DRILLING FLUIDS FOR GEOTHERMAL OPERATIONS

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DRILLING FLUIDS FOR GEOTHERMAL OPERATIONS

• RECENT DEVELOPMENTS

John D. Tuttle Boart Longyear/Sinclair Well
Products 2006 GRC Convention San Diego, Ca
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GEOTHERMAL EXPERIENCEJOHN D. TUTTLE

• 28 YEARS GEOTHERMAL DRILLING FLUIDS EXPERIENCE
• EXTENSIVE GEOTHERMAL EXPERIENCE USA
  (CALIFORNIA, NEVADA, IDAHO), MEXICO, INDONESIA,
  SWEDEN, GUATEMALA
• DESIGNED AND FIELD-TESTED NEW ADDITIVES AND
  GEOTHERMAL DRILLING FLUID SYSTEMS IMPLEMENTED
  COST-EFFECTIVE SOLIDS REMOVAL HYDRAULICS
  PROGRAMS

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GEOTHERMAL MUD SYSTEMSGENERAL CONCEPT

• PROJECT-SPECIFIC MUD DESIGN
• TEMPERATURE TIME STABILITY
• SIMPLICITY OF DESIGN (KISS)
• USE OF LOCALLY AVAILABLE and/or COST-EFFECTIVE
  MUD PRODUCTS
• EMPHASIS ON SOLIDS REMOVAL EQUIPMENT AND
  HYDRAULICS PROGRAM

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GEOTHERMAL MUD SYSTEMS RECENT INNOVATIONS

• Specialty and Blended Additives for Control of
  Viscosity, Fluid Loss, Inhibition, Lost
  Circulation
• Solids Removal Equipment
• Hydraulics Optimization
• Clay-Free Geothermal Mud System
• Air/Foam Drilling
• Formation Damage Considerations

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DRILLED SOLIDS REMOVAL

• Solids Removal Equipment for Geothermal Drilling
  Operations

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SOLIDS REMOVAL EQUIPMENTSELECTION PROCESS

• What are the criteria for selecting solids
  removal equipment?
• Efficient Solids Removal Equipment will Reduce
  Treatment and Dilution Costs, Reduce
  Trouble-Time, and Improve Hole Conditions
• Well Design Considerations (Hole Volumes,
  Directional Considerations, etc.)
• Mud Weights and Relative Mud Cost/Bbl
• Sump/Reserve Pit vs Closed System
• Equipment Rental Cost

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Rig-Owned Equipment - Minimal cost/day for basic
solids removal equipment
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1,000/day for current state-of-the-art
separation equipment
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Dewatering Polymer Mixing/Injection Unit
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Successful Drilled Solids Removal Program with
Dewatering
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OPTIMIZED HYDRAULICS PROGRAM

• Significant reductions in drilling time and well
  costs can be realized by implementing an
  effective Hydraulics program
• PROPER BIT SELECTION
• MUD PUMP OPTIMIZATION (triplex v. duplex)
• BIT NOZZLE SIZING (maximize HHP _at_ BIT)
• DRILLING FLUID RHEOLOGY
• USE PROFESSIONAL DESIGN SUPPORT

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VISCOSITY and RHEOLOGY CONTROL

• Polymer Viscosifiers

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GEOTHERMAL SYSTEM POLYMER VISCOSIFIERS

• Modified PHPA Polymer Popular Geothermal
  viscosifier provide instant viscosity and sweeps
  with a minimal increase in solids blended for
  temperature stability available in either dry
  state or as liquid emulsions
• Blended Synthetic Co-Polymers Combinations of
  old/new generation long chain polymers good
  temperature stability provide excellent
  viscosity
• Thixotropic Polymers PHS, XCD Provide superior
  suspension properties, gel structures, and shear
  thinning inhibitive good temp stability
  excellent for deviated wellbores

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VISCOSITY and RHEOLOGY CONTROL

• Thinners Degellants

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GEOTHERMAL MUD SYSTEM THINNERS

• Tannin and Lignite Thinners/Dispersants
  Standard thinners for low and moderate
  temperature systems effective with higher solids
  systems
• Blended Polymer Thinners Combinations of low
  molecular weight dispersants deflocculants,
  specifically designed for Geothermal drilling
  operations provide thinning as well as control
  of HT gelation at BHT extended long-term
  temperature stability
• New 3rd Generation Synthetic Polymer Blends
  Starch derivatives and new interpolymer
  polyacryalate polymeric/acid blends provide
  excellent thinning and degelling at elevated
  temperatures effective in low concentrations
  cost effective (stable to over 600F)

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FLUID/WATER LOSS CONTROL

• Filtrate Reducers

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GEOTHERMAL MUD SYSTEM FILTRATE REDUCERS

• Traditional starch and polymer additives and
  lignite provide cost-effective fluid loss at
  moderate temperatures
• New Synthetic Polymer Blends Synthetic
  acrylamides and sulfonic acrylamide copolymer
  blends, provide HTHP fluid loss and stability in
  temperatures gt600F resistant to contaminates

