- Title : Advanced Drilling System by John Crowther
- Publish : Anadrill Schlumberger
- Type Document : pdf
- Release : December 1994
- Total Page : 109 Page
- Size : 1.11 Mb
Download Free by Netload : [ http://adf.ly/XV9S6 ]
Decrypted Contents
PowerPak Motors
1.1 Highlights
PowerPak is a positive displacement downhole drilling motor (PDM) powered by the circulating drilling fluid. The pressure drop across the motor is directly proportional to the drilling torque developed at the bit. The rotational speed depends primarily on the circulation rate, and is only slightly affected by the torque.
1.2 Details
1.2.1 Cross-Over Subs, Dump Valves, or Flex Subs
Cross-Over Subs (or Top Subs) are available for simple connection from the drill string to the stator/motor. Cross-Over Subs are available for all PowerPak motor sizes. A Dump Valve allows the drill pipe to fill with drilling mud when running a motor into a well, and to drain when pulling out of the hole. The valves close when the flow rate reaches a given threshold. Dump Valves are only available for motor sizes 4-3/4” through 11-1/4”. Flex Subs are available for 3- 1/8” through 9-5/8” motors. These replace the dump valve or cross-over and help prevent failure of the stator connections by reducing the bending stresses. Dump valves should only be run when required by the Client.
1.2.2 Power section
The power section, consisting of a stator and rotor, converts hydraulic power from the drilling fluid into mechanical power to rotate the bit. It operates by the reverse application of the Moineau pump principle. The stator is composed of an elastomer with a helicoidal lobe pattern cross section, with n lobes, molded inside a steel housing. The rotor is a machined stainless steel shaft, with a cross section similar to the stator, but with n-1 lobes. The contact of elastomeric stator lining and metal rotor surfaces forms continuous sealing lines and multiple closed fluid hambers. When drilling mud is circulated through the power section the rotor is forced to rotate.
Rotors/stators are available in various configurations: with standard or extended length sections, standard or over-sized (OS) stators, and standard or undersize (US) rotors. Refer to the master orders for details. Chrome plated, tungsten carbide coated and non-plated rotors are available. Tungsten carbide plated rotors are recommended for salt-saturated or corrosive drilling muds.
1.2.3 Transmission section
This section transmits the rotary motion and torque produced by the rotor/stator down to the drive shaft/bearing section of the motor. The transmission couplings also convert the eccentric rotation of the rotor to concentric rotation at the bearing section. This section also includes the surface-adjustable bend housing. Heavy-duty transmissions are available for Extended Power Sections and special transmissions are required for 1:2, 2:3 and some GT lobe configurations.
This section transmits the rotary motion and torque produced by the rotor/stator down to the drive shaft/bearing section of the motor. The transmission couplings also convert the eccentric rotation of the rotor to concentric rotation at the bearing section. This section also includes the surface-adjustable bend housing. Heavy-duty transmissions are available for Extended Power Sections and special transmissions are required for 1:2, 2:3 and some GT lobe configurations.
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