كورس عن سائل الحفر والبمبات ومعدات فصل الشوائب-Drilling Fluid,Mud Pumps and conditioning Equipment| Arabian Drilling Company
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Three systems of rotary drilling operation:
Rotating system
Hoisting system
Circulating system
Circulating system includes the following.
Drilling mud
Pumping and Conditioning Equipment
Drilling Fluid
Mitigate severe drill string corrosion
Preventing entrainment of gas
Drilling troublesome shales
Any mud with water content more than 30% does not burn.
Costs less than oil base mud.
Disadvantage of oil emulsion mud
High water loss
-The problem of contamination from ground water
-Its flammability
-Safety and health concerns for the crew (slipperiness and dirtiness are objectionable and can cause accidents)
-Equipment used to move a liquid drilling fluid of Circulating System is as below.
-Mud Tanks i.e. Active tank, Reserve tank, Slug pit, Trip tank etc.
-With enough mud storage capacity for cleaning, conditioning and mixing of mud.
-Act as reservoir for cooling off return mud.
-Two or three mud pumps
-Large GPM required for top holes and high pressure for greater depths.
-One pump as stand by.
-Single acting pump > 3 pistons moving inside liners in one direction.
-Double Acting Pump > 2 pistons moving inside two liners in both direction.
-Electric Motor
-Chain and sprockets or Belts and Pulleys
-Pinion Shaft or Jack shaft
-Bull Gear
-Bull Gear or Herringbone gear
-Crank Shaft
-Connecting Rod
-Cross Head
-Pony Rods,
-Main Bearing, Eccentric Bearings, Jack shaft Bearings
-Built in System > Crank shafts picks up the oil from sump and sprays
-External lube oil pump
-Major Parts
-Module, Liner, Piston, Piston rubber (Natural Rubber or oil resistant synthetic rubber), Piston Rod, Seat, Valve
-Liner Packing > weep hole
-Volumetric Efficiency
-Ratio of theoretical volume and Actual Volume
-Duplex Pump efficiency no more than 90%.
-Triplex closer to 100 %. 97% is most common.
-What causes Drop in Efficiency
-Mud cut with air and gas is the most frequent cause of reduction in efficiency.
-Poor Suction
-Leakage of mud between piston and liner
-Leakage in valve and seat
-Leakage in Liner and fluid end body
Pressure rating of different size of liners is the limit to max. operating pressure of the system.
-Flooded suction means suction full of mud without air
-If suction is not full, air will enter which reduces efficiency.
-Supercharging ( centrifugal pump) pump ensures flooded suction
It is due to the insufficient suction head (Incoming mud can not keep up with the piston speed).
-Suction valve strike harder on seat causing premature failure of valve seals.
-Piston rod carries the shock to power end causing added stress.
-Pulsation Dampener
-Suction Dampener
-Discharge line Dampener
Discharge line > should be short, preferably without bends, rigidly anchored.
Slope in discharge line
Lubricating and Cooling
-The piston rubber can burn and damage liner in 30 minutes if not cooled.
-Cooling spray should completely flush the entire stroke area.
-Check angle and direction of cooling water nozzles
-Inspect your fluid end parts when pump not in use.
-Check suction strainer when pump not in use
Two or three shale shakers on a rig
10 to 20 bbls capacity
-De-sander
-De-slitter
-Mud cleaner
-Mud Gas Separators
-Mud Agitators
-Shale Shaker
Mud flow on the screen is controlled by changing angle of screen either uphill or down hill.
To determine right size of screen, the mud should travel down one-half to two third of the length of screen before completely passing through it.
The greater the screen mesh size, smaller the particle size
20 mesh screen > 765 micron
100 mesh screen > 149 micron
Shale Shakers (cont’d)
Salts dissolved in mud can cause screen plugging. The dissolved salts coat the screen wires as the water evaporates and leave the coats on the screen mesh wall. When salt is hardened, it causes plugging. So regular screen washing is required.
