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Drilling Hydraulics

Drilling Hydraulics

Hydraulics is the study of fluid in motion.Provide efficient use of the rig’s circulating equipment to provide maximum hydraulic energy, power or force to the hole bottom.Lower overall drilling cost.

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The fluid in motion provides power through the bit nozzles.

Drilling Fluid

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Functions of Drilling Fluid

Carry rock cuttings to the surfaceClean cuttings from beneath the bitLubricate and cool the drill string and bitStabilize the hole wallControl subsurface pressure

Circulation System

PumpsStandpipe

Kelly HoseGooseneckSwivelKelly

Drill Pipe

Drill Collars

Bit

Annulus

Tanks

Reserve Pit

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Resistance to Fluid Motion

Restrictions in the systemRough surfacesLength of the systemFluid propertiesAmount of fluid flowing

Pressure (lb./sq. in.)

A force or push is needed to move the fluid and overcome the resistance to motion.This force or push is defined as pressurePressure has units of pounds per square inch. (psi)Pressure is developed by the pistons in the pump pushing against the fluid.

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Pressure

The magnitude of the pressure indicates the difficulty in pushing the fluid through the circulation system.The higher the pressure the more resistance there is to flow.

Principle Factors Affecting Pressure

Flow rateFlow areaLength or DistanceFluid Properties (Viscosity & Weight)

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Flow Rate Affects Pump Pressure

Pipe length = 1000 feetPipe size = 4½ inch

Circulation Rate

400 GPM

800 GPM (2 times)

Pressure

67 PSI

244 PSI (almost 4 times)

Flow Area

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Flow Area Affects Pump Pressure

Circulation rate = 400 GPMPipe length = 1000 feet

Pipe size

5 inch

4½ inch

Pressure

38 PSI

67 PSI (76% more)

Flow area

14.4 in2

11.5 in2

Length of the system or distance the fluid moves affects pressure.

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Distance Affects Pump Pressure

Circulation rate = 400 GPMPipe size = 4½ inch

Pipe length

1000 feet

2000 feet (2 times)

Pressure

67 PSI

134 PSI (2 times)

Weight of the fluid affects pressure.

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Fluid Properties Affect Pump PressureMud Weight

Circulation rate = 400 GPMPipe size = 4½ inch

Mud weight

10 PPG

12 PPG

Pressure

67 PSI

80 PSI (20% more)

Viscosity of fluid- Resistance to Flow

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Plastic Viscosity

Circulation rate 400 GPMLength 1000 ft.Pipe Size 4½”Mud Weight 10 PPGPV = 15 CP. Pressure = 125 PSIPV = 50 CP. Pressure = 148 PSI

Increased Pump Pressure

Increased flow rateReduced flow areaIncreased length or distanceHigher mud weightHigher viscosity

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Standpipe Pressure

The total pressure required to push the fluid through the system.

Pressure at end of the flow line is zero

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Pump Pressure

PumpsStandpipe

Kelly HoseGooseneckSwivelKelly

Drill Pipe

Drill Collars

Bit

Annulus

Tanks

Reserve Pit

Maximize power or force at the Bit

Adjust principle factors so maximum allowable surface pressure is not exceeded.Within these limits we will make adjustments to deliver the maximum power or force to the hole bottom.

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Theories on Bottom Hole Cleaning

Maximum Jet Impact ForceMaximum Bit Hydraulic Horsepower

Jet Impact Force

PumpsStandpipe

Kelly Hose

Bit

MaximumForce

System

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Jet Impact Force

1342 psi - 48%

PumpsStandpipe

Bit

2800

System

1456 psi - 52%

Hydraulic Horsepower

PumpsStandpipe

Kelly Hose

Bit

Maximumpower

System

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Hydraulic Horsepower

1820 psi - 65%

PumpsStandpipe

Bit

2800

System

980 psi - 35%

Which Theory Should Be Used?Which Theory Should Be Used?

Impact Force?Horsepower?

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ShallowLarger Diameter Hole

DeeperSmaller Diameter Hole

Which one to use?

Hydraulic Horsepower14% Higher Jet Exit Velocities35% Higher Pressures

Jet Impact Force20% Higher Flow Rates

Annular Velocity Needed toRemove Cuttings

Local ExperienceHole Cleaning– Expected Drilling Rate– Cuttings Carrying Capacity of the Fluid– Hole angle– Properties of Formation being Drilled

Properties of Formation up the Hole

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Good Hydraulics Program

Uses equipment efficientlyDoes not exceed specified limitsAssists objectives of the drilling operationProvides a useable holeConsiders differences in applications

Optimum Hydraulic System Provides

Maximum Hydraulic Power at BitAdequate Annular HydraulicsLower Over-all Drilling Cost

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HCC Hydraulics Output

HCC Hydraulics Output