PRODUCED WATER TREATMENT CARACAS, VENEZUELA NOVEMBER 6-7, 2001
By: Kevin Kevin Junie Juniell Senior Process Engineer NATCO Group Houston, TX
Outline •INTRODUCTION •WHAT IS PRODUCED WATER? •PROPERTIES OF PRODUCED WATER •ENVIRONMENTAL ISSUES •HOW IS PRODUCED WATER HANDLED? •WHY TREAT PRODUCED WATER? •WATER CHEMISTRY ISSUES •HOW TO TREAT PRODUCED WATER •SUSPENDED OIL REMOVAL •SUSPENDED SOLIDS REMOVAL •CHEMICAL TREATMENT •BACKWASH WATER TREATMENT •MATERIAL SELECTION ISSUES
•CONCLUSION
• Sources
• Formation Water • Water-flood water • Water Water fro from m opera operati tion onss- i.e. i.e. kill kill fluids • Chemicals from treatment
Produced Water Sources Platform Ocean Surface Chemicals Bottom of Ocean Subsea Safety Safety Valve
Formation Water
Seawater Injection
Oil
Injection Water
Components in Produced Water l l l l l l l
Water Organics Salts Solids Biological Matter Added Materials NORM – Naturally Occurring Radioactive Material
Typical Composition Water,%
90 to 99.9
Organics,%
0.1 to 0.2
Salts,ppm
100 to 350000
Solids,ppm
10 to 50
Bacteria,colonies/ml
10,000
Example Produced Water -
10,000 BWPD
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1000 ppm oil of 34 º API
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100 ppm solids of SG = 2.0
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10 ppm dissolved organics
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50,000 ppm TDS , SG = 1.03
-
100 °F @ 100 psig
Salinity Gulf of Mexico Seawater
27,000 to 44,000 mg/l mostly sodium chloride
New Mexico field 75,000 mg/l mostly magnesium sulphate
Environmental Regulations GOVERN EMISSIONS INTO WATER, AIR OR LAND (MUST HAVE UNDERSTANDING OF IMPACT ON ENVIRONMENT) l
DICTATE LEVEL OF TREATMENT FOR DISPOSAL INTO WATER BODIES (INTERNATIONAL, FEDERAL, STATE AND LOCAL) l
CHANGE IN REACTION TO DEVELOPING TECHNOLOGY (HOWEVER PRESSURE TO INSTILL TIGHTER LIMITS) l
NON-COMPLIANCE CAN BE DEVASTATING FOR OPERATORS
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INVESTMENTS IN ENVIRONMENTAL COMPLIANCE DO NOT SHOW UP ON THE BOTTOM LINE – OR DO THEY? l
How Produced Water is Handled • Disposal (Surface, Subsurface) • Enhanced Recovery (Waterflood, Steamflood) • Agriculture (Irrigation) •Process/Plant Water •It is estimated that the produced water volume will reach 3-6 times the oil volume over the life of an oilfield
Produced Water vs. Life of Oilfield
Gas Oil y t i t n a u Q
Water
Time
What is Water Treatment? 1.
PREPARE WATER FOR INJECTION INTO WATERFLOOD OR DISPOSAL ZONE
2.
PREPARE WATER FOR OVERBOARD/SURFACE DISPOSAL
3.
UTILITY AT FACILITY
4.
AGRICULTURAL USE
5.
RECOVER OIL TO RE-ROUTE TO THE CASH REGISTER
Produced Water Treatment Objectives for Oilfield Use l
REDUCE SUSPENDED OIL CONCENTRATION TO COMPLIANCE LEVELS OR TO LEVELS SPECIFIED BY RESERVOIR DEPT.
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REDUCE SUSPENDED SOLIDS CONCENTRATION TO COMPLIANCE LEVELS OR TO LEVELS SPECIFIED BY RESERVOIR DEPT.
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ADDRESS ANY WATER CHEMISTRY ISSUES (CHEMICAL INJECTION SYSTEM)
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EXCLUDE OXYGEN FROM THE SYSTEM
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MINIMIZE CAPITAL AND OPERATING EXPENSE (DOWNTIME)
How Clean Does The Water Need To Be? ”Typical” Waterflood • Solids < 5-10 mg/l •Oil< 5-10 mg/l • 95% removal of 5+ micron
Overboard in US GOM Oil 42 mg/l daily max., 29 mg/l monthly avg.
