12 a hydraulics summary
TRANSCRIPT
DRILLINGHYDRAULICS
Courtesy of Baker Hughes
Goal of Drilling Hydraulics
Enhance Bit PerformanceLower Over-all Drilling Cost
Drilling Hydraulics
Bit HydraulicsClean the Bit And Hole BottomCool the Bit
Annular HydraulicsLift Cuttings and CavingsLimit Annular Pressure DropLimit Hole Erosion
Downhole Tool Hydraulics
How to achieve these Goals?
ActualSituation
"Optimization"
Recommend
EvaluateCommunicate
Factors which Affect Pump Pressure
Flow RateFlow AreaLength of Circulation SystemFluid Properties
Pump Pressure
Flow Rate
Pressure Required (psi)Flow Rate (gpm)
400
800
41
147 (3.6 times 41)
10 lb/gal mud 1000 ft of 5" XH 19.50 drill pipe
∆p0.1582 L⋅ ρ
0.8⋅ µ a
0.2⋅ v
1.8⋅
d1.25
= Friction loss for Bingham Plastic
14.4 in.2
11.5 in.2
Pressure Required (psi)
5" XH 19.50 lb/ft
4-1/2" XH 16.60 lb/ft41
67 (63% more)
Pipe Size Flow Area (in.2)
400 gpm 10 lb/gal mud 1000 ft of 5" and 4-1/2" drill pipe
Flow Area
∆p0.1582 L⋅ ρ
0.8⋅ µ a
0.2⋅ v
1.8⋅
d1.25
= Friction loss for Bingham Plastic
Length of Circulation Loop
Pressure Required (psi)Length (ft)
1000
2000
41
81 (twice as much)
400 gpm 10 lb/gal mud 5" XH 19.50 drill pipe
∆p0.1582 L⋅ ρ
0.8⋅ µ a
0.2⋅ v
1.8⋅
d1.25
= Friction loss for Bingham Plastic
Fluid Properties
Pressure Required (psi)Mud Weight (lb/gal)
10
12
41
49 (20% more)
400 gpm 10 lb/gal mud 1000 ft of 5" XH 19.50 drill pipe
∆p0.1582 L⋅ ρ
0.8⋅ µ a
0.2⋅ v
1.8⋅
d1.25
= Friction loss for Bingham Plastic
Pump Pressure Distribution
0 100 200 300 400 500 600 700 800 9000
400
800
1,200
1,600
2,000
2,400
2,800
Flow Rate (gpm)
Pressure (psi)
System Losses
Available for bitAs flow rate increases, the amount of pressure available for the bit decreases
Optimization of Hydraulic System
Reduce System Losses
Optimum Flow Rate
Large Flow Area
Optimum Lengths
Low Mud Weight
Low Viscosity
MaximumHydraulic Energyat the Bit
Two Optimization Methods
Jet Impact Force – Maximum force at bit
Hydraulic Horsepower – Maximum energy at bit
0 100 200 300 400 500 600 700 800 900Flow Rate (gpm)
IF (lb)
Max. Impact Force
Maximum Impact Force
Jet impact force is maximized when momentum is maximized. This occurs when the bit losses are 49% of the available pump pressure.
M = m v
mass ρ q⋅= q
velocityqAt
=q
F jρ q
2⋅
A t=
qF j q ρ ∆p b⋅⋅= q
Jet Impact Force
1342 psi - 48%Bit
System
2800
1456 psi - 52%
Maximum Force at the Bit
P H ∆p b q⋅= ∆p b P Hρ q
3⋅
A t2
=q
0 100 200 300 400 500 600 700 800 900Flow Rate (gpm)
HHP (hp)
Max. HHP
Maximum HHP
Hydraulic Hp is maximized when the energy dissipated at the bit is maximized. This occurs when 65% of pump pressure is dissipated at the bit.
Hydraulic Horsepower
1820 psi - 65%Bit
System
980 psi - 35%
Maximum Energy at the Bit
2800
0 100 200 300 400 500 600 700 800 9000
400
800
1,200
1,600
2,000
2,400
2,800
Flow Rate (gpm)
Pump Pressure (psi)
HHP
35%
Impact Force
52%
Design Pump Pressure
Pressure used by the System
System Losses
Bit Loss
0 100 200 300 400 500 600 700 800 9000
400
800
1,200
1,600
2,000
2,400
2,800
Flow Rate (gpm)
Pump Pressure (psi)
System Losses
Bit Loss
HHP
35%
65%
Impact Force
52%
48%
Design Pump Pressure
Pressure remaining for the Bit
0 100 200 300 400 500 600 700 800 9000
400
800
1,200
1,600
2,000
2,400
2,800
Flow Rate (gpm)
Pressure loss through the bit (psi) IF,HHP
System LossesBit Loss
Max. Impact Force
Max. HHP
Design Pump Pressure
Maximum HHP and Impact Force
100%92% 93% 100%
0%
20%
40%
60%
80%
100%
120%
Max. HHP Max. Impact Force
Comparison at Maximum Conditions
HHP Impact Force
0 100 200 300 400 500 600 700 800 9000
400
800
1,200
1,600
2,000
2,400
2,800
Flow Rate (gpm)
Pressure loss through the bit (psi) IF, HHP
System LossesBit Loss
Max. HHP
Max. Impact Force
20% Higher
Design Pump Pressure
Higher Flow Rate at Impact Force
0 100 200 300 400 500 600 700 800 9000
400
800
1,200
1,600
2,000
2,400
2,800
Flow Rate (gpm)
Pressure at the bit (psi) IF, HHP
System Losses
Bit Loss
Max. HHP
Max. Impact Force
35% Higher
Design Pump Pressure
Higher Pressure at Hydraulic Horsepower
ShallowLarger Diameter Hole
DeeperSmaller Diameter Hole
Which one to use?
