GB2406591A

GB2406591A - Centraliser for drill or production strings

Info

Publication number: GB2406591A
Application number: GB0321744A
Authority: GB
Inventors: Karl Schmidt
Original assignee: ENVIROSPEC ENERGY SERVICES
Current assignee: ENVIROSPEC ENERGY SERVICES
Priority date: 2003-09-17
Filing date: 2003-09-17
Publication date: 2005-04-06
Anticipated expiration: 2023-09-17
Also published as: GB2406591B; GB0321744D0

Abstract

A drill pipe 9 includes blades 5 and a wear protection band 6. The blades and band are formed of composite material and are either bonded or pre-moulded to the drill pipe.

Description

240659 1

Description

The invention relates to composite material for rotary drilling and production equipment and in particular to profiled elements, in form of blades, half shells or solids bonded and or moulded to the drill-pipe, tubing or casing.

In the field of prospecting (drilling) for and production from oil and gas deposits, extensive use is made of rotary drill-pipe string made up of single joint of drill-pipe and possibly other tubular elements which are joined together end to end via threaded connections.

A drill string typically comprises a long string of connected drill-pipe section that extend from the surface into a well bore followed by the drill bit at the bottom of the drill string. Casing is typically installed at various depth throughout the well bore from the surface to prevent the wall of bore from caving in; to prevent the transfer of fluids from various drilled formation from entering the well bore and visa versa; and to provide a means for recovering oil and or gas if the well is found to be productive.

During rotary drilling the drill pipe is subjected to shock and abrasion whenever the drill pipe comes into contact with the walls of the well bore or the casing itself In many cases the drill pipe extends under ground along a curved path, rather than extending vertically; and in these instances a considerable amount of torque can be induced created by frictional forces developed as a result of rotating the drill pipe with its tool joints coming into contact with the casing or the wall of the well bore.

In the past drill pipe protectors have been placed at different location along the length of drill pipe to keep the drill pipe and its tool joints away from the wall of the casing and or well bore. These protectors are typically made from rubber or other elastomeric materials. Those protectors are typically clamped onto the O.D. of the drill pipe and thus offer some wear protection for the casing, however they often become loose and frequently are the source of generating high torque.

Although wear protection for the casing is paramount the drill pipe also needs protecting without the increase of torque.

In the past the problem of casing wear protection along with torque reducing and drill pipe wear have addressed through improvement in Low friction alloys typically applied as a weld build up to the drill pipe tool joint O.D. To date experience has shown than these techniques have only been marginally effective and that any welding on fully heat-treated steel such as drill-pipe can change the metallurgical property of the steel thus compromising the mechanical properties.

This invention provides a type of protection that offers wear resistance for the drill pipe and wear protection for the casing without the need for welding and or any heat source, using a composite structure of a totally non metallic nature, it offers high abrasion resistance, extremely strong adhesion and high compression loading. Apart from offering abrasion resistance and standoff, by centralising the drill string within the well bore, it also act as skewer to help convey debris produced by the drill bit, thus enhances hole cleaning and optimises the flow of drilling fluid ECD (equivalent circulating density).

FIG 1: is a view in side elevation of a drill-pipe including its length are a number of composite material blades and wear protection bands according to the invention.

FIG 2: is a view on a larger scale of the wear protection band moulded to the tool joint or bonded to the tool joint as 2 half shells.

FIG 3: is a view on a larger scale of composite material blades moulded to the drill pipe, or as pre-moulded blades bonded to the drill-pipe.

1. Geological formation and or casing.

2. Direction of Drill-pipe movement with right hand rotation.

3. Debris (cuttings created by the drill bit.

4. Pin Tool joint.

5. Composite material blade 6. Composite material wear protection band 7. Direction of drilling fluid and cuttings.

8. Box tool joint.

9. Drill-pipe body.

10. Composite material blade.

11. Composite material wear protection band moulded directly to tool joint.

1 la. Composite material wear protection band and or stop collar, 2 half shells bonded to tool joint or the Pipe body.

12 Composite material blade moulded directly to drill pipe body.

12a. Composite material pre-moulded blade of various shape and sizes, straight or helical, bonded to drill-pipe body.

Claims

Claims relating to Patent application no. 031744.5 dated 17/09/2003

Claims.

1) Accessories to drill string and or production tubing string for the use inside a borehole in an underground formation, and or casing and tubing installed in such a formation. The accessories (6,10,11,12) are attached to the outside surface or the drill pipe and or tubing (8,9) thus having an outside diameter larger than the drill pipe or tubing and substantially less than the inside diameter of the borehole in an underground formation or that of casing and tubing installed in such formation 2) The shape and size of the accessories (6.10. l l,12) may vary but are generally in the form of blade, fins or half-shells.

3) The accessories are manufacture from a composite material and are premoulded to a precise shape and tolerance to fit the mating drill pipe or tubing outside diameter.

4) The accessories are attached to the outside diameter of the drill pipe or tubing using a specially adapted bonding agent (glue).

5) Each drill pipe or tubing may have one or several accessories attached to its outside diameter, linear to its longitudinal axis or helically along its longitudinal axis or both.