Erosion Testing & CFD Erosion Modelling. John Peters, NEL, 29 January 2014

Transcription

1 Erosion Testing & CFD Erosion Modelling John Peters, NEL, 29 January 2014

2 National Measurement System (NMS) NMS is a network of laboratories and processes Maintains national measurement infrastructure Represents position of UK measurement

3 NEL (Scotland, UK) UK National Standard for Fluid Flow and Density Measurement A global centre of excellence in flow measurement, flow systems and fluid dynamics. World class research, development, modelling, calibration, consultancy, measurement and testing Energy, Oil & Gas Low Carbon Technologies Environment

4 (Particle) Erosion A major issue world-wide in oil & gas exploration and production piping i systems Causes major wear, damage to piping, equipment, components Potential damage, significant errors in flowmetering systems

5 Contents (Particle) erosion basics Factors which affect erosion NEL erosion testing CFD erosion modelling Benefits of combined testing & modelling Summary

6 (Particle) Erosion Basics

7 Erosion- (Sand) Particle Erosion Damage Eroded holeoriginally 4mm wall Erosion in a hydrocyclone Flow Erosion in a 50mm bend downstream of a valve Choke valve severe wear

8 Erosion Damage at base of coupon/ probe fitting New fitting

9 Particle Erosion Sand particle hits a metal/hard surface Material removed t

10 In This Presentation.. Particle Erosion - impingement of particles on material surfaces, removal of material Abrasion Wear - particles rubbing across surfaces, between moving parts, into bearings ONLY

11 DO NOT CONFUSE WITH. Cavitation erosion - collapse of bubbles on surfaces Liquid jet erosion - high velocity liquid jets impinging on a surface Droplet erosion - liquid droplets in a high velocity gas stream impinging i i on a surface. NOT COVERED IN THIS PRESENTATION ALL THESE EROSION MECHANISMS REMOVE MATERIAL!

12 Compound Particle Wear Mechanisms The potential for compound wear should also be considered. One mechanism may be more dominant than the other, or two stage such as: Particle erosion AND corrosion Particles and multiphase flows Sand induced corrosion - e.g. interference/removal corrosion inhibitor film Erosion then corrosion - e.g. failure of Inconel lining

13 Erosion Sand Particle Erosion Damage lmpingement of high fluid/particle velocities, produces rapid wear (material removal) Rapid, severe levels of damage, wear: Safety issues, hazards Loss of pressure containment - pipe rupture Bends, tees, wall erodes throughh Component breaks up, e.g. choke internals Internal wear of down-hole equipment

14 New vs worn View of badly worn chokes!

15 Factors Which Affect Erosion

16 Erosion- HowMuchSand?? Do not need much sand. (sand + high velocity) Sand production varies significantly - often small fraction % by weight < 0.01% can cause major erosion problems e.g kg for 1 MMSCF gas, or 2 kg per 1000 barrels Sand particle size varies widely From microns (flour) to

17 Particle Erosion Basics Erosion highly dependant upon impact velocity Small particles < 60 microns (µm) are often less erosive than bigger particles >150 microns Most steels, Inconel & Stellite - similar resistance Ceramics & Tungsten Carbide times better BUT they are brittle

18 Factors Affecting Erosion Fluid velocity: Wear = f (velocity) 2.6 Quantity (mass) of sand Quantity (mass) of sand Average particle size e.g. 250 microns, typical Sand shape, sharpness, hardness Fluid flow regime - liquid, gas, multiphase g q,g, p Piping configuration, flow path profile, shape Equipment component design Equipment, component design Materials of construction Angle of impingement

19 Wear-rate vs Impingement Angle Maximum Erosion Occurs in Different Locations Tungsten Carbide Ductile Metal Angle (degrees)

20 Nature of Erosion May be evenly distributed all-over Often very localised erosion hot-spots Often small steps up/down, changes in internal bore, surface irregularities trigger local vortices, sand becomes trapped within, rotating grinding wheel!...an erosion crater develops Once an erosion scar starts, it keeps digging Can be unstable and rapid, complex process Often not well managed or understood

