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Title:
SYSTEM AND METHOD FOR ENGAGING AND DISENGAGING DRILL BIT OR OTHER DEVICE TO DOWNHOLE DRIVE SYSTEM
Document Type and Number:
WIPO Patent Application WO/2017/074259
Kind Code:
A1
Abstract:
A drive system housing is provided with an engagement-disengagementmechanism that is advantageous to connect (make up) or disconnect (break out)drill bit or other device connection from the drive system housing. The drive systemhousing comprises: an upper housing and a lower housing connected thereto by athreaded connection provided at a first end of the lower housing, wherein the upperand the lower housing define an axis; and a plurality of castellations projectingsubstantially axially from a second end of the lower housing and circumferentiallyspaced around the axis, wherein at least partially unscrewing the threadedconnection is configured to cause axial displacement of the lower housing towardsa drive shaft which is coaxially positioned within the upper and the lower housing,and wherein the axial displacement of the lower housing towards the drive shaft isconfigured to compel the castellations of the lower housing into mating engagementwith complementary castellations provided at the drive shaft.

Inventors:
MORIN ANDREW DAVID (AU)
RAFFAN PETER JAMES LOCHORE (SG)
Application Number:
PCT/SG2016/050521
Publication Date:
May 04, 2017
Filing Date:
October 25, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
TURBODYNAMICS PTE LTD (SG)
International Classes:
E21B19/18; E21B4/00; E21B7/06; E21B17/20; E21B19/16; E21B23/02
Foreign References:
US20140262530A12014-09-18
US20140251695A12014-09-11
US4739842A1988-04-26
US20040011520A12004-01-22
US20140231144A12014-08-21
Attorney, Agent or Firm:
AMICA LAW LLC (#14-01 Chevron House, Singapore 2, SG)
Download PDF:
Claims:
What is claimed is:

1 . A drive system housing comprising: an upper housing and a lower housing connected thereto by a threaded connection provided at a first end of the lower housing, wherein the upper and the lower housing define an axis; and a plurality of castellations projecting substantially axially from a second end of the lower housing and circumferentially spaced around the axis, wherein at least partially unscrewing the threaded connection is configured to cause axial displacement of the lower housing towards a drive shaft which is coaxially positioned within the upper and the lower housing, and wherein the axial displacement of the lower housing towards the drive shaft is configured to compel the castellations of the lower housing into mating engagement with complementary castellations provided at the drive shaft.

2. The housing of claim 1 , wherein at least partially screwing the threaded connection is configured to cause axial displacement of the lower housing away from the drive shaft, and wherein the axial displacement of the lower housing away from the drive shaft is configured to compel the castellations of the lower housing to disengage from the complementary castellations of the drive shaft.

3. The housing of any one of claims 1 to 2, further comprising: a stabilizer mounted at least around the complementary castellations of the drive shaft.

4. The housing of any one of claims 1 to 3, wherein a second end of the drive shaft is provided with one of box connection and pin connection.

5. The housing of any one of claims 1 to 3, wherein a second end of the drive shaft is connectable to a drill bit. 6. The housing of any one of claims 1 to 5, wherein the upper housing forms part of a downhole drive system which is selected from the group consisting of turbodrill and positive displacement motor.

7. A downhole drive system comprising the drive system housing of any one of claims 1 to 6.

8. A method operative at a lower housing of a drive system housing, wherein a first end of the lower housing is connected by a threaded connection to an upper housing of the drive system housing, wherein the upper and the lower housing define an axis, the method comprising: at least partially unscrewing the threaded connection to cause axial displacement of the lower housing towards a drive shaft which is coaxially positioned within the upper and the lower housing, and thereby compelling castellations at a second end of the lower housing into mating engagement with complementary castellations provided at a first end of the drive shaft, wherein the castellations at the second end of the lower housing are projecting substantially axially therefrom and circumferentially spaced around the axis.

9. The method of claim 8, further comprising: mounting a stabilizer at least around the complementary castellations of the drive shaft.

