Lesson 6 Foam Drilling-1 - PETE 689 Underbalanced Drilling,...

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Unformatted text preview: PETE 689 Underbalanced Drilling, UBD Lesson 6 Foam Drilling Read: UDM Chapter 2.52.6, Pages 2.752.130 Harold Vance Department of Petroleum Engineering Harold Vance Department of Petroleum Engineering The Pattern Of Foam 1 cm 1/2 inch Classic static foam pattern on the left. Foam in flow probably looks more like the one on the right. Harold Vance Department of Petroleum Engineering Types of Flow Regimes (Lorenz, 1980) LIQUID AERATED LIQUID FOAM MIST GAS Harold Vance Department of Petroleum Engineering Fluid Phase Continuity Air/Gas Water Foam or Gaseated (5097% Gas) Mist (97100% Gas) Harold Vance Department of Petroleum Engineering 1000/1 500/1 100/1 50/1 30/1 10/1 Mist Aerated Foam 99.8% Injection Ratio Harold Vance Department of Petroleum Engineering Foam Quality 90% Foam and Gaseation FOAM GASEATION "Emulsion". Mixture. Separates easily. Hard to Separate. "NO" Pressure Surges. Heading and pressure surges. Huge lifting capacity. Normal lifting capacity. Plugs lost circulation Reduces lost circulation and reduces head. by reducing head. Harold Vance Department of Petroleum Engineering Why Foam? Reasons for UB Drilling with Foam 1. Stops lost circulation. 2. Improve drilling rate. 3. Protects the reservoir. 4. Avoid differential sticking. 5. Hole cleaning with low fluid volume. Harold Vance Department of Petroleum Engineering Lifting Capacity Powder Regrinding And Mud Ring Formation Large Cuttings Air/Mist Harold Vance Department of Petroleum Engineering Foam Lost Circulation with Foam Reduced the mud density no junk. Foam plugs lost zones. Harold Vance Department of Petroleum Engineering Lost Circulation with Foam The Foam bubbles are lost zone plugging agents! Harold Vance Department of Petroleum Engineering Improve Drilling Rate Low bottom hole pressure increases drilling rate. For hard rock, the new air hammer works with foam. Harold Vance Department of Petroleum Engineering Effect of Differential Pressure Perfect Cleaning DRILLING RATE Bit Flounder not uncommon with foam 500 p b p p +500 +1000 DIFFERENTIAL PRESSURE (psi) Harold Vance Department of Petroleum Engineering 0 Protect Reservoir No formation damage with no influx into the well bore. Minimal pressure surges. Controllable pressures. Harold Vance Department of Petroleum Engineering Protect Reservoir Foam is Perfect UB Fluid In underbalance condition, flow is into the hole. Fluid does not ruin the foam. Harold Vance Department of Petroleum Engineering Protect Reservoir Foam is perfect UB Fluid In overbalance condition, foam bubbles block the matrix. Foam bubbles also block fractures. Harold Vance Department of Petroleum Engineering Differential Pressure Sticking DRILL PIPE PH FILTER CAKE , K Pf PH > Pf DRILL COLLAR Harold Vance Department of Petroleum Engineering No Differential Pressure Sticking DRILL PIPE PH No FILTER CAKE , K Pf PH > Pf DRILL COLLAR Harold Vance Department of Petroleum Engineering Foam Lifting Capacity Needs Only Limited Fluid Volume Relative Lifting Force 1.0 0.8 0.6 0.4 0.2 0 Actually acts like this Stable Foam Dry Wet Foam Relative Velocity 2 1 Theory 0 0.2 Harold Vance Department of Petroleum Engineering 0.4 0.6 Foam Quality 0.8 1.0 Hole Cleaning with Limited Fluid Volume Powder Regrinding And Mud Ring Formation Large Cuttings Air/Mist Harold Vance Department of Petroleum Engineering Foam Theoretical Foam Types Stable Foam: 12% Surfactant. Stiff Foam: 1% Surfactant, 34% Gel, Polymer. Use of viscosified water instead of fresh nonviscosified water in the incompressible fluid component. Viscosity additives: CMC, Xantan Gum, Polymers, etc.. Harold Vance Department of Petroleum Engineering General Foam Agents Foamer to reduce surface tension of water. Polymers to strengthen