21 Abrasion Wear

22 Abrasion - Sand Particles Sand particles get between surfaces and cause abrasive wear Gate valves sliding surfaces Badly scored ball

23 Abrasion (Wear) - Sand Particles Into bearings and seals Leaking seals, valve seats Higher friction, higher operating forces/torques Excessive forces - seizure of parts Downhole equipment Often short operating life Erosion testing verifies performance

24 Erosive Flow Tests: Valves (Abrasion) Seat leakage Sand in ball valve seat assembly

25 NEL Erosion Testing

26 Typical Sand Particle Size Distribution Used by NEL for Testing Particle Size Aperature/Mesh size microns % Retained by Weight to BS < Average size 275 microns

27 Computer 3-D image of NEL Erosive Flow Facility (sand/water) with various flowmeters installed.

28 Water-Sand Erosion Facility Facility design, development supported by National Measurement System (NMS) Currently undertaking NMS flow project to assess the performance of different flowmeters in erosive flow conditions Compare before and after test results, findings Present results at a flow conference

29 NEL Erosive Flow Testing Definitive erosion performance data Independent tests, controlled conditions Design development work Design, development work Performance testing, evaluation Endurance, valve cyclic testing Product verification testing API slurry testing - with viscosifier

30 NEL Erosion Testing Controlled erosive flow conditions, similar to/simulate field conditions Fluid - water/sand or gas/sand Different erosive wear characteristics ti and patterns in piping and components Accelerated testing techniques: High sand concentrations Soft materials, hard materials, reference materials Higher velocities Sand particle size Scaling wear

31 Erosion Testing- Wear (Material Loss) Detect, measure, assess wear (quantify/qualify) A balance, sufficient wear (measurable) vs time Before, during and after tests Visual inspection, photos Dimensional measurement Vernier calipers, micrometer Co-ordinate measurements (CMM) Laser 3-d scanning - profilometry Ultrasonic wall thickness measurement Precision weighing Comparison materials Coupon erosion tests

32 UT matrix on a pipe elbow

33 Benefits of Erosive Flow Testing Good performance on test = good in the field Testing essential to test seals, bearings and all moving parts Accelerated field conditions - simulated under controlled conditions Testing identifies Design weak points Local erosion hot-spots t Show surprises, not evident from CFD

34 CFD Erosion Modelling

35 Erosion o Equations F ( α ).sin( α ). C l erosion = msand.. G. K. ρ t. A pipe U n

36 Erosion o Equations e.g. DNV RPO501 bend erosion equation F ( ).sin( i( ). C l erosion msand. α α =. G. K. U t. A ρ pipe pp mass of sand n n.~ 2.6 bend geometry particle size effect material properties particle velocity

37 CFD Example: Check Valve Calculation process FLOW Define Geometry Mesh Velocity magnitude

38 CFD Example: Check Valve Streamlines

39 CFD Example: Check Valve Particle path prediction Small Particles Large Particles

40 CFD Example: Check Valve Contours of erosion

41 Health & Safety Executive: Failed Piping Investigation Erosion? FLOW Elbow 1 (eroded in field) 50mm nb reduced bore ball valve Piping Configuration

42 Eroded hole Flow Original Wall thickness approx. 4mm Section of 50mm bore pipe elbow

43 Air-Sand Tests - Effect of the Reduced-Bore Valve Without valve With valve Angle (degrees)

44 CFD Model of Valve & Bend: Wet Sand/Gas vs Dry Gas/Sand mm/year mm/year Wet Gas/Sand Dry Gas/Sand

45 Investigation Concluded Fitting a bend on the outlet of reduced bore valve caused sand particles to be concentrated into smaller impingement area on the bend Erosion pattern observed on the wall of the bend not like dry gas pattern (NEL tests); like the wet gas CFD prediction NEL produced HSE Erosion Review Document Erosion in Elbows in Hydrocarbon Production Systems: Review Document. HSE 2003 Research Report 115