Water Chemistry Issues l
HIGH DISSOLVED SOLIDS CONTENT
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HIGH SCALING TENDENCY
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MIXING PRODUCED WATERS
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MIXING PRODUCED WATER AND SURFACE WATER
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CORROSION POTENTIAL/CORROSION CONTROL
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CONTROL OF BACTERIA GROWTH (AEROBIC/ANAEROBIC)
Open System Versus Closed System Design l
1. 2. 3. 4. 5. 6. 7.
ADVANTAGES OF CLOSED SYSTEM EXCLUDE OXYGEN MINIMIZE CORROSION MINIMIZE SCALE FORMATION MINIMIZE AEROBIC BACTERIA PRESERVE PROCESS HEAT EXCLUDE OUTSIDE CONTAMINANTS MINIMIZE EMISSIONS
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1.
ADVANTAGES OF OPEN SYSTEM CHEAP TO BUILD
REVIEW 1. WHAT IS PRODUCED WATER? 2. WHY MUST PRODUCED WATER BE TREATED? 3. HOW IMPORTANT IS PRODUCED WATER TREATMENT TO AN OPERATING FACILITY? 4. WHY IS A CLOSED SYSTEM PREFERRED? 5. WHAT MUST BE CONSIDERED WHEN MIXING PRODUCED WATER WITH FRESH WATER? 6. HOW DOES PRODUCED WATER TEEATMENT AFFECT PROFITABILITY? 7. WHAT ARE SOME USES OF PRODUCED WATER IN AN OILFIELD OPERATION? 8. HOW CLEAN MUST PRODUCED WATER BE?
Process Definition Bulk oil removal
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Free oil removal
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Dispersed oil removal
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Water polishing
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Proposal / injection
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Processes That Treat Produced Waters • Specific Gravity Differences
•Flotation •Enhanced Gravity • Physical trapping •Chemical Treatment
SUSPENDED OIL/SOLIDS SETTLING STOKES LAW
V =
FDsg(water-oil)(d2)
where:
V F
V = = particle moving velocity = force
D sg= density d m
= droplet size = viscosity
FACTORS AFFECTING PERFORMANCE BASED ON STOKE’S LAW 1. DROP SIZE 2. TEMPERATURE (VISCOSITY,DENSITY) 3. GRAVITATIONAL FORCE HENCE, OUR GOAL IN PROCESS SYSTEM DESIGN IS TO MAXIMIZE OR ENHANCE THE FACTORS TO PROMOTE GOOD SEPARATION. EXAMPLES…..
Bulk Oil Removal (Gravity) TECHNOLOGY
Skim Tanks Horizontal Skimmers Vertical Skimmers API Separators
PURPOSE
Mitigate flow surges Evolve entrained gas Reduce oil concentrations Provide solids settling
Horizontal Separator Oil droplets >150 microns Settleable solids >50 micron Retention time <10 minutes
Onshore / Offshore Production Surge Protection Potential Pitch & Roll Concerns
Vertical Separator
Oil droplets >150 microns Settleable solids >25 micron Retention time <10 minutes Offshore Production Minimal Surge Protection Less Sensitive to Pitch / Roll
API Separator Oil droplets >150 microns Settleable solids >50 micron Retention time 20 + minutes
Refinery Waste Water Industrial Waste Water
API Separator Options l
Inlet Distribution Headers for Flow Control
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Solids Hopper for Solids Collection
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Flight and Rake System for Solids/Oil Removal
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Adjustable Rotating Pipe Skimmer for Oil Removal
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Rotating Drum Skimmer for Enhanced Oil Removal
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Corrugated Plate Pack for 50 Micron Oil Droplet Removal Efficiency
Free Oil Removal TECHNOLOGY
PURPOSE
Corrugated Plate Interceptors (Upflow or Downflow ) Matrix PlateSeparators Liquid/Liquid Hydrocyclones
Primary separation of oil from water
Solid/Liquid Hydrocyclones Primary separation of oil free solids from water
Down Flow CPI Oil Removal (Gravity)
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Plates at 45º Angle
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Plate spacing 18mm
