Case Studies from the Oil & Gas Industry: Down hole to Flow Assurance & Separation Alex Read

Transcription

1 Case Studies from the Oil & Gas Industry: Down hole to Flow Assurance & Separation Alex Read

2 Overview! CFD in Oil & Gas Industry Drivers! Application & validation examples: from down hole to flow assurance & separation! All about me: Degrees in Engineering, CFD and Business from University of Leeds, UK & Rice University, Houston, USA 12+ years at CD-adapco Engineer à Customer Support for Northern EU à Regional lead for Southern US/LATAM à O&G Industry Lead Works closely with many of the world s leading O&G companies

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4 Industry Drivers Change in economic reserves to deep-water, HPHT & unconventionals, Technology & simulation à innovation and understanding of new challenges Capital/risk intensive Technology & simulation à minimize & quantify risks, maximize durability Improvements in modeling capabilities, experience & confidence Simulating systems: multi-physics, -fidelity, complex geometries, HPC

5 Application Areas! Upstream Down hole tools Completions Subsea Flow Assurance Offshore Separation Gas dispersion/explosions! Midstream Flow conditioning/metering! Downstream Refining

6 Gravel packing: DEM! Gravel pack: coarse gravel used to filter sand from the wellstream! Challenge: understand the packing process & distribution

7 Slurry flow in pipe Uniform solid volume fraction (vf) and slurry velocity (V) g Measurement plane 1m V D L=10m d=90 µm, vf=0.19, D=103mm, V=3 m/ s d=270 µm, vf=0.2, D=51.5mm V=5.4 m/s d=480 µm, vf=0.203, D=51.5mm V=3.41 m/s d=165 µm, vf=0.189, D=51.5mm, V=4.17 m/ s d=165 µm, vf= D=51.5mm V=3.78 m/s d=165 µm, vf=0.273, D=495mm V=3.46 m/s

8 Erosion

9 Subsea: Flow Induced Vibration Challenge: Production restricted due to fatigue concerns on subsea manifolds & jumpers Solution: STAR-CCM+ was used to predict the fatigue life, allowing an increase in production rate. Different designs were evaluated producing a 2X increase in fatigue life and a 3X reduction in erosion. Impact: The increased production rate over the life of the well meant the ROI for the simulation was several hundred million dollars. 9

10 Flow Assurance: Multiphase Flow in Pipeline

11 STAR-OLGA coupling (TMF, Cranfield) Model the long pipe using OLGA with slug tracking Pressure and temperature Mass flux, velocity and density of each phase Flow direction Model pipe elbow using STAR-CCM+

12 Slug flow pass an elbow (TMF, Cranfield) Note the passing of liquid slug in blue. Note the increase in pressure as liquid slug passes. Gas volume fraction Pressure on the outer part

13 Slug flow pass an elbow (TMF, Cranfield) Coupling model Experiment Slug frequency (Hz) Slug velocity (m/s) slug front: 2.8 to 3.6 slug tail: 3.0 to Peak force on bend (N) 44 to to 60 Maximum force on bend (N) 54 60

14 Severe slugging in riser (TMF, Cranfield) 1 Experiment Star-CD-1 STAR-CCM+ Star-CD-2 STAR-CCM+ Riser top Riser DP, bar inch riser Flow time t, s 10.5 m Riser base 55 m pipeline Riser DP = Pbase - Ptop

15 Flow Assurance: Pigging Stratified gas-liquid flow Dispersed solid-liquid flow

16 Slug catcher: STAR-CCM+/OLGA Challenge: Assess performance of slug catcher using STAR-CCM+ Solution: OLGA used to simulate upstream pipeline system to predict slugging event. OLGA coupled to STAR-CCM+ for detailed transient VOF simulation to predict slug catcher performance for 2 hour slug event Impact: Coupled solution provides ability to perform system-wide simulation ensuring high fidelity of inlet conditions at vessel and highfidelity 3D simulation of slug catcher with STAR-CCM+

17 Separation Eulerian-Eulerian results: Velocity magnitude through inlet diffuser Page 17

18 Separation: Vane pack de-misters

19 August 2008

20 Droplets trapped by vane pack (126 mmscfd, K=0.195) 150 microns 50 microns 5 microns

21 Efficiency of Vane Pack at 57 bar 100 % mass of droplets removed Design (K = 0.32) 126 MMSCFD (K = 0.195) 105 MMSCFD (K = 0.161) 94 MMSCFD (K = 0.146) Droplet size (micron)

22 Separation: Flare knock out drum Challenge: Reduce liquid oil carried over to flare from drum Solution: Through STAR-CCM+, CD-adapco Consulting Services identified cause of carry-over, quantified and suggested options to improve design Impact: Improved flare combustion Before After Avoided damage to flare tip Reduced risk (of flaming rain) 22

23 Flow Conditioning er Ult et M nic o s ra

24 Conclusions! Industry changes increased use of simulation! Examples / experience in wide variety applications! Simulating Systems multi-physics/fidelity simulations

25 Thank You! Questions?