American Oil and Gas Reporter - October 2018 - 44

SpecialReport: Gulf of Mexico Engineering Revival
host facility for all major deepwater
producing regions except the U.S. Gulf,
where only two of 53 installed platforms
are FPSOs. The factors that have prevented a wider acceptance of FPSOs in
the Gulf are the same reasons for deselecting an FPSO as a universal wet tree
host candidate, namely the extensive
pipeline network, limited availability
of Jones Act-compliant shuttle tankers
to transport the produced crude, and
the need for a disconnectable turret
mooring and riser system to enable
sail-away of the FPSO in advance of
an approaching hurricane.
Qualitatively assessing the various wet
tree host platform candidates shows that
the semisubmersible is the most versatile
option that best satisfies requirements for
a universal wet tree host facility. It also
is reflective of current trends in the Gulf,
where 12 of the 15 deepwater projects
with a host platform that have been sanctioned or advanced to FEED since 2012

have been semisubs. These facilities are
in water depths ranging from 4,000 to
7,000 feet and have topsides operating
payloads from 10,000 to 50,000 tons.
Benefits Of Standardization
The industry has made great strides
in reducing CAPEX requirements for
deepwater developments by employing a
standardization strategy for subsea, topsides equipment, hulls, moorings and risers. The vision is to streamline procurement by standardizing specifications for
procured equipment, thereby realizing
significant schedule and cost compression
benefits. One study estimates standardization has the potential to improve the
total value of deepwater projects by as
much as 30 percent by reducing direct
costs, project overruns and cycle times.
The JIP 33 Capital Project Complexity
Initiative begun by a consortium of operators in 2015 sought to drive structural
reduction in upstream project costs (in-

TABLE 2
Universal Wet Tree Host Facility Suitability
Platform Type
Deselection Factor

TLP

Spar

Semisub

FPSO

Water Depth Range
Payload Range
Flexibility of Expansion
Flexibility of Relocation
Integration & Installation
Contracting Flexibility

FIGURE 1

cluding subsea trees) with a focus on
noncompetitive collaboration and standardization. Preliminary estimates of the
first phase indicate potential reductions
of 10-20 percent in equipment capital
expenditures, and 40 percent in schedule
compression, and improved quality and
reliability.
The industry can reduce CAPEX
substantially by focusing on "re-baselining" the scope and specifications for
a field development's host facility and
subsea components. An example is
Shell's efforts to reset the base line
used to develop future projects. Shell
engaged third-party engineering companies to deliver "unconventional" designs of topsides, hulls and seabed systems to enable delivery of safe and affordable solutions for developing small,
complex marginal reservoirs. The designs were calibrated with a minimum
technical scope developed by Shell's
internal engineering team to meet all
internal safety standards.
In addition to the minimum technical
scope, a number of optional functionalities
related to flow assurance, uptime and
operational and field expansion flexibility
were identified. A rigorous process was
used to justify or reject each optional
functionality and value enhancing ones
retained and added to the minimum scope
(Figure 1). This methodology of "zerobased design," rigorous benchmarking,
learning from those with simpler facilities,
and using only value-added options has
yielded dramatic capital cost reductions.
Semisubmersible Host

Shell's Process for Developing Competitive Scope
For Marginal Deepwater Field Developments
CAPEX

Shell
requirements

Minimum Technical
Scope in Industry

Equipment
availability,
testing capability &
accomodation type

Minimum Technical
Scope for Shell

44 THE AMERICAN OIL & GAS REPORTER

Optional
functionality: spare
and low-maintenance
equipment

Competitive
Scope

Overinflated
Scope

The four-column ring pontoon hull
configuration is the universally accepted
standard configuration for a semisubmersible production platform. This basic
configuration is scaled up or down easily
to match the payload and footprint of
the topsides, the size of which is driven
by the reservoir, production rates and
subsea requirements. Major variants of
this basic configuration are the tuning of
the hull and riser system, and the type of
deck structure.
In the past, a great deal of time and
effort has been spent on recycling between
the hull and riser system which has been,
by default, a steel catenary riser (SCR).
The acceptance of the steel lazy wave
riser (SLWR) decouples the hull from
the riser system. This allows for an inter-
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