HWO / Snubbing

HWO / Snubbing

Hydraulic Workover or Snubbing as it is sometimes referred to is a well intervention method which has been existence for many years pioneered largely in the US on land but gained popularity in the North Sea during the late 80's early 90's and is still used albeit less frequently offshore.

Principle of Operation:

HWO is a live well intervention service using 'jointed pipe' through a mini rig and using a hydraulic 'jacking ram' to squeeze or 'snub' the pipe into the well against the well pressure. Once the desired well depth is reached many operations can be performed but most importantly the pipe can be rotated and large volumes of fluids circulated through the pipe. This makes HWO ideally suited for milling / drilling and large clean out operations of sand, scale and general fill.


HWO is generally used for 'heavy duty' well operations and typically include:

  • Large cleanout , sand bailing and scale milling operations
  • Tubing repair / change out operations (where well kill may not be desired)
  • Heavy duty fishing operations (where large forces / pulling weights are forecast)
  • Large perforating operations (where perf guns exceed the weight limits of wireline)


HWO equipment is large, heavy and significant with regard to transportation, storage and rig up and rig down operations. The 'package' will consist of:

  • Mast unit including guying system
  • Work basket and hydraulic jacking ram assembly
  • BOPS including stripper rams and work rams
  • High pressure riser assembly
  • Pipe handling / pipe make up equipment
  • Pipe rack / laydown area
  • Fluid pumping system / storage tanks & surface pipework

Useful data can be located - here