Oil casing pipe is the lifeblood of keeping oil wells running. Due to different geological conditions, the downhole stress state is complex, and the comprehensive action of tension, compression, bending and torsional stress acts on the pipe body, which puts forward higher requirements on the quality of the casing itself. Once the casing itself is damaged for some reason, it may lead to the reduction of production of the entire well, or even to be scrapped. Oil casing can be divided into: conduit, surface casing, technical casing and oil casing according to the usage.
Different types of American standard oil casings are used in the oil production process:
For the purpose of maintaining drilling, to avoid contamination of shallow and shallow gas layers, to support wellhead devices, and to bond the weight of other layers of casing; technical casings will be of different grades The pressure is separated to ensure the normal flow of drilling fluid quantitatively; the manufactured casing is maintained. Install crack guards, leak guards and liner for maintenance drilling and stratified drilling fluid drilling rigs. The oil pipe should have properties such as corrosion resistance and corrosion resistance. In the case of complex geological conditions, the oil pipe should have anti-collapse and anti-microbial erosion effects. With the vigorous development of the oil industry, the direct buried pipes, American standard oil casings and tank bottoms of oilfields are seriously corroded, especially American standard oil casings, which seriously affect the production, development, design and surrounding environment of oilfields. There is corrosion on the inner and outer walls of oil and gas wells, and the internal corrosion is more serious.
Steel grade of petroleum casing:
H40, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc.
The processing form of the oil casing end:
short round thread, long round thread, buttress thread, special buckle, etc.
Anti-corrosion countermeasures for oil casing:
1. First of all, do a good job of water quality standards, and strictly monitor and manage water quality. Implement cleaning and separate injection, strengthen the cleaning of main water pipelines, ensure that the water quality in the station and the bottom of the well meets the standard, and reduce the introduction of corrosion sources into the annular space;
2. For the water injection wells that have been newly put into production, the annular protective fluid mainly used for sterilization shall be added, and a system shall be formed to add it regularly;
3. In view of the accelerated effect of mechanical abrasion on the corrosion of oil casing, it is recommended to add a rubber ring to the tubing coupling or add a centralizer to the serious part of the well deviation to prevent the tubing from scratching the casing during operation and water injection. one side contact sleeve;
4. In view of the serious bacterial corrosion under the scale and the slow growth and killing of the SRB at high temperature, high temperature water or steam of 100 degrees Celsius can be injected into the annular space regularly to kill the SRB under the scale;
5. Before the corrosion in the casing of the water injection well is effectively controlled, it is not recommended to promote the use of cathodic protection and coating casing.
The important position of oil pipe:
1. Oil pipelines use a lot of money and spend a lot of money, so there is a huge potential for saving expenses and reducing costs. The consumption of OCTG can be calculated according to the amount of drilling feet per year. According to the specific situation of our country, in general, 62kg of oil well pipe is required for every 1m of drilling, including 48kg of casing and 10kg of oil pipe. Drill pipe
3kg, drill collar 0.5kg;
2. The mechanics and environmental behavior of oil pipes have an important impact on the adoption of advanced technology and production and efficiency in the oil industry;
3. The failure loss of oil pipes is huge, and its safety, reliability and service life are of great importance to the oil industry.
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