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NOV 60.3568 Publication

Date Published: June 6, 2013

© 2013 National Oilwell Varco, All rights reserved

Page 1 of 2 | This publication is for information purposes and does not necessarily represent products or

services offered by National Oilwell Varco.

SUBSEA PIPE HANDLER 

 A subsea pipe handler for making up and breaking out a drill string for testing of a subsea blowoutpreventer (BOP) is disclosed (Fig. 1).

The subsea pipe handler includes a housing that can be mounted between a subsea BOP stack and asubsea wellhead connector (Figs. 1 and 2). A drill string can pass through the housing through centralopenings at the top and bottom of the housing. A pipe guide with a central passage is mounted in thecentral opening at the bottom of the housing. Inside the housing is an iron roughneck and one or more

slip manipulators. For example, three slip manipulators may be provided, each for engaging a specificpipe diameter range (Fig. 3). When not testing, the iron roughneck and slip manipulators are offset fromthe central opening, or in the parked position, so that they do not interfere with normal drillingoperations.

The iron roughneck has upper and lower wrenches for clamping onto pipe joints (Fig. 2). Appropriatemechanisms, such as hydraulic cylinders, are used to move the jaws of the wrenches between closed

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NOV 60.3568 Publication

Date Published: June 6, 2013

© 2013 National Oilwell Varco, All rights reserved

Page 2 of 2 | This publication is for information purposes and does not necessarily represent products or

services offered by National Oilwell Varco.

and open positions. The upper wrench is rotatable about a vertical axis relative to the lower wrench toallow a connection to be made up or broken out between two pipe joints. A centralizer is mounted onthe upper wrench to assist in aligning the top portion of the drill string with the bottom portion duringstabbing. The wrenches can be extended to and retracted from above the central opening usingappropriate translation mechanisms coupled to the iron roughneck.

Each slip manipulator has slips for supporting a drill string, or a lower portion thereof, at the bottom of the housing. The slip manipulator further includes a mechanism for extending the slips to the centralopening at the bottom of the housing, inserting the slips into the pipe guide in the central opening, and

later removing the slips from the pipe guide. Control of slip manipulators and iron roughneck can occur via cables that can be run parallel to the marine riser or via hydraulic lines integrated into the marineriser.

When it is desired to breakout the drill string, one of the slip manipulators is controlled to insert its slipsinto the pipe guide and around the pipe extending through the pipe guide. The drill string is thenlowered until the pipe joint sits in the seat formed by the top end of the slips (Fig. 4). Then, thewrenches are controlled to engage the drill string at the location where the drill string is to be brokenout. The upper wrench is rotated to break out the connection between the pipe joints. A top driveconnected to the top of the drill string is further used to rotate the upper portion of the drill string out of the lower portion (Fig. 5). The upper portion of the drill string is then raised out of the housing and BOPstack by moving the top drive up. The upper portion of the drill string is removed from the housing andBOP stack so that any of the BOPs in the stack can be tested without damaging the drill string.

During testing, the lower portion of the drill string rests in the slips in the pipe guide, and the upper portion of the drill string is held above the BOP stack by the top drive. After the testing is complete, theupper portion of the drill string can be reconnected to the lower portion of the drill string using a reverse

of the breakout process described above. The iron roughneck and slip manipulator can then bereturned to the parked position to allow normal drilling operations to continue.