Orifice Plate Diagnostics and Prognosis Presented by Jennifer Ayre, Swinton Technology on behalf of Mark Skelton, BP Exploration Operating Co. Slide 1 Oil and Gas Focus Group Meeting Weds 11 th May 2011, Norwich

BP CATS Metering Team have a Vision Slide 2

Less Expensive Auditing Less Calibration Less Frequent Inspections Slide 3

4 The Vision Preventative Maintenance, Accuracy Assurance, Mismeasurement Alerts

So Here is the Story... Slide 5

1 st Orifice Plate Inspection 5167 years B.C Slide 6

Since then, nothing changed… Slide 7

… until now! 2008 & 2009: DP Diagnostics described diagnostic methods for DP meters 2010: Swinton Technology developed “Prognosis” with DP Diagnostics BP CATS have given Prognosis an extensive field trial & CoP TGT have given Prognosis an initial field trial This presentation discusses the results of these field trials Slide 8

A Brief Review of the Diagnostic Methods 3 DP’s give 3 DP pairs,each pair provides a DP ratio and 2 mass flows. Ideally 6D downstream Slide 9

The Diagnostic Methods & Presentation ● 1 DP pair gives 1 DP ratio and 2 mass flows ● The difference between the DP ratio and an ISO calculated value is divided by a comparable uncertainty (y-axis) ● The difference between the 2 mass flows is divided by an assigned uncertainty (x-axis) ● The DP pair y and x coordinates form one point in the diagnostics box.The other 2 DP pairs provide 2 more points in diagnostics box (-1,1) (1,1) (1,-1) (-1,-1) Slide 10

The diagnostic software can be applied via the meter’s flow computer Field Data Flow Computer Metering Supervisory PC + Diagnostics Software Additional I/O Metering Supervisory PC Applying the Diagnostic Solution Diagnostics PC The diagnostic software can be applied via the meter’s flow computer OR via a separate I/O device to a dedicated PC DCS, Historians Maint Scheduling etc Slide 11

The Trials Testing at CEESI Colorado Testing at CEESI Iowa BP CATS Field Trial CoP TGT Field Trial Slide 12

13 Slide

BP operates CATS in Teesside, UK The terminal receives gas from multiple operators including BP & ConocoPhillips BP CATS has metering stations with multiple large orifice meters in parallel Field trials of Prognosis were carried out on one flange tapped 16”, beta ratio orifice meter in a BP CATS metering station The stations natural gas flow was averaging (approx) 525 tonnes /hr BP CATS Slide 14

BP CATS, May 2010 Pipe ID ” d=8.195” (0.596 beta) Slide 15

BP CATS Field Trial Examples Baseline (correct operation) Incorrectly entered inlet diameter Incorrectly entered orifice diameter Saturated DP transmitter Incorrectly calibrated DP transmitter Reversed plate Worn orifice edge Slide 16

Baseline Results at BP CATS First baseline test results were inside the NDB (as required) The theoretical correction factor was applied due to downstream tap >6D & thermowell upstream of this tap Slide 17

18 Keypad Diameter Orifice Errors (d= 8.195”) d=8.100” -2.6% flowrate error d=8.295” +2.9% flowrate error Slide 18

19 Keypad Diameter Inlet Errors (D = ”) ID=13.938” (sch 100) -0.5% flowrate error ID=13.562” (sch 120) +0.4% flowrate error Slide 19

Saturated DP Transmitter (DPt=17.5kPa) DP transmitter stack: Low range transmitter, 0–15kPa, saturated If used it induces a -6.2% flowrate error Pattern indicates a DP problem & that it’s a traditional DP problem Also: Slide 20

21 DP Transmitter Calibration Issues (Correct Calibration: 4mA-0kPa & 20mA-62kPa) 20mA – 60kPa -1.6% flowrate error 20mA – 64kPa +1.6% flowrate error Slide 21

22 Reversed Orifice Plate A reversed plate in stream 5 produced a -15% error. Streams 2,3 & 5 were on line However all meters stated the same flowrates!? Meter 5’s flow resistance is reduced, & flow favours stream 5 by +15%, so error cancels this! Similar equilibrium existed for all other stream combinations tried It is not possible to monitor orifice meter performance in parallel runs by inter-comparing the parallel meters Slide 22

Reversed Orifice Plate (cont.) Stream 5’s reversed plate diagnostic result All meters read the same however.., Prognosis indicated the error Slide 23

Worn Orifice Edge Stream 5’s plate was deliberately worn, inducing a -2% error Streams 1,2 & 5 on line Again all meters showed same flow Prognosis alone indicated the error Slide 24

25 ConcoPhillips TGT CoP operates TGT in Lincolnshire, UK The terminal is co-owned by BP & CoP It receives gas from multiple operators Initial field trials of Prognosis were carried out on a corner tap 36”, beta ratio orifice meter at TGT The natural gas flow was averaging (approx) 400 tonnes /hr Slide 25

Baseline Results at CoP TGT A slight bias in the diagnostic baseline was found due to the downstream tapping configuration A small zeroing factor was therefore applied Slide 26

27 Keypad Diameter Inlet Errors (D = mm) ID= mm -0.65% flowrate error ID= mm +0.75% flowrate error Slide 27

28 Summary Swinton Technology have developed the DP Diagnostics orifice meter diagnostics concept into a practical industrial product (‘Prognosis”) Field tests at BP CATS & CoP TGT were successful and are ongoing Prognosis is designed to warn of orifice meter system malfunctions, hence reducing costly exposure Most orifice meter errors could be seen at ≤ 1% error Slide 28

Reduced Carbon Footprint (orifice) Assurance of Compliance and Accuracy Less visits to remote operations Less Frequent Meter Inspections Reduced safety risks Proof of meter performance over time Observed Benefits

30 Observed Benefits BP and CoP regard Prognosis as a means of assurance that a meter does not have a problem Custody transfer orifice meters are currently regularly inspected with routine maintenance. A system showing that the meter is OK, saves on needless maintenance Besides the cost saving this also reduces the quantity of gas released to the environment & personnel exposure to the dangers of the high pressure system Slide 30

Realisation Slide 31

The Future..... Wow look at this!! Centralised Remote Diagnostics at a Glance !!! Slide 32

DECC Statement "DECC actively supports the use of two or three different DP measurements and associated software for diagnostic purposes on DP meters as introduced by Dr Richard Steven in [1] and [2] as it has the potential to detect measurement errors as they arise, and to therefore greatly reduce the required frequency of maintenance activities associated with DP-based measurement systems. Operators of relevant systems are encouraged to approach DECC with a view to adopting condition-based monitoring strategies featuring this method.” [1] 2008 NSFMW paper: Diagnostic Methodologies for Generic Differential Pressure Flow Meters [2] 2009 NSFMW paper: Significantly Improved Capabilities of DP Meter Diagnostic Methodologies

Thank You QUESTIONS? Slide 34