bit hydraulics theory
TRANSCRIPT
Bit Hydraulics Optimization
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Purposes
Control formation pressuresDrive motor/turbineCool the bitClean cuttings from the hole bottomClean cuttings from the bitTransport cuttings to surface
Drilling Fluid Circulation
BitHydraulics
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Nozzle Flow Area (TFA - sq.in.)Nozzle Pressure Drop (psi)Nozzle Horsepower (HSI)Nozzle Impact Force (lbf)Nozzle Velocity (ft/sec)
Bit Hydraulics OptimizationFluid PressureFluid Flow RateFluid Density and Viscosity
PHP= PxQ1714
BHP=PxQ
1714
FrictionalPressureLosses
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Pressure Loss Factors
Equipment and Wellbore Geometry– Flow Area– Length– Constrictions
Flow RateMud Properties
– Weight– Plastic Viscosity– Yield Point
Pressure InPressure Out
Flow In Flow Out
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PStdpipe=PSurf.Eq.+PDrill String+PMWD/Motor+PBit+PAnnulus
Pressure LossesSurface Equipment
– Standpipe– Kelly Hose– Swivel– Kelly
Drill String– Pipe– Collars– BHA
Motor/TurbineBit NozzlesAnnulus
Drill String– Pipe– Collars– BHA
Surface Equipment– Standpipe– Kelly Hose– Swivel– Kelly
Motor/TurbineBit NozzlesAnnulus
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Case Stand Pipe Hose Swivel Kelly
Length(Ft.)
ID(In.)
Length(Ft.)
ID(In.)
Length(Ft.)
ID(In.)
Length(Ft.)
ID(In.)
1 40 3.0 45 2.0 4 2.0 40 2.25
2 40 3.5 55 2.5 5 2.5 40 3.00
3 45 4.0 55 3.0 5 2.5 40 3.25
4 45 4.0 55 3.0 6 3.0 40 4.0
Pressure Losses Surface EquipmentSurface Equipment
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Drill PipeDrill Pipe DD11 DD22
Pressure Losses Drill StringDrill String
ID (in.)OD(in.)
Nominal Weight(lb/ft) Body Tool Joint
3 ½ 15.5 2.992 2 1/8 – 2 9/16
5 19.5 4.276 2¾ – 3¾
5 25.6 4.000 3¼ – 3¾
6 5/8 25.2 5.965 4 5/8 - 5
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Pressure Losses Drill StringDrill String
Heavy Weight Drill PipeHeavy Weight Drill Pipe
ID (in.)OD(in.)
Nominal Weight(lb/ft) Body Tool Joint
3 ½ 25.3 2 1/16 2 3/16
4 ½ 41.0 2 ¾ 2 7/8
5 49.3 3 3 1/16
DD11 DD22Drill PipeDrill Pipe
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IDOD(in.)
Weight(lb/ft)
OD(in.)
Weight(lb/ft)
ID(in.)
4 ¾ 54.0 1 ½
4 ¾ 44.0 2 ½
8 165.0 1 ½
8 143.0 3 ¼
Pressure Losses Drill StringDrill StringHeavy Weight Drill PipeHeavy Weight Drill PipeDD11 DD22
Drill PipeDrill Pipe
Drill CollarsDrill Collars
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Pressure Losses MWD andMWD andDownhole DrivesDownhole Drives
MWDPDMTurbineRSS
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Pressure Losses BitBit
Flow RateMud WeightNozzle TFA
Pressure Drop
HSIJIF
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Pressure Losses AnnulusAnnulus
Flow RateMud WeightCasing IDDrill String ODLength
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Example of Pressure LossesHole Size =8-1/2"Depth Out = 15,000 feetMax. Standpipe Pressure = 3000 psi Flow Rate = 238 GPMMud Weight = 14.5 ppg
At Maximum HSISurface Equipment Loss = 20 psiInternal Drill String Loss = 968 psiMWD/Motor Loss = 0Bit Pressure Drop = 1890 psiAnnulus Loss = 122 psiTotal Loss = 3000
PStdpipe=PSurf.Eq.+PDrill String+PMWD/Motor+PBit+PAnnulus
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Hydraulics Optimization3000 psi Standpipe Pressure
Standpipe HP
JIF/sq. in.Bit Nozzle HPSystem Loss HP
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Flow Rate RequirementsFlow Rate RequirementsHydraulic Recommendations
Flow Rate must be high enough to transport cuttings. Back-reaming, bit body balling and lack of chips at surface indicate cuttings transport or sloughing problems.
Flow Rate must be low enough to avoid hole erosion, equipment wear, and excessive standpipe pressure.
High flow rates often require large or open nozzles.
Bits with large junk slots, high open face volume, widely spaced teeth/inserts and numerous jets are helpful.
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Maximum Hydraulic HorsepowerMaximum Hydraulic HorsepowerHydraulic Recommendations
Maximize nozzle HSI when cutting structure or bottom hole balling is the limitation.
Deep holes, high mud weights, water-based mud and reactive formations, cuttings packed on teeth indicate static or dynamic chip hold down problems.
Maximum HSI obtained when nozzle pressure drop is 65% of standpipe pressure.
Aggressive designs with widely-spaced blades and teeth are helpful.
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Maximum Jet Impact ForceMaximum Jet Impact ForceHydraulic Recommendations
Maximize JIF in shallow holes where cuttings return and bit/hole balling are both potential limitations.
Common in shallow holes with high ROP in reactive formations.
Obtained when the pressure drop across the bit is 50% of the total pump pressure.
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Other GuidelinesOther GuidelinesHydraulic Recommendations
30 to 50 gpm per inch of hole diameter.
3 to 7 HSI recommended (not always possible).
18% or less flow through centerjet (=18% of TFA).
Blank nozzles generate crossflow. Blank the nozzle pointing to the cone with fewest gauge row inserts.
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Hydraulic Program DesignGoal: Determine nozzle sizes and flow rate
to deliver maximum HSI or JIF within specified operating constraints.
1. Maximum Standpipe Pressure2. Minimum and Maximum Flow Rate3. Maximum Pump Horsepower4. Mud Weight5. MWD and Motor Considerations6. Fixed Flow Rate7. Fixed TFA
Constraints:
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Hydraulic Program Calculation Method
1. Identify Maximum Standpipe Pressure.2. Specify HSI or JIF optimization and TFA/GPM constraints.3. Find GPM giving maximum HSI or JIF based on frictional losses.4. Derive Nozzles from TFA at optimum GPM.
Nozzles ?Flow Rate ?
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Hydraulic Program Cases
Case 1 Case 2
Case 3 Case 4 Case 5
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Hydraulic Program Demo
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Field ResultsHydraulic OptimizationHydraulic Optimization
Carboniferous FormationOil Base Mud in North Sea
Shale FormationWater Base Mud in Columbia