Method and apparatus for cleaning internal surfaces of downhole casing strings and other tubular goods
A downhole cleaning assembly and method of cleaning a tubular. Generally, the downhole assembly is connected to a work string concentrically located within a casing string. In one embodiment, the downhole assembly comprises a tool body operatively connected to a work string. At least one pad member is connected to the tool body, with the pad member having cutting technology, such as, for example, hardened elements or “inserts,” (commonly used in connection with drill bits) along certain outer peripheral surfaces of the pad member. Such cutting technology includes, but is not necessarily limited to, Polycrystalline Diamond Compact (PDC) inserts, tungsten carbide inserts or diamond bit elements commonly used in connection with drill bit technology.
THIS APPLICATION CLAIMS THE BENEFIT OF, AND PRIORITY FROM, U.S. PROVISIONAL PATENT APPLICATION SER. NO. 61/126,333 FILED MAY 2, 2008, SER. NO. 61/128,724 FILED MAY 23, 2008, AND SER. NO. 61/134,853 FILED JUL. 14, 2008, WHICH ARE INCORPORATED BY REFERENCE HEREIN.
STATEMENTS AS TO THE RIGHTS TO THE INVENTION MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENTNONE
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention pertains to a method and apparatus for removing debris from the inner surfaces of well bores. More particularly, the present invention pertains to a method and apparatus for mechanically removing dried cement and other hardened debris from internal surfaces of casing and/or other tubular goods. More particularly still, the present invention pertains to a method and apparatus for cleaning the inner surfaces of casing strings and/or other tubular goods using cutting technology, such as, for example, hardened elements or inserts.
2. Brief Description of the Prior Art
It is frequently desirable to remove cement and/or other debris from internal surfaces of oil or gas wells. In many instances, it is especially beneficial to remove dried cement and/or other debris from internal surfaces of casing strings and other tubular goods installed in well bores.
After a well has been drilled to a desired depth, large diameter pipe called casing is typically installed in the well and cemented in place. Such casing provides structural integrity to the well bore, and isolates downhole formations from one another. After a sufficient length of casing is installed into a bore hole, cement is typically pumped down the internal bore of said casing, out the bottom of the casing, and up the annular space existing between the outer surface of the casing and the inner surface of the bore hole. When the cement hardens, a cement sheath is formed around the outer surface of the casing.
During cementing operations, a portion of the cement that is pumped down the inner bore of the casing often adheres or sticks to the inner surfaces of the casing. Additionally, drilling mud (typically containing suspended solids and/or additives) can likewise adhere or stick to the inner surfaces of the casing or other tubular goods. Such cement and other debris can negatively impact the ultimate productivity of a well. Therefore, it is frequently beneficial to clean the inner surfaces of the casing string to remove debris (including, without limitation, excess or residual cement), especially in advance of well completion operations.
By way of illustration, but not limitation, it is typically very important to remove cement and/or other debris (such as hardened drilling mud or additives) from internal surfaces of casing prior to engaging in well completion activities. In such cases, drilling mud is totally removed from a well bore, and replaced with brine or other “clear” completion fluid that is less damaging to downhole formations. It is generally very desirable to remove cement and/or other debris from the inner surfaces of the casing before such drilling mud is totally replaced with completion fluid(s).
Although different methods have been employed for this purpose, mechanical cleaning devices have historically been used to remove such cement and other debris from internal surfaces of well bores. For this reason, after casing is cemented in a well, mechanical scraping devices (commonly referred to as “scrapers”) are often conveyed into such well (typically on drill pipe or other tubular workstring) and used to mechanically scrape or abrade the inner surfaces of the casing in order to remove such cement and/or other debris. However, existing scrapers and related devices are inefficient, susceptible to wear, and have provided less than optimal results.
In many cases, existing scrapers fail to fully remove cement and other debris from internal surfaces of casing and other tubular goods. Frequently, existing scrapers can “ride over” cement and other hardened debris adhering to the inner surfaces of the casing and/or other tubular goods, and will fail to break up such cement or other debris for ultimate removal from the well bore. Further, when the amount of cement or other hardened debris on the internal surfaces of casing is excessive, existing scrapers have been known to fail and/or break apart downhole. Such failure can result in portions of the scraper tool being lost in the well, which can negatively impact subsequent operations in the well and/or productivity of such well. In many cases, the amount of cement or other debris present on the internal surfaces of casing is not known when the scrapers are initially being run into a well. While conventional scrapers may be sufficient to remove relatively small amounts of debris from casing, there is great risk that such conventional scrapers can fail or break apart when confronted with greater amounts of cement or other debris.
