Oil and Gas Focus Group Meeting 23 April 2014
Oil with Water Flow Metering
with Cone Meters
Jennifer Rabone, Swinton Technology
Richard Steven, DP Diagnostics
Terry Cousins, CEESI
1
Introduction
• The necessity to meter oil production with high
water cut has grown over recent years.
• Some wells are now producing oil with water cuts
over 50% (some reaching 90%).
• Measurement without separation is often favoured
for economic reasons.
• Little independent data available on performance of
oil flow custody transfer metering systems
operating with high water content.
2
Traditional Procedures
The common method of oil with water metering:
– use a standard volume meter (e.g., a USM or turbine
meter) to provide total volume flow rate (Qtotal);
Qtotal
– take a sample downstream of a mixer to find that volume
flow rate’s ‘water cut’ (ω).
Qwater
ω =_____
Qtotal
Qwater = Qtotal *ω
Qoil = Qtotal* (ω -1)
3
CEESI Oil with Water Test Loop
Turbine Meter Tests
• 20% Water Cut, 0.6 m/s
5
Cone Meter Tests (0.438 beta)
• 50% water cut
0.6 m/s
• 50% water cut
1.2 m/s
6
Cone Meter Tests (0.438 beta)
• 50% water cut
1.6 m/s
• 20% water cut
1.6 m/s
7
Cone Meter Tests (0.438 beta)
• 75% water cut
1.6 m/s
Sample probe 5D downstream of cone exit:
• Analysis for 1.6 m/s showed water in oil mix
matched reference values to within 2%
• Smaller cone (higher beta) requires higher flow rate
8
Cone Meter Tests
•
•
•
•
Good water with oil flow mixer
Simpler than traditional mixer designs
Joint mixer and flow meter for water in oil?
Wet Gas analogy…
9
Analogy with Wet Gas Flow
Wet Gas
Gas
Liquid
Water in Oil
Oil
Water
10
Cone Meter Diagnostics
• Third tapping downstream
• Three DP Measurements
11
Cone Meter Diagnostics
• Three Flow Meters instead of One
• Three DP Ratios
• DP Reading Integrity Check
• 4 points plotted on
a ‘Normalised
Diagnostic Box’
12
Cone Meter Baseline Flow Data
• 6 diagnostic (‘footprint’) parameters found with low
uncertainties and match for water and for oil
• Unaffected by whether the fluid is water or oil
13
Cone Meter Flow Data
• Three flow rate predictions (on water in oil) in
agreement is a diagnostic check that the cone
meter is mixing the oil and water to a near
homogeneous flow
0.05 <= ω <= 0.8
14
Analogy with Wet Gas Flow
Wet Gas
Water in Oil
Steven.R, “Horizontally Installed Differential Pressure Meter Wet Gas Flow
Performance Review,” North Sea Flow Measurement Workshop 2006.
15
Cone Meter Correction
Using homogeneous model’s correction results:
• Correction to
within 3%
16
Cone Meter Correction
Using linear fits
M traditional = 0.9857, M expansion = 0.9825 & M PPL = 0.9650.
17
Cone Meter Diagnostic System
Examples
• Baseline
18
Cone Meter Diagnostic System
Examples
• Oil Data – Wrong ID (+10% bias)
19
Cone Meter Diagnostic System
Examples
• Water Data – Wrong Cone diameter (-5.5% bias)
20
Cone Meter Diagnostic System
Examples
• Water In Oil – Serviceable meter
21
Cone Meter Diagnostic System
Examples
• Water In Oil – Wrong Cd (-4.6% bias)
(Cd=0.791+(-2e-7*Re) instead of Cd=0.791+(-2e-8*Re))
22
Cone Meter Diagnostic System
Examples
• Water In Oil – Saturated DP (-2.8% bias)
23
Cone Meter Diagnostic System
Examples
• Water In Oil – Drifted DP (+1.5% bias)
24
Conclusions
• Oil with water flow metering is becoming increasingly
common & important.
• CEESI is initiating a JIP to test in detail the effects of
higher water cuts on three manufacturers Coriolis
meters.
• Cone meters can be used as a combined mixer +
meter station.
• Utilising a wet gas flow meter analogy, a 6”, 0.483β
cone meter’s performance in oil with water flow could
be characterised by the homogeneous model.
25
Conclusions
• A sampling system’s water cut result can then be
used to allow the cone meter to predict the oil and
water flow rates.
• Theory the same
for any DP meter
design.
• The generic DP meter diagnostic system ‘Prognosis’
was unaffected by the ‘adverse’ flow conditions and
operates normally (unlike other meter diagnostics).
• Diagnostic system provides indication of quality of
26
mixing.
Cousins, T., Hodges, C., Steven, R. & Meyer, D.,
“The Emperor’s New Clothes? - Oil with Water Flow Metering,”
North Sea Flow Measurement Workshop 2013.
Thank You
Questions?
[email protected]