CA2058080C - Composite stator construction for downhole drilling motors - Google Patents

Composite stator construction for downhole drilling motors

Info

Publication number
CA2058080C
CA2058080C CA 2058080 CA2058080A CA2058080C CA 2058080 C CA2058080 C CA 2058080C CA 2058080 CA2058080 CA 2058080 CA 2058080 A CA2058080 A CA 2058080A CA 2058080 C CA2058080 C CA 2058080C
Authority
CA
Canada
Prior art keywords
helical
stator
rotor
drilling
stator former
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
CA 2058080
Other languages
French (fr)
Other versions
CA2058080A1 (en
Inventor
John Forrest
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Baker Hughes Holdings LLC
Original Assignee
Drilex Systems Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Drilex Systems Inc filed Critical Drilex Systems Inc
Publication of CA2058080A1 publication Critical patent/CA2058080A1/en
Application granted granted Critical
Publication of CA2058080C publication Critical patent/CA2058080C/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B4/00Drives for drilling, used in the borehole
    • E21B4/02Fluid rotary type drives
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01CROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
    • F01C1/00Rotary-piston machines or engines
    • F01C1/08Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing
    • F01C1/10Rotary-piston machines or engines of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • F01C1/101Moineau-type

Abstract

A composite stator construction for a downhole drilling motor which provides improved sealing and distortion properties. The elastomer which maintains the sealing/pumping action of the motor is applied in a uniform thickness to a rigid metallic form. In the stator, the rigid former has the basic configuration of the stator and is mounted within the casing of the motor. In the rotor, the elastomer can be applied directly to a metallic rotor core. The basic geometry is provided by the metallic former thereby reduces distortion of the lobes under increased torsional forces.

Description

2~8~go COMPOSITE STATOR CONSTRUCTION
FOR DOWNHOLE DRIVING MOTORS

Background Of The Invention I. Field of the Invention This invention relates to drilling motors for downhole applications and, in particular, to a composite stator construction for the drilling motor whi~h i~proves the pumping capabilities of the motor by providing an elastomer coating over a rigid stator former. Alternatively, the elastomeric coating may be applied to the rotor.

II. Description of the Prior Art Downhole drilling motors provide direct bit drive in directional drilling or deep drilling by pumping drilling fluid through the motor. The working portion of the motor comprises an outer casing having a multi-lobed stator mounted therein and a multi-lobed rotor disposed within the stator. Typically, the rotor has one less lobe than the stator to facilitate pumping rotation. The rotor and stator interengage at surfaces shaped in the form of helical lobes to form a sealing surface which is acted upon by the drilling fluid to drive the rotor within the stator. In the prior systems, one or the other of the stator/rotor is made of an elastomeric materiaI to maintain a seal therebetween.
In the present design of stators, the elastomer is continuous from the interior helical surface to the outer cylindrical surface which is bonded to the outer casing of the motor. Because of variations in the thickness of the elastomer material of the prior known stators, selection of the elastomer's physical properties necessitates a .

2 ~ 0 6~432-126 compromise between a high modulus valve to preserve the shape of the lobes under operating stresses and -the need to affect a satisfactory se~1 be-tween the inner surface of the stator and the outer surface of the rotor. As the rotor rotates and precesses within the stator, a seal. is Eormed at each point of contact. However, it is dif~icult to produce satis~actory elastomer moldings which are rigid enough to prevent distortion of the stator surface. ln the event the bit torque exceeds the hydraulic torque developed by the motor while -the drill string is rotatedl the stator will overrun the rotor damaging the elastomer. Furthermore, a variable thickness elastomer generates heat in the core which leads to premature deterioration in the material properties.
summar~ of the Present Invention This invention relates to a downhole drilling motor for driving drilling tools, said drilling motor comprising: a housing having an inlet end and an outlet end through which drilling fluid is pumped for activation of said drilling motor;
a composite stator disposed within said housing having an inlet and an outlet communicating with said inlet and outlet ends of said housing, said stator including a rigid stator former having a helical configuration and an elastomeric material applied to an inner surface of said stator former to form an inner sealing surface for said composite stator; and a helical rotor disposed in said composite stator for rotation therein, said rotor sealingly engaging said elastomeric surface of said stator construction to form at least one fluid space through which '': .

