Summary
Taurt field, located in the Mediterranean Sea in 108-m water depth, is the
first BP-operated subsea-to-shore gas development. Phase 1 of the project
consists of two subsea wells producing directly from the subsea manifold to the
onshore gas-processing plant with a 68-km, 20-in. pipeline. The field has been
brought into production and was successfully ramped up to 230 MMscf/D despite
facility constraints during initial startup. The main flow-assurance issues
experienced during the initial startup are hydrate risks because of
Joule-Thomson (J-T) cooling and liquid-production handling onshore,
particularly because of potential completion-brine return.
The experience during initial startup highlights the importance of
collecting good fluid samples during exploration and appraisal, and obtaining
downhole and wellhead pressures and temperatures during flowback. Confirming
the condensate yield helps prediction of liquid holdup in the pipeline that
will affect the prediction of liquid production coming onshore during ramp up.
More-accurate prediction of the wellhead temperature affects the requirement
for hydrate inhibitor, which also affects the liquid holdup in the pipeline and
liquid production coming onshore.
Transient simulations help in selecting the dewatering strategy to be either
a pigged or a pigless operation by predicting the amount of remaining water and
how it impacts the production ramp up. Simulations also help prediction of the
liquid production for setting up temporary liquid-handling facilities to
prevent the possibility of completion-brine return upsetting the processing
plant.
Comparison with the actual liquid-production data suggests that simulations
should have been performed with less-conservative condensate yield, although
predicting the completion-brine return onshore is still difficult. After
obtaining the latest fluid composition and the actual operating conditions, the
hydrate-management strategy was revisited, and this resulted in cost savings
and simpler operating procedures.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
30 May 2009
- Meeting paper published:
5 August 2009
- Manuscript approved:
27 August 2009
- Published online:
10 June 2010
- Version of record:
10 June 2010
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