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ESP's v Gas Lift
10 August 2005
Trying to find out about ESP's versus gas lift - reliability of
ESP's, cost and frequency of interventions etc.
2 answer(s)
simon.hough
Snr. drilling Engineer
Chevron Corporation
Total Posts: 5
Join Date: 19/04/06
Gas lift completions generally have good reliability since they have
no moving parts, although reliability is likely to decrease as the
number of unloading valves/mandrels increases. Because of their good
reliability, gas lift completions typically require fewer ”œrepair”
interventions throughout their life than other artificial lift
methods. Wireline interventions may however have to be carried out
if reservoir/well conditions change and gas lift valves have to be
changed out. Notwithstanding this, completion lives typically exceed
10 years. As a result the majority of subsea wells that require
artificial lift use gas lift. Its track record, subsea and platform,
is extensive. ESP completions are generally less reliable than GL
with run lives varying enormously between a couple of days and in
excess of 10 years. If well conditions - in particular reservoir
temperature - are fairly benign, a run life of 2 years for a single
ESP should be achievable, although the probability of an early
failure is still significant. The time between workovers could be
improved by running tandem pumps, as on Otter. The
incremental ”œorder of magnitude” capital cost estimate for one well
over the cost of a natural flow well are £ 0.1mm for gaslift and £
0.8 mm for tandem ESPs with mean time to failure at 10 and 2-3 years
respectively. These numbers were taken from a study recently carried
out for us by Helix RDS and are incremental to the cost of a natural
flow well. The estimates do not include the costs of additional
facilities or modifications which would likely exceed the
incremental well costs for both methods.
wsanderson_old
N/A
Myspread Users
Total Posts: 3
Join Date: 29/06/05
Gas lift completions generally have good reliability since they have
no moving parts, although reliability is likely to decrease as the
number of unloading valves/mandrels increases. Because of their good
reliability, gas lift completions typically require fewer ”œrepair”
interventions throughout their life than other artificial lift
methods. Wireline interventions may however have to be carried out
if reservoir/well conditions change and gas lift valves have to be
changed out. Notwithstanding this, completion lives typically exceed
10 years. As a result the majority of subsea wells that require
artificial lift use gas lift. Its track record, subsea and platform,
is extensive. ESP completions are generally less reliable than GL
with run lives varying enormously between a couple of days and in
excess of 10 years. If well conditions - in particular reservoir
temperature - are fairly benign, a run life of 2 years for a single
ESP should be achievable, although the probability of an early
failure is still significant. The time between workovers could be
improved by running tandem pumps, as on Otter. The
incremental ”œorder of magnitude” capital cost estimate for one well
over the cost of a natural flow well are £ 0.1mm for gaslift and £
0.8 mm for tandem ESPs with mean time to failure at 10 and 2-3 years
respectively. These numbers were taken from a study recently carried
out for us by Helix RDS and are incremental to the cost of a natural
flow well. The estimates do not include the costs of additional
facilities or modifications which would likely exceed the
incremental well costs for both methods.
Posted by

Malcolm Macdonald

Consultant Completions & Interventions Engineer

NexenCNOOC

Total Posts: 3
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