Well casing guide string and repair method

• US 5,370,183 A
• Filed: 08/11/1993
• Issued: 12/06/1994
• Est. Priority Date: 08/11/1993
• Status: Expired due to Fees

• Current Assignee: Atlantic Richfield Company (BP PLC)
• Original Assignee: Atlantic Richfield Company (BP PLC)
• Inventors: Reynolds, Randy D., Ellis, H. Andrew, Peterson, Erik L.
• Primary Examiner(s): Neuder, William P.
• Application Number:
  US08/105,081
• Time in Patent Office: 482 Days
• Field of Search: 166/277, 166/380, 166/55.7, 166/241.1
• US Class Current: 166/277
• CPC Class Codes: E21B 17/05 Swivel joints
• CPC Class Codes: E21B 29/00 Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
• CPC Class Codes: E21B 29/10 Reconditioning of well casings, e.g. straightening

Abstract

Well casing is repaired using a guide string for maintaining contact with a lower casing section disposed in the well, particularly an open hole portion of such well. The guide string is connected to a swivel and milling tool and lowered into the casing section remaining in the open hole portion of the well for machining the upper end of the casing section. The swivel prevents build-up of angular momentum of the guide string which may decouple the guide string from the milling tool when the milling tool rotatably decelerates or snags during the machining or milling operations. The milling tool and swivel may be retrieved and the guide string, with a safety joint or fishing head, reinserted in the well during installation of a new casing section.

Claims

1. An assembly for repairing a casing section disposed in a wellbore comprising:

an elongated tubular guide string adapted to be inserted in said casing;

a casing milling tool connected to a work string for rotation to machine the upper end of said casing; and

a swivel interconnecting said guide string and said work string including said milling tool whereby said guide string is connected to said milling tool and said work string but is rotationally independent of the rotation of said work string and said milling tool.

2. The assembly set forth in claim 1 wherein:

said swivel includes a first part adapted to be connected to said milling tool and a second part adapted to be connected to said guide string.

3. The assembly set forth in claim 2 including:

bearing means interposed between said first part and said second part to permit substantially free rotation of said parts relative to each other.

4. A method for repairing a well casing which includes a first section having an upward facing end and a second section which is disposed generally above said first section;

said method comprising;

inserting a guide string within said well casing and extending into said first casing section, said guide string having an upper end extending above said upward facing end of said first casing section;

removing said second casing section from said wellbore;

lifting said guide string partially out of said first casing section and connecting a milling tool and swivel to said guide string;

lowering the assembly of said milling tool, said swivel, and said guide string into said first casing section and engaging said milling tool with said first casing section; and

rotating said milling tool to machine said upper end of said first casing section while permitting free rotative movement of said guide string relative to said milling tool.

5. The method set forth in claim 4 including the step of:

raising said guide string in said first casing section and disconnecting said milling tool and said swivel means from said guide string; and

lowering said guide string into said first casing section until said guide string rests on support means for said guide string.

6. The method set forth in claim 5 including the step of:

installing a third casing section in said well above said first casing section, connecting said third casing section to said first casing section and retrieving said guide string from said well.