OCTG/ Drill Tools Repairs
Casing and tubing can also be known as OCTG in the oil and gas industry
OCTG are new and used pipe products, such as casing, tubing, drill pipe, line pipe, structural pipe, and more, which are used in the production of oil and gas, as well as, other applications in many industries.
What is casing and tubing?
Casing:
Casing is used for lining the complete borehole which has been dug into the ground to procure oil. Similar to the drill pipe, the oil well casing pipe is also subjected to axial tension, therefore they are required to be made from high-quality strong steel material. Casing is large diameter pipe which is held in place in the borehole using cement.
The diameters of casing pipe range from 4.5″ to 36″. The well-cemented pipe acts as the structural component of the well and offers hole integrity. It prevents the well from collapsing when the drilling process is on. Good quality, well cemented casing can stay in place for the whole life of the well.
The oil well casing pipe is further divided into:
Conductor Casing – Conductor casing is the first boundary between the surface and the subsurface. It helps prevent well collapse, keeps away the groundwater, and most importantly provides structural support. Conductor casing is installed in the ground by either drilling it or hammering it down. It is available in sizes ranging from 18″ to 36″.
Surface Casing – The purpose of surface casing is primarily environmental and to ensure safety. It helps in separating the freshwater zones, offers protection from blowout, and supports the wellhead and blow out prevention (BOP) equipment. Therefore surface casing is required to maintain very high safety standards. It is responsible for supporting the next casing in line. It may vary in size depending on the purpose, but the most common size of surface casing is 13 3/8”.
Intermediate Casing – Intermediate casing is not always required in all types of oil and gas production. If used, it is placed between the surface and the production casing. It is available in sizes ranging from 13 3/8” to 16”.
Production Casing – Production casing helps provide structural integrity and pressure control of the hydrocarbon-bearing sections, mainly during the production of oil.
Production Liner – Production liners can be suspended from the production casing or one of the previous casings. They help in reducing the cost significantly as the liner is not required to run through the full depth of the well. Liners can be pre-perforated to help save time and cost.
The oil well casing is subject to high axial tension because of the external pressure received from the rocks surrounding it and the internal pressure during the oil extraction. A well-cemented casing can be very useful in the drilling process in several ways:
Holds the drill string, preventing the unstable upper formation from caving in
Helps the prevention of contamination of water well zones
Provides an even, internal bore for easy installation of the production equipment
Helps prevention of the contamination of production zones
Helps prevention of fluid (oil) loss
Helps seal off the high-pressure zones from the surface of the earth
OCTG pipes and accessories supplied by AOS, conform to API 5CT and are sourced primarily within our extensive partner network of reputable mills
We supply full size coverage of tubings and casings ranging from 2 3/8” to 36” across all commercially available grades and a wide range of accessories to fulfill your drilling and production needs.
