5 2 PDM mechanical components

Explain the components of a PDM power section.. Name the 2 types of PDM bearing sections and state when each should be used 5.. 3 –Drive Train Assembly Transmits rotational speed and to

At the end of this lecture, YOU will be able to:

1 Name the 4 major components of a PDM tool

2 Explain the components of a PDM power section

3 List the components of a PDM drive line system

4 Name the 2 types of PDM bearing sections and state when

each should be used

5 List the operational considerations for using PDM tools

Positive displacement

motors

Down Hole Motor

Any mud motor consists of 4 basic

parts:

1 Dump Valve Assembly

2 Power Section

3 Drive Train Assembly

4 Bearing Assembly.

1 - Dump valve assembly

Allows the mud to fill or drain from the drill-string while tripping

The motor will function perfectly without a dump valve However, it allows the drill string to fill on the trip in and to be pulled

"dry"

2 - Power section

The rotor has spiral-helix shape

The stator is a steel housing, lined with elastomer rubber compound

The rotor is produced with matching 'lobe" profile and similar helical

pitch to the stator, but with one lobe less

When assembled, the rotor and stator form a continuous seal along their matching contact points

2 - Power section

Fluid is pumped into the motor's progressive cavities

The force of the fluid movement causes the shaft to rotate within the stator

The rotational force is then transmitted through the connecting rod and drive shaft to the bit

2 - Power section

 Each complete spiral of the stator is called a stage

 Interference fit between rotor O.D

and stator I.D controls motor power

 Mud motors are divided into slow, medium and high speed types by changing the shape and the number of the stages and by the number of "lobes" and resultant cavities of the stator

 The greater the number of lobes, the higher the motor torque and the lower the RPM.

Torque and RPM output Comparison

3 –Drive Train Assembly

 Transmits rotational speed and torque from power section to the bearing and drive shaft

 Compensates eccentric rotation of the rotor and absorbs its

down thrust

4 - Bearing section

4 - Bearing section

Off-bottom Thrust Bearings:

support the hydraulic thrust and weight of the internal

components when the tool is off bottom They are normally ball bearing type design

On-bottom Thrust Bearings:

transmit the drilling load from the non-rotating motor housing to the rotating drill bit These bearings take the load while drilling

Bearing loads must be balanced

4 – Sealed Bearing

Section

 Has on bottom, off bottom and radial bearings

 Has journal bearings for axial load instead of roller

 Journal bearings lay in a sealed oil bath for cooling

 No drilling fluid is diverted through the bearing section for

cooling

 Less journal axial load bearings needed

 Ability to produce shorter bit to bend lengths

 Heat sensitive

 Expensive bearing section to repair

Selection Criteria for a

Bearing Section

 WOB

 Down hole Temperature

 Drilling Fluids solid content

 Type of drilling fluid used

 Build rates needed

 Hole section bearing pack is going to be used in

 Anticipated down hole bit side loads

Selection Criteria for a Power

Section

 Type of bit being used and formation type

 Down hole Temperature

 Drilling Fluids solid content

 Type of drilling fluid used

 Build rates needed

 Hole section power pack is going to be used in

 Hydraulics needed to clean the hole

Positive displacement motors

Now, YOU should be able to:

1 Name the 4 major components of a PDM tool

2 Explain the components of a PDM power section

3 List the components of a PDM drive line system

4 Name the 2 types of PDM bearing sections and state

when each should be used

5 List the operational considerations for using PDM tools

Any questions before

the test?

This is a closed book test Please put

away your notes and handouts now.