10. The method of any one of claims 8 to 9, further comprising: applying a rig tong to the lower housing to connect or disconnect the drive shaft from the upper housing. 1 1 . The method of any one of claims 8 to 10, wherein a second end of the drive shaft is provided with one of box connection and pin connection.

12. The method of any one of claims 8 to 10, wherein a second end of the drive shaft is connectable to a drill bit.

13. The method of any one of claims 8 to 12, wherein the drive system housing forms part of a downhole drive system which is selected from the group consisting of turbodrill and positive displacement motor.

14. The method of claim 8, further comprising: at least partially screwing the threaded connection to cause axial displacement of the lower housing away from the drive shaft, and thereby compelling the castellations at the second end of the lower housing to disengage from the complementary castellations provided at the first end of the drive shaft.

15. A method operative at a lower housing of a drive system housing, wherein a first end of the lower housing is connected by a threaded connection to an upper housing of the drive system housing, wherein the upper and the lower housing define an axis, the method comprising: at least partially screwing the threaded connection to cause axial displacement of the lower housing away from a drive shaft which is coaxially positioned within the upper and the lower housing, and thereby compelling castellations at a second end of the lower housing to disengage from complementary castellations provided at a first end of the drive shaft, wherein the castellations at the second end of the lower housing are projecting substantially axially therefrom and circumferentially spaced around the axis.

16. The method of claim 15, wherein a second end of the drive shaft is provided with one of box connection and pin connection.

17. The method of any one of claims 15 to 16, wherein a second end of the drive shaft is connectable to a drill bit or other device.

18. The method of any one of claims 15 to 17, wherein the drive system housing forms part of a downhole drive system which is selected from the group consisting of turbodrill and positive displacement motor.

Description:
SYSTEM AND METHOD FOR ENGAGING AND DISENGAGING DRILL BIT OR OTHER DEVICE TO DOWNHOLE DRIVE SYSTEM

Field of the Invention

The invention relates to engagement and disengagement mechanism for downhole drive system, and method of operating the mechanism.

Background

In order to connect a drill bit or other device to a downhole drive system drive shaft, e.g. Turbodrill or positive displacement motor (PDM) or other similar drilling machine, a male and female threaded connection is generally used, which may either have a "Pin Down" or male thread on the drive system shaft for connection to a "Box Up" or female thread on the drill bit or other device. Alternatively, a "Box Down" or female thread may be provided on the drive system shaft for connection to a "Pin Up" or male connection on the drill bit or other device.

A common method of connecting the drill bit or other device particularly with PDM is to use a drive shaft with an extended section allowing a rig tong to be applied directly thereon. A rig tong is a standard piece of equipment found and used on drilling rigs for the purpose of torqueing and un-torqueing threaded connections used in the drill string of a drilling assembly. In this case, the drill bit or other device generally has slots incorporated to allow a steel plate known as a breaker plate to be fitted into the slots. The breaker plate is placed and securely engaged into the rotary table on a drilling rig. The standard rig tong then applies the necessary torque to assemble (make up) or disconnect (break out) the drill bit or other device to or from the drive shaft connection.

For various reasons, particularly with Turbodrills, it is sometimes beneficial or necessary to reduce the length of the portion of the drive shaft that extends from the lower end of the drive system housing. In order to achieve an ideal minimal length, this consequently results in insufficient length of the protruding drive shaft, which may be either "Pin Down" or "Box Down", to apply the standard rig tong directly onto the drive shaft. This necessitates an additional device or means to lock the drive shaft to the drive system housing. The rig tong may then be applied directly to the additional device or in some cases to the housing rather than the drive shaft in order to impart the necessary torque to connect (make up) or disconnect (break out) the drill bit or other device connection.

In one existing solution, a system whereby a clamp, usually in two halves, is bolted together around the end of the drive shaft to allow application of the standard rig tong on the larger outer diameter of the clamp. However, this solution still requires some shaft length to allow engagement of the clamp on the shaft. This solution also necessitates positioning and bolting or securing of the clamp and removal of the same which can be a time consuming process. In another existing solution described by Downie et al in WO 2010/106335

A2, a "lock and key" device is placed through the housing to engage with the drive shaft. However, this solution has limitations in relation to the amount of torque or force that can be safely applied. Accordingly, this solution may not be applicable to downhole drive systems with larger outer diameter (OD) sizes which require relatively high torque for connecting (make up) or disconnecting (break out) the drill bit or other device.