Pyramid screens have 40% more surface area than a flat screen which almost double the screen flow capacity.
Shale Shakers (cont’d)
Shale shaker can remove particle above 74 micron.
Solid Control Equipment
-Desander removes solids ranging 74 to 40 micron.
-Dessilter removes solids ranging 40 to 20 micron.
-Mud Cleaner removes solids ranging 20 to 7 micron.
-Centrifuge removes solids ranging 7 to 4 micron.
-Desander
-More useful while drilling top holes as it removes large solid build up in the mud.
-Usually has 1 to 3 cones.
-Cone diameter is 6 to 12 inches.
-It is installed down stream shale shaker
-Removes solids 10 to 20 micron
-Desilting the drilling mud can drastically reduce
-mud pump wear,
-hole problem,
-bits wear,
-time required to drill the hole,
-amount of water required for mud treatment.
-Operating pressure of Desander and desilter
-Desander operates at 25 to 35 psi
-Desilter operates at 30 to 45 psi
-Never use centrifugal pump that is used for desander or desilter for any other purpose.
-Maintenance of hydro cyclone
-Most common problem are cones wear due to excessive pump pressure
-Plugging due to large cuttings which come from shale shaker torn screen.
-Inspect centrifugal pump for proper discharge and operating pressure.
-Regular inspection and cleaning of cones helps avoid plugging problem.
The underflow of hydro cyclone goes to fine mesh screen. The drilled solid larger than screen size go to waste pit.
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Drilling Fluid
Drilling Fluid:
Drilling fluid has mainly two types.
mostly called drilling mud
water base mud 95% in drilling operation, cheap as compare to oil base.
Oil base mud harder to dispose off, effects on environment
Used in special conditions.
Its disadvantages limit its use.
-Cleans the bottom of hole
-Regrinding the chips already broken off from formation is wasted effort.
-High velocity stream creates turbulence and removes cuttings off bottom.
-Transport cuttings to surface
-Annular Velocity
-The annular velocity contributes major factor in transporting cuttings from bottom to surface.
-Liquid mud requires annular velocity 100 to 200 ft per hr.
-Gas or air fluid requires annular velocity 3000 ft per hr.
-Cools the bit and lubricates the drill stem
-Supports the walls of the well bore
-Prevents entry of formation fluid into well bore which can cause kick or if not controlled, leads to blow out
-Transmits hydraulic power to down hole motors
-Reveals the presence of oil, gas or water from the formation being drilled
-Reveals information about the formation, through the cuttings
-Density
-Viscosity
-Gel strength
-Filtration.
-Ph
-Too heavy column of mud can fracture the formation and lead to lost circulation.
-Excessive mud weight can slow down ROP.
-Barite, BaSo4, is the most common weighting material with SG 4.2 TO 4.35.
-Barite does not hydrate or react with water.
-Other weighting material are calcium carbonate, sodium chloride and some other inorganic salts.
Device used to measure mud density is mud balance
-Bentonite - Naturally occurring clay, used in fresh water
-Attapulgite is used when make up water is salty.
-Polymer - a chemical that consists of large molecules in repeating structure
-Carboxymethylcellulose (CMC) and Starch
-Polymers dissolve in water and increase viscosity without added solids.
-Polymers form more powerful collides and gel than Bentonite.
-Polymers affect other mud properties of mud than viscosity and are so more useful.
-Viscosity is decreased by adding water or chemicals. Water decreases the density where as chemicals do not.
-Chemical used to reduce viscosity and gel strength are called dispersants which are Lignite's, polyphosphates and lignosulphates used in water base mud.
-Lignite's and Lignosulphates also reduce the fluid loss and the thickness of the filter cake.
