
around for years, but industry seeks new version for ocean
floor use
By William M. Taggart IV




W
           hy is the offshore oil-and-gas sector
           struggling with writing a new standard
           for an old subject?
  It has to do with the unique location where
these new high integrity pressure protection
systems (HIPPS) will locate—subsea.
      As the oil/gas industry moves into deeper
and deeper waters, the tool of choice is increas-
ingly becoming subsea production.
  Locating the classic Christmas tree well head
on the ocean floor saves the weight and cost of
the pipes required to extend those wellheads to
the surface, but it also involves changing the well-
head into something resembling a NASA project.
  With subsea wells going in at 10,000 plus feet
where ambient conditions are less than 40°F
at 4500 psig external pressure, access to the
plumbing is only via remote operated vehicles
(ROV). ROVs are expensive to operate and in
short supply.
  Still, why HIPPS?
  The answer is many of the newer subsea wells
are accessing deeper, higher-pressure reser-
voirs, which can only deliver product to nearby
existing infrastructure (platforms and pipelines,
designed for lower pressure fields) to remain an
economical venture.
  A HIPPS system located downstream of a sub-
sea well provides a barrier (called a “spec break”)
between the high-pressure oil/gas reservoirs
and the lower pressure infrastructure.




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      INTECH MONTH 2009    WWW.ISA.ORG
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   In this case, HIPPS is the only means that                 several concerns with
                                                                                           FaSt Forward
would allow tying into the lower rated systems.               the North Sea designed       l Many of the newer subsea wells are access-
The costs for a separate high-pressure infra-                 systems serving in the         ing deeper, higher-pressure reservoirs.
structure could very quickly result in costs that             U.S. jurisdictional wa-      l The likelihood of a HIPPS failure is minimal
not only make the development uneconomical,                   ters without additional        by its very design.
but also would result in expending more energy                redundant design safe-       l At 10,000 feet, regular testing and operation
than would be gathered from the wells.                        guards being included.         has to be a built-in part of the system.
   Along the same lines, there are many reser-                   Recognizing this di-
voirs, which industry has overlooked in the past              rective of redundancy to offset a lack of regional
because they either would not flow or not flow                  operating experience, and wanting to establish
at an economical rate.                                        a uniform set of rules and requirements for Sub-
   In today’s climate, these wells are receiving              sea HIPPS, industry has formed the API 17O
more attention, and prospectors are consider-                 committee, with participation from the MMS,
ing options like subsea pumps in order to ob-                 to produce a new recommended practice.
tain that higher and economically viable flow                     A concern of the MMS is that for mandated
rate. Subsea pumps come with their own set of                 safety devices (down-hole safety valves, Christ-
challenges, one of which includes a potential to              mas tree master valves, platform-boarding
over pressure the downstream flow line. HIPPS                  valves, and the like) frequent testing is required
is one option to mitigate this problem.                       to confirm their efficacy.
   Another reason for using HIPPS is as water                    Leak testing of valves, which authorities there
depths increase, it is becoming harder and hard-              have waved in some North Sea applications,
er to lay high pressure piping systems. The very              would not be acceptable to the MMS because of
weight of the high-p
								
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