SQUEEZE CEMENTING DEFINITION Squeeze Cementing is the process of applying hydraulic pressure to force or squeeze a cement slurry into the desired perforations, fractures, channels, or voids and force filtrate water from the slurry to create a solid mass which will harden to provide the desired seal. Squeeze Cementing is as much an Art as it is a Science. Area Experience is essential. PROBLEM DETERMINATION • Why Are We Squeezing? • Shut off unwanted water or gas production • Abandonment of non-productive zone • Seal off troublesome zone during drilling • Injection profile modification in injection wells PROBLEM DETERMINATION • Why Are We Squeezing? • Shut off unwanted water or gas production • Abandonment of nonproductive zone • Seal off troublesome zone during drilling • Injection profile modification in injection wells PROBLEM DETERMINATION Why Are We Squeezing? • Repair mud or gas channeling on primary cement job • Isolate a formation prior to perforating • Insufficient top of cement on primary job • Repair casing leak PROBLEM DETERMINATION • Do We Need To Squeeze Now Or Wait? • Cost considerations • Equipment • Time delays for after-the fact squeezes • Well construction plans PROBLEM DETERMINATION • What Criteria Should We Use For Determining The Need For A Squeeze Job? • Sonic evaluation logs • Primary cement job design • Primary cement job performance • Flow rate • Centralization • Mud properties • Experience • Offset well data PROBLEM DETERMINATION • Will A Squeeze Job Do What We Want It To? • Most voids and channels will be fluid-filled. • Mud channels must be displaced for squeeze to work. • Most channels cannot receive cement slurry under squeeze pressure. • High pressure squeeze increases formation stress around the wellbore. MYTHS IN SQUEEZE CEMENTING MYTH - CEMENT SLURRY ENTERS THE FORMATION MATRIX • Cement average particle size 20-50 microns • > 2000 md formation permeability required Berea Sandstone - 350 md Fact - Cement particles are too large to enter the matrix of most formations except in cases of extremely high permeability or fractures. Fact - Filtrate enters MYTH - SQUEEZING PRODUCES A HORIZONTAL PANCAKE OF CEMENT Fact • Fracture orientation normally vertical rather than horizontal • Fracture may be at an angle to the wellbore in deviated wells MYTH - SQUEEZING PRODUCES A HORIZONTAL PANCAKE OF CEMENT Fact • Fracture orientation normally vertical rather than horizontal • Fracture may be at an angle to the wellbore in deviated wells Wrong Right TRI-AXIAL LOADING OF ROCKS • Fracture orientation is perpendicular to least principle stress • Least principle stress is normally horizontal • Therefore most induced fractures are vertical TRI-AXIAL LOADING OF ROCKS • Fracture orientation is perpendicular to least principle stress • Least principle stress is normally horizontal • Therefore most induced fractures are vertical MYTH - ALL PERFORATIONS ARE OPEN DURING INJECTION Fact • Perforations may be partially plugged • Injection pressure of perforations varies • Cement will take path of least resistance • Solids laden injection fluid should be avoided MYTH - HIGH FINAL SQUEEZE PRESSURE IS NECESSARY Fact • Final Squeeze Pressure Does Not Need To Equal Future Working Pressure. • Squeeze Pressure Is Applied Across Node Before Cement Develops Compressive Strength • Fractures May Be Created • Productivity