H

Hang up depth (HUD)

The point or the depth where a tool of a certain size no longer can pass through the borehole. 
 

Head well

A well that yields the most if pumping is stopped at intervals. 
 

Heavy crude

Crude with high gravity, i.e. low API weight, generally lower than 28 degrees. The high gravity is caused by the crude’s large content of heavy hydrocarbons. 
 

Highly deviated wells

Wells with angles at 30-80 degrees. 
 

Hole opener

A tool that can widen a borehole due to its special cutting flanges along the sides. By turning it in the area below the casing, it can widen the hole. 
 

Hook up

A process where the different modules that have been shipped out to the construction site are mounted. The process encompasses connecting single parts, wiring pipelines and cables, mounting of equipment etc. 
 

Horizontal drilling

Directional drilling where the angle of the borehole’s deviation reaches at least 80 degrees from vertical. 
 

Hot shot

Express delivery 
 

Hydrates

A solid connection of water and hydrocarbons that is generated at certain pressures and temperatures. 
 

Hydroclones

Conical seperators used for removing sand and other particles from the drilling mud. Also called desanders or desilters.