-Disadvantages if viscosity is too high
-Requires high pump pressure, wear & tear of mud pump
-Swabbing which can cause a kick
-Surge pressure, fracture formation, cause lost circulation
-Measuring Viscosity by Marsh Funnel
-Funnel v1 quart or 1 Liter of clean fresh water at a temperature of 21 deg. Cent. flows out of funnel in 26 seconds.
-iscosity is based on how long it takes 1 qt or liter of mud to flow through the funnel.
Plastic Viscosity (Pv), Yield Point (Yp) and Gel strength
Pv = 600 rpm reading-300 rpm reading
Units in centipoises
Yp = 300 rpm reading – plastic viscosity
Units in lbs per 100 sq-ft
High gel strength may require high pump pressure to break circulation and can cause formation break down.
Bentonite increases gel strength as well as viscosity.
The 1st, 30 second test shows how quickly the mud gels. The sample remains undisturbed for 30 seconds and reading is taken at 3 rpm of direct indicating viscometer which gives initial gel strength, in lb/100 sq-ft.
The 2nd 10 minutes test shows how strongly it gels. The sample remains undisturbed for 10 minutes and reading is taken at 3 rpm of direct indicating viscometer which gives 10 minute gel strength in lb/100 sq-ft.
In case of shale, no cake forms. Water in the mud contacts the shale surface where there is just enough permeability which causes the shale to swell and slough.
Disadvantages
The cake thickness is proportional to fluid loss which reduces the hole dia. and can lead to pipe sticking.
High fluid loss may cause sloughing and caving of shale formations
High fluid loss in porous formation can also hinder the interpretation of electric logs.
Distilled water is neither acid nor alkaline which has Ph of 7.
Ph scale is from 0 to 14.
Mud must be alkaline with a Ph of 8 to 13 to allow the chemicals in the mud to work well and minimize corrosion.
Most commonly used chemical to increase Ph is Caustic Soda (Sodium Hydro oxide), Na OH.
-Flocculants cause drilled solid to stick together
-Corrosion Control Agents reduce corrosion to the metal parts that salts in the mud can cause.
-De-foamers breaks up the foams when formation gas contaminates the mud.
-Anti differential sticking additives help free sticking pipe
-Emulsifier improve lubricating properties, lower fluid loss and help prevent the bit from balling.
-Oil base Mud > oil, emulsifier, stabilizing agent, salt and water less than 5%
-Oil emulsion mud > water base mud with some oil added.
-Invert - emulsion mud or invert oil mud > oil base mud with some water added (10 to 60 %).
-Synthetic Mud > vegetable and mineral oil, less environmentally hazardous
Oil mud is used for following reasons.
Protecting producing formations
Drilling water-soluble formations
Drilling deep, high temperature holes
Preventing differential pressure sticking
Liquid
may be water, oil or mixture of water and oil with additives.mostly called drilling mud
water base mud 95% in drilling operation, cheap as compare to oil base.
Oil base mud harder to dispose off, effects on environment
Gas
May be dry air or gas, or may be air or gas mixed with water and foaming agent to form mist or foam.Used in special conditions.
Its disadvantages limit its use.
Functions of the Circulating System
Circulating a fluid while drilling:-Cleans the bottom of hole
-Regrinding the chips already broken off from formation is wasted effort.
-High velocity stream creates turbulence and removes cuttings off bottom.
-Transport cuttings to surface
-Annular Velocity
-The annular velocity contributes major factor in transporting cuttings from bottom to surface.
-Liquid mud requires annular velocity 100 to 200 ft per hr.
-Gas or air fluid requires annular velocity 3000 ft per hr.
-Cools the bit and lubricates the drill stem
-Supports the walls of the well bore
-Prevents entry of formation fluid into well bore which can cause kick or if not controlled, leads to blow out
-Transmits hydraulic power to down hole motors
-Reveals the presence of oil, gas or water from the formation being drilled
-Reveals information about the formation, through the cuttings
Properties of Drilling Mud
Properties of Drilling mud are its-Density
-Viscosity
-Gel strength
-Filtration.
