Case Study |
Link to Abstract |
PDF |
1.
Optimising Long Distance Gas-Condensate Flowlines
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Abstract |
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2. Optimising a Tieback to Existing
Facilities
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Abstract |
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3. Optimising an Extension to an
Existing
North Sea
Asset
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Abstract |
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4. Life of Field Stability of a
North Sea
Oil Development
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Abstract |
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5. Life of Field Cooldown in a Deepwater
Development
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Abstract |
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6. Life of Field Corrosion of a
Flowline System
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Abstract |
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7. Hydrodynamic Slug Size in Multiphase
Flowlines
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Abstract |
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8. Non-Newtonian Flows in Pipelines
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Abstract |
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Abstract
This case study is drawn from a conceptual study carried
out for an independent
UK
based Oil and Gas company. The flowline was sized by combining an integrated
reservoir/flowline simulator with simple discounted
cash flow economics. The operability of the flowline was also an
important issue as the speed at which it could safely
alter its production rate was stipulated in the Gas
Sales Contract (GSC). The study demonstrates how many conceptual
issues in gas-condensate systems can be studied using
steady state simulators, thus allowing transient simulation
to be deferred until the later phases of design.
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to read Full Document
(
192K)
Case Study No. 1 - Optimising Long Distance Gas-Condensate
Flowlines
Case Study No. 2 - Optimising a Tieback to Existing Facilities
Abstract
This study was carried out for a
US
oil company operating
in the central
North Sea
. It shows
that even short conceptual studies can benefit tremendously
from an integrated reservoir–flowline approach
to the analysis.
Click
to read Full Document (
115K)
Case Study No. 3 - Optimising an Extension to an Existing
North Sea
Asset
Abstract
This study was carried out for a
UK
based oil company operating
in the
North Sea
wishing to extend one of its existing subsea production
systems. The
case study shows how as flowline systems grow they
can become as much of a restriction to flow as the
wells or reservoir. Therefore, detailed evaluation of the overall
deliverability is best achieved using an integrated
reservoir model coupled to a representative well,
flowline and riser network model. Such evaluations are now commonplace using
the latest Life of Field simulation tools.
Click
to read Full Document (
119K)
Case Study No. 4 - Life of Field Stability of a
North Sea
Oil Development
Abstract
Transient operability issues can significantly affect the
NPV of subsea developments. Severe slugging, for example, can dictate major
design parameters such as flowline routes and diameters
and hence affect the overall CAPEX. It can also affect revenue by reducing the
operability of flowline-riser systems. Consequently, such issues should be analysed
at the earliest possible opportunity during design. By automating the analysis of the output
from transient multiphase flow simulators, it is possible
to gain a greater understanding of the operability
of such systems during conceptual design. This case study describes a method employed by Feesa
on several previous Flow Assurance operability studies.
Click
to read the Full Document (
225K)
Case Study No. 5 - Life of Field Cooldown in a Deepwater Development
Abstract
Transient multiphase flowline simulators can help
engineers understand many different Flow Assurance
issues and have proved to be a useful tool during
the design of many oil and gas developments. However not all transient issues benefit
from being studied using such complex and costly tools,
either because the problem is straightforward or an
accurate solution is not required or the simulator
is not best suited to model the physical phenomenon
of interest.
Cooldown of subsea flowlines can be one such issue. This case study was motivated by experience
gained in the design of a large West African deepwater
development. It
shows how the requirement for expensive transient
simulations can be minimised when assessing the key
Flow Assurance issue of cooldown, leaving time to
study more important aspects of the system. Rather than focusing on the minutiae of gas-liquid
distribution and cooldown time, it is suggested that
time is better spent on the bigger picture in front-end
design, answering important questions such as how
does operability affect the NPV of the project?
Click
to read the Full Document ( 219K)
Case Study No. 6 - Life of Field Corrosion of a Flowline System
Abstract
This corrosion study was carried out in conjunction with
a large engineering company as part of a FEED for
a deepwater development. A method was employed to aid communication
between the Flow Assurance and Corrosion disciplines. This interdisciplinary approach removed the
need to identify an arbitrary corrosion design case.
Click
to read the Full Document ( 195K)
Case Study No. 7 - Hydrodynamic Slug Size in Multiphase Flowlines
Abstract
Hydrodynamic slugs are understood to be initiated
by the instability of waves on the gas-liquid interface
in stratified flow under certain flowing conditions. When hydrodynamic slugs are numerous, the pipeline
is said to be operating in the slug flow regime.
The slug flow regime is characterised by complex
gas-liquid flows often exhibiting chaotic behaviour.
Commercially available one-dimensional transient
flow simulators rely on correlations to model the
complex three-dimensional multiphase phenomena within
a slug. These
correlations can be tuned to field data giving good a posteriori predictions for operating facilities. However, their ability to make a priori predictions of slug flow (including
slug size and frequency) remains limited. Hence, good design practice still requires
the application of healthy design margins.
This note considers the subject of hydrodynamic slugging
and qualitatively addresses the accuracy of the prediction
methods.
Click
to read the Full Document ( 255K)
Case Study No. 8 - Non-Newtonian Flows in Pipelines
Abstract
There are many analytical methods that can be employed
by Flow Assurance engineers to great benefit and saving. One such example is for the analysis of
Non-Newtonian fluids, such as gelled oils. A method has been developed and successfully
employed on such diverse systems as a deepwater flowline
containing a gelled oil and
the effluent stream from a pharmaceutical reactor. Gelled oils in pipelines present a particularly
difficult problem as their rheological behaviour can
be a function of temperature and the history of how
the gel was formed. This leads to considerable uncertainty associated
with the fluid properties. Given these uncertainties, a fit-for-purpose
model is described which predicts the flows of gels
in pipes. This
model provides a cost-effective and inexpensive alternative
to expensive add-ons to transient simulators.
Click
to read the Full Document ( 215K)
