A CENTRALIZER WITH LOW FRICTION BUTTONS AND METHOD OF FABRICATION THEREOF

Abstract

A centralizer with low friction buttons comprising a plurality of collars including a first collar and a second collar; a plurality of bow springs, each bow spring having a first end and a second end; and a plurality of low friction buttons. The plurality of bow springs extend between the first and second collar such that the first and second end of each bow spring is connected to the first and second collar respectively; the plurality of low friction buttons are mounted on the bow springs such that they act as the only point of contact between the centralizer and borehole during movement of the pipe casing while getting it to the total depth during drilling operation, said buttons being of the type whose coefficient of friction is lesser than the rest of the body of the centralizer.

Claims

1. A centralizer provided for lowering friction comprising: a plurality of collars including a first collar and a second collar; and a plurality of bow springs, each bow spring having a first end and a second end; wherein a plurality of buttons are mounted on said plurality of bow springs such that the first and second end of each bow spring is connected to the first and second collar respectively; the plurality of buttons are mounted on the bow springs such that at least one button from any plurality of bow springs is in contact with the borehole wall and act as the only/preferable point of contact between the centralizer and borehole; and said low friction buttons having low coefficient of friction than the rest of the body thus reducing torque and drag, thereby increasing the longevity of the centralizer.

2. The centralizer as claimed in claim 1, wherein the low friction buttons are mounted on the bow springs such that they constitute the air gaps between borehole wall and the centralizer, thereby allowing said low friction buttons to touch on the borehole wall during run in the hole, providing minimum loss of the applied torque and high running force to the centralizer.

3. The centralizer as claimed in claim 1, wherein said low friction buttons are composed of metal alloy.

4. The centralizer as claimed in claim 3, wherein said metal alloy is preferably stainless steel.

5. The centralizer as claimed in claim 1, wherein said centralizer is designed for open-hole and cased-hole logging applications.

6. The centralizer as claimed in claim 1, wherein the coefficient of friction of said low friction buttons in water-based mud ranges from 0.10-0.15.

7. The centralizer as claimed in claim 1, wherein the coefficient of friction of said low friction buttons in oil-based mud ranges from 0.05-0.10.

8. The centralizer as claimed in claim 1, wherein the buttons are fitted in holes punched on centralizer.

9. The centralizer as claimed in claim 8, wherein the holes are preferably oval with transverse diameter in range of 11-17 mm and longitudinal diameter in range of 13-15 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and brief description:

[0028] FIG. 1 is a perspective view of the centralizer in accordance with the present invention.

[0029] FIG. 2 is a schematic diagram elucidating the role of low friction buttons during run in the borehole.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In the drawings and description that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness.

[0031] Disclosed herein is a centralizer for use either in open or cased-hole applications. The centralizer described herein may be coupled to a wellbore tubular.

[0032] Referring to FIG. 1, an example of perspective view of the centralizer 100 in accordance with the present invention is shown. As depicted, the centralizer 100 comprises first collar 101, second collar 102, a plurality of bow springs 103 connecting the collars 101, 102. Plurality of bow springs 103 further comprises a specially designed button 104 buttons made up of stainless steel or material with similar wear properties, integrated into the centralizer 100 fabricated on the first contact points or within highly deviated portion of centralizer having radially outward protrusion, so as to act as the first point of contact on the centralizer and help to reduce the wear and abrasion of the centralizer, by acting as the point of contacts and reducing the co-efficient of friction and consequently reducing the torque.

[0033] The collars 101 and 102, and the plurality of bow springs 103 may be formed from steel, a composite, or any other similar high strength material.

[0034] The centralizer 100 or its parts may be formed from one or more composite materials. A composite material comprises a heterogeneous combination of two or more components that differ in form or composition on a macroscopic scale.

[0035] In another preferred embodiment of the present invention, the stainless steel buttons are placed inside the collars as well.

[0036] Referring to FIG. 2, a low friction button 105 is mounted on the centralizer 100, fitted closely to the outer surface of the pipe casing 104. During drilling operation, the pipe casing 104 moves in the borehole 108, in order to get itself to the total depth of the borehole. During this run-in-hole (RIH) process, the low friction button 105 touches the borehole 108 wall and help to reduce the start-up torque while running of the pipe casing 104. It gives the centralizer 100 extremely low co-efficient of friction as only the low friction button 105 contact the hole and no part of bow spring is in touch with the borehole 108. Thus, an air cushion is formed between the bow springs and the borehole 108. In such a way, the low friction button 105, reduce drag during RIH.

[0037] The centralizer 100 is able to get pipe down through tangent and build sections where the friction forces are greatest due to side loading. The low friction button make the lowering and running of pipe casing 104 extremely easy.

[0038] The holes are punched in the centralizer sheet wherein the holes are preferably oval with transverse diameter in range of 11-17 mm and longitudinal diameter in range of 13-15 mm. More particularly, the holes are punched with profile 13.5-14.5 mm/11.5-12.5 mm and counter punched with maximum limit of 16.5 mm.

[0039] When the centralizer is in operation, due to specially designed button which comprises of stainless steel or material with similar wear properties, integrated into the centralizer, fabricated on the first contact points or within highly deviated portion of centralizer having radially outward protrusion, act as the first point of contact on the centralizer and help to reduce the wear and abrasion of the centralizer, thereby reducing the co-efficient of friction and consequently reducing the torque.

[0040] As those with ordinary skill in the art will understand, various features illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative examples that are not explicitly illustrated and described. The combinations of features illustrated provide representative examples for typical centralizer. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. Those with ordinary skill in the art will recognize that the teachings of the present disclosure may be applied to other applications or implementations.

[0041] While the best mode has been described in detail, those familiar with the art will recognize various alternative designs within the scope of the following claims.