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Plate pack material is
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316SS or FRP
Coalescing Plate
Up Flow CPI Solids Removal (Gravity)
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Plates at 60º Angle
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Plate spacing 25mm
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Plate pack material is
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316SS or FRP
Matrix Plate Separators (Gravity) Oil droplets d90 @ 50 micron Settleable solids d50 @ 25 micron Velocity 1–3 ft/min
Onshore / Offshore Production Minimal Surge Protection Insensitive to Pitch / Roll
REVIEW 1. DESCRIBE STOKE OKE’S LAW? AW? 2. WHAT WHAT ARE ARE COMMON COMMON WATER WATER TREA TREATI TING NG PROCES PROCESSE SES S THAT THAT AR ARE E BASED ON STOKE’S LAW? 3. HOW HOW DOES DOES THE THE SIZ SIZE E OF THE THE OIL OIL DR DROP OPLE LET T AFFE AFFECT CT THE THE PERFORMANCE OF OIL REMOVAL EQUIPMENT? 4. WHIC WHICH H OIL OIL WILL WILL PERF PERFOR ORM M BET BETTE TER R – 16 API API OR OR 34 34 API API? ? WHY? 5. HOW HOW DO DO PL PLATE ATE SEPA SEPARA RATO TORS RS WORK WORK? ? 6. WHICH WHICH ORIENT ORIENTAT ATION ION IS BETT BETTER ER FOR FOR SEPA SEPARA RATIO TION N– HORIZONTAL OR VERTICAL? 7. WHICH WHICH ORIENT ORIENTAT ATION ION IS LESS LESS SENS SENSIT ITIV IVE E TO TO MOTI MOTION ON – HORIZONTAL OR VERTICAL? 8. WHAT WHAT IS IS THE THE ADVA ADVANT NTAG AGE E OF AD ADDIN DING G MAT MATRI RIX X PAC PACKI KING NG TO A SKIMMER OR SEPARATOR VESSEL? WHAT ARE POTENTIAL DISADVANTAGES OF THIS TYPE OF INTERNALS?
Liquid/Liquid Hydrocyclones
Enhanced Gravity Convert Pressure Energy to Centrifugal Energy Insensitive to Motion or Surges No Chemicals or Power (if high enough pressure) Small Oily Reject Stream (2% of Inlet Flow)
Liquid/Liquid Hydrocyclones
Operating Principles l Internal geometry creates a vortex (inlet,taper) l Centrifugal force accelerates separation l Oil droplets separate and coalesce in the center l Oil is funnelled into the overflow for removal
PRINCIPLE OF OPERATION
L/L Hydrocyclones l
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Developed, proven technology High efficiency Flexible, Easy to Expand Compact Design Lightweight
L/L Hydrocyclone Vessel Liner Bundle
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Easy to Install for Future Expansion Individually Accessible
Liner Design l
Corrosion resistant liner Oilspin AVh
material l
Erosion resistant liner material
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Ease of operation
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No moving parts
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Low maintenance
Oilspin AV
Oilspin AVi
“Typical” Performance Corrected Efficiency
1.00 0.90 0.80 l a 0.70 v o m e r 0.60 f o y 0.50 t i l i b 0.40 a b o r P0.30
0.20
LQ AV"dev 2"
0.10 0.00 0.0
5.0
10.0
15.0 20.0 Droplet daimeter, micron
25.0
30.0
35.0
Produced Water Treatment Fuel Gas Supply From HP Separator
Liquid/Liquid Hydrocyclone
PVC
LC
PV
Degasser From LP Separator
LC
PC
To Hazardous Drain
PV
LP Sep From Test Separator
Flowmeter
Discharge LVC
PV
Reject to LP Separator
L/L Hydrocyclone Construction Efficiency equal to or better
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than all competing hydrocyclones Internal geometry and Stellite
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inlet reduce erosion Cones : duplex SS Tails:
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Sanicro 28 Easily installed and removed -
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no special tools required
Installation
BP GEISUM PLATFORM NORTH SEA
PRODUCED WATER 23,000 BWPD
OILSPIN AVi INSTALLATION DESIGN •MINIMIZE SPACE •MINIMIZE INSTRUMENTS •INCREASE OPERATING FLEXIBILITY •OVERALL REDUCTION IN COST •MAINTAINING HIGHEST EFFICIENCY
OILSPIN AVi -
UNLIMITED TURNDOWN!!!
