Drilling Muds Training Presentation

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  • Bentonite: Its Origin Large volumes in western U.S. Formed during Cretaceous Period Formed by volcanic ash http://www.webcamcruise.com/USA%20Map_fichiers/usa_map.jpg
  • Bentonite Mining
  • Wyoming Sodium Bentonite High swelling clay Ability to adsorb large quantities of water Composed of many stacks of platelets like a stack of cards Expands up to 20 times its volume One inch3 covers 66 football fields One inch high contains between 35,000-40,000 layers (stresses good mixing)
  • Venturi Style Mixing Hopper Bentonite going into hopper @ 200 mesh (74 Microns) Bentonite platelets (1/2 Micron) mechanically separated by high velocity fluid from jet hopper Hopper Jet Venturi Pipe
  • Mixing System
  • Examples of Un-yielded Bentonite This image shows a poorly This image shows the un- mixed 40 Viscosity SUPER yielded bentonite on your GEL-X poured over the hand when dipping it into screen on a Marsh Funnel the mix tank
  • Make-Up Water Most important block of fluid system! Makes 95-99% of a drilling fluid! Bad Water = Bad Drilling Fluids
  • Do These Problems Sound Familiar? Bentonite does not mix like it should When we turn off the mixing equipment the bentonite settles and leaves water on the surface It takes a lot more bentonite to get the same viscosity The pump is making all kinds of noises when pumping the slurry Polymer gets all stringy when we mix it
  • Make-Up Water Is there a problem with the Bentonite? Probably not. Most likely the culprit is low pH ( 10-3 3 Acid Rain (2.5-5.5), Vinegar, Cola 10-4 4 Beer 10-5 5 Black Coffee, Tea OH-) 10-6 6 Normal Rain (5.6) Bentonite 10-7 Neutral 7 Pure Water, Saliva, Blood, Sweat (H+= Mixing 10-8 OH-) 8 Seawater (7.8-8.3) 10-9 9 Baking Soda Increasingly Basic (H+ < 10-10 10 Phosphate Detergents, Chorine Bleach 10-11 11 Household Ammonia Reference: Audesirk, 10-12 12 Washing Soda T., Audesirk, G., & Byers, B. 2003. Life On Earth. Third Edition. 10-13 13 Oven Cleaner OH-) Prentice Hall. Upper Saddle River 10-14 14 1-Molar Sodium Hydroxide (Na0H)
  • Functions of HYDRAUL-EZ Drilling Fluid Cool bit & lubricate the hole Clean the hole, suspend & transport cuttings Hold the hole open, stabilize the hole Control fluid-loss, loss circulation, and frac-outs Reduce torque associated with sticky soil Control sub-surface pressure
  • Characteristics of HYDRAUL-EZ Drilling Fluid Viscosity Gel Strength Fluid Loss Sand Content Density, Hydrostatic Head
  • Viscosity The resistance of a fluid to flow; the greater the resistance, the greater the viscosity or thickness Measured with a marsh funnel and cup Viscosity only tells us the thickness of a fluid Two fluids with the same viscosity can be vastly different in terms of its ability to clean the hole
  • Units for Bingham Plastic FluidsWe use the following units, typically, to describe therheological behavior of drilling fluids Plastic viscosity, PV (cp) Yield Point, YP (lb/100 ft2) Apparent Viscosity, AV (cp) Gel strengths (??)How can this possibly make any sense?