-Ph
Density
-The density or weight of the mud and its height determines the hydrostatic pressure of mud column to prevent the kick.-Too heavy column of mud can fracture the formation and lead to lost circulation.
-Excessive mud weight can slow down ROP.
-Barite, BaSo4, is the most common weighting material with SG 4.2 TO 4.35.
-Barite does not hydrate or react with water.
-Other weighting material are calcium carbonate, sodium chloride and some other inorganic salts.
Mud Weight
Density is expressed in weight per unit volume i.e Kg/m3, PPG, SG, PCF, PSI/FTDevice used to measure mud density is mud balance
Viscosity
-Viscosity is resistance to flow which is developed with following materials.-Bentonite - Naturally occurring clay, used in fresh water
-Attapulgite is used when make up water is salty.
-Polymer - a chemical that consists of large molecules in repeating structure
-Carboxymethylcellulose (CMC) and Starch
-Polymers dissolve in water and increase viscosity without added solids.
-Polymers form more powerful collides and gel than Bentonite.
-Polymers affect other mud properties of mud than viscosity and are so more useful.
-Viscosity is decreased by adding water or chemicals. Water decreases the density where as chemicals do not.
-Chemical used to reduce viscosity and gel strength are called dispersants which are Lignite's, polyphosphates and lignosulphates used in water base mud.
-Lignite's and Lignosulphates also reduce the fluid loss and the thickness of the filter cake.
-Disadvantages if viscosity is too high
-Requires high pump pressure, wear & tear of mud pump
-Swabbing which can cause a kick
-Surge pressure, fracture formation, cause lost circulation
-Measuring Viscosity by Marsh Funnel
-Funnel v1 quart or 1 Liter of clean fresh water at a temperature of 21 deg. Cent. flows out of funnel in 26 seconds.
-iscosity is based on how long it takes 1 qt or liter of mud to flow through the funnel.
Plastic Viscosity (Pv), Yield Point (Yp) and Gel strength
Plastic Viscosity (Pv)
Plastic viscosity is a fluid’s resistance to flow. It is measured by direct indicating viscometer and its units are centipoises.Pv = 600 rpm reading-300 rpm reading
Units in centipoises
Yield Point (Yp)
It is the measure of forces required to start the mud to flow. It is measured by direct indicating viscometerYp = 300 rpm reading – plastic viscosity
Units in lbs per 100 sq-ft
Gel Strength
It is the measure of mud ability that holds cuttings in place when circulation is stopped and prevents cutting from falling back to bottom.High gel strength may require high pump pressure to break circulation and can cause formation break down.
Bentonite increases gel strength as well as viscosity.
Testing Gel Strength
Requires two testsThe 1st, 30 second test shows how quickly the mud gels. The sample remains undisturbed for 30 seconds and reading is taken at 3 rpm of direct indicating viscometer which gives initial gel strength, in lb/100 sq-ft.
The 2nd 10 minutes test shows how strongly it gels. The sample remains undisturbed for 10 minutes and reading is taken at 3 rpm of direct indicating viscometer which gives 10 minute gel strength in lb/100 sq-ft.
Filtration:
Filtration takes place when the mud hydrostatic forces the liquid part (water or oil) of drilling mud into the permeable formation.In case of shale, no cake forms. Water in the mud contacts the shale surface where there is just enough permeability which causes the shale to swell and slough.
Fluid loss
Liquid part (water or oil) of the mud that flows into the formation is called fluid loss.Disadvantages
The cake thickness is proportional to fluid loss which reduces the hole dia. and can lead to pipe sticking.
High fluid loss may cause sloughing and caving of shale formations
High fluid loss in porous formation can also hinder the interpretation of electric logs.
Prevention of Fluid loss
Water sensitive formations cause sloughing and caving which increases hole size and viscosity and damage the producing zone. Calcium Hydro oxide Ca (OH)2, Gypsum Ca SO4, Calcium Chloride CaCL2 are used to inhibit the mud.Ph
The Ph of a fluid is its relative acidity or alkalinity.Distilled water is neither acid nor alkaline which has Ph of 7.
