Centralized Bi-Center Reamer and Method of Use
This apparatus provides an underreamer and a reamer or hole opener to enlarge an existing pilot hole thereby permitting further operation to be carried out in a well bore. The underreamer can be inserted down a well bore in the unexpanded condition and, since the radius of the eccentrically mounted cutters of the reamer or hole opener added to the radius of the unexpanded underreamer equals the pass through diameter (the inner diameter of the restriction), the entire assembly or apparatus can be inserted to the position requiring enlarging. The underreamer is expanded to engage the adjacent wall of the well bore and stabilize the reamer as it enlarges the hole. Since movement resulting from the lateral forces are restrained by the centralizer/underreamer as well as the bullnose or smaller pilot hole drill bit, the bi-center reamer can readily open the well bore to the desired diameter without lateral deviation.
This application relates to a centralized bi-center reamer and a method for drilling and enlarging a hole with such device; specifically, to a bottom hole assembly that provides a centralizing underreamer or roller assembly to centralize a bi-center reamer, which enlarges a drilled hole mounted above.
BACKGROUNDDuring the drilling of subterranean holes for the exploration and production of oil and gas, by way of example, it may be useful to both drill and enlarge a smaller diameter or pilot hole. At other times, a small diameter or pilot hole has been drilled which must be enlarged to properly install casing in the well. In a normal bi-center application, the pilot hole provides the centralizing element guide to keep a bi-center bit centered so it will ream a larger hole. Although inherently unstable, bi-centered bits having shear-type (PDC) cutter elements which enlarge the bore-hole have long been used in the industry. See, for example, U.S. Pat. No. 5,678,644 for a Bi-Center and Bit Method for Enhancing Stability issued Oct. 21, 1997 and U.S. Pat. No. 5,957,223 for a Bi-Center Bit with Enhanced Stabilizing Features issued Sep. 28, 1999. Bi-centered technology has a tendency to move off the true desired line of drilling because of the nature of the eccentric side forces acting on the tools. The present disclosure relates to an apparatus and method for using the bi-centered technology for underreaming while overcoming this inherent tendency for the bi-center assembly carried on the bottom hole assembly (BHA) to move off the desired direction of travel.
To run a conventional bi-center bit, normally there is no pilot hole and the hole is drilled and reamed simultaneously. The drill bit and reamer diameter size is always smaller than the pass-through diameter. In many cases, however, drillers need to open a hole that has been previously drilled to the pass-through diameter or just slightly smaller. In this case, an underreamer is normally run to open the hole to the desired size that is larger than the pass-through diameter. The preferred embodiment of the present invention utilizes one or more fixed low-torque cutters that are cantilevered from the bottom hole assembly (BHA). This avoids using an expandable arm as found in a standard underreamer that is inherently weaker than a fixed cutter cantilevered from a body. Alternatively, the centralized bi-center underreamer could utilize a shear type polycrystalline diamond compacts (PDC) underreamer, which would be centralized and stabilized in the center of the well bore by the accompanying centralizer/underreamer.
SUMMARY OF INVENTIONAn apparatus for enlarging a bore hole provides a selectively-engageable centralizer to engage a well bore on a proximal portion of a bottom hole assembly and a bi-centered reamer on a distal portion of the bottom hole assembly. This apparatus can be fabricated so the selectively-engageable centralizer provides hard-facing on a face of a plurality of well bore engaging arms, thereby preventing wear from movement over the well bore as well as starting the underreaming function of the tool assembly.
Alternatively, this apparatus could provide a selectively-engageable centralizer having a plurality of rolling cutter cones for engaging the well bore. This apparatus could alternatively be fabricated the bi-centered reamer is composed on one large roller or several smaller roller cutter cones mounted eccentrically on the reamer portion of the bottom hole assembly such that the outer diameter of the reamer portion is smaller than the inner diameter of a passage through which the apparatus passes on the distal portion of the bottom hole assembly.
The apparatus can also be fabricated wherein the bi-centered reamer is a scraping reamer have a plurality of PDC buttons on a portion of the extending reamer eccentric body. The apparatus can be fabricated to provide the centralizer and the reamer portion of the bottom hole assembly on two tubular bodies connected together or, alternatively, fabricated on an integral body.
The apparatus can additionally provide a bit connected to the reamer portion of the bottom hole assembly or may be inserted in a well bore utilizing a bull-nose plug connected to the reamer portion of the bottom hole assembly.
A method for enlarging a pilot bore hole is also disclosed herein comprising inserting a centralizer and an bi-center underreamer apparatus in a zone to be enlarged while keeping the centralizer arms from deployment; opening the centralizer arms by increasing hydraulic pressure to thereby centralize and stabilize the bi-center underreamer as it engages the bore hole; and, rotating the centralizer and reamer combination to enlarge the pilot bore hole. This method can further comprise comprising rotating the BHA while increasing pump pressure on the centralizer to fully extend the centralizer arms to engage the well bore before advancing the centralizer and bi-centered underreamer in the well bore.
