MEG Regeneration for Floating Production Units

Transcription

1 MEG Regeneration for Floating Production Units part of Aker FPSO Seminar, 2010 Holmen Fjordhotell, Nesbru By Jan Gregor Høydahl Sørli Aker Process Systems AS 2008 Aker Solutions

2 Outline Introduction Concept Selection Technology Development Operational Experience Summary 7-Jun-10 Slide 2

3 Introduction What is MEG? Mono ethylene glycol A thermodynamic inhibitor for prevention of hydrates Risk of hydrate formation Natural Gas Free Water present Low T High P MEG is preferred hydrate inhibitor for medium to long multiphase flow lines 7-Jun-10 Slide 3

4 The Closed Loop MEG System Well Formation Water Condensed Water Production pipeline Corrosion Products Slug catcher Lean MEG Injection Rich MEG <50%wt MEG Lean MEG Storage Lean MEG 90%wt MEG MEG REGENERATION High Soluble Salts Low Soluble Salts Water 7-Jun-10 Slide 4

5 The Closed Loop MEG System Impurities will accumulate and/or precipitate in a closed loop system if not taken care of Main concerns: Formation water Sodium (Na + ) and other monovalent cations (K + ) Calcium (Ca 2+ ) and other divalent cations (Mg 2+, Ba 2+, Sr 2+ ) Organic acids Pipeline corrosion (CO 2, H 2 S, HAc) Iron (Fe 2+ ) Completion fluids Highly soluble salts (high density) e.g. CaCl 2, CaBr 2, Ca(HCOO) 2 Scale in pipeline Formation water salt load Scale in pipeline Scale potential dependent of: Solubility Saturation ratio (degree of supersaturation) Tendency to form on surfaces Kinetics 7-Jun-10 Slide 5

6 Chemistry of MEG systems Various types of salts have different properties Low soluble salts (Ca 2+, Mg 2+, Fe 2+, CO 3 2-, CHO 3- ) Divalent cations will easily precipitate and form scale on undesired locations at low concentration Precipitation by alkalinity and temperature control All salts must be removed High soluble salts (Na +,K +, Cl - ) Monovalent cations may accumulate up to > mg/l without precipitation Precipitation by super saturation Accumulation can be tolerated Other Chemicals Some components (acetate, formate, corrosion inhibitor ) will not precipitate but accumulates in the Reclaimer APS Design Philosophy Taking control by precipitation in controlled manner 7-Jun-10 Slide 6

7 Outline Introduction Concept Selection Technology Development Operational Experience Summary 7-Jun-10 Slide 7

8 Concept Selection Highly dependent on salt loads and client needs Different Design Philosophies: Full Stream versus Slip Stream Full Stream Concept Removes all the salts to prevent scaling in the pipelines Rich MEG Pre-treatment Reclamation Ormen Lange Re-concentration (Norsk Hydro) Lean MEG Hydrocarbons Low soluble salts High soluble salts Water Slip Stream Concept Removes the necessary salts to prevent scaling in the pipelines Rich MEG Pre-treatment Re-concentration Ormen Lange (Norsk Hydro) Lean MEG Hydrocarbons Low Soluble Salts Water Reclamation High soluble salts 7-Jun-10 Slide 8

9 MEG Regeneration system design Full stream reclamation WATER MEG WATER SALT HEAT DISTILLATION COLUMN (Reconcentration) SALT FLASH SEPARATOR (Reclamation) MEG 7-Jun-10 Slide 9

10 Rich MEG MEG Regeneration system design Slip stream reclamation Water Pre-treatment Vessel Reflux drum Fe 2+, Ca 2+, (Mg 2+ ), CO 3 2- Hydrocarbons Particle removal MEG Distillation Column Lean MEG rundown to Storage Particles Vacuum Skid Na +, K +, Cl -, Ac - MEG Flash Separator Salt-free Lean MEG Particles Recovered MEG from Centrifuge M To centrifuge Production chemical accumulation 7-Jun-10 Slide 10

11 Ormen Lange General (Norsk Hydro) Concept Selection Concept selection highly dependent on salt loads and client needs Slip Stream more suited for units with periods with no/low formation water production Slip Stream allows larger reconcentration trains, thus suited for bigger capacities Typically, Slip Stream is smaller in size Slip Stream needs more advanced Pre-treatment (to remove the low soluble salts) Reduced Criticality of Reclaimer 7-Jun-10 Slide 11

12 Outline Introduction Concept Selection Technology Development Operational Experience Summary 7-Jun-10 Slide 12

13 Technology Development Compact Design Offshore/FPSO 11.5x22.3x22m 16x14x19m 18x14x21.5m 7-Jun-10 Slide 13

14 Technology Development Reduction of heating medium and power consumption Further development Vacuum slip stream design Reduction of operational costs (heating medium) Technical solution for solid separation in Pre-treatment tested and qualified (WSD 200 disk type centrifuge) Cyclone testing ongoing New improved internals for Flash Separator found, tested and qualified Kjeller MEG loop with many new findings and results which can be applied into the design 7-Jun-10 Slide 14

15 Outline Introduction Concept Selection Technology Development Operational Experience Summary 7-Jun-10 Slide 15

16 Santos Gas II FPSO (MODEC / Petrobras Brazil) Data Full Stream Off Shore 1x100% train configuration Salt removal: kg/day In operation from Jun-10 Slide 16

17 Reference list and Operational Experience Plants in operation: Åsgard B, Norway, Statoil, production start-up 2000 Shah Deniz, Azerbaijan, BP, production start-up 2006 Ormen Lange, Norway, Shell, production start-up 2007 Britannia Satellites, UK, ConocoPhillips, production start-up 2008 KG-D6, India, Reliance, production start-up 2009 Cidade de Santos FPSO, Brazil, MODEC/Petrobras, prod. startup 2010 Pluto, Australia, Woodside, production start-up 2010 Plants under construction: Troll/Kollsnes, Norway, Statoil (regeneration only) Gorgon/Jansz, Australia, Chevron, production start-up 2013 Tamar, Noble Energy, construction starting in 2010/ Jun-10 Slide 17

18 Reference list and Operational Experience Plants in early design phase: Shtokman, Russia, SDAG (Gazprom/Total/Statoil), FEED Barzan, Qatar, RasGas (ExxonMobil/Qatar Petroleum), FEED Shell FLNG, Shell, FEED Liwan 3.1, Husky/China Limited, FEED Various conceptual studies worldwide 7-Jun-10 Slide 18

19 Outline Introduction Concept Selection Technology Development Operational Experience Summary 7-Jun-10 Slide 19

20 Summary Ormen Lange (Norsk Hydro) Understanding the chemistry involved is vital proven by operational experience. Two possible reclamation concepts: Full stream reclamation The entire feed is vaporized Reconcentration and reclamation in one operation Slip stream reclamation Conventional reconcentration (water removal) process at atmospheric pressure Saves energy costs and eases operation The reclaimer operation (high solubility salts removal) is performed on a slip stream of the regenerated MEG High availability Reclaimer only required during formation water production otherwise bypassed Reuse of chemicals (corrosion inhibitor / ph stabilizer) 7-Jun-10 Slide 20

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