Oilspin AV i Interactive Hydrocyclone Method of operation - on line
Oilspin AV i Interactive Hydrocyclone Method of operation - off line
Oilspin AV i Interactive Hydrocyclone Method of operation - on line
Oilspin AV i Interactive Hydrocyclone Hydrocyclones switched
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individually or in groups
H. P. SOURCE
2 years operating
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experience on Tyra East Ideal for test
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separators,
frequently changing systems or difficult separations L. P. DRAIN
Oilspin AV i Interactive Hydrocyclone Eliminates need for
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multiple or compartmented vessels
H. P. SOURCE
Fully automatic hydraulic
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operation New manual activation
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system under development.
L. P. DRAIN
SUSPENDED SOLIDS REMOVAL SOLID/LIQUID HYDROCYCLONES TYPICAL APPLICATIONS
PRODUCED WATER DESANDING WELLHEAD DESANDING FILTER PRE-TREATMENT SAND WASHING
Hydrocyclone Design
•MULTI LINER VESSEL •D95 >15 MICRONS • VARIOUS DUMP OPTIONS •CERAMIC LINERS AVAILABLE
Large Diameter Range
15” 12”
9”
Small Diameter Range
1” Canned 1” Vessel 1” Cutaway 2”Canne d 2”Vessel
12 mm Desanders d90 5 to 7 microns l Flowrate typically below 0.1 m3 /h so huge numbers required l Very prone to blockage l Upstream strainers or desanders required for protection l
Ceramic Desanders l
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Default 3” ceramic desander Flowrate/efficiency modified by vortex finder selection Capacity 10 to 30 m3 /h each Potted underflow or continuous (>2%) d90 15 to 50 microns 2” and 1” also available taking d90 down to 11 microns
Performance Range
Solid/Liquid Hydrocyclone Installation Gamra, Libya Well-head Desanders l
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3,700,000 bpd
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90 off 15 PHQ
95% removal > 100 microns l
Aquifer water
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Solid/Liquid Hydrocyclone Installation Al Furat Petroleum
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Omar Phase II Field, Syria
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110,000 bpd
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13 off 10 PHQ
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95% removal > 40 microns
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River water
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Mounting arrangements
Solid/Liquid Hydrocyclone Installation l
Anadarko/Sonatrach Algeria
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HBNS Development
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10 Micron Separation
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150,000 bwpd Aquifer Water 306 off 2CLQ
Solid/Liquid Hydrocyclone Installation l l l
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Maersk Petroleum Qatar Al-Shaheen Field Development 98% > 10 micron rating
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75,000 BWPD Produced water
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146 off 2PHQ
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Used in conjunction with Oilspin AV LLC’s
High Pressure Wellhead Desander Halliburton for PDO Welltesting Operations l Designed to separate solids from multi-phase fluids l Welltesting and clean up l First fully coded ASME VIII Division 2 hydrocyclone vessel supplied globally l 3” x 7 way, 10,000 psi unit
Wellhead Desander Shell/PDO Marmul Field l
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Compact with high throughput Ultra high erosion resistance No backflushing Reduced weight & size compared with conventional filters Continuous or batch operation
Wellhead Desander l l
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Wide operational envelope Maintains separation during slugging, varying flow rates, very high GLR and varying phase composition Gas/liquid ratios between 5 and 100 possible Higher pressure, higher GLR Pressure drop 1-15 bar depending on application High erosion resistance due to inlet geometry and materials
Sandw dwa ash System l
Designed to separate and remove oil contaminated solids to produce oil free sand (<10g/kg oil on sand by weight)
PROCESS WATER
OILY WATER
MOZLEY HYDROCYCLONES
RECIRCULATION
Sand Cleaning System
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Designed to separate and remove oil contaminated solids to produce oil free sand (<10g/kg oil on sand by weight) No chemical addition required Cleans sand by physical attrition Compact system Maintains cleaning efficiency with varying solid concentrations
Chev Chevro ron n Cabi Cabind nda a Kung Kungul ulo o Fiel Field d Desandin Desanding g Skid for for Water Water Injection Injection Platform