The present application relates to a centralized bi-center reamer having eccentrically spaced cutters run below a conventional underreamer operating as a centralizer used to stabilize and centralize the bi-center reamer in the pilot hole. This embodiment of the present invention is an apparatus for insertion through a smaller diameter casing or tubing (not shown) with the centralizer arms disengaged from the well bore wall 52. As shown in
The underreamer or centralizer arms 30 are not primarily intended to cut the formation, but serve to centralize and stabilize the bi-center reamer portion in the center of the hole thereby allowing the hole or well bore to be opened to the desired diameter. However, the hard-facing on the pads 31 on the extendable arms 30 will function to minimally underream the formation in the well bore. It is also suggested that the underreamer be allowed to reach full extension through rotation while increasing pump pressure to move the arms into full contact before moving the reamer 20 forward in the well bore 70. Expandable rollers may be substituted to centralize and stabilize the reamer while it performs its primary function.
Alternatively, cutter cones 33, as shown in
The reamer or hole opener portion 20 of this apparatus enlarges a pre-existing pilot hole 50 in a well bore to a larger hole size 52. The cantilevered fixed post 42, journal 43 and cutter body 40 are inherently stronger than typical underreamer extendable arm cutters. The present embodiment adds the strength of these fixed cantilevered arms to the bi-center technology permitting deployment through smaller diameter casing or tubing thereby permitting enlarging of particularly difficult bore holes.
As more fully shown in
The choice of the number and size of the cutter cones is also derived from knowledge of those experienced in this art and although the preferred embodiment shows two cones, and as noted the devices could conceivable be fabricated with a single larger cone or several smaller cones. The limitation on the number of cones used is the pass-through size, which must be accommodated. The benefits of a fixed post cantilevered reamer or hole opener are more fully described in U.S. Pat. No. 5,992,542, which is incorporated herein by reference as if copied herein verbatim.
Returning to
As one may readily appreciate from disclosure of
The foregoing description has been directed to particular embodiments of the invention in accordance with the requirements of the statutes and for purposes of illustration and explanation of the manufacture and use. It will be apparent to those skilled in the art that many modifications and changes in the procedures set forth will be possible without departing from the scope and spirit of the invention. It is the applicant's intention to encompass all such modifications and variations.
Claims
1. An apparatus for enlarging a bore hole comprising:
- a selectively-engageable underreaming centralizer to engage a well bore on a proximal portion of a bottom hole assembly; and,
- one or more rolling cutter cones mounted eccentrically on a distal reamer portion of the bottom hole assembly such that the outer diameter of the reamer portion is smaller than the inner diameter of a passage through which the apparatus passes on a distal portion of the bottom hole assembly.
2. The apparatus of claim 1 wherein the selectively-engageable underreaming centralizer provides hard-facing on a face of a plurality of well bore engaging arms.
3. The apparatus of claim 1 wherein the selectively-engageable underreaming centralizer provides one or more rolling cutter cones for engaging the well bore.
4. (canceled)
5. (canceled)
6. The apparatus of claim 1 wherein the underreaming centralizer and the eccentric roller cone portion of the bottom hole assembly are on two tubular bodies connected together.
7. The apparatus of claim 1 wherein the underreaming centralizer and the eccentric roller cone portion of the bottom hole assembly are fabricated on an integral body.
8. The apparatus of claim 1 additionally providing a bit connected to the distal eccentric roller cone portion of the bottom hole assembly.
9. The apparatus of claim 1 additionally providing a bull-nose plug connected to the distal eccentric roller cone portion of the bottom hole assembly.
10. A method for enlarging a pilot bore hole comprising:
- inserting a underreaming centralizer and an eccentric roller cone assembly apparatus in a zone to be enlarged while keeping the underreaming centralizer arms from deployment;
- opening the underreaming centralizer arms by increasing hydraulic pressure to thereby engage the eccentric roller cone assembly into engagement with a section of the pilot bore hole and centralize and stabilize the roller cone assembly as it engages the bore hole; and,
- rotating the underreaming centralizer and eccentric roller cone assembly combination to enlarge the pilot bore hole.
11. The method of claim 10 further comprising rotating the bottom hole assembly while increasing pump pressure on the underreaming centralizer to fully extend the underreaming centralizer arms to engage the well bore before advancing the underreaming centralizer and eccentric roller cone assembly in the well bore.
Type: Application
Filed: Nov 16, 2009
Publication Date: Sep 15, 2011
Inventor: Allen Kent Rives (Cypress, TX)
Application Number: 13/129,317
International Classification: E21B 7/00 (20060101); E21B 10/34 (20060101);