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Welding methods for downhole hydraulic control lines Disclosure Number: IPCOM000222198D
Publication Date: 2012-Sep-24
Document File: 3 page(s) / 140K

Publishing Venue

The Prior Art Database

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Deploying Hydraulic control lines downhole requires them to be filled with fluid throughout the operation in order to be able to both function the attached tool and verify the system integrity throughout the deployment by maintaining a constant pressure. During many installations it is necessary to cut and re-connect these lines when and if required.

Today downhole Hydraulic lines are connected together using metal/metal compression seals. Welded connections are not currently used due to the presence of fluid throughout the hydraulic lines when deploying downhole.

Welded connections are often preferred to the metal/metal compression type seals as they are seen to be more reliable.


This memo introduces different methods of connecting hydraulic control lines using available welding technologies under the presence of hydraulic control line fluid.

This invention enables these connections to be made;


  • Without reducing the pressure rating of the system
  • Under the presence of fluid
  • With Industry Recognized connection reliability
  • While Reducing rig time during deployment

Detailed Description of the Invention Including Examples and Drawings

Option 1: Dissolvable Plug

A dissolvable plug is used in order to prevent fluid contamination into the weld area on both ends of the control line. The dissolvable plug would be made of a material/composite which would dissolve in the specific hydraulic fluid contained within the control line after a specified period of time. This plug would be inserted internally to the control line a suitable distance up the control line in order to keep the fluid back from the area about to be welded. The plug would hold back fluid for a specified amount of time to keep the weld area free from contamination. The control line ends would then be butt welded together using standard orbital welding practices and machinery. After completion of the weld, the plug will dissolve in the given amount of time allowing fluid to pass through the welded section of the...