Steel casing is a thin-walled steel pipe used in oil pipelines, oil wells,
and natural gas wells. It can withstand high pressure, high temperature and
corrosive media. The following are some of the major steel casing standards.
1.API5CT
API5CT is a petroleum casing standard formulated by the American Petroleum
Institute, including different grades of casing, such as H40, J55, K55, N80,
L80, C90, C95, P110 and Q125.
2. ISO 11960: Petroleum casing standard formulated by the International
Organization for Standardization, similar to API 5CT, including different grades
of casing.
3.GB/T 9711.1: Petroleum casing standards formulated by the China National
Standardization Organization, including L175, L210, L245, L290, L320, L360,
L390, L415, L450, etc.
4.SY/T6194: Petroleum casing standard formulated by China Petrochemical
Industry Standards, including Casing and Tubing types, used at different depths
and conditions of oil wells.
These standards specify the size, chemical composition, mechanical
properties, quality requirements, etc. of oil casing to ensure its safety and
reliability during oil and gas extraction.
Types of steel casing
Steel casing can be divided into: conduit, surface casing, technical casing
and oil layer casing according to usage.
Guide sleeve: Mainly used for drilling in oceans and deserts to separate
seawater and sand to ensure smooth drilling.
Surface casing: Mainly used for the first drilling, drilling through the soft
surface stratum to the bedrock. In order to seal this part of the stratum from
collapse, it needs to be sealed with surface casing. Surface oil casing
protection drill
The well is protected from contamination by shallow water and gas layers,
supports wellhead equipment and maintains the weight of other layers of
casing.
Technical casing - Separates the pressure at different levels to facilitate
the normal flow of drilling fluid and protect the production casing so that
anti-burst devices, anti-leak devices and tail pipes can be installed in the
drilling well.
Reservoir oil casing (production casing): extracts oil and natural gas from
reservoirs beneath the earth's surface and is used to protect drilling wells and
separate drilling mud into layers. When producing oil casing, the outer diameter
usually ranges from 114.3 mm to 508 mm.
Steel grade of steel casing
According to the strength of the steel itself, steel casing can be divided
into different steel grades, namely J55, K55, N80, L80, C90, T95, P110, Q125,
V150, etc. Different well conditions and well depths require different steel
grades. In corrosive environments, the casing itself is also required to have
corrosion resistance. In places with complex geological conditions, the casing
is also required to have anti-collapse properties.
How to choose the right steel casing?
When selecting steel casing, there are several factors to consider:
1. Material: High-quality anti-corrosion and wear-resistant materials should
be selected, such as polyurethane, chlorinated polyvinyl chloride, polyester,
etc., to ensure the anti-corrosion and wear-resistant properties of the
casing.
2. Specifications: According to the diameter and length of the oil pipe that
needs to be protected, select the casing of the corresponding specifications to
ensure that it can completely cover the oil pipe.
3. Thickness: Thickness is one of the important indicators to measure the
quality of casing. A casing with moderate and uniform thickness should be
selected to ensure its strength and wear resistance.
4. Production technology: Choose casings with exquisite production
technology, tight braiding layer, smooth surface and no burrs to ensure their
quality and reliability.
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