Differential sticking

Differential sticking
A diagram showing forces at work during differential sticking. The small black arrows represent pressure exerted on the drill pipe from the wellbore, the red arrows represent pressure exerted on the pipe from the formation (smaller than in the wellbore) and the large black arrow represents the net force on the pipe, which is pushing it into the wall.

Differential sticking is a problem that occurs when drilling a well with a greater well bore pressure than formation pressure, as is usually the case. The drill pipe is pressed against the wellbore wall so that part of its circumference will see only reservoir pressure, while the rest will continue to be pushed by wellbore pressure. As a result the pipe becomes stuck to the wall, and can require millions of pounds of force to remove, which may prove impossible. In many cases the drilling fluid (mud) weight is simply reduced, thus relieving the pressure difference and releasing the stuck pipe string. Should this option be unavailable, as in sour gas wells, a specialty fishing company is called to retrieve the stuck pipe or 'fish'. Many options exist once a fishing company is on site: oil or nitrogen may be pumped down the well, or the fish may be 'washed over' using a carbide shoe on a string of washpipe. Jarring is not usually attempted with differential sticking due to the massive amount of pressure that holds the pipe in place.

External links



Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Underbalanced drilling — Underbalanced drilling, or UBD, is a procedure used to drill oil and gas wells where the pressure in the wellbore is kept lower than the fluid pressure in the formation being drilled. As the well is being drilled, formation fluid flows into the… …   Wikipedia

  • List of oil field acronyms — Contents 1 # 2 A 3 B 4 C …   Wikipedia

  • Gulf of Mexico — The Gulf of Mexico in 3D perspective Earth s oceans (World Ocean) Arctic Ocean Atlanti …   Wikipedia

  • Petroleum — For other uses, see Petroleum (disambiguation). Proven world oil reserves, 2009 …   Wikipedia

  • Persian Gulf — Khaleej redirects here. For other uses, see Khaleej (disambiguation). Persian Gulf …   Wikipedia

  • Oil shale — For the scientific technical journal, see Oil Shale (journal). Not to be confused with Shale oil or Tight oil. Oil shale Sedimentary Rock Combustion of oil shale Composition …   Wikipedia

  • Pipeline transport — An elevated section of the Alaska Pipeline …   Wikipedia

  • Royal Dutch Shell — plc Type Public limited company Traded as LSE:  …   Wikipedia

  • OPEC — Organization of Petroleum Exporting Countries …   Wikipedia

  • Oil well — The pumpjack, such as this one located south of Midland, Texas, is a common sight in West Texas. An oil well is a general term for any boring through the earth s surface that is designed to find and acquire petroleum oil hydrocarbons. Usually… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”