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GEOTHERMAL MUD SYSTEMALKALINITY CONTROL

• Caustic Soda Lime Typical additives for
  adjusting pH, controlling H2S, and treatment of
  carbonate contamination.
• KOH Caustic Potash provides effective pH
  increase while also providing K ion inhibition
  (preferred over Caustic Soda in sensitive or
  hydratable clay zones)

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FORMATION STABILITY INHIBITION

• Shale Control, Clay Swelling, and Inhibition

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GEOTHERMAL MUD SYSTEMFORMATION INHIBITION

• Gilsonite/Asphalt-based additives provide shale
  stability primarily through mechanical inhibition
• K-ion Inhibition K-Lignite, TORKease, KCl,
  Others As needed for specific stability issues
• Silicate Blends Proprietary blend of sulfonated
  salts and metal complexes (Al3, etc.) provides
  shale and clay stability through ionic inhibition

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Formation InhibitionPotassium and Aluminum Ions

• K ion Inhibition (from KOH, KCl, K-Lignite,
  others) Provides stability for mixed layer clays
  and illites destabilizes kaolinite (turning
  inactive kaolinite into active illites)
• Al3 ion Inhibition (from Aluminum Silicate
  specialty blends) Provides superior stability
  for all clays, including kaolinite. Temperature
  stability for geothermal drilling operations

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Formation Inhibition

• Relative configuration of clay crystal lattice
  and various cations/anions

Na

-
Al3
-
-

Al3
-

-
OH-
-
-


Al3
-

-
K
Na

-
-
-

-
OH-
-
-

Clay lattice structure
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MUD LUBRICITY
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GEOTHERMAL MUD SYSTEMLUBRICITY

• TORKease Renowned geothermal lubricant for
  over 30 years provides excellent lubricity
  qualities at temperatures in excess of 600F
  reduces open hole torque and drag at low
  concentrations frees stuck pipe
  environmentally friendly resistant
  to contaminates
• non-damaging

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LOST CIRCULATION
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GEOTHERMAL MUD SYSTEMLOST CIRCULATION

• COTTONSEED HULLS/SAWDUST Conventional LCM
  additives provide effective loss control
  degraded over time by temperature
• MAGMA FIBER Spun rock wool highly effective
  LCM, and totally acid soluble temperature
  stability in excess of 800F
• POLY-PLUG Proprietary, time-released resin
  with sized LCM one-sack system creates
  rubber-like consistency excellent plugging
  action and moderate temperature stability (400
  degrees F)
• CEMENT PLUGS
• FOAM/AIR DRILLING Stiff foams using PHPA or
  other viscosifier, Corrosion/Scale Inhibitor, HT
  Foamer, Caustic Soda

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POLY-PLUG LCM PLUG
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GEOTHERMAL FORMATION DAMAGE

• WHAT IS DAMAGING TO THE PRODUCING FORMATIONS?
  Drilled Solids, LCM, Bentonite, Polymers, Cement,
  etc.
• TO WHAT EXTENT IS FORMATION DAMAGE CORRECTABLE?
• HOW DO WE MINIMIZE FORMATION DAMAGE?!

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GEOTHERMAL DRILLING OPERATIONS FORMATION DAMAGE
CONTROL

• DRILLED SOLIDS Contamination of production
  intervals poor hole cleaning drilling blind
  (solids go into formation)
• LOST CIRCULATION MATERIALS Utilize degradable
  materials (Magma Fiber, etc)
• LOST CIRCULATION MATERIALS Partially-degradable
  materials (Sawdust, Cottonseed Hulls, Drilling
  Paper, etc.)
• BENTONITE Minimize when possible
• INHIBITION Use ionic inhibition (K, Al3)
  where appropriate

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GEOTHERMAL BENTONITE -FREE MUD SYSTEM

• Minimizes production zone damage
• High ROPs possible
• Readily available products
• Mud properties are easily maintained
• System is cost-effective

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BENTONITE-FREE MUD SYSTEM COMPONENTS

• Viscosifier Proprietary high-temp blended PHPA,
  especially for sweeps
• Fluid Loss Modified PACs and 3rd generation
  synthetic acrylamide copolymers (temp stable to
  gt400F)
• Inhibition KCl, KOH, Aluminum Silicate Blends
• Lubricity TORKease
• Other Additives Corrosion Scale Inhibitors,
  Foamers, pH Modifiers

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Final Questions to Ponder

• Do we really need HTHP fluid loss?
• Drilled Solids Removal how do we
  cost-effectively implement?
• LCM Product Degradability Is this a critical
  issue?
• How do we maximize penetration rates reduce
  overall well costs?
• Can we drill Bentonite-free?

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THANK YOU

• I appreciate the opportunity to make this
  presentation for the attendees of the GRC Annual
  Convention
• For further or personal discussions regarding
  innovative drilling fluids additives for
  Geothermal applications, I can be contacted at
  Sinclairs GRC display at Booth 36