General Overview of Deepwater Riser Design, the content is: Introduction, Riser Types, Main Selection Factors, Design Procedure, Dynamic Example of Riser Modeling and Summary
5. Introduc>on
• What
is
Riser?
A
riser
is
a
pipe
that
connects
and
surface
facility
to
a
subsea
system
• What
is
Deepwater?
Above
1000L
depth
• What
is
Riser
Design?
It
means
to
achieve
the
func>onal
requirements
7. Riser
Types
• Material
Type:
Steel,
Flexible,
Titanium
and
Composite
• BOP
(X-‐Tree)
LocaDon:
Subsea
and
Surface
(Dry
and
Wet)
• ConfiguraDon
Type:
SCR,
SLWR,
Hybrid
Riser,
TTR
• FuncDonal
Type:
Drilling,
Produc>on,
Injec>on,
Export,
Comple>on/Workover
8. Material
Type:
Steel
Pipe
Failure
types
very
well
known,
proven
technology,
more
suppliers
9. Material
Type:
Unbonded
Flexible
Pipe
The
main
advantage
of
using
flexible
pipes
is
their
ability
to
work
under
extreme
dynamic
condiDon
compared
with
rigid
carbon
steel
pipes
Only
3
suppliers:
GE
Oil
&
Gas,
NOV,
and
Technip
Complex
mechanism
of
failures
Heavier
&
expensive
than
steel
10. Material
Type:
Titanium
Titanium
alloys
have
a
unique
combina>on
of
proper>es,
such
as
high
strength,
low
elasDc
modulus
and
density,
which
make
them
a[rac>ve
for
use
in
offshore
riser
systems.
14. Material
Type:
Composite
Material
• Weight
• Strength
• Corrosion
• Fa>gue
• Less
expensive
to
build
complex
component
• Thermal
proper>es
§ Orthotropic
material
§ More
bri[le
§ More
expensive
than
steel
§ Complex
repair
procedure
Advantage
Disadvantage
15. Surface
x
Subsea
BOP
The
comparison
of
a
conven>onal
subsea
BOP
drilling
system
and
a
surface
BOP
drilling
system
clearly
shows
the
reduc>on
in
size,
weight,
loads,
and
physical
deck
area
required
to
drill
a
well
using
surface
BOP.
19. Advantage
/
Disadvantage
• Simple
in
design
with
few
complicated
component
• Economically
a[rac>ve
in
terms
of
both
installa>on
and
construc>on
• High
top
tension
• Low
fa>gue
performance
at
riser
top
and
TDZ
27. Key
Selec>on
Factors
• Water
depth
• Environmental
condiDons
• Geographical
locaDon
• Reservoir
pressure
and
temperature
• Corrosive
fluids
• Number
of
wellheads
• Wellhead
type
• Cost
and
schedule
• Operator
34. Overview
• Pre-‐FEED
§ Determine
technically
feasible
riser
solu>ons
§ Determine
cost
comparison
between
riser
solu>ons
§ Iden>fy
risks
associated
with
riser
system
§ Concept
selec>on
35. Overview
• FEED
§ Further
develop
selected
concept
(or
concepts)
to
enable
Operator
to
commence
the
Execu>on
Phase
with
high
degree
of
confidence
and
low
level
of
risk
§ Develop
documenta>on
to
enable
an
ITT
(invita>on
to
tender)
package
to
be
issued
to
Execu>on
Phase
contractors
• Detail
Design
§ Detailed
design
of
the
riser
system
to
enable
fabrica>on
and
installa>on
39. Modeling
Considera>ons
• Built
the
FE
global
model;
• Most
components
can
be
modeled
as
pipe
elements
with
the
key
proper>es
defined:
– Bending
s>ffness
– Axial
s>ffness
– Mass
– Drag
diameter
– Buoyancy
diameter
41. Global
FE
Model
Example
of
SRC
Global
Model
of
FE
created
in
Orcaflex
soLware.
42. Riser
Analysis
Type
• Collapse,
Burst
and
buckling
checks
• Top
tension
determina>on
• Operability
analysis
• DriL-‐off
analysis
• Recoil
analysis
• Hang-‐off
analysis
• Riser
installa>on
analysis
• Fa>gue
analysis
(VIV,
VIM
and
wave
fa>gue)
43. Design
Criteria
&
Standards
Code
• Drilling
Riser
(API
RP
16Q)
Envelope
Parameter
API
RP
16Q
Limit
AMJIG
Limit
Drilling
Mean
Flex-‐Joint
Angle
2
2
Maximum
Flex-‐Joint
Angle
4
4
von
Mises/Yield
Stress
0.67
0.67
Extreme,
Non-‐
Drilling
Maximum
Flex-‐Joint
Angle
90%
of
Max
90%
of
Max
von
Mises/Yield
Stress
0.67
0.80
Survival,
Non-‐
Drilling
Maximum
Flex-‐Joint
Angle
90%
of
Max
90%
of
Max
von
Mises/Yield
Stress
0.67
1.00
48. Summary
• There
are
diverse
riser
types
• Riser
design
is
complex
task
that
involve
several
itera>on
analysis,
involving
inter-‐
discipline
itera>on;
• Some
>me,
technical
factor
are
overpassed
by
not
technical
factor;
