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Casing Diameters of a Borehole Casing Diagram premium gas tight connections on a casing string. Casing is a large diameter pipe that is assembled and inserted into a recently drilled section of a borehole. Similar to the bones of a spine protecting the spinal cord, casing is set inside the drilled borehole to protect and support the wellstream.
The production liner has the same function as a complete string of production casing. A typical casing arrangement in a well is shown in the diagram below. In this case, the surface casing is set to a depth of about 3,000 ft (910 m). Two intermediate strings are set in this well — a 13 + 3 ⁄ 8 in (340 mm) string and a 9 + 7 ⁄ 8 in (250 mm ...
The tube well casing houses the inlet, cylinder, piston valves and rising main of a "down-the-hole" type hand pump. Casing to support the external surfaces of the borehole against collapse may be needed, either temporarily or permanently, and is often made of PVC pipe, which has the advantages of being both cheap and inert.
Sometimes, the process of running in and cementing the casing is also included. After a well has been drilled, should the drilling fluids be removed, the well would eventually close in upon itself. Casing ensures that this will not happen while also protecting the wellstream from outside incumbents, like water or sand. [1] Perforated shoe
In a completed well, there may be many annuli. The 'A' annulus is the void between the production tubing and the smallest casing string. The 'A' annulus can serve a number of crucial tasks, including gas lift and well kills. A normal well will also have a 'B' and frequently a 'C' annulus, between the different casing strings.
In the diagram, these are stands of drill pipe which are 2 or 3 joints of drill pipe connected and stood in the derrick vertically, usually to save time while tripping pipe. Drill string (#25) is an assembled collection of drill pipe, heavy weight drill pipe, drill collars and any of a whole assortment of tools, connected and run into the ...
It is often helpful to visualize the well as a U-shaped tube. Column Y of the tube represents the annulus, and column X represents the pipe (string) in the well. The bottom of the U-tube represents the bottom of the well. In most cases, fluids create hydrostatic pressure in both the pipe and annulus.
From 2011 until August 2012 the record was held by the 12,345-metre (40,502 ft) long Sakhalin-I Odoptu OP-11 Well, offshore the Russian island Sakhalin. [11] The Chayvo Z-44 extended-reach well took the title of the world's longest borehole on 27 August 2012. Z-44's total measured depth is 12,376 metres (40,604 ft).