H-casing of the oil well part#2

The casing is a large diameter pipe that is assembled and inserted into a recently drilled section of a borehole and typically held into place with cement.

Dimensions, Materials, and Connections:

•Outside Diameter and Wall Thickness

•Weight

•Length

•Steel Grades

•Casing Connections

•Determine the pipe body structure

•The outside diameter of casing couplings determines the hole size that best fit the casing size

•Wall thickness determines inside diameter and pipe weight

Steel Grades for Casing

•Composition of Steel Alloys

•The raw steel material used for casing manufacturing does not have one defined microstructure

•Both the steel microstructure and mechanical properties can be improved mainly with the addition of special steel alloys and thermal processes

•After a complex manufacturing procedure the steel used for casing tubular is adapted to suit specific environments and service levels

Premium Connections (Proprietary Connections):

•Hydril

•Manesman

•VAM

Etc.

•API Connection – Round Thread:

Characteristics:

•Eight (8) threads per inch

•Thread profile “V” shaped with 60° between flanks

•Taper close to ¾” per foot

•Crest and root thread round cut,

•Leak trajectory along the threads

•Not recommended for gas wells or HP wells

•Short and weak engagement surface.

•API Connection – Buttress Thread:

Other Characteristics

•Higher possibility of leaking than the round thread

•Lower bursting strength than the round thread

•Strong for axial and flexing loads

•Prone to strand and stuck while making connections

•Does not work well under compression

•Best threads are located toward the tip of the pin