Orifice Plate Diagnostics and

Transcription

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

2 BP CATS Metering Team have a Vision Slide 2

3 Less Frequent q Inspections Less Calibration Less Expensive Auditing Slide 3

4 The Vision Preventative Maintenance, Accuracy 4 Assurance, Mismeasurement Alerts

5 So Here is the Story... Slide 5

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

7 Since then, nothing changed Slide 7

8 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

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

10 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) (-1,1) (1,1) 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) Slide 10 (1,-1)

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

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

13 Slide 13

14 BP CATS 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 Slide 14

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

16 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

17 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= ) d= % flowrate error d= % flowrate error Slide 18 18

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

20 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: 15.7 kpa ( )kpa Slide 20

21 DP Transmitter Calibration Issues (Correct Calibration: 4mA-0kPa & 20mA-62kPa) 20mA 60kPa 20mA 64kPa -1.6% flowrate error +1.6% flowrate error Slide 21 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, d & 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 22 Slide 22

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

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

25 ConcoPhillips TGT CoP operates TGT in Lincolnshire, UK The terminal is co-owned 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 25

26 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 27

28 Summary Swinton Technology have developed d the DP Diagnostics orifice meter diagnostics concept into a practical industrial i 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 28

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

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 30 of the high pressure system Slide 30

31 Realisation Slide 31

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

33 DECC Statement "DECC actively supports the use of two or three different DP measurements and associated software for diagnostic purposes p 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 hdecc with a view to adopting condition-based d 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

34 Thank You QUESTIONS? Slide 34