Well intervention

Well intervention vessel Skandi Constructor (former Sarah) with X-bow.

A well intervention, or well work, is any operation carried out on an oil or gas well during or at the end of its productive life, which alters the state of the well or well geometry, provides well diagnostics, or manages the production of the well.

Types of well work


Main article: Pumping (oil well)

Pumping is the simplest form of intervention as it does not involve putting hardware into the well itself. Frequently it simply involves rigging up to the kill wing valve on the Christmas tree and pumping the chemicals into the well.

Wellhead and Christmas tree maintenance

Main article: Well integrity

The complexity of Wellhead and Christmas tree maintenance can vary depending on the condition of the wellheads. Scheduled annual maintenance may simply involve greasing and pressure testing the valve on the hardware. Sometimes the downhole safety valve is pressure tested as well.


Main article: Wireline (cabling)

Slickline operations may be used for fishing, gauge cutting, setting or removing plugs, deploying or removing wireline retrievable valves, and memory logging.

Braided line

Main article: Wireline (cabling)

Braided line is more complex than slickline due to the need for a grease injection system in the rigup to ensure the BOP can seal around the braided contours of the wire. It also requires an additional shear-seal BOP as a tertiary barrier as the upper master valve on the Christmas tree can only cut slickline. Braided line includes both the core-less variety used for heaving fishing and electric-line used for logging and perforating.

Coiled tubing

Main article: Coiled tubing

Coiled tubing is used when it is desired to pump chemicals directly to the bottom of the well, such as in a circulating operation or a chemical wash. It can also be used for tasks normally done by wireline if the deviation in the well is too severe for gravity to lower the toolstring and circumstances prevent the use of a wireline tractor.


Main article: Snubbing

Snubbing, also known as hydraulic workover, involves forcing a string of pipe into the well against wellbore pressure to perform the required tasks. The rigup is larger than for coiled tubing and the pipe more rigid.


Main article: Workover

In some older wells, changing reservoir conditions or deteriorating condition of the completion may necessitate pulling it out to replace it with a fresh completion.

Subsea well Intervention

Main article: Subsea

Subsea well intervention offers many challenges and requires much advance planning. The cost of subsea intervention has in the past inhibited the intervention but in the current climate is much more viable. These interventions are commonly executed from light/medium intervention vessels or mobile offshore drilling units (MODU) for the heavier interventions such as snubbing and workover drilling rigs.

See also


This article is issued from Wikipedia - version of the 11/29/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.