Patent Application
20070163778
The present invention relates generally to well casing couplings and well casing centralizers. More particularly, relating to a combined well casing coupling and centralizer that is suitable for use in drilling with casing operations.
In a standard operation of drilling and completing an oil well multiple steps are performed through the process. First, a bore hole of a desired diameter and depth is drilled into a formation using a drill bit and a drill string comprising of coiled tubing or multiple sections of rigid drilling pipe coupled together. Once the bore hole has been drilled, the drill string is removed from the bore hole and a casing string is inserted. The casing string includes multiple sections of pipe connected end-to-end by threaded couplings. Centralizing devices are attached along the length of the casing at regular intervals to center the casing within the bore hole so when the casing is cemented in the bore hole the cement is evenly distributed around the casing. Most of these centralizers have an outside diameter (OD) equal to or smaller than the bore hole interior diameter (ID). Others yet can have a greater OD and include spring loaded mechanisms that compress to conform to the bore hole ID.
Many types of centralizers have been used in the industry and the centralizers range from devices that are attached to the casing by a friction system, are bolted on, are positioned around the casing between the casing couplings or are formed as part of a casing coupling.
Examples of casing centralizers can be found in U.S. Pat. Nos. 6,464,013; 5,575,333; 4,595,058; 3,762,472; 2,309,791 and 1,807,050.
Recently, new developments have been made in the art of drilling and completing a well which remove the step of using a separate drill string and casing string to complete a well. In the drilling of shallow to medium depth formations advancements have been made that allow the use of the casing string as the drill string, thereby eliminating the need of using a separate drill string, this operation is typically termed “drilling with casing”.
While the need to use a separate drill string is eliminated in drilling with casing, the casing must still be centralized in order to be properly cemented. The prior art centralizers are not capable of standing up to the force and abuse to which they are subjected during a drilling operation. As such, the present invention provides a centralizer that withstands the force and abuse during the drilling operation while maintaining a highly regulated specification for use, which is not attainable by prior art centralizers.
In accordance with the present invention, a casing centralizer coupling which meets strict American Petroleum Institute (API) specifications and is capable of use in drilling with casing operations is provided.
In general, in one aspect, a casing centralizer coupling is provided. The coupling includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. And each of the plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section
In general, in another aspect, a casing centralizer coupling is provided. The coupling includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. Each of the plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section and opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges.
In general, in another aspect, a casing centralizer coupling is provided. The coupling includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. Each of the plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section and opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges. And at least a portion of each of the plurality of centralizing blades are hard faced.
In general, in another aspect, a combined casing coupling and casing centralizer is provided. The combined casing coupling and casing centralizer includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. Each of said plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section, opposed outwardly beveled transverse edges, opposed outwardly beveled longitudinal edges, and wherein at least the outwardly facing surface is hard faced.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.
Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.
The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:
The same reference numerals refer to the same parts throughout the various figures.
Referring now to the drawings, and particularly to
Now with reference to
With reference to
The casing centralizer coupling 10 includes a plurality of centralizing blades 20 arranged radially around and project outwardly from an exterior surface 22 of the body 12. Each centralizing blade 20 extends along a length of the exterior surface 22 in a general longitudinal direction. Each centralizing blade 20 includes outwardly beveled transverse edges 24 and 26, outwardly beveled longitudinal edges 28 and 30, and an outwardly facing surface 32 having an arcuately shaped transverse cross section. The outwardly facing surface 32 can be hard faced.
As can be seen in
Additionally, the outwardly beveled transverse edges 24 and 26 clearly shown in
Each centralizing blade 20 having the unique transverse and longitudinal profiles can either be formed integrally with the body 12 for example through integral machining or casting. Preferably, the blades 20 are of a multi-component construction formed onto the body 12 using a specialized process.
With reference to
The multi-component centralizing blade is created by a specialized process which results in a casing centralizing collar that meets current American Petroleum Institute (API) Grade specifications. The specialized process includes welding the core member 40 to the exterior surface 22 of the body 12 using a welder, such as a pulse arc GMAW robot welder, thereby making the core member integral with the body. The first, second, third and fourth fillet members 42, 44, 46, 48 are formed by the welder in the process of welding the core member 40 to the body 12. The use of a pulse arc GMAW robot welder eliminates the requirement of preheating the body 12 to reduce deformation caused by heat generated by a standard MIG welder.
The process further includes a step of forming the surface member 50 onto the core member 40 as illustrated. The surface member 50 is formed of a hard face material which is deposited upon the core member 40 using a robot plasma system. The core member 40 acts as a heat sink during this process and absorbs and dissipates a sufficient amount of heat generated during the deposition of the hard face material so that the body 12 is not dimensional distorted. Hard facing is defined as the application of a hard material on the surface of a softer material or substrate. The hard face material of the surface member 50 is of a tungsten hard facing material comprising tungsten in a matrix, such as a chromium nickel (CrNi) matrix. Most preferably, of a tungsten carbide hard facing material comprising tungsten carbide in a matrix, such as chromium nickel (CrNi).
In a test sample, the core member 40 was a flat bar having a dimension of 0.25 inches×0.75 inches and the body was a standard API L casing coupling. However, other casing couplings having API 5B, 5CT and 5C2 specification can also be utilized. It is contemplated that other API standard couplings could reasonably be used. Further, any casing coupling having specifications defined by another system which meet or exceed the API standards could also be used.
The test sample demonstrated a Vickers hardness, tensile strength and bend test results of the HAZ and other critical areas of the casing centralizer coupling meeting API N-80 specifications.
In a further step, the casing centralizer coupler 10 can be H2S environment certified by post weld heat treating the core member 40 prior to depositing the hard facing material of the surface member onto the core member 40.
With reference to
A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
