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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.
In cased hole completions (the majority of wells), once the completion string is in place, the final stage is to make a connection between the wellbore and the formation. This is done by running perforation guns to blast holes in the casing or liner to make a connection. Modern perforations are made using shaped explosive charges, similar to ...
This requirement of well design creates a well where each hole section is ever-decreasing in diameter. The only conventional way to combat this effect is to start with an enormous hole at the top (sometimes 30") in order to run as many as five casing strings and still end up with a 6" hole in the targeted reservoir.
Casing is run to protect or isolate formations adjacent to the wellbore. It is generally not possible to drill a well through all of the formations from surface (or the seabed) to the target depth in one hole-size section. For example, fresh-water-bearing zones (usually found only near the surface) must be protected soon after being penetrated.
These assumptions are used by a well engineering team designing the casing and completion programs for the well. Also considered in the detailed planning are selection of the drill bits, Bottom hole assembly, and the drilling fluid Step-by-step procedures are written to provide guidelines for executing the well in a safe and cost-efficient manner.
A 7 + 5 ⁄ 8 in (190 mm) production casing is set at a depth of about 15,000 ft (4,600 m) and a 5 in (130 mm) production liner set to TD. Probably, this well required a high mud weight at the bottom of the hole and cementing the 7 + 5 ⁄ 8 in (190 mm) casing at TD would have resulted in too much pressure and lost circulation. If lost ...
A production packer is designed to grip and seal against the casing ID. Gripping is accomplished with metal wedges called "slips." These components have sharpened, carburized teeth that dig into the metal of the casing. Sealing is accomplished with large, cylindrical rubber elements.
A casing column is lowered down the hole. Since BHM takes place in an open hole, the casing shoe is located just above the upper border of the production interval (an ore body) leaving the rest open; A BHM tool is lowered into the hole; High-pressure water is pumped down and the tool is rotated and moved up and down.