How to choose anti corrosive OCTG casing and tubing?
OCTG casing and tubing are important equipment for crude oil production，The quality and service life of OCTG casing and tubing are closely related to the safety and cost of crude oil production.
The quality and service life of oil casing are closely related to the safety and cost of crude oil production.
The quality and composition of crude oil vary greatly from region to region in the world, but corrosive media are ubiquitous substances in wells in various regions of the world.
Since the casing and tubing is in direct contact with the crude oil, corrosion resistance becomes an important feature of the casing and tubing.
How to select a casing and tubing with good corrosion resistance and high cost performance? You can choose from the following aspects?
First, it is necessary to define the corrosive substances and their content in oil wells.Corrosive substances and their content in oil wells determine the material and production process of casing and tubing corrosion protection layer.
Secondly, the operating temperature of the well should be defined.
The degree of corrosion of the casing and tubing in a well increases with the temperature of the well.
In addition, many corrosion resistant of the casing and tubing have definite limits and requirements for the temperature of the operating environment.
For example, HDPE liner tubing, also known as polycore tubing, should not exceed 100 degrees Celsius for maximum operating temperature.
At present, with the development of technology, the maximum operating temperature of this anti corrosive liner tubing has been raised to 140 C.
Thirdly, it is important to know the well depth, which determines the operating temperature and load of the well.This is closely related to the operating environment of the casing body.
Fourthly, it is necessary to define the specific use of OCTG casing and tubing. such as water injection, oil extraction, Oil recovery，steam injection or ground piping.
Fifthly, it is necessary to make clear whether there is sucker rod wear in oil wells. If it is a well that with both corrosion and wear, its wear resistance should be fully considered when choosing anti-corrosion OCTG casing and tubing.
For example, HDPE Liner tuibing can resist both corrosion and wear, and its wear resistance is 5 times that of ordinary steel.
Clarifying the above five problems will help us choose the most suitable anti-corrosion oil casing for our own oil well conditions.
At present, there are many kinds of anti-corrosion and wear-resistant oil casings in the market. Their respective use environments are as follows:
1.HDPE liner tubing/ polycore tubing:
The well depth is not more than 1800 meters and the temperature is not more than 100℃, and it is an oil well and water well with corrosion and wear.
2.HTPT Liner Tubing：
The well depth is not more than 4000 meters and the temperature is not more than 140℃, and there is corrosion and wear in oil wells and water wells
3.FBE Coated TubingFusion bond epoxy tubing and Titanium Nano Polymer Coated Tubing
It is suitable for water injection wells, oil production wells, oil transmission surface pipelines, etc. at pH value of 3 ~ 13 and working temperature not higher than 100℃.
4.Tungsten plated tubing
Working temperature not exceeding 390℃, and used for corrosion and wear of water injection wells, oil production wells, oil transmission surface pipelines, etc.