Ph scale is from 0 to 14.
Mud must be alkaline with a Ph of 8 to 13 to allow the chemicals in the mud to work well and minimize corrosion.
Most commonly used chemical to increase Ph is Caustic Soda (Sodium Hydro oxide), Na OH.
Other Additives
-To improve the mud properties , other additives are as follows.-Flocculants cause drilled solid to stick together
-Corrosion Control Agents reduce corrosion to the metal parts that salts in the mud can cause.
-De-foamers breaks up the foams when formation gas contaminates the mud.
-Anti differential sticking additives help free sticking pipe
-Emulsifier improve lubricating properties, lower fluid loss and help prevent the bit from balling.
Oil base Mud
-Liquid phase is oil, diesel or synthetic oil.-Oil base Mud > oil, emulsifier, stabilizing agent, salt and water less than 5%
-Oil emulsion mud > water base mud with some oil added.
-Invert - emulsion mud or invert oil mud > oil base mud with some water added (10 to 60 %).
-Synthetic Mud > vegetable and mineral oil, less environmentally hazardous
Oil mud is used for following reasons.
Protecting producing formations
Drilling water-soluble formations
Drilling deep, high temperature holes
Preventing differential pressure sticking
Coring
Minimizing gelation and corrosion problems (when used as a packer fluid).Mitigate severe drill string corrosion
Preventing entrainment of gas
Drilling troublesome shales
Oil Emulsion Mud
Advantage of oil emulsion mudAny mud with water content more than 30% does not burn.
Costs less than oil base mud.
Disadvantage of oil emulsion mud
High water loss
Disadvantages of oil base mud
-It is expensive-The problem of contamination from ground water
-Its flammability
-Safety and health concerns for the crew (slipperiness and dirtiness are objectionable and can cause accidents)
-Equipment used to move a liquid drilling fluid of Circulating System is as below.
-Mud Tanks i.e. Active tank, Reserve tank, Slug pit, Trip tank etc.
-With enough mud storage capacity for cleaning, conditioning and mixing of mud.
-Act as reservoir for cooling off return mud.
Mud Pumps
-Heart of circulating system-Two or three mud pumps
-Large GPM required for top holes and high pressure for greater depths.
-One pump as stand by.
Reciprocating Pump
-Reciprocating pump is a positive displacement pump.-Single acting pump > 3 pistons moving inside liners in one direction.
-Double Acting Pump > 2 pistons moving inside two liners in both direction.
Triplex Mud Pump
-Major Components of Power end-Electric Motor
-Chain and sprockets or Belts and Pulleys
-Pinion Shaft or Jack shaft
-Bull Gear
-Bull Gear or Herringbone gear
-Crank Shaft
-Connecting Rod
-Cross Head
-Pony Rods,
-Main Bearing, Eccentric Bearings, Jack shaft Bearings
Lubricating System
-Bearings and cross heads requires lubrication.-Built in System > Crank shafts picks up the oil from sump and sprays
-External lube oil pump
Fluid End
-Suction and discharge sections-Major Parts
-Module, Liner, Piston, Piston rubber (Natural Rubber or oil resistant synthetic rubber), Piston Rod, Seat, Valve
-Liner Packing > weep hole
-Volumetric Efficiency
-Ratio of theoretical volume and Actual Volume
-Duplex Pump efficiency no more than 90%.
-Triplex closer to 100 %. 97% is most common.
-What causes Drop in Efficiency
-Mud cut with air and gas is the most frequent cause of reduction in efficiency.
-Poor Suction
-Leakage of mud between piston and liner
-Leakage in valve and seat
-Leakage in Liner and fluid end body
Controlling Pump Output
Pump speed and pressures are varied by changing the input power or changing the horse power.Pressure rating of different size of liners is the limit to max. operating pressure of the system.