46 Potential Erosion Areas Down-hole equipment Wellhead Flow paths, chokes, Piping, bends Flowmeter system & inlet piping config. Piping configurations - Bends, Tees, Reducers

47 Piping Configuration FLOW

48 Meter Piping Configuration FLOW

49 CFD Example: Choke Body Erosion FLOW Erosion areas

50 Erosion Scar Around a hole in a Choke Valve Cage

51 Choke Plug Accelerated Wear Test!

52 Cone Flow Meter - Water/Sand Erosion Test FLOW CFD

53 NEL Erosion Testing & CFD Modelling Extensive knowledge & experience - Design, develop test programme, fabricate test fixture, piping configuration Determine test parameters Undertake erosion test programme Inspect, measure and assess wear levels throughout Determine CFD erosion model predictions Compare, validate CFD model with test data Report wear findings Use CFD model to predict field wear-life

54 Benefits of Testing & Modelling Combined Testing can validate CFD erosion model predictions Powerful design combination- to optimise component design for minimum wear Validated CFD model - simulate and predict field wear-life of components & pipelines Tool-kit Optimise production, minimise wear Risk Assessment & management - develop sand management & maintenance strategies.

55 Sand Management

56 Sand Management Minimise and eliminate sand production Install down-hole screens Gravel packs Install sand traps Optimise production rates

57 Sand Management Sand tolerant system Design, production equipment, piping i system Understand erosive flow regimes Install sand monitors, monitor sand production Wear-life prediction, maintenance programme

58 On-line Sand Monitoring Different types of monitors Intrusive Non-intrusive Optimise production - minimise sand rate Measure sand rate, quantify sand over time Use to estimate material loss Monitor critical wear areas, wear rate prediction

59 On-line Sand Monitoring Factors influencing performance Design process conditions flow regime Design, process conditions, flow regime, liquid/sand/multiphase Piping configurations, location, installation Set-up/calibration, operation, reliability, repeatability, accuracy

60 Summary

61 Summing Up Erosion is a complex wear regime: small changes can significantly affect wear levels Erosive flow testing is essential to understand the wear characteristics of components and validate equipment performance CFD erosion models need to be validated with test data to have confidence in modelling field conditions

62 Summing Up Erosion Testing often identifies an erosion hot- spot, which CFD model doesn t show! CFD can optimise designs for erosion: predict the wear life of components in field conditions Part of the tool-box for pipeline integrity, risk and maintenance management

63 Thank you for listening Any questions?

64 Forthcoming NEL Erosion Presentations Subsea UK, Aberdeen 5-6 February 2014 AOG Conference, Perth, Australia February th European Sand Management Forum, Aberdeen March 2014 Contact me at jpeters@tuvnel.com

65 NEL Contact Tel: + 44 (0) NEL Contacts Audit & Allocation Alick MacGillivray amacgillivray@tuvnel.com CFD John Dods jdods@tuvnel.com Densitometers Norman Glen nglen@tuvnel.com Erosion John Peters jpeters@tuvnel.com Flow Consortium Phil Mark pmark@tuvnel.com Heavy Oil Chris Mills cmills@tuvnel.com Calum Hardie chardie@tuvnel.com Measurement Consultancy Craig Marshall cmarshall@tuvnel.com l Chris Mills cmills@tuvnel.com Measurement Uncertainty Alick MacGillivray amacgillivray@tuvnel.com Meter Diagnostics Craig Marshall cmarshall@tuvnel.com MeterVue Phil Mark pmark@tuvnel.com Multiphase Terri Leonard tleonard@tuvnel.com PPDS Lynn Hunter lhunter@tuvnel.com Single Phase Metering Bob Belshaw bbelshaw@tuvnel.com Training Helen Tulloch htulloch@tuvnel.com Umbilicals Janice MacLeod jmacleod@tuvnel.com Valve Testing John Dods jdods@tuvnel.com Wet Gas Emmelyn Graham egraham@tuvnel.com For general queries contact the sales team on sales@tuvnel.com