Using Completion Reliability For Improved Sand Control ... Completion... · assessment of...
Transcript of Using Completion Reliability For Improved Sand Control ... Completion... · assessment of...
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Using Completion Reliability For Improved Sand Control Selections DEVEX , 10 May 2012 Christian Capderou
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Sand Control Completion Selection
Short list of alternatives
Expected Productivity
Deviation in reservoir
Rock Mechanics
Sand Retention Criteria
Fines Migration
Reliability
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Why is sand face completion reliability important ?
Higher Well Uptime
Lower Work Over Frequency
Well Integrity
Higher Cumulative Production
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History of Reliability Engineering applied to well completions
1950 : Reliability engineering emerges from the US Air Force to improve reliability of electronic equipment.
1990 : Molnes publishes his work on SCSSV Failure Mode and reliability
1991-1993 : Patterson and Upchurch use exponential distribution for ESP run life prediction
1993 : Molnes introduces exponential distribution and constant failure rate for upper completion components and systems
1997 : Oliveira proves that weibull provides a better fit for a particular ESP data set.
2003 : G. King publishes the first sand control reliability data base base on exponential distribution
2004 : Frota established that Weibull distributions are suitable for reliability analysis of sand control completions.
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The bath tub curve
Wear Out Infant Failures
t
Haz
ard
rate
h(t)
Useable Life
Constant Failure Rate
Increasing Failure Rate
Decreasing Failure Rate
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Analysis steps
Data Mining • Definition of
failure • Full Field • Sand control
related only
Ranking • Right Censored
Data • Reverse Ranking
(1/k)
Life Data Analysis • h(t) = f(t)/R(t) • R(t) = exp(-H(t)) • Curve Fitting
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Data mining
Scope – Open Hole Gravel Pack
– Expandable Sand Screen
– Cased Hole Oriented Perforating ( requires external data)
Key information used
Failure defined as either sand control failure or production curtailment due to sand production.
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Open Hole Gravel Pack Extended Data Set
0%
2%
4%
6%
8%
10%
12%
0%
25%
50%
75%
100%
0 2 4 6 8 10 12
Haza
rd ra
te , h
(t)
Relia
bilit
y R(t)
Life t, yearR(t) Weibull 2P Exponential h(t) Poly. (h(t))
Internal Data Set – 147wells – 721 well .years
– 31 failures – Platform /Subsea wells only – Both oil and gas producers
Distribution Exponential
MTTF years 23
Failure rate (λ) 0.043
Distribution Weibull 2 P
Scale Factor (years) 44
Shape Factor 0.65
MTTF Years 60
0.97
1.14
Weibull 2P Exponential
Correlation coefficient
26.86
27.53
Weibull 2P Exponential
Least Square Difference
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Expandable Sand Screens Life Data Analysis
Internal Data Set (partial) – 22 wells – 62 well .years – 6 failures – Platform wells only – Both oil and gas producers
Distribution Exponential
MTTF years 10
Failure rate (λ) 0.1
Distribution Weibull All
Scale Factor (years) 5.7
Shape Factor 1.67
MTTF (years) 6.1
0%
25%
50%
75%
100%
0%10%20%30%40%50%60%70%80%90%
100%
0 1 2 3 4 5 6 7
Harz
ard
Rate
h(t
)
Relia
bilit
y R(
t)
time t, years
Weibull 3P All R(t) Exponential h(t)
0.94
0.64
Weibull 3P All Exponential
Correlation Coefficient
0.02
0.11
Weibull 3P All Exponential
Least Square Difference
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Comparison to published data
Expandable screens Chevron SPE 84262 Failure Rate 1/year 0.097 0.016* MTTF exponential (years)
10.3 62.5*
MTTF Weibull (years) 6.1 n/a
OHGP Chevron SPE 84262 Failure Rate 1/year 0.043 0.020* MTTF Exponential (years)
23 50*
MTTF Weibull (years) 60 n/a
*Infant failures are excluded from the figures quoted in SPE 84262
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Conclusions
The use of Life Data Analysis techniques provides a fact based assessment of completion reliability
The use of the Weibull distribution allows to account for infant failure.
In the fields evaluated OHGP appears to be significantly more reliable than ESS.
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Q & A
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Sand Face Completion Reliability
From SPE 101511 (2004)
Sand Face Reliability can result in heated debates over the validity of the data and analysis….
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SPE 84262 Results