the film around the air bubbles. Soda Ash to soften water and raise the pH to 10. Harold Vance Department of Petroleum Engineering Fluids for Foam Drilling Fresh water. Saline or brackish water. Oils not used to date. Harold Vance Department of Petroleum Engineering Small Foam Unit Harold Vance Department of Petroleum Engineering Large Foam Job Harold Vance Department of Petroleum Engineering Foam Theory Harold Vance Department of Petroleum Engineering Foam Structure Required Elements Gas Liquid Foaming Agent A surface active agent Harold Vance Department of Petroleum Engineering The Pattern Of Foam 1 cm 1/2 inch Classic static foam pattern on the left. Foam in flow probably looks more like the one on the right. Harold Vance Department of Petroleum Engineering Transfoam (Weatherford) All of the following may not apply to transfoam. Some of the methods of handling Transfoam may vary. It is a slightly different type of foamer. Harold Vance Department of Petroleum Engineering Foam Rules Smaller bubbles are more stable. Polymers make the skin around the bubbles tougher. Bentonite makes the skin around the bubbles more stable. Harold Vance Department of Petroleum Engineering Foam Rules Soda ash in the water makes the foamer work better. Soda ash in the water buffers the pH at about 10. Different foamer may work best in certain areas. Harold Vance Department of Petroleum Engineering Effect Of Pressure On Foam Stability, Correlation with Bubbles Man Diameter 1.000 900 0.700 0.600 0.500 0.400 0.300 0.200 0.100 0.000 Bubbles mean diameter ( m ) 800 700 600 500 400 300 200 100 0 0 5 10 15 20 25 30 35 40 45 50 Pressure ( bar ) After Saintpere et.al. Harold Vance Department of Petroleum Engineering Drainage velocity (ml/min) Polyhedral Foam Contact True Foam Plateau Border Harold Vance Department of Petroleum Engineering Bubble Pressure Redistribution Lesser Pressure R Greater Pressure r From high pressure to lower pressure Depends on film permeability Gas diffusion. Harold Vance Department of Petroleum Engineering Foam Structure Stabilization Harold Vance Department of Petroleum Engineering Stronger Bubbles Smaller bubbles. More foamer. Of the right kind. Add a surfactant. Polymer. Other agent. Harold Vance Department of Petroleum Engineering Surface Active Materials Retard Drainage Increase surface viscosity. Oxygen reactive additives. Migrating surfactants. Ionically charged foamers. Harold Vance Department of Petroleum Engineering Migrating Surfactant Harold Vance Department of Petroleum Engineering Ionically Charged Foamer + - + - + - + + + Most foam system and most foamers are anionic in nature. If part of the outer wall of the bubble should become cationically charged the inner and outer walls would be attracted and the wall would become thinner at that point. Harold Vance Department of Petroleum Engineering Ionically Charged Foamer Ionically charged foamers will cause both walls of each bubble to carry the same electrical charge. - - - - - - - The walls will then repel, becoming thicker. - Harold Vance Department of Petroleum Engineering Foamer Considerations Concentration Contaminants Temperature Solubility Harold Vance Department of Petroleum Engineering Foamer Concentration 300 250 Half life in seconds 200 150 100 50 0 0 0.2 0.4 0.6 0.8 1 1.2 % Foamer concentration Harold Vance Department of Petroleum Engineering Major Factors of Foam Stability FACTOR Foamer concentration Solubility Temperature Contamination CHANGE Increase Increase Increase Increase EFFECT on DRAINAGE Decrease Decrease Increase ----- EFFECT on STABILITY Increase Increase Decrease Decrease All these factors are interdependent if T goes up, instability increase, solubility of the foamer increase. If solubility increase, stability increase. Harold Vance Department of Petroleum Engineering Disrupting Factors Bubble Size