2 t~ 8 ~
~32-126 drilling fluid is pumped to ro-tatively drive said rotor within said composite s-tator thereby driving said drilling tool.
The present invention overcomes the disadvantages of the prior known drilling motors by incorporating a rigid stator former to which a uniform thickness of elastomer material is molded thereby improving the sealing properties of the components while also stiffening the stator for transmission of increased torsional forces.
The drilling motor of the present invention incorporates an elastomer material of nominallv uniform thickness molded to one of either the stator or rotor of the motor. In this manner, the elastomer is backed by a rigid surface to prevent distortion and degradation which maximizes operating performance. In a preferred embodiment, a metallic stator former is incorporated into the motor casing to increase the amount of torsional force to be transmi~ted without shearing of the elastomer or a severe distortion of the geometry of the stator. The elastomer is molded directly to the stator former -in a uniform thickness. The thickness of the elastomer may be varied depending upon ' 2a .
'' -2 ~ S~ ~

the application. Additionally, the space between the stator former and the outer casin~ may be filled with an additional elastomer or resin for support.
In the case of the rotor, the elastomer again is molded to the rotor surface in an approximately uniform thickness which would cooperate with a metallic stator. As with the stator, the alastomer would be supported by the formed lobes of the metallic rotor core for improved operation. The elastomer may be molded or extruded over the rotor. It is also contemplated that older rotors may be repaired hy applying a thin layer of elastomer thereby eliminating any non-conformities.
In an alternative embodiment, the elastomer coated rotor or stator may be used in a pump for delivering fluids such as a sump pump. The rotor would be mechanically driven within the stator to pump the fluid through the chamber.
Again, the elastomer coating on either the rotor or stator would improve sealing contact while the rigid backing provided to the elastomer improves the shear strength of the lobes.
Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.

Brief Description Of The Drawing The present invention will be more fully understood by reference to the following detailed description o~ a preferred embodiment of the present invention when read in conjunction with the accompanying drawing, in which like reference characters refer ~o like parts throughout the views and in which:
FIGURE 1 is a transverse cross-sectional view of a drilling motor incorporating the composite stator construction of the present invention; and "" ' ' :
.

2~5~9 FIGURE 2 is a longitudinal cross-sectional view of an alternative embodiment of the dxilling motor showing an elastomer coated rotor.

Detailed Description Of A Preferred Embodiment Of The Present Invention Referring to Figure 1 of the drawing, there i~ shown a lateral cross-section of the drive seckion 12 o~ a downhole drilling motor 10. In a preferred embodiment of the invention, the motor 10 is a mull:i-lobed assembly used to drive drilling tools and the like by pumping drilling ~luid through the drive section 12 of the motor 10. Such downhole drilling motors 10 are typically utilized to provide direct drive of drilling tools in d.irectional and horizontal drilling operations. The downhole positive displacement motor 10 of the present invention is capable of generating high torque at low rotary speeds without distortion of the geometry of the stator/rotor drive 12. As is typical of such motors 10, the statorJrotor drive 12 converts the fluid energy of the drilling fluid in a rotational and precessional motion to turn the drill bit.
The drive section 12 of the motor 10 includes an outer casing 14 within which is disposed a rigid stator former 16.
The stator former 16 has a helical, multi-lobed configuration. Unlike the prior known stator constructions which are formed entirely of an elastomer, the stator former 16 of the present invention is formed o~ a rigid material, such as metal, for improved strength. The rigid stator former 16 has a uniform thiokness creating helical spaces 18 between the housing casing 14 and the stator former 16. In one embodiment of the present invention, the helical spaces 18 may be filled with an elastomer or other resin to provide added support to the stator former 16. The stator former 16 .

.
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2~aso is secured within the housing 14 such that the drilling ~luid will flow through the stator former 16.
A multi-lobed helical rotor 20 is disposed within the stator former 16 for rotation therein as drilling fluid is pumped through the stator former ~6 to drive the drill bit.
The rotor 20 has one fewer lobe than the stator former 16 to allow rotation and precession of the rotor 20 within the motor 10. As with the stator former 16, the rokor 20 is machined from metal with the multi-lobed helical configuration.
In order to form the necessary seal between the stator and rotor to create the flow chambers through which the drilling fluid is pumped thereby driving the rotor 20, either the stator former 16 or the rotor 20 must include an elastomer layer to provide sealing interengagement. In a first embodiment, an inner surface 22 of the stator former 16 is supplied with an elastomeric material 24 of nominally uniform thickness which sealingly engages the rotor 20 as it rotates therein. Unlike the elastomer stators of the prior art wherein the thickness of the elastomer varies in accordance with the geometry of the stator, the uni~orm thickness of the elastomeric layer 24 supported by the metallic stator former 16 provides greater heat dissipation.
The stator former 16 also supports the elastomeric layer 24 allowing the use of a softer elastomer for improved sealing with the rotor 20. However, the rigidity of the stator former 16 maintains the shape of the stator lobes allowing a greater amount of 'corsional force to be transmitted without shearing of the lobes 26 or severe distortion of the inner geometry. Accordingly, the composite stator cannot deflect enough to allow the rotor 20 to overrun the lobes 26 in the event bit torque exceeds the hydraulic torque developed by the motor 10 while the drill string is rotated.