Hydraulic Horsepower14% Higher Jet Exit Velocities35% Higher Pressures
Jet Impact Force20% Higher Flow Rates
90% of Maximum HHP
0 0.2 0.4 0.6 0.8 10%
20%
40%
60%
80%
100%
120%
Fraction of Surface Pressure across Bit
% of Maximum HHP
90%
65%
Optimization of Hydraulic System
Choose equipment to keep system losses at minimum for the anticipated range of flow rates and depthSelect Optimization Method - Impact Force or Hydraulic HorsepowerDetermine optimum flow rateAdjust flow rate to meet requirements or limitsDetermine TFA
Rules of ThumbFlow RateFlow rate should be maintained at 30 to 60 gpm per inch of bit diameter
Hydraulic HpAim at 2.5 to 5 hydraulic Hp per square inch of bit diameter.
Bit Pressure dropDesign for 48% to 65% Pressure drop across bitIf system losses are greater than 48% of pump pressure then optimize for jet velocity.
Jet VelocityMaintain jet velocity above 250 feet per second
Flowrate LimitsAnnulusHole ErosionHole CleaningLoss of Circulation
Downhole ToolsPDMTurbineMWD
PumpSPMLiner Size
Cuttings AnalysisErosion vs. chip formation
Roller ConeBit Hydraulics
Three Major Mechanismsof Bit Hydraulics
• Remove the drilled-up particles to the surface
• Clean the cones and cutting structures
• Remove the layer of filter cake and crushed• material from the borehole bottom
Factors Which Determine Which Mechanism will become the Dominant
Problem
nFormation
nBorehole Bottom Condition
nHydraulic and Mechanical Operating Parameters
nProperties of Drilling Fluid
Hydraulic Mechanism Neededto Improve Mechanical Efficiency of
Roller Cone Bit
* Remove the drilled-up particles to the surface
APPROXIMATELY 20 TO 30 FT/HR* Remove the layer of filter cake and crushedmaterial from the borehole bottom
* Clean the Cones and Cutting StructuresHigh ROP
Low ROP
Development of the Crushed ZoneAs the cutting element penetrates into a formation, the formation directly below the element is crushed and compacted.
The process continues, forming a pocket of crushed, permeable material until the stress level is sufficiently high to propagate cracks and generate major chips.
As the high stress is released, the large chips are removed leaving behind a pocket of crushed formation.
Crushed Formation
Uniform Layer of Fines
IMPERMEABLE FORMATION
FILTER CAKE
PERMEABLECRUSHED ZONE
MUD PRESSUREWELLBORE
FORMATION
Improve Bottomhole Cleaning byIntensifying Jet Velocity and
Pressure on Bottom
Jet Flow
POTENTIAL CORE100% EXIT VELOCITY AND PRESSURE
CREATED BY ENTRAINING SURROUNDING FLUID
TURBULENCE
Velocity and Pressure on Bottomis Increased by
Increasing Nozzle Diameter
Decreasing Distance Off Bottom
Asymmetrical Nozzle ArrangementThe larger size nozzle has an effect on the jet flow due
to the larger potential core delivering more of the available power to the bottom before it dissipates into the surrounding fluid.
X
LargerPotentialCore
D 2 D
Nozzle Distance Off Bottom
The nozzle distance off bottom has an effect on the jet flow due to the jet having less distance available to entrain the surrounding fluid and dissipate the available power.
X
2 XPotential Core
Increase the Jet Action by Concentrating the Available Power
3 Identical Size Nozzles Asymmetrical Arrangement1 Large Nozzle with 2 Smaller Nozzles
Measure of Jet Intensity
7.710
15
20
X/D Ratio
100%77%
51%
38%
Velocity
100%59%
26%
15%
Pressure
X/D Ratio Needed to Produce Desired Hydraulic Mechanism
High Flow Rates for Bit Cleaningand Dispersing Shale - High ROP
APPROXIMATELY 20 TO 30 FT/HR
High Velocities for Bottom ScouringLow ROP
X/D Ratio
Less Than 7.7
7.7-15
Hydraulic Mechanism Neededto Improve Mechanical
Efficiency of Roller Cone Bit
IncreasingHydrostatic Pressure
High Flow Rates for Bit Cleaning and Dispersing Shale – High ROP
APPROXIMATELY 20 TO 30 FT/HR
High Velocities for Bottom-ScouringLow ROP
IncreasingHydraulic Horsepower
PDC Bit Hydraulics
Junk Slot Area Face Volume
Nozzle Orientation
TILT
OFFSET
FLOWVECTOR
OFFSET
Ports
• Ports are used when space limitations prevent the use of nozzles.
• Ports help to distribute hydraulic energy to areas of the bit that may not be adequately covered by nozzles.
• Ports provide a larger potential TFA in high flow rate or low standpipe pressure applications.
• Ports can be specified in any equivalent nozzle size.
Reverse Impinging Hydraulics
• Remove bit body material so cuttings have no surface to stick to.
• Impact the chip from the rear stressing it across the weakest axis.
• Provide large open face volume and smooth transition to annulus.
Chipmaster Hydraulic Concept
Original Concept Refined Version
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