Summary of the Invention

Embodiments of the invention provide a simple yet very robust engagement/disengagement mechanism in a drive system housing, which reduces the length of the portion of the drive shaft that extends from the lower end of the drive system housing yet allows direct application of rig tong to the housing to impart the necessary torque to connect (make up) or disconnect (break out) the drill bit or other device connection.

According to a first aspect of the invention, a drive system housing is provided. The drive system housing comprises: an upper housing and a lower housing connected thereto by a threaded connection provided at a first end of the lower housing, wherein the upper and the lower housing define an axis; and a plurality of castellations projecting substantially axially from a second end of the lower housing and circumferentially spaced around the axis, wherein at least partially unscrewing the threaded connection is configured to cause axial displacement of the lower housing towards a drive shaft which is coaxially positioned within the upper and the lower housing, and wherein the axial displacement of the lower housing towards the drive shaft is configured to compel the castellations of the lower housing into mating engagement with complementary castellations provided at the drive shaft.

According to a second aspect of the invention, the drive system housing of the first aspect of the invention forms part of a downhole drive system.

According to a third aspect of the invention, a method is provided and operative at a lower housing of a drive system housing, wherein a first end of the lower housing is connected by a threaded connection to an upper housing of the drive system housing, wherein the upper and the lower housing define an axis. The method comprises: at least partially unscrewing the threaded connection to cause axial displacement of the lower housing towards a drive shaft which is coaxially positioned within the upper and the lower housing, and thereby compelling castellations at a second end of the lower housing into mating engagement with complementary castellations provided at a first end of the drive shaft, wherein the castellations at the second end of the lower housing are projecting substantially axially therefrom and circumferentially spaced around the axis.

According to a fourth aspect of the invention, a method is provided and operative at a lower housing of a drive system housing, wherein a first end of the lower housing is connected by a threaded connection to an upper housing of the drive system housing, wherein the upper and the lower housing define an axis. The method comprises: at least partially screwing the threaded connection to cause axial displacement of the lower housing away from a drive shaft which is coaxially positioned within the upper and the lower housing, and thereby compelling castellations at a second end of the lower housing to disengage from complementary castellations provided at a first end of the drive shaft, wherein the castellations at the second end of the lower housing are projecting substantially axially therefrom and circumferentially spaced around the axis.

Brief Description of the Drawings The invention will be described in detail with reference to the accompanying drawings, in which:

Figure 1 A is a partial see-through view of a drive shaft having a box connection and arranged in an engaged position according to one embodiment of the invention; Figure 1 B is a partial see-through view of the drive shaft of Figure 1 A arranged in a disengaged position;

Figure 1 C is a perspective view of Figure 1 A with the optional stabiliser removed from the lower housing;

Figure 1 D is a perspective view of Figure 1 B with the optional stabiliser removed from the lower housing;

Figure 2A is a partial see-through view of a drive shaft having a pin connection and arranged in an engaged position according to one embodiment of the invention;

Figure 2B is a partial see-through view of the drive shaft of Figure 2A arranged in a disengaged position;

Figure 2C is a perspective view of Figure 2A with the optional stabiliser removed from the lower housing; and Figure 2D is a perspective view of Figure 2B with the optional stabiliser removed from the lower housing.

Detailed Description of Embodiments of the Invention

In the following description, numerous specific details are set forth in order to provide a thorough understanding of various illustrative embodiments of the invention. It will be understood, however, to one skilled in the art, that embodiments of the invention may be practiced without some or all of these specific details. It is understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the invention. Embodiments of the invention provide a system and method for engaging a drive system housing 100 to a drive shaft 30, and disengaging the drive system housing 100 from the drive shaft 30.

