DEEP7 2017 - Subsea 7 - page 12

TRANSFORMING THE ECONOMICS
OF FIELD DEVELOPMENT
LONG-DISTANCE
TIE-BACKS
By
Olivier Lodeho
Strategic Technology Programme Manager for Flowline Systems
&
Sigbjørn Daasvatn
Strategic Technology Programme Manager for Subsea Processing
In a low-cost oil and gas environment, one
option for operating companies is to utilise
effective subsea field development solutions
that eliminate the need for traditional
platforms or vessels with topside processing
facilities.
This applies to geographically remote areas
and small-pool developments of maturing
brownfield areas. In such scenarios, lower
development costs can be most effectively
achieved through long-distance tie backs.
The economics of longer tie-backs are
governed by a number of factors, including:
• The distance from existing installations
• The fluid temperature and pressure
• The water depth
• The recoverable volumes, reservoir size and
fluid properties
• The potentially lower recovery rates
compared with platform wells
The goal
We aim to achieve a situation where operators
can tie-back remote fields to existing subsea
facilities over longer distances than is
currently possible.
To do this, we are currently identifying
design drivers to define the optimal distances
for passive insulated, actively heated and
cold flow transport pipelines for thermal
management and their smart combination
with subsea boosting.
This technology is transforming the
economics of field development in
areas lacking existing infrastructure
In particular, by conditioning oil-dominated
well-streams in cold flow systems
(image above)
,
remote fields can be connected to central host
facilities using uninsulated small-diameter
transport pipelines over very long distances.
This technology enables the prospect of
total subsea production facilities with
no requirement for manned platforms,
transforming the economics of field
development.
Subsea 7 has an alliance with OneSubsea,
a market-leading provider of Subsea
Production Systems (SPS). Operating jointly
as the Subsea Integration Alliance, this
enables us to deliver effective combinations
of SURF and SPS expertise.
The challenges of
long-distance tie-backs
Especially in oil-dominated tie-backs, greater
transport distances increase the technical
and economic challenges of managing
temperature and pressure. Subsea 7 has
developed a number of technologies to enable
long-distance tie-backs.
The thermal and hydraulic challenges
are considerable. The carried fluid is a
multi-phase mix of oil, gas, water and
other chemicals which are likely to have a
detrimental interaction over long distances.
It is difficult to conserve the heat of
production fluids over long distances and
the fluid temperature is gradually
An increasing number of offshore oil and gas developments can be made
viable through eliminating the need to add expensive topside facilities.
12
deep7
Technology Magazine from Subsea 7
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