ReDistribution. Bubble Wall Thinning. Gravity drainage. Evaporation. Harold Vance Department of Petroleum Engineering Causes of Bubble Disruption Big Bubbles are weaker than small bubbles. Salt water weakens the bubble surface. Oil weakens the bubble surface. Some solids weaken the bubble. Harold Vance Department of Petroleum Engineering DEFOAM Harold Vance Department of Petroleum Engineering Bubble Disruption Defoamers Most defoamers weaken the bubble film like an alcohol or oil. Some defoamers use fine silicate solids to disrupt the bubble film. Time and gravity drainage. Harold Vance Department of Petroleum Engineering Foaming Agent Chemicals Harold Vance Department of Petroleum Engineering Straight Foamers Anionic in Nature Ethoxyl Alcohol Ether Sulfates Alpha Olephin Sulfonates Widest applicability. Excellent solubility. Good thermal stability. Hydrocarbon tolerance. High Costs. Harold Vance Department of Petroleum Engineering Foam Boosters AminoPropyl Betaines (Amphoteric) Will change properties with a change in pH from acid to basic. Excellent stability. Good thermal stability. Good brine solubility. Fair yield. Relatively expensive. Harold Vance Department of Petroleum Engineering Foam Boosters Alkanol Amides (Cationic) Good thermal stability. Expensive. Incompatible with most foam systems. Harold Vance Department of Petroleum Engineering Foam Stabilizers Sodium Sulfosuccinates (Anionic) Common. Good freshwater solubility. Good thermal stability. Extremely poor brine solubility. Harold Vance Department of Petroleum Engineering Foam Stabilizers AlkylPhenol Ethoxylates (Nonionic) Excellent surface activity. Soluble in all waters. Good thermal stability. Compatible with other additives. Provides poor foam quality. Harold Vance Department of Petroleum Engineering Foam Stabilizers Quaternary Ammonium Chlorides (Cationic) Provides: Corrosion inhibition. Biocidal properties. Clay stability. Excellent brine solubility. Good foam quantity. Poor fresh water solubility. Poor lifting capacity. Requires high concentration. Harold Vance Department of Petroleum Engineering Foam Stability Improvement Polymers Harold Vance Department of Petroleum Engineering Polymer Uses Drill solid flocculation. Increased viscosity. Increased lubricity. Stabilize clays. Increase foam stability. Harold Vance Department of Petroleum Engineering Polymers Organic or synthetic. Many monomers (repeating units). Varied structures. Harold Vance Department of Petroleum Engineering Polymers Polyacrylamides Widely used. MW = 810 million. Varied ionic charge. Harold Vance Department of Petroleum Engineering Synthetic Polymers PartiallyHydrolyzed Polyacrylamide (PHPA) Synthetic Synthetic polymer. Powder or liquid. Harold Vance Department of Petroleum Engineering Polymers Carboxymethyl Cellulose Natural polymer from plants. Cotton. Viscosity control. Natural, Organic (CMC) Harold Vance Department of Petroleum Engineering Polymers HydroxyEthyl Cellulose (HEC) Anionic. Fluid loss control. Viscosity control. Harold Vance Department of Petroleum Engineering Natural, Organic Polymers Natural, Organic Guar Gum Natural polymer. Nonionic, Branched chain. MW = 200,000 Low temperature. Harold Vance Department of Petroleum Engineering Polymers Xanthan gum (XC) Viscosity control. Biopolymers Shear thinning. Increase foam stability, but with poor lifting ability. Harold Vance Department of Petroleum Engineering Fresh or salt water compatible. Clay and Shale Stabilizers Hole Stability Harold Vance Department of Petroleum Engineering Clay Swelling Mechanisms Simple adsorption. Osmotic swelling. Harold Vance Department of Petroleum Engineering Stabilizing Agents KCl Excludes water attraction. Ammonium chlorides. Amine salts. Cationic polymers. Harold Vance Department of Petroleum Engineering General Foam Types Stable foam Stiff foam Foaming agent Polymer