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Production casing is cemented through the zone and the pay section is selectively perforated. Gas and water are easily controlled as is sand. The formation can be selectively stimulated and the well can be deepened. This selection is adaptable to other completion configurations and logs are available to assist casing decisions.
Steel casing pipe is often specified as ASTM A-252 which is a structural grade material that does not require hydrostatic testing and the inspection requirements are not stringent and it usually costs less than other grades such as A-53, [2] A-139 or API 5L. Used natural gas line pipe is also used as casing on many projects because it is often ...
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.
Artificial lift is the use of artificial means to increase the flow of liquids, such as crude oil or water, from a production well. Generally this is achieved by the use of a mechanical device inside the well (known as pump or velocity string) or by decreasing the weight of the hydrostatic column by injecting gas into the liquid some distance down the well.
A float collar is installed near the bottom of the casing string. Cement plugs land on it during the primary cementing operation, thus retaining inside the casing a small portion of the cement slurry that may have become contaminated as the top plug scrapes the inside of the casing. It is similar to a float shoe; often both are used for redundancy.
Casing hangers must be designed to take the full weight of the casing, and provide a seal between the casing hanger and the spool. Casing Hangers may also be suspended within the wellhead by means of radial distortion of the wellhead bore e.g. the "Pos-Grip" method. This is installed to support the individual casing strings in the well.
Rotary assemblies [2] are commonly used where formations are predictable and the rig economics are an issue. In such an assembly the weight of the drill collars gives the BHA the tendency to sag or flex to the low side of the hole, collar stiffness length and stabiliser diameter and placement are engineered as a means of controlling the flex of the BHA.
Spiral casing: The spiral casing around the runner of the turbine is known as the volute casing or scroll case. Throughout its length, it has numerous openings at regular intervals to allow the working fluid to impinge on the blades of the runner.