What is seamless OCTG casing pipe & tubing?
"OCTG" stands for Oil Country Tubular Goods, special oil pipes. Refers to a type of steel pipe specially used for oil and natural gas extraction. OCTG pipe includes casing pipe, tubing pipe and drill pipe.
Seamless casing is a casing made of seamless steel pipe. Seamless pipe is a pipe product used to transport fluid or gas. It is characterized by no welds, so it is also called seamless steel pipe. Compared with welded steel pipes, seamless pipes have higher strength and pressure resistance, and are suitable for withstanding harsh conditions such as high pressure, high temperature, and corrosive media.
OCTG casing is a steel pipe used to support the well walls of oil and gas wells to ensure the normal operation of the entire oil well during the drilling process and after completion. Oil casing is the most consumed type of oil well pipe. As the depth of oil and gas drilling continues to increase, the demand for higher-grade oil casings is gradually expanding. High-grade steel, non-API and special buckle oil casings will Become the main trend of products.
Function of seamless OCTG casing:
OCTG casing is a steel pipe used in oil wells to establish a pressure-resistant sealing zone from the oil and gas reservoir to the surface. Casing pipe mainly has the following seven functions:
(1) Prevent well collapse and excessive erosion of the well wall by drilling fluid.
(2) Prevent the freshwater layer and low-pressure layer from being polluted.
(3) Prevent oil and gas leakage.
(4) Control the amount of oil and gas entering the well.
(5) Provide conditions for controlling the pressure in the well.
(6) To facilitate the installation of artificial lifting equipment for oil production.
(7) Provide channels for oil and gas flow.
Seamless OCTG casing size:
The size of the first layer of casing run into the well is limited by the size of the last production casing run. Once the diameter of the oil layer casing is determined, the diameters of the intermediate casing and surface casing and the corresponding drill bit size can be determined. The casing diameter size refers to the outer diameter of the objects that can be allowed to pass through the pipe when there are no obstacles. This size is very important. It represents the maximum allowable size of drill bits and tools to pass through the pipe. Testing the diameter size of the casing can indicate whether the casing cross section is deformed, and can also reflect to a certain extent whether the casing is straight. When selecting a well size suitable for a certain size of casing, the outer diameter of the coupling and the well must be considered. wall mud cake to ensure adequate wellbore clearance.
When choosing seamless OCTG casing size, several factors should be considered. As the diameter of the wellbore increases, the cost of the oil well increases accordingly; the cost of a large-diameter well must be compatible with the economic benefits that can be obtained. The method of oil production determines the choice of pipe size, because a self-blowing well may become a pumping well in the later stages of production. oil well. When encountering high-yield oil and gas wells, recovery rate is also an important issue worthy of consideration. Several oil pipe strings need to be run into multiple layers of oil at the same time in order to reasonably exploit the oil well. At this time, the casing size should be increased. If you want to install several layers of intermediate casing, you should increase the diameter of the surface casing, otherwise the oil layer casing gauge will become smaller. Large boreholes and heavy casing strings require larger drilling rigs, but are still cost-effective in terms of development economics.
Read more: Seamless Casing vs. ERW Casing