Pres Pr essu sure re Le Lett Dow Down n Hy Hydr droc ocyc yclon lone e Ceramic cyclonic device for reducing slurry pressure l Used Used on de desa sand nder er un unde derf rflo lows ws l Very high erosion erosion resistance resistance l Sized to suit each duty l
Sand Fluidizer l
Device under development
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Uses a small amount of water to fluidise and transport settled sand
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Competitor to Merpro Tore
Centrifuge
REVIEW 1. BY WHAT MECHANISM DO LIQUID/LIQUID HYDROCYCLONES WORK? 2. IS HYDROCYCLONE PERFORMANCE AFFECTED BY THE SIZE OF THE OIL DROPLET? 3. WHAT HAPPENS TO HYDROCYCLONE PERFORMANCE AS FLOW RATE DECREASES? IF A VESSEL HAS 20 LINERS INSTALLED AND THE FLOW RATE DECREASES BY 40%, WHAT ADJUSTMENT MUST BE MADE? 4. HOW DOES THE DIAMETER OF THE SOLID/LIQUID HYDROCYCLONE AFFECT FLOW RATE AND PARTICLE SIZE REMOVED? 5. DESCRIBE HOW THE INTERACTIVE LIQUID/LIQUID HYDROCYCLONE SYSTEM WORKS? 6. WHEN WOULD IT BE APPROPRIATE TO USE POLYURETHANE LINERS IN A SOLID/LIQUID HYDROCYCLONE? 7. WHY IS THE LEVEL CONTROL VALVE PLACED DOWNSTREAM OF THE LIQUID/LIQUID HYDROCYCLONE VESSEL? 8. WHY IS A DEGASSER VESSEL PLACED DOWNSTREAM OF A LIQUID/LIQUID HYDROCYCLONE VESSEL?
Dispersed Oil Removal (Flotation) TECHNOLOGY
PURPOSE
Hydraulic Induced Gas Flotation Units Horizontal Hydraulic IGF Horizontal Sparged IGF Single Cell Hydraulic IGF Hydraulic Column IGF MPE Sparged Column IGF Mechanical Induced Gas Flotation Units
Separation of emulsified oil from water Separation of oil coated solids from water
Horizontal Hydraulic IGF Inlet oil concentration 200-300ppm
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Outlet oil concentration 20-30ppm
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90-98% Removal Efficiency
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Onshore / Offshore Production Handles Upsets
Advantages of Horizontal Hydraulic IGF l
No Internal Moving Parts
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Over and Under Internal Baffles to Prevent Short Circuiting
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25-50 % Water Recycle Rate for Increased Gas Contact Time
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Dual Internal Eductors for Increased Gas Bubble Dispersement
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Mechanical Wipers or Spillover Weirs for Oil Removal
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PVC or 316 SS Internals
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ASME Code Design Cylindrical Vessel Design for Improved Solids Collection
Mechanical Induced Gas Flotation (Pressurised)
Cycloturbine l l
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2 or 4 per vessel Rotor creates negative pressure in draft tube, pulling down gas from above the liquid surface Gas bubbles are thrown out by the rotor and impinge on the stator Turbine design enhances flow pattern and gas/oil contact
CYCLOTURBINES • 65 SCFM/BBL GAS:WATER RATIOS • BUBBLE SIZE = <50 MICRONS • EFFECTIVE DISTRIBUTION • GEAR REDUCTION DRIVE
AUTOSTABLE SKIMMER
• SITS AT OIL / WATER INTERFACE • MINIMIZES OIL SKIMS <2% • HANDLES UPSETS • OPERATES UNDER MOTION • NO MOVING PARTS
Floating skimmers l
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Oil draw off regulated by oil outlet valve Oil box and floating skimmer designed to provide gas seal between water and separated oil External buoyancy chambers keep skimmer close to surface
Floating skimmers
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Internal buoyancy chambers regulate skimmer depth and therefore amount skimmed Insensitive to motion or throughput
Produced Water Treatment Mechanical Induced Gas Flotation Maximum operating pressure 4 barg lMaximum inlet oil concentration 1000 ppm lTypical efficiency 90-98% oil removal with chemicals lTypical efficiency 80 - 90% without chemicals l
Produced Water Treatment Mechanical Induced Gas Flotation Typical outlet concentration 15-20 ppm lTypical solids removal 20-50% lPatented by Ceca (Elf) and supplied under licence l
Single Cell Hydraulic IGF Inlet oil concentration 200-300ppm Outlet oil concentration 30-50ppm 75-90% Removal Efficiency
Onshore / Offshore Production Handles Upsets Less Sensitive to Pitch / Roll
Single Cell Sparged IGF Inlet oil concentration 200-300ppm Outlet oil concentration 30-50ppm 75-90% Removal Efficiency
Onshore / Offshore Production Handles Upsets Less Sensitive to Pitch / Roll
Vertical Downflow Column IGF
Inlet oil concentration 200-300ppm Outlet oil concentration 20-30ppm 90-98% Removal Efficiency Counter Current Contacting Onshore / Offshore Production Handles Upsets Insensitive to Pitch / Roll
REVIEW 1. DESCRIBE HOW FLOTATION WORKS. 2. WHAT IS THE DIFFERENCE BETWEEN HYDRAULIC FLOTATION AND MECHANICAL FLOTATION? 3. HOW IS OIL REMOVED IN THE HYDRAULIC IGF? 4. HOW IS OIL REMOVED IN THE MECHANICAL IGF? 5. WHAT CAN AFFECT THE PERFORMANCE OF THE IGF? 6. WHAT IS THE MAXIMUM INLET OIL CONTENT THAT THE IGF CAN HANDLE?