Reference is made to Figures 1 A to 1 D illustrating one embodiment having a box connection drive shaft 30. Figures 1 A and 1 C show the drive shaft 30 and lower housing 20 in an engaged position. Figures 1 B and 1 D show the drive shaft 30 and lower housing 20 in a disengaged position.

The drive system housing 100 comprises: an upper housing 10 and a lower housing 20 which define an axis. A first end of the lower housing 20 is threaded or provided with a threaded connection 12, and is to connect to a threaded end of the upper housing 10 by threaded engagement. At a second end of the lower housing 20, a set of one or more castellated or splined sections or castellations 22 project substantially axially therefrom and are circumferentially spaced around the axis. The castellations 22 may be machined on the lower housing 20.

At the drive shaft 30 which is coaxially positioned within the lower 10 and the upper housing 20, a complement set of one or more castellated or splined sections or complementary castellations 32 are provided or machined thereon. In particular, the complementary castellations 32 are formed on an annular structure which is integrally formed at or fixedly coupled to a portion of the drive shaft 30, project substantially in the axial direction and are circumferentially spaced around the axis. Both sets of castellated or splined sections 22, 32 are suitably dimensioned and arranged to allow mating engagement of the drive shaft 30 to the lower housing 20.

Starting from a disengaged position (Figures 1 A and 1 C), un-torqueing and at least partially unscrewing the lower housing 20 is performed. Due to a threaded engagement between the lower housing 20 and the upper housing 10, un-torqueing and at least partially unscrewing the lower housing 20 results in a relative displacement or axial displacement of the lower housing 20 (and its castellated or splined sections 22) towards the drive shaft 30 (and its castellated or splined sections 32) until both sets of castellated or splined sections 22, 32 are brought into mating engagement. The drive shaft 30 and lower housing 20 are now engaged and secured to each other (Figures 1 B and 1 D), a rig tong can then be applied directly to the lower housing 20 in order to connect (make up) or disconnect (break out) the drill bit or other device connection to or from the drive system housing 100. The drill bit or other device (not shown) may be a separate element connectable to the box connection 34a or an integral element formed with the box connection 34a of the drive shaft 30.

Disengaging the drive shaft 30 from the lower housing 20 is simply a reverse of the above-described procedure. Starting from an engaged position (Figures 1 B and 1 D), at least partially screwing back together the threaded connection 12 between the lower housing 20 and upper housing 10 and re-torqueing results in a relative displacement or axial displacement of the lower housing 20 (and its castellated or splined sections 22) away from the drive shaft 30 (and its castellated or splined sections 32) until both sets of castellated or splined sections 22, 32 are disengaged. It is to be appreciated that the above-described engagement and disengagement mechanism and procedure in relation to a drive shaft 30 having a box connection 34a as illustrated in Figures 1 A to 1 D are equally applicable to a drive shaft 30 having a pin connection 34b as illustrated in Figures 2A to 2D.

It is to be appreciated that the invention may be applied to downhole drive systems such as, but not limited to, turbodrills, positive displacement motors (PDM) or other similar drilling machines. It is to be appreciated that the invention provides a simple yet very robust engagement/disengagement mechanism which can be applied to all outer diameter sizes and torque values of downhole drive systems, and can be utilized with either "Pin Down" or "Box Down" drive shaft connections. The invention also does not require specific tooling and thus resulting in shorter overall handling time. The invention also negates the requirement of any clamp to engage on the drive shaft or any key and lock device to fully and securely engage the drive system housing to the drive shaft.

It is to be appreciated that the optional stabiliser 40 shown in Figures 1 A and 2A does not form any part of the engagement/disengagement mechanism or procedure which is equally applicable with or without a stabiliser fitted on the lower housing. In certain embodiments requiring a stabiliser 40, the stabiliser 40 is mounted at least around the complementary castellations 32 of the drive shaft 30.

It is to be understood that the embodiments and features described above should be considered exemplary and not restrictive. Many other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. Furthermore, certain terminology has been used for the purposes of descriptive clarity, and not to limit the disclosed embodiments of the invention.