  • Marsh Funnel and Cup - Viscosity
  • Viscosity & Pump Performance Higher viscosity fluids will reduce the flowability of cuttings Higher viscosity fluids will drastically reduce pump performance Higher viscosity fluids will increase pumping and material costs
  • Viscosity & Pump PerformancePump curves are based on clear water at sea level andunder ideal conditions Example 40 gpm pump with clear water, 26 viscosity 40 viscosity 10-15% capacity = 34-36 gpm 60 viscosity 25-30% capacity = 28-30 gpm 80 viscosity 40-50% capacity = 20-24 gpm
  • Gel Strength Most important drilling fluid characteristic The ability of HYDRAUL-EZ to form gels and suspend cuttings in borehole If drill cuttings are not suspended, they will pack off borehole and cause pressure buildup, fracturing, and stuck pipe
  • Gel StrengthTwo methods to increase the gel strength of a drillingfluid 1. Add more HYDRAUL-EZ, which also increases viscosity (resistance to flow) 2. Add a gel strength enhancing polymer to HYDRAUL-EZ slurry HYDRAUL-EZ/polymer system - HYDRAUL-EZ with SUSPEND-IT is most desirable since it forms a high gel strength, pump-able slurry
  • Gel Strength If cuttings are flowing out of the hole, we know we 45 have an open hole 40 35 30 If the hole is open, we dont 25 get stuck 20 15 10 HYDRAUL-EZ offers 5 0 superior gel strength 1 0 MIN GEL S UPER GEL -X HYDR AUL -EZ
  • One Minute Gel Strength @ 60 Viscosity SUPER GEL-X HYDRAUL-EZ
  • Four Minute Gel Strength @ 60 Viscosity SUPER GEL-X HYDRAUL-EZ
  • Ten Minute Gel Strength @ 60 Viscosity SUPER GEL-X HYDRAUL-EZ
  • Gel Strength No viscosity increase with HDD designed drilling fluids Recommend SUSPEND-IT when coarse sands and gravel are anticipated
  • Fluid Loss Measure of amount of drilling fluid lost through a permeable formation Fluid loss can be measured with a filter press Bentonite platelets shingle off wall of the hole and form a filter cake when slurry is pumped under pressure This cuts off water to surrounding sand or gravel
  • Fluid LossTwo methods to tighten or reduce amount of fluidgoing into formation Add more HYDRAUL-EZ, which increases platelets but increases viscosity (resistance to flow) Add fluid loss polymer to HYDRAUL-EZ slurry HYDRAUL- EZ/polymer system HYDRAUL-EZ with SUPER PAC or REL PAC is most desirable since it forms a low solids pump-able slurry
  • Bentonite SuspensionHYDRAUL-EZ Drilling Fluid Seals Borehole Sidewall Hydrostatic Pressure Bentonite Particles Soil Bentonite Filter Cake Formed by Grains Clogging and Bridging
  • Fine to Medium Sand Water percolating Total saturation through sand
  • Fine to Medium Sand HYDRAUL-EZ and REL- Water or drilling fluid with PAC Drilling Fluid poor fluid loss MINIMAL Fluid Loss HIGH Fluid Loss
  • Controlling Fluid LossMinimal Fluid Loss = Borehole Stability
  • Fluid Loss SUPER PAC and REL-PAC enhance the performance of HYDRAUL-EZ A thick filter cake does not translate to a reduction in fluid loss
  • Modified Natural PolymerUsed in Coarse Non-Reactive Soils Manufactured in liquid and powdered form, cellulose polymers are used primarily to control fluid loss and stabilize difficult holes REL-PAC and SUPER PAC Dry and liquid cellulose polymers which are added to HYDRAUL-EZ systems to create superior borehole stability
  • Holding the Hole OpenMaintaining a stable hole while drilling through soil,sand, gravel or other non-consolidated formationsPositive pressure of drilling fluid (filter cake,circulating pressure, hydrostatic pressure) Similar to coffee grounds in a vacuum sealed canKeys Filter cake Particle bridging character of the polymers in CETCOs formulations
  • Density/Hydrostatic Pressure of Boring Fluids
  • Borehole Stability Major function of HYDRAUL-EZ fluid is to keep the hole open Hole is held open by hydrostatic pressure from a HYDRAUL-EZ fluid pressing against a lower formation pressure across a filter cake The pressure difference need not be great, but must always be positive
  • What Is Loss Circulation? Loss circulation refers to the total or partial seepage of drilling fluid into the formation through crevices or porous media Not to be confused with frac-outs which refer to fluid breaking through the surface
  • Coarse Unconsolidated Formations Sand Gravel Partial and or gradual loss of return flow may be experienced in coarse soil conditions. Utilize a drilling fluid with good fluid- loss control such as a HYDRAUL-EZ/PAC polymer fluid (soda ash is also important to get maximum yield out of HYDRAUL- EZ) Reduce the mud weight as much as possible by good solids control practices and checking mud properties frequently
  • Driller-Created Loss Circulation Problems High solids/high density drilling fluids increase hydrostatic pressure on formations Example: Mud Weight X 0.052 X Depth = Hydrostatic Pressure 9.0 pound mud @ 200 depth: 9.0 X 0.052 = 0.468 X 200 = 93.6 PSI of Hydrostatic Pressure on the Formation 14 pound mud @ 200 depth: 14 X 0.052 = 0.728 X 200 = 14