Water Polishing (Physical Trapping)
TECHNOLOGY Media Filtration Nutshell Filter Cartridge Filter
PURPOSE Separation of emulsified oil from water Separation of oil coated fines from water
Produced (Oily) Water Multi-Media Filter Proven technology l Dual/multimedia l Anthracite/sand/garnet combinations l Max inlet oil 30-50 ppm l Outlet oil < 5 ppm l Max inlet TSS 30 - 50 mg/l l Efficiency typically 95% removal of particles > 5 microns l
Water Injection Systems Media Filters l
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Best technology for removing solid particulates from produced water Flux rates 15 - 35 m3/m2/h on produced water Polyelectrolyte required Surfactant usually required for backwash Gas scour used during backwashing Hundreds of operating references
Media Filter - Installation
MEDIA FILTER INTERNALS
INLET DISTRIBUTOR
COLLECTION LATERALS
Backwash Sequence
Nutshell Filter
Max inlet oil 50-100 ppm lOutlet oil < 5 ppm lMax inlet TSS 30 - 50 mg/l lEfficiency typically 95% removal of particles > 10 microns (or 90% > 5 microns) l
Nutshell Filter l l
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Effective oil removal filter Handles waxy oils without fouling Solids removal worse than suppliers claim Flux rates 30 - 35 m3 /m2 /h Polyelectrolyte not required Surfactant not required Sensitive to biocides Can be retrofitted to existing filters
Retrofitted Nutshell Filter
Nutshell Filter l
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Normal flow dowward through the crushed nutshell media Nutshells are recirculated through the Powerhead to strip off the oil Dirty water passes through a screen to drain Clean nutshell media returns to the filter vessel
Cartridge Filters l
Polishing filters for produced water where treatment specification is very tight
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Vertical or horizontal horizontal vessels vessels Cartridges made by Pall and supplied to special NATCO design
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Sized on basis of hydraulic and solids loadings
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Absolute cartridges cartridges (cannot be compared compared with cheap nominal cartridge elements)
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Quick opening and counterbalanced lid designs available
Coalescer Technology for Complex Gas Condensate Application l l l
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Inlet oil up to 10% Outlet Outlet oil below below 10 ppm Used for low flow applications with small oil droplets Ideal solution for gas condensate fields where LLC’s and IGF’s do not work well
Pall Phasesep l
Does not disarm unlike glass fiber media
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Low Maintenance/ High Reliability
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Effectively handles process upsets Efficiently separates difficult low IFT liquids Competitive coalescers lose efficiency as IFT gets below 20 dyne/cm Surfactants (in sulfur compounds, corrosion inhibitors and found naturally in hydrocarbons) lower IFT
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IFT = interfacial tension
BACKWASH WATER TREATMENT ISSUES What are the contaminants?