May Be Damaged • High Pressure Does Not Ensure Placement In Desired Location SQUEEZE TECHNIQUES SQUEEZE TECHNIQUES • Pressure To Squeeze • High Pressure Squeeze • Low Pressure Squeeze • Pumping Technique • Hesitation Squeeze • Running or Walking Squeeze • Placement Technique • Squeeze Packer • Bradenhead (Including Coiled Tubing) HIGH PRESSURE SQUEEZE Surface Pressure + Displacement Fluid Hydrostatic + Cement Slurry Hydrostatic = Total Bottom Hole Pressure Greater Than Formation Fracture Pressure HIGH PRESSURE SQUEEZE Surface Pressure + Displacement Fluid Hydrostatic + Cement Slurry Hydrostatic = Total Bottom Hole Pressure Greater Than Formation Fracture Pressure HIGH PRESSURE SQUEEZE LOW PRESSURE SQUEEZE Surface Pressure + Displacement Fluid Hydrostatic + Cement Slurry Hydrostatic (Low Fluid Loss Cement) = Total Bottom Hole Pressure Less Than Formation Fracture Pressure LOW PRESSURE SQUEEZE SQUEEZE TECHNIQUES • Pressure To Squeeze • High Pressure Squeeze • Low Pressure Squeeze • Pumping Technique • Hesitation Squeeze • Running or Walking Squeeze • Placement Technique • Squeeze Packer • Bradenhead (Including Coiled Tubing) “HESITATION” SQUEEZE “RUNNING/WALKING” SQUEEZE SQUEEZE TECHNIQUES • Pressure To Squeeze • High Pressure Squeeze • Low Pressure Squeeze • Pumping Technique • Hesitation Squeeze • Running or Walking Squeeze • Placement Technique • Squeeze Packer • Bradenhead (Including Coiled Tubing) SQUEEZE TOOL METHOD • Retrievable Or Drillable Squeeze Packer Set Above Injection Point • Isolates Casing Above Packer From Squeeze Pressure • Higher Squeeze Pressures Possible • Annulus Pressure Applied To Help Prevent Casing Collapse BRADENHEAD METHOD • Spot Cement Across Squeeze Interval • Pull Workstring Above Cement Top • Close BOP/Bradenhead & Reverse Tubing Clean • Apply Squeeze Pressure Disadvantages • Casing Exposed To Squeeze Pressure • Limited Squeeze Pressure Advantages • Cost Reduction • Wash Cement Out Of Casing COILED TUBING METHOD • Form Of Bradenhead Method + PSI CHOKE • Inside Production Tubing • Higher Pressure Possible • Improved Control Of Slurry Placement CEMENT SQUEEZE SLURRY DESIGN FACTORS INFLUENCING THE SETTING OF CEMENT • Temperature • Pressure • Additives • Contamination With Mud/Well Fluid • Dilution With Mud/Well Fluid FACTORS INFLUENCING THE SETTING OF CEMENT (CONT.) • Mixing Water • Inorganic Materials (chlorides, sulfates, etc.) • Fertilizers • Decomposed Plant Life • Soil Chemicals • Waste Effluents SLURRY DESIGN CRITERIA • Thickening Time • Slurry Stability • Test Schedule • Free Water • Fluid Loss • Settling • Rheology • Gel Strength • Compatibility • Formation • Wellbore Fluids FLUID LOSS CONTROL VS FILTER CAKE DEVELOPMENT 1000 cc - Neat Cement Slurry 300 cc Fluid Loss Slurry 75 cc Fluid loss Slurry 25 cc Fluid Loss Slurry FILTER CAKE PRIMARY CEMENT CEMENT NODE DEVELOPMENT PERFORATION TUNNEL PERMEABLE ROCK MATRIX FLUID LOSS vs. FILTERCAKE API Fluid Loss Permeability of Filter Time to form at 1000 psi Cake at 1000 psi 2” Filter Cake (cc/30 min) (md) (min) 1200 5.0 0.2 300 0.54 3.4 100 0.09 30.0 50 0.009 100.0 EFFECT OF HESITATION ON THICKENING TIME GEL STRENGTH DEVELOPMENT • High Pump Pressures • False Indication Of Squeeze • Difficult Reversing Out • High Pump Pressures • Formation Breakdown • Pump Hole Through Slurry During Hesitation Squeeze TOOL SELECTION SQUEEZE PACKERS • Drillable • Cast Iron • Composite • Retrievable LOCATION OF SQUEEZE PACKERS TOOL LOCATION • Set In Cemented Casing When Possible • Close to Interval To Minimize Cement Drillout • Adequate Distance From Perfs For Staging Volume • Displace Tubing Volume Before Staging • Safe Distance From Perfs To Prevent Casing Collapse (Next slide will illustrate this) MECHANISM OF SQUEEZE JOB CASING COLLAPSE JOB EXECUTION JOB EXECUTION • Well Preparation • Well Fluid Circulated And Balanced • Perforations Open • Pressure Test Surface Treating Lines, Workstring, And Tools To Maximum Expected Pressure • Use Clean Workover Fluids For Injection • Solids in workover fluid may clog perforations • Illustrated on next slide. • Avoid/Minimize Fracturing • Control Squeeze Pressures • Use Low Fluid Loss cement slurries PLUGGED PERFORATIONS PERFORATION WASHING COILED TUBING CONTAMINATION SQUEEZE LOGISTICAL / TECHNICAL & FINANCIAL ADVANTAGES • No Rig Required • Work Through Existing Wellhead & Production Equipment • Efficient Well Kill Operation • Continuous Pipe • Mobile Injection Point CEMENT SYSTEMS • Conventional • Co-Polymer Fluid Loss Control • Reduced Node Acid Solubility Rate • LATEX System • Filter Cake Development • Enhanced Bonding & Ductility • Lowest Acid Solubility Rate SPECIALIZED CEMENT SYSTEMS • Thixotropic Cement • Foam Cement • Microfine Cement • Chemical Treatments • Temperature-dependent, Internally catalyzed • Externally catalyzed • Combinations SLURRY / FLUID SPECIFICATIONS • Filter Cake / Fluid Loss • Slurry Stability • Thickening Time • Slurry Composition • Acid Solubility Rate FLUID LOSS CONTROL VS FILTER CAKE DEVELOPMENT 1000 cc - Neat Cement Slurry 300 cc Fluid Loss Slurry 75 cc Fluid loss Slurry 25 cc Fluid Loss Slurry FILTER CAKE PRIMARY CEMENT CEMENT NODE DEVELOPMENT PERFORATION TUNNEL PERMEABLE ROCK MATRIX TYPICAL JOB PROCEDURE • Fluid Packing the Wellbore • Laying in Spacer • Laying in Cement-Initial Squeeze • Laying in Remaining Cement • Build Final Squeeze Pressure • Contamination & Clean-Out • Spotting Accelerator Fluid LAYING IN CEMENT VISCOSIFIED WASH FLUID (BIOZAN) + PSI CHOKE 5 BBL WATER SPACER CEMENT SQUEEZING / HESITATE VISCOSIFIED WASH FLUID (BIOZAN) INCREASE PRESSURE + PSI INCREMENTALLY CHOKE 5 BBL WATER CEMENT FINAL SQUEEZE PRESSURE VISCOSIFIED WASH FLUID (BIOZAN) SQUEEZE PRESSURE +PSI CHOKE 5 BBL WATER SAFETY = TOC + 100' TOC CEMENT CLEAN-OUT SLICK WATER 500-700 PSI + PSI VISCOSIFIED WASH FLUID CHOKE (BIOZAN) CONTAMINATED CEMENT Combination Nozzle Taper to flat at check valve OD Cross Section A-A +3/8” Thick Upper Section Side holes are tangential to Internal Radius Total of 6 holes All holes are 1/8 inch Internal Radius is undercut as shown Lower Section Total of 9 holes All holes are 5/16 inch 8 Side Holes alternate 30 up-down on Internal Radius Centerline 3” OD Cross Section C-C A 3/4” Ball A 0.7” Hole C C D D Ref: Walker, Gnatt, and Crow, Wolrd Oil, June, 1992 Cross Section D-D ACCELERATOR IN PLACE SLICK WATER + PSI 500-700 PSI CHOKE TEA SQUEEZE APPLICATIONS BLOCK SQUEEZE • Performed To Isolate Zone • Perforate & Squeeze Below Zone • Perforate & Squeeze Above Zone • Drill Out & Test • Difficult To Remove Trapped Fluid/Mud • Avoid Fracturing CIRCULATING SQUEEZE • “Suicide Squeeze” • Drillable Tool Set Between Perforations • Circulation Path Back Into Casing Above • Improved Channel Cleaning • Probability Of Sticking • Casing Collapse Possible • Not A Recommended Practice ABANDONMENT SQUEEZE • Retainer Set High To Meet Regulatory Plugging Requirements • Perform Low Pressure Squeeze Through Retainer • Sting Out & Dump Cement On Top Of Retainer CHANNELS • Channel Must Be Void Of Mud • Allow Production To Clean Channel If Possible • Clean Channel With Acid Or Chemical Washes • Perform Low Pressure Squeeze • Inject Into Production Perfs Or Adjacent To Problem Zone UNWANTED PRODUCTION • Water Coning From Below • Gas Cap Production Due To Depletion • Channels • Vertical Fractures • Natural • Created • High Vertical Permeability Initial Current CORROSION HOLES • Often Occur Above Cement Top • May Require Multiple Stages • Caution With Tools Due To Weak Or Enlarged Casing • New Holes Often Created During Squeeze • Use Low Pressure Squeeze CASING SPLIT • Often Occur Above Cement Top • May Require Multiple Stages • Caution With Tools Due To Restrictions Or Enlarged Casing • Split Length May Increase During Squeeze • Use Low Pressure Squeeze LINER TOP • Poor Mud Displacement During Primary Cement Job • Gas Migration Channel • No Cement Returns To Liner Top • Solids Bridging • Losses Due To High ECD • Planned “Tack & Squeeze” • Microannular Flow • Reduced Fluid Density • Difficult To Inject Fluids Into Leak RECEMENTING • Raise The Top Of Cement • Displacement Plug Method • Packer Method (Drillable) • Circulate To Surface To Condition/Clean Annulus • Use Large Volumes Of Flush/Spacer • Mod/Low Fluid Loss Cement • Casing Collapse Possible With Packer Method Displacement Plug Packer FRACTURED OR VUGULAR ZONES • Multiple Stages Likely Tail • Lead Or First Stage • Lost Circulation Material • High Fluid Loss Cement • Thixotropic Cement • Foam Cement Lead • Quick Setting Cement • Reactant Preflushes • Second Stage • Low Fluid Loss Cement LOSS CIRCULATION ZONE • Multiple Stages Likely • Lead Or First Stage • Lost Circulation Material • High Fluid Loss Cement • Thixotropic Cement • Foam Cement • Quick Setting Cement • Sodium Silicate Preflushes • Second Stage Low Fluid Loss • Reactive Systems - FlexPlug, Gunk, DOC, BDO CASING SHOE SQUEEZE • Formation In Shoe Area Unable To Support Hydrostatic During Continued Drilling • High Pressure Squeeze May Be Considered To Fill Fracture Plane With Cement • Moderate To High Fluid Loss Cement • Reactive Preflush • Channel To Nearby Weak Formation Above Shoe • Clean Channel With Clean Fluids • Perform Low Pressure Squeeze To Prevent Creating Fracture And Increasing Problem LONG PERFORATED INTERVAL • Difficult To Inject Into All Perforations At Once • Acid Washing Optional • As Perforations Are Squeezed Others Will Take Fluid • Often Requires Multiple Stages • Perform Low Pressure Squeeze • Low Fluid Loss Cement With Extended Thickening Times and Low Gel Strength Development • Patience • Ball Sealers Optional • Spot Cement Across Entire Interval With Coiled Tubing Or Tailpipe COLLAR LEAKS • Often Extremely Low Injection Rate • Internally Catalyzed Chemical Treatments • Microfine Cements • Neat EPSEAL • Perforate To Increase Injection Rate PROFILE MODIFICATION • Injection Wells Taking Fluid Into Small Portion Of Perforated Interval • Poor Flood Sweep Efficiency • Water Breakthrough Into Producer • Often Low Frac Gradient Due To Depletion • Internally Catalyzed Chemical Treatment