Summary
As oilfield developments become more challenging and economically
challenging, flow assurance has become crucial to the feasibility of projects.
Consequently, flow-assurance issues such as hydrates or wax deposition must now
be considered early in concept selection. Modern numerical methods, coupled
with the latest software engineering techniques, now allow the rigorous
calculation of multiphase thermal hydraulic behavior in an integrated asset
model (IAM) on time scales acceptable for concept selection.
This paper describes the application of a new IAM tool to analyze options
for the development of fields in the western part of BP’s Angolan deepwater
Block 18. Novel aspects include the embedding of field scheduling rules such
that the drilling schedules were predicted automatically from the model. In
addition, different field architectures were considered including tubing and
pipeline sizes, looping of pipelines and subsea multiphase boosting, and the
impact on production rates and drilling schedules was quantified. Furthermore,
the option to tie back to the planned Greater Plutonio floating production
storage and offloading (FPSO) vessel was also modeled with the forecast ullage
profile being imposed on production from the new fields. All calculations were
performed using rigorous multiphase thermal-hydraulic models allowing
flow-assurance constraints to be analyzed simultaneously.
Introduction
In the last 10 years, as oil companies have begun to explore and develop
fields in deep and ultradeep waters, numerous flow-assurance issues have come
to the fore and have started to drive field concept selection. In particular,
problems associated with poor deliverability, thermal performance, and
wax/hydrate avoidance have presented challenges that have necessitated special
measures such as subsea production boosting and highly insulated production
flowlines.
In the early stages of design, during concept selection, it is critical that
unworkable development concepts are screened out, leaving only those that are
technically feasible. Moreover, because economic feasibility is strongly
governed by the achievable production rates and revenues, reliable predictions
of the system’s deliverability are also essential.
In the past, field-development designers have been somewhat fixated on
capital expenditure and to a greater or lesser extent have focused their
efforts on modifications to drive down costs. However, while this approach is
not unreasonable given the tools available to them, failing to properly
quantify the effects of these changes on the system deliverability and, hence,
the revenue stream is frequently detrimental, leading to suboptimal designs.
This is especially true given the sensitivity of project economics to the
production rates achieved in the initial years of production.
This paper describes the application of a new IAM tool, called
Maximus, to the selection of development concepts for BP’s planned
western area evelopment (WAD). This future development is located in Angolan
deepwater block 18 approximately 30 km to the west of the planned Greater
Plutonio FPSO, and comprises five potential fields.
Owing to the distribution of the fields, WAD presents several flow-assurance
challenges. In addition, given the comparatively small reserves base of the
five fields, proper assessment of system deliverability was considered
essential. Hence, it was decided to screen all reasonable field-development
options using the new IAM tool to provide accurate system-deliverability
predictions through the lifetime of the project while simultaneously applying
various flow-assurance constraints. Thus, it was possible to quantify the
effects of a range of system parameters on the production rates and operability
of each concept.
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
16 October 2006
- Meeting paper published:
24 September 2006
- Revised manuscript received:
6 February 2007
- Manuscript approved:
26 February 2007
- Version of record:
20 June 2007
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