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Options for removal
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Equipment required
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Concerns
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Experience of the class
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DISPOSAL Discharge / Injection TECHNOLOGY Disposal Caisson Skim Pile Submerged Column Flotation Unit (SCFU)
PURPOSE No slick no sheen No disposal well plugging
Skim Pile • Free Oil Removal from Open Drains • Internal Baffles with Oil Risers for Improved Separation • No Solids Build up in Vessel • No Moving Parts • Internal or External Oil Removal Pump • No Deck Space Required • Minimal Platform Weight
Submerged Column Flotation Unit (SCFU) •Combination of Flotation and Disposal In Single Vessel • No Deck Space Required
• Minimal Platform Weight (Partially Submerged in Water) • No Internal Moving Parts • Low Maintenance • Insensitive to Motion • Reduced Installed Cost
DISPOSAL METHODS Submerged Column Flotation Unit (SCFU) This Submerged Column Flotation Unit (SCFU) is installed offshore Brazil on a FPSO. Directly mounted to the hull, this unit is designed to treat 115,000 bpd of Produced Water. The system was installed to eliminate deck space and weight requirements and minimize the impact of pitch and roll on flotation performance – a major concern for conventional vessels.
SCFU Installed On Deepwater Floating Production Platform No Space Available on Topsides for Conventional Flotation l
Serve as Degassing Vessel for Upstream Hydrocyclones l
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Final Disposal After Flotation
Met Outlet Water Specification of 20 ppm l
Compact Offshore Produced Water Treatment System Minimal Deck Space Required l
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Reduced Weight
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No Moving Parts
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Insensitive to Pitch and Roll
REVIEW 1. WHAT ARE THE MECHANISMS EMPLOYED TO MAKE THE MULTI-MEDIA FILTER WORK PROPERLY? 2. WHAT ARE THE MECHANISMS USED TO MAKE THE NUTSHELL FILTER WORK PROPERLY? 3. IF A MULTI-MEDIA FILTER IS USED IN OILY WATER SERVICE, WHAT STEP IS ADDED TO THE BACKWASH PROCEDURE? 4. WHEN ARE CARTRIDGE FILTERS REQUIRED IN PRODUCED WATER? 5. WHAT ADVANTAGE IS OFFERED BY THE SKIM PILE?
Common Produced Water Treating Chemicals Chemical
Purpose
Dose Rate
Normal Dose Point
Polyelectrolyte
Filter Aid
1-2 ppm
Upstream of Media Filter
Coagulant
Filter Aid
0.5-1 ppm
Upstream of Media Filter
Reverse Demulsifier
Break Emulsions
10-25 ppm
Upstream of Flotation Unit
Surfactant
Cleanse Oil Off 2-4 gal. per Media Bed backwash
Biocide
Biological Control
400 ppm for 4 hours (intermittent)
Scale Inhibitor
Scale Control
10-20 ppm
Downstream of Booster Pumps
Corrosion Inhibitor
Corrosion Control
10-20 ppm
Downstream of Booster Pumps
In Bottom of Filter Various
Water Analysis as a Diagnostic Tool
Review Information from Manual
Range of droplet sizes removed by various types of de-oiling equipment MEMBRANE FILTER CENTRIFUGE MEDIA FILTER COALESCER
HYDROCYCLONE
WITH CHEMICAL
FLOTATION PLATE SEPARATOR API GRAVITY
0.1
1
10
100
1000
Oily Water Treatment Required Minimum Design Parameters Flow Rate
Oil/Water
Pressure
Available pressure upstream. Required pressure downstream.
Temperature
Operating temperature.
Contaminant Loading Inlet/Outlet
Oil / Solids/Oxygen/Bacteria.
Chemical Analysis of Water Anions-Cations-pH Density
Oil - Water - Solids.
Particle Size Analysis
Oil-Solids
Oily Water Treatment Required Minimum Design Parameters Existing Process Upstream/Downstream
Type of equipment and performance.
Motion Characteristics
Pitch/Roll/etc.
Design Conditions
Temperature/Pressure
Ambient Conditions
Environmental Data/etc.
Outlet Requirements
Oil/Solids/Bacteria/Oxygen/Pressure/ Temperature
Process Design and Control
Review PFD and P&ID’s from PWTS Proposal
SIZING CRITERIA 1. Gravity Settling Devices
Stoke’S Law for Drop Rise
2. CPI
Flux Rate, Drop Size
3. Hydrocyclone Devices
Droplet Removal Efficiency, Capacity per Liner
4. Filtration Equipment
Flux Rate, Particle Size Removal
5. Flotation Equipment
Retention Time per Cell
Performance Testing 1. Suspended Solids 2. Oil Content 3. Biological Content 4. Sampling Techniques
MATERIAL SELECTION ISSUES CLASS DISCUSSION OF RELEVANT EXPERIENCE IN VENEZUELA
Engineered Systems Approach To Produced/Oily Water Treatment
