Orifice Plate Diagnostics and Prognosis

Presented by

Jennifer Ayre, Swinton Technologyon behalf of

Mark Skelton, BP Exploration Operating Co.

Slide 1

Oil and Gas Focus Group MeetingWeds 11th May 2011, Norwich

BP CATS Metering Teamhave 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

1st Orifice Plate Inspection

5167 years B.C

Slide 6

Since then, nothing changed…

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… 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• Email etc

Slide 11

The Trials

Testing at CEESI Colorado

Testing at CEESI Iowa

BP CATS Field Trial

CoP TGT Field Trial

Slide 12

Slide 13

• 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”, 0.596 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 13.738”

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 edgeSlide 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 = 13.738”)

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: kPakPa 2.112.67.15 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”, 0.5997 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

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27

Keypad Diameter Inlet Errors (D =850.335mm)

ID=870.335mm-0.65% flowrate error

ID=830.335mm+0.75% flowrate error

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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

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?

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