Foaming agent Polymer Bentonite Transfoam pH sensitive foam (amphoteric) Harold Vance Department of Petroleum Engineering Foam Quality Gas phase percent by volume % Whole number Decimal equivalent e.g. 75, 75%, or 0.75 Expressed as: Harold Vance Department of Petroleum Engineering Foam Quality (In theory) 055% 55%94% 94%99.9% 100% Aerated Fluid Foam Mist Gas/Air Harold Vance Department of Petroleum Engineering Hole Cleaning Powder Regrinding And Mud Ring Formation Large Cuttings Air/Mist Harold Vance Department of Petroleum Engineering Foam Factors Effecting Foam Quality Pressure. Depth. Gas content. Liquid content. Harold Vance Department of Petroleum Engineering Maintaining Foam Quality Gas and liquid injection rates. Backpressure on the system. Measurement. Calculation (computer models). Harold Vance Department of Petroleum Engineering Foam Texture The "stability" of Foam Not measured at present. Assumed in all the Math. A source of error, but we don't know how much. Best available guess is "half life". Harold Vance Department of Petroleum Engineering Foam Texture The Foam Strength Small bubbles mixed at jet bit. Good foaming agent. Polymer for film strength. Harold Vance Department of Petroleum Engineering Liquid Volumes Begin with 1/10 of Conventional Mud Rate required to give a 120'/min (40m/min) annular velocity. EXAMPLE: In an 8.75" hole, 400 gpm is a normal mud rate. For foam start with 40gpm as an initial try. Harold Vance Department of Petroleum Engineering Liquid Volume This may have to be increased up to 5070% of normal mud volume to buffer the steering tool or EMMWD. Gas then likewise has to increase. Be careful of friction dominate phase. Harold Vance Department of Petroleum Engineering Rheological Models Harold Vance Department of Petroleum Engineering Bingham Plastic The fluid will not flow until a certain minimum shear stress is exceeded. Once that minimum stress has been exceeded, additional shear stress is directly proportional to the shear rate. Harold Vance Department of Petroleum Engineering Shear Stress and Shear Rate for a Bingham Plastic Fluid (Bourgoyne et al., 1986) = 0 = p + + p = p - - Shear Rate, Harold Vance Department of Petroleum Engineering Power Law A PowerLaw fluid with the application of any shear stress. Shear stress is a function of shear rate for a Power Law fluid, it is not a linear relationship. Harold Vance Department of Petroleum Engineering Shear Stress vs. Shear Rate for a PowerLaw Fluid (Bourgoyne et al., 1986) Shear Stress, t n<1 = .n Shear Rate, g = . . n-1 Harold Vance Department of Petroleum Engineering The Published Experts Don't Agree About Foam Fluid Behavior Bingham Plastic Power Law Mitchell Krug Beyer Okpobiri Ikoku Sanghani Harold Vance Department of Petroleum Engineering Actually Foam sometimes flows as a plug. And sometimes with a velocity profile across the hole cross section. Viscosity changes with pressure and temperature as well as chemical content. Harold Vance Department of Petroleum Engineering Foam Flow Foam sometimes flows as a plug. Harold Vance Department of Petroleum Engineering Foam Flow Foam sometimes flows high viscosity profile. Harold Vance Department of Petroleum Engineering Foam Testing It is difficult to measure the viscosity of a foam. Instead a halflife test is used. Harold Vance Department of Petroleum Engineering Foam Testing Half Life Procedure Waring Blender Stop Watch 1000ml Cylinder Harold Vance Department of Petroleum Engineering Half Life Procedure Foaming Agent 0.5% (0.5ml) Foam Testing 100ml water Waring Blender Stop Watch 1000ml Cylinder Harold Vance Department of Petroleum Engineering Half Life Procedure Mix on high for 30 sec Foam Testing Waring Blender Stop Watch 1000ml Cylinder Harold Vance Department of Petroleum Engineering Half Life Procedure Pour into cylinder and measure time for 50ml of water to