The document discusses bit hydraulics optimization. It describes how drilling fluid circulation is used to control formation pressures, drive downhole motors, cool the bit, clean cuttings from the hole and bit, and transport cuttings to the surface. It outlines factors that influence pressure losses like equipment geometry, flow rate, and mud properties. The goals of hydraulics optimization are to determine nozzle sizes and flow rates that deliver maximum hydraulic horsepower or jet impact force while meeting constraints like standpipe pressure, pump power, and mud weight. The method and examples of hydraulic program design and cases are provided.

1. Bit Hydraulics Optimization

2. 2 DP
9/27/2022
Purposes
 Control formation pressures
 Drive motor/turbine
 Cool the bit
 Clean cuttings from the hole bottom
 Clean cuttings from the bit
 Transport cuttings to surface
Drilling Fluid Circulation
Bit
Hydraulics

3. 3 DP
9/27/2022
Nozzle Flow Area (TFA - sq.in.)
Nozzle Pressure Drop (psi)
Nozzle Horsepower (HSI)
Nozzle Impact Force (lbf)
Nozzle Velocity (ft/sec)
Bit Hydraulics Optimization
Fluid Pressure
Fluid Flow Rate
Fluid Density and Viscosity
PHP=
PxQ
1714
BHP=
PxQ
1714
Frictional
Pressure
Losses

4. 4 DP
9/27/2022
Pressure Loss Factors
 Equipment and Wellbore Geometry
– Flow Area
– Length
– Constrictions
 Flow Rate
 Mud Properties
– Weight
– Plastic Viscosity
– Yield Point
Pressure In
Pressure Out
Flow In Flow Out

5. 5 DP
9/27/2022
PStdpipe=PSurf.Eq.+PDrill String+PMWD/Motor+PBit+PAnnulus
Pressure Losses
 Surface Equipment
– Standpipe
– Kelly Hose
– Swivel
– Kelly
 Drill String
– Pipe
– Collars
– BHA
 Motor/Turbine
 Bit Nozzles
 Annulus
 Drill String
– Pipe
– Collars
– BHA
 Surface Equipment
– Standpipe
– Kelly Hose
– Swivel
– Kelly
 Motor/Turbine
 Bit Nozzles
 Annulus

6. 6 DP
9/27/2022
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 Equipment

7. 7 DP
9/27/2022
Drill Pipe D1 D2
Pressure Losses Drill 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

8. 8 DP
9/27/2022
Pressure Losses Drill String
Heavy 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
D1 D2
Drill Pipe

9. 9 DP
9/27/2022
ID
OD
(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 String
Heavy Weight Drill Pipe
D1 D2
Drill Pipe
Drill Collars

10. 10 DP
9/27/2022
Pressure Losses MWD and
Downhole Drives
 MWD
 PDM
 Turbine
 RSS

11. 11 DP
9/27/2022
Pressure Losses Bit
 Flow Rate
 Mud Weight
 Nozzle TFA
Pressure Drop
HSI
JIF

12. 12 DP
9/27/2022
Pressure Losses Annulus
 Flow Rate
 Mud Weight
 Casing ID
 Drill String OD
 Length

13. 13 DP
9/27/2022
Example of Pressure Losses
Hole Size =8-1/2"
Depth Out = 15,000 feet
Max. Standpipe Pressure = 3000 psi
Flow Rate = 238 GPM
Mud Weight = 14.5 ppg
At Maximum HSI
Surface Equipment Loss = 20 psi
Internal Drill String Loss = 968 psi
MWD/Motor Loss = 0
Bit Pressure Drop = 1890 psi
Annulus Loss = 122 psi
Total Loss = 3000
PStdpipe=PSurf.Eq.+PDrill String+PMWD/Motor+PBit+PAnnulus

14. 14 DP
9/27/2022
Hydraulics Optimization
3000 psi Standpipe Pressure
Standpipe HP
JIF/sq. in.
Bit Nozzle HP
System Loss HP

15. 15 DP
9/27/2022
Flow Rate Requirements
Hydraulic 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.

16. 16 DP
9/27/2022
Maximum Hydraulic Horsepower
Hydraulic 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.

17. 17 DP
9/27/2022
Maximum Jet Impact Force
Hydraulic 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.

18. 18 DP
9/27/2022
Other Guidelines
Hydraulic 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.

19. 19 DP
9/27/2022
Hydraulic Program Design
Goal: Determine nozzle sizes and flow rate
to deliver maximum HSI or JIF within
specified operating constraints.
1. Maximum Standpipe Pressure
2. Minimum and Maximum Flow Rate
3. Maximum Pump Horsepower
4. Mud Weight
5. MWD and Motor Considerations
6. Fixed Flow Rate
7. Fixed TFA
Constraints:

20. 20 DP
9/27/2022
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 ?

21. 21 DP
9/27/2022
Hydraulic Program Cases
Case 1 Case 2
Case 3 Case 4 Case 5

22. 22 DP
9/27/2022
Hydraulic Program Demo

23. 23 DP
9/27/2022
Field Results
Hydraulic Optimization
Carboniferous Formation
Oil Base Mud in North Sea
Shale Formation
Water Base Mud in Columbia