Thus it is an object of the present invention to efficiently and effectively clean the inner surfaces of casing strings and/or other tubular goods using mechanical scrapers or other devices employing cutting technology, such as, for example, hardened elements or inserts.
SUMMARY OF THE PRESENT INVENTIONThe present invention comprises a method and apparatus for cleaning the internal surfaces of well bores, casing strings and/or other tubular goods using mechanical cleaning assemblies or other devices employing cutting technology, such as, for example, hardened elements or “inserts,” (commonly used in connection with drill bits) disposed along certain outer peripheral surfaces of said cleaning assemblies or other devices. Such cutting technology includes, but is not necessarily limited to, Polycrystalline Diamond Compact (PDC) inserts, tungsten carbide inserts or diamond bit elements commonly used in connection with drill bit technology.
The apparatus of the present invention generally comprises a downhole cleaning assembly. Although said downhole scraper assembly can have many different shapes, sizes and configurations, the present invention as described herein has a general configuration following a conventional “M&M”-type scraper design that is well known to those having skill in the art. However, it is to be observed that the present invention can also be used in connection with other cleaning assemblies, mechanical scrapers and/or downhole tools embodying many different configurations.
In a preferred embodiment, said downhole cleaning assembly is adapted to be connected to a tubular work string and can be concentrically received—and manipulated—within a well bore (especially any casing or other tubular goods installed within such well bore). Such downhole cleaning assembly generally comprises a central mandrel operatively connected to such tubular work string. A central flow bore extends longitudinally through said mandrel, and permits fluid communication with the central bore of said tubular work string.
At least one recess is disposed along the outer peripheral surface of said mandrel, with at least one pad member received within each such at least one recess. In said preferred embodiment, at least one biasing member is operatively positioned between the mandrel and each of said at least one pad members. Said biasing member urges said at least one pad member radially outward relative to said mandrel. When said downhole cleaning apparatus is concentrically received within a well bore, said biasing member beneficially urges said at least one pad member against the inner surfaces of such well bore.
In said preferred embodiment, said pad members have a substantially arcuate shape and are disposed at different points along the length of said mandrel. Further, said pad members are disposed about the periphery of said mandrel, and are phased or staggered circumferentially relative to one another. As such, said pad members have an effective coverage area of 360 degrees around the outer periphery of said mandrel, while forming at least one flow path passing between said pad members. Said flow path permits fluid to flow along the length of the cleaning apparatus, even when said scraper pad members are mechanically contacting the inner surface of a casing string.
In the preferred embodiment, drill bit cutting elements are disposed on or in connection with said pad members. Such bit technology improves the performance of the cleaning assembly in removing dried cement, drilling mud and/or other debris from the internal surfaces of well casing and/or other tubular goods.
Also disclosed herein is a method of cleaning the internal surfaces of tubular goods. The method comprises lowering a work string concentrically within the casing string or other tubular goods to be cleaned. The work string will have provided therewith a downhole cleaning assembly operatively associated with the work string. Pad members of the cleaning assembly are biased against the inner surface of the casing string, thereby resulting in constant pressure of said pad members against the internal casing wall. The method provides for cleaning the inner diameter of the casing string as the downhole cleaning assembly is lowered, rotated and/or reciprocated on such work string. The method further comprises circulating a drilling fluid through the inner bore of the work string, out the bottom of the work string or other bottom hole assembly, and around the outer surface of such bottom hole assembly and work string. The work string may be stationary or rotating during circulation.
An advantage of the present invention includes the ability to thoroughly clean the internal surfaces of casing and other tubular goods of a course material such as cement and other materials. Another advantage is a design that permits easy removal, replacement and/or interchangeability of pad members (and related cutting technology) including, without limitation, at remote locations such as on drilling rigs and the like.
The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed.
Central mandrel 11 has a plurality of recesses formed along its outer peripheral surface, with
Prior art pad members 40 are operatively associated with biasing means 12 (typically helical springs) for biasing said pad members 40 radially outwardly relative to central mandrel 11. When cleaning apparatus 10 is concentrically inserted within casing, spring loaded pad members 40 will allow for substantially constant pressure of the external surfaces of pad member 40 against the casing wall at all times. Additional biasing means 12 may be employed, for instance, when additional force is required to adequately urge the pads radially outward relative to central mandrel 11.
