Dual Bore Packer with Axially Offset Mandrel Threads
A dual bore packer features axially offset tapered thread connections so that the pressure rating and size of the connections in each of the bores can be as large as possible. This is enabled by providing as thick a wall as possible between the bores in the zone where the connecting tapered thread is placed.
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The field of the invention is dual bore packers and more particularly packers where the mandrel end connections are axially offset to allow greater wall area about the thread for the required pressure rating.
BACKGROUND OF THE INVENTIONTypically dual bore packers have two adjacent bores with threaded end connections for connecting a tubular string or a cable. One application for dual bore packers is for electric submersible pump service where the smaller of the bores is for a power cable to the pump and the larger bore is connected to the discharge of the pump to bring produced fluids to the surface. Some examples of dual bore packers with axially aligned threads are U.S. Pat. No. 9,611,722 and U.S. Pat. No. 6,390,198.
Typically the threaded connections have to deliver a required pressure rating and if the threads are disposed next to each other at the upper face of the mandrel there has to be a tradeoff between making the thread as large as possible for less resistance to flow and making the connections stout enough to handle the anticipated operating pressures for the application. Since the thread forms are tapered juxtaposing two threads near each other limits the available wall between them so as to reduce the pressure rating of the connections. In dual bore packers the center of each bore is offset from the center of the packer.
The present invention offers a simple solution to this design conflict between making the bores as large as possible and giving the connections the highest possible pressure rating. The solution is to axially offset the threads in adjacent bores to maximize the available surrounding wall thickness so that in a given packer mandrel size the diameter and pressure rating of the two bores is maximized. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention can be determined from the appended claims.
SUMMARY OF THE INVENTIONA dual bore packer features axially offset tapered thread connections so that the pressure rating and size of the connections in each of the bores can be as large as possible. This is enabled by providing as thick a wall as possible between the bores in the zone where the connecting tapered thread is placed.
A mandrel end 10 of a dual bore packer of a type known in the art is shown in
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
Claims
1. A connection arrangement for a multi-bore packer for borehole use, comprising:
- a mandrel having multiple bores coextensive from a common top to a common bottom end of said mandrel, each said bore having a connection within said mandrel wherein said connections within said bores are axially offset from each other.
2. The connection arrangement of claim 1, wherein:
- said connections do not axially overlap.
3. The connection arrangement of claim 2, wherein:
- said connections comprise tapered thread.
4. The connection arrangement of claim 2, wherein:
- at least one said connection starts at an end of said mandrel.
5. The connection arrangement of claim 2, wherein:
- said bores are different sizes.
6. The connection arrangement of claim 2, wherein:
- said bores have centers offset from a center of said mandrel.
7. The connection arrangement of claim 2, further comprising:
- a power cable for an electric submersible pump connected to one of said bores and a tubular string connected to another of said bores to direct flow from said pump to a remote location.
8. The connection arrangement of claim 1, wherein:
- said mandrel comprises two said bores.
Type: Application
Filed: May 10, 2017
Publication Date: Nov 15, 2018
Applicant: BAKER HUGHES A GE COMPANY, LLC (Houston, TX)
Inventors: Jack D. Farmer (Houston, TX), James C. Doane (Friendswood, TX), Gary L. Anderson (Humble, TX)
Application Number: 15/591,773