appear Foam Testing Time is half life Foam Water Waring Blender Stop Watch 1000ml Cylinder Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Harold Vance Department of Petroleum Engineering Stable Foam Mixing System (Hutchison) This is not a very good method Meter Blender For Detergent Solution Meter Compressed Air or Gas 20 Gpm Positive Displacement Pump Detergent Additives Water Foam Generator Foam manifold Annulus Work string Blowdown Harold Vance Department of Petroleum Engineering Modern Foam Mixing System Chemical Metering Pump To Mud Pump Chemical Metering Pump Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Rotating Head Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Gas Fluid Mixing System Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Foam Mixing The real key to satisfactory operation is the use of precision injection pumps. Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Self Contained Foam Unit Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Weatherford Foam Unit Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Compressor Used in Foam Drilling Harold Vance Department of Petroleum Engineering Rotary Primary Compressor in a Unitized Package Foam Drilling Equipment Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Booster Compressor in a Unitized Package Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Baker model F bit float Harold Vance Department of Petroleum Engineering Foam Drilling Equipment Baker model GB string float maybe used every 500' Harold Vance Department of Petroleum Engineering Weatherford TransFoam Recyclable Foam Harold Vance Department of Petroleum Engineering Weatherford Transfoam It is an amphoteric material capable of reaction as either an acid or base. A combination of two (or more) foaming agents that cause foam at a high pH and interfere and cause the foam to go flat at a low pH. Harold Vance Department of Petroleum Engineering Transfoam Applications Environmental concern. Space limitations. Limited disposal options. Harold Vance Department of Petroleum Engineering Intentional destabilization. Transfoam Process Description Gas removal in separator. Liquid cleaning in shaker, cyclone and centrifuge. Add make up foamer. Reactivation. Decrease pH (10 to < 5) Foam immediately disappears. Increase pH Harold Vance Department of Petroleum Engineering Simplified Transfoam Foam/DeFoam/ReForm Cycle Acid Foam (100% Volume) + Activator Liquid less than 5% Foam Foam (100% Volume) Harold Vance Department of Petroleum Engineering Transfoam Recyclable Foam System Supplemental Defoamer Addition (if necessary) To Air Pit Separator Separator pH Signal to Control Acid Feed Blooie Line Acid Feed Cuttings P Shaker Solids Control Acid Storage Recirculation Line P pH Signal to Control Alkaline Feed pH Lime Hopper Lime Feed Recovered Solution Ready for Reuse Mud Pits Polymer Flocculant Addition if Necessary Harold Vance Department of Petroleum Engineering Considerations Limitless cycles. Makeup foamer required for loss to formations and solids. Water soluble, nontoxic additions. Harold Vance Department of Petroleum Engineering Advantages Cost Efficient Less Chemical Used Less Makeup Water Less Space Environmental Offshore Less Disposal Harold Vance Department of Petroleum Engineering Advantages Adaptable fluid. Any water base drilling mud can be used. Harold Vance Department of Petroleum Engineering Limitations Acid environment. Good separator required. Defoamer possibly required. Availability. Corrosion ? Personnel. Equipment. Harold Vance Department of Petroleum Engineering Canada Concord Unitfoam A conventional foam used with a defoamer. Foam is killed with defoamer, then rebuilt with foamer. Harold Vance Department of Petroleum Engineering END Harold Vance Department of Petroleum Engineering ...
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