.
: . .

, ~ , .~ .
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2 ~ 0 In an alternative embodiment, instead of applying the elastomeric material to the stator former 16, the elastomer is applied to the outer helical surface 28 o~ the rotor 20 as shown in Fig. 2. Again, seal:ing engagement between the rotor 20 and stator 16 is formecl as the rotor 20 rotates within the motor 10. The lobed geometry of the rotor 20 provides support for the elastomer preventing distortion.
The application of the elastomer over the rotor 20 can be utilized to refurbish worn or damaged rotors by applying a thin uniform layer of elastomer.
It is contemplated that the elastomer can be applied to either the rotox 20 or the stator former 16 in any number of ways including extruding the elastomer directly onto the metallic surface or forming an elastomer sleeve which i5 bonded to the particular surface. Additional methods of application may be appropriate for providing an elastomer of uniform thickness.
It is contemplated in accordance with the present invention that the composite rotor or stator construction could be used in drilling motors and pumps for delivering fluids. In a pump either the stator or the rotor could be the driven member to create the fluid pumping chamber. The elastomer applied to the rigid stator former or rotor provides improved sealing and pumping action while the rigidness of the components allows higher torques for increased fluid delivery.
The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modifications will be obvious to those skilled in the art without departing from the scope and spirit of the appended claims.
What is claimed is:

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Claims (13)

1. A downhole drilling motor for driving drilling tools, said drilling motor comprising:

a housing having an inlet end and an outlet end through which drilling fluid is pumped for activation of said drilling motor;

a composite stator disposed within said housing having an inlet and an outlet communicating with said inlet and outlet ends of said housing, said stator including a rigid stator former having a helical configuration and an elastomeric material applied to an inner surface of said stator former to form an inner sealing surface for said composite stator; and a helical rotor disposed in said composite stator for rotation therein, said rotor sealingly engaging said elastomeric surface of said stator construction to form at least one fluid space through which drilling fluid is pumped to rotatively drive said rotor within said composite stator thereby driving said drilling tool.
2. The drilling motor as defined in claim 1 wherein said elastomeric material is applied to said inner surface of said stator former in a uniform thickness along said inner surface, said stator former providing rigid support of said elastomeric layer.
3. The drilling motor as defined in claim 1 wherein a plurality of helical spaces are formed between said stator former and said housing.
4. The drilling motor as defined in claim 3 wherein said helical spaces between said stator former and said housing are filled with an elastomer material for additional support of said composite stator.
5. The drilling motor as defined in claim 2 wherein said uniform elastomeric layer is formed as a helical sleeve mounted to said inner surface of said stator former.
6. The drilling motor as defined in claim 2 wherein said uniform elastomeric layer is extruded over said inner surface of said stator former.
7. A downhole drilling motor for driving drilling tools, said drilling motor comprising:

a housing having an inlet end and an outlet end through which drilling fluid is pumped for activation of said drilling motor;

a rigid stator former having a helical configuration including a helical inner surface, said stator former secured within said housing wherein drilling fluid is pumped through said stator former; and a rotor having a helical outer surface disposed in said stator former for rotation therein as drilling fluid flows through said housing driving said drilling tool;