Suction
-For 100% volumetric efficiency, flooded suction is required-Flooded suction means suction full of mud without air
-If suction is not full, air will enter which reduces efficiency.
-Supercharging ( centrifugal pump) pump ensures flooded suction
Fluid knocking
Fluid Knocking also called hydraulic hammer or water hammerIt is due to the insufficient suction head (Incoming mud can not keep up with the piston speed).
Effect of fluid knocking
-Metal fatigue in the pump parts and discharge line-Suction valve strike harder on seat causing premature failure of valve seals.
-Piston rod carries the shock to power end causing added stress.
-Pulsation Dampener
-Suction Dampener
-Discharge line Dampener
Pressure Relief Valve
Protects the pump when discharge line or bit nozzle gets pluggedDischarge line > should be short, preferably without bends, rigidly anchored.
Slope in discharge line
Priming
Fill up the pump prior to run it > dry liner may ruin the piston.Lubricating and Cooling
-The piston rubber can burn and damage liner in 30 minutes if not cooled.
-Cooling spray should completely flush the entire stroke area.
-Check angle and direction of cooling water nozzles
-Inspect your fluid end parts when pump not in use.
-Check suction strainer when pump not in use
Shale Shakers
The 1st equipment to remove cuttings from return mud.Two or three shale shakers on a rig
Sand Trap
Drilled solid fall through shale shaker screens into sand trap.10 to 20 bbls capacity
Sloping sides
Solids larger than 74 micron settle out in sand trap-De-sander
-De-slitter
-Mud cleaner
-Mud Gas Separators
-Mud Agitators
-Shale Shaker
Mud flow on the screen is controlled by changing angle of screen either uphill or down hill.
To determine right size of screen, the mud should travel down one-half to two third of the length of screen before completely passing through it.
The greater the screen mesh size, smaller the particle size
20 mesh screen > 765 micron
100 mesh screen > 149 micron
Shale Shakers (cont’d)
Salts dissolved in mud can cause screen plugging. The dissolved salts coat the screen wires as the water evaporates and leave the coats on the screen mesh wall. When salt is hardened, it causes plugging. So regular screen washing is required.
Pyramid screens have 40% more surface area than a flat screen which almost double the screen flow capacity.
Shale Shakers (cont’d)
Shale shaker can remove particle above 74 micron.
Solid Control Equipment
Desander and Desilter
-Shale Shaker removes solids ranging up to 74 micron.-Desander removes solids ranging 74 to 40 micron.
-Dessilter removes solids ranging 40 to 20 micron.
-Mud Cleaner removes solids ranging 20 to 7 micron.
-Centrifuge removes solids ranging 7 to 4 micron.
-Desander
-More useful while drilling top holes as it removes large solid build up in the mud.
-Usually has 1 to 3 cones.
-Cone diameter is 6 to 12 inches.
-It is installed down stream shale shaker
Desilter
-Cone size is 3 to 5” dia.-Removes solids 10 to 20 micron
-Desilting the drilling mud can drastically reduce
-mud pump wear,
-hole problem,
-bits wear,
-time required to drill the hole,
-amount of water required for mud treatment.
-Operating pressure of Desander and desilter
-Desander operates at 25 to 35 psi
-Desilter operates at 30 to 45 psi
-Never use centrifugal pump that is used for desander or desilter for any other purpose.
-Maintenance of hydro cyclone
-Most common problem are cones wear due to excessive pump pressure
-Plugging due to large cuttings which come from shale shaker torn screen.
-Inspect centrifugal pump for proper discharge and operating pressure.
-Regular inspection and cleaning of cones helps avoid plugging problem.
Mud Cleaner
The hydocylone removes the silt and discharge to next down stream tank.The underflow of hydro cyclone goes to fine mesh screen. The drilled solid larger than screen size go to waste pit.
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