In most cases, prior art pad members 40 are disposed at different points along the length of central mandrel 40 (as depicted in
Referring back to
Central mandrel 11 of cleaning assembly 10 typically has a plurality of recesses (such as recesses 15 and 16) about its outer peripheral surface for placement of additional pad members. With a staggered configuration of multiple pad members 40 about the body of central mandrel 11 (such as depicted in
Central mandrel 111 has a plurality of recesses formed along its outer peripheral surface (including recesses 115 and 116) in much the same manner as central mandrel 11 of prior art cleaning assembly 10 (depicted in
When cleaning apparatus 110 is concentrically inserted within casing 170, spring loaded pad member embodiments 50 will allow for substantially constant pressure of the external surfaces of pad member embodiments 50 against the internal wall surfaces of casing 170. Additional biasing means 112 may be employed, for instance, when additional force is required to adequately urge the pads radially outward relative to central mandrel 111.
Still referring to
Although the apparatus set forth herein is described primarily in connection with scraper tools having removable pad members, it is to be observed that drill bit cutting technology (such as, for example, PDC or tungsten carbide inserts, or diamond bit elements) can be incorporated on any number of different tools in any number of configurations. By way of example, but not limitation, such drill bit cutting technology can be incorporated on the outer surfaces of conventional stabilizers, well bore cleanout tools, mills, stabilizer sleeves, mill sleeves, stabilizer blades and/or other devices, or particular elements thereof, that can be inserted into a well bore. Further, such tools incorporating drill bit cutting technology can be used to mechanically clean the inner surfaces of virtually any tubular goods; such uses are not limited solely to cleaning cement from the inner surfaces of casing.
It is to be further observed that the conventional scraper described herein is just one type of existing scraper embodiment that could be used in accordance with the present invention; other scraper embodiments can also be used.
The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.
Claims
1. A pad member adapted to be received on a scraper tool comprising at least one cutting element disposed on said pad member.
2. The pad member of claim 1, wherein said at least one cutting element comprises at least one polycrystalline diamond compact insert.
3. The pad member of claim 1, wherein said at least one cutting element comprises at least one tungsten carbide insert.
4. The pad member of claim 2, wherein said pad member further comprises:
- a. a body section having at least one bore disposed in said body section; and
- b. a polycrystalline diamond compact insert received within each of said at least one bore.
5. The pad member of claim 3, wherein said pad member further comprises:
- a. a body section having at least one recess in said body section; and
- b. a tungsten carbide insert received within each of said at least one recess.
6. An apparatus for cleaning cement and hardened debris from the inner surface of casing and other tubular goods comprising:
- a. a body having an outer peripheral surface;
- b. at least one pad member disposed along the outer peripheral surface of said body; and
- c. at least one cutting element disposed on said pad member.
7. The apparatus of claim 6, wherein said at least one cutting element comprises at least one polycrystalline diamond compact insert.
8. The apparatus of claim 6, wherein said at least one cutting element comprises at least one tungsten carbide insert.
9. The apparatus of claim 7, wherein said pad member further comprises:
- a. a body section having at least one bore disposed in said body section; and
- b. a polycrystalline diamond compact insert received within each of said at least one bore.
10. The apparatus of claim 8, wherein said pad member further comprises:
- a. a body section having at least one recess in said body section; and
- b. a tungsten carbide insert received within each of said at least one recess.
11. A downhole assembly for use in a well bore on a work string concentrically located within a casing string, said downhold assembly comprising:
- a. a mandrel operatively connected to said work string, said mandrel having a longitudinal through-bore and a recess along its outer peripheral surface;
- b. pad member received within said recess, said pad member having an opening formed therein;
- c. a cutting element, operatively positioned within said opening of said pad member; and
- d. a biasing member, operatively positioned between said mandrel and said pad member, adapted for biasing said cutting element against the inner diameter of said well bore.
12. The downhole assembly of claim 10, wherein said at least one cutting element comprises at least one polycrystalline diamond compact insert.
13. The downhole assembly of claim 10, wherein said at least one cutting element comprises at least one tungsten carbide insert.
Type: Application
Filed: May 4, 2009
Publication Date: Nov 5, 2009
Inventor: Rickey C. Voth (Broussard, LA)
Application Number: 12/387,520
International Classification: E21B 37/02 (20060101);