one of said helical inner surface of said stator former and said helical outer surface of said rotor having a uniform thickness of elastomeric material applied thereto for sealing engagement of the other of said helical inner surface of said stator former and said helical outer surface of said rotor; said sealing engagement forming at least one fluid space through which drilling fluid is pumped to rotatively drive said rotor within said stator former thereby driving said drilling tool.
8. The drilling motor as defined in claim 7 wherein said elastomeric material forms a helical sleeve bonded to one of said helical inner surface of said stator former and said helical outer surface of said rotor.
9. The drilling motor as defined in claim 7 wherein said elastomeric material is extruded over one of said helical inner surface of said stator former and said helical outer surface of said rotor.
10. The drilling motor as defined in claim 7 wherein a plurality of helical spaces are formed between said stator former and said housing, said helical spaces filled with an elastomer material for support of said stator former.
11. In a downhole drilling motor for driving drilling tools of the type comprising a housing having an inlet end and an outlet end through which drilling fluid is pumped for activation of said drilling motor, a rigid stator former having a helical configuration including a helical inner surface, said stator former secured within said housing such that drilling fluid is pumped through said stator former, and a helical rotor disposed in said stator former for rotation therein, said rotor having an outer helical surface, the improvement comprising an elastomeric material applied to one of said helical inner surface of said stator former and said helical outer surface of said rotor such that a sealing engagement is formed between said elastomeric surface and the other of said stator former and said rotor creating at least one fluid space through which drilling fluid is pumped to rotatively drive said rotor within said housing thereby driving said drilling tool, said elastomeric material having a substantially uniform thickness to form a helical sealing surface.
12. The drilling motor as defined in claim 11 wherein a plurality of helical spaces are formed between said stator former and said housing, said helical spaces filled with an elastomeric resin to provide added support of said stator former.
13. The drilling motor as defined in claim 11 wherein said elastomeric material forms a helical sleeve bonded to one of said helical inner surface of said stator former and said helical outer surface of said rotor.
CA 2058080 1990-12-20 1991-12-19 Composite stator construction for downhole drilling motors Expired - Lifetime CA2058080C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US63224790A 1990-12-20 1990-12-20
US07/632,247 1990-12-20

Publications (2)

Publication Number Publication Date
CA2058080A1 CA2058080A1 (en) 1992-06-21
CA2058080C true CA2058080C (en) 1997-11-18

Family

ID=24534732

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2058080 Expired - Lifetime CA2058080C (en) 1990-12-20 1991-12-19 Composite stator construction for downhole drilling motors

Country Status (7)

Country Link
CA (1) CA2058080C (en)
DE (1) DE4141851C2 (en)
FR (1) FR2670838B1 (en)
GB (1) GB2255594B (en)
HU (1) HU207569B (en)
MX (1) MX9102551A (en)
NL (1) NL9102097A (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19821867A1 (en) * 1998-05-15 1999-11-18 Artemis Kautschuk Kunststoff Downhole deep drilling motor based on eccentric mono-pump principle
US6905319B2 (en) 2002-01-29 2005-06-14 Halliburton Energy Services, Inc. Stator for down hole drilling motor
US7549487B2 (en) 2006-08-07 2009-06-23 Coiled Tubing Rental Tools, Inc. Mandrel and bearing assembly for downhole drilling motor
US7624819B1 (en) 2008-08-01 2009-12-01 Coiled Tubing Rental Tools, Inc. Universal joint assembly
US8869917B2 (en) 2011-06-22 2014-10-28 Coiled Tubing Rental Tools, Inc. Housing, mandrel and bearing assembly for downhole drilling motor
US8899351B2 (en) 2012-07-16 2014-12-02 Halliburton Energy Services, Inc. Apparatus and method for adjusting power units of downhole motors
CN103758756B (en) * 2014-01-22 2016-01-06 中国石油天然气股份有限公司 Balanced type metal screw pump

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2527673A (en) * 1947-02-28 1950-10-31 Robbins & Myers Internal helical gear pump
US3499389A (en) * 1967-04-19 1970-03-10 Seeberger Kg Worm pump
FR2349729A1 (en) * 1976-04-27 1977-11-25 Tiraspolsky Wladimir Hydraulic machine with helical rotor - has internal and external helices assembled from separately machined longitudinal sections
DE2713468C3 (en) * 1977-03-26 1982-09-02 Allweiler Ag, 7760 Radolfzell Stator for progressing cavity pumps
US4265323A (en) * 1979-09-13 1981-05-05 Christensen, Inc. Direct bit drive for deep drilling tools
US4676725A (en) * 1985-12-27 1987-06-30 Hughes Tool Company Moineau type gear mechanism with resilient sleeve
EP0358789A1 (en) * 1988-09-14 1990-03-21 FOREG Aktiengesellschaft Stator for an eccentric worm pump
DE4006339C2 (en) * 1990-03-01 1994-08-04 Gd Anker Gmbh & Co Kg Stator for an eccentric screw pump

Also Published As

Publication number Publication date
FR2670838B1 (en) 1995-07-07
DE4141851C2 (en) 1995-10-26
GB2255594B (en) 1994-07-20
HU913691D0 (en) 1992-02-28
GB2255594A (en) 1992-11-11
NL9102097A (en) 1992-07-16
MX9102551A (en) 1992-06-01
GB9125527D0 (en) 1992-01-29
FR2670838A1 (en) 1992-06-26
DE4141851A1 (en) 1992-07-02
CA2058080A1 (en) 1992-06-21
HU207569B (en) 1993-04-28
HUT59735A (en) 1992-06-29

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