During the oil drilling process, the drill collar is an important component connecting the drill bit and the ground equipment. Due to the flow of drilling fluid and the presence of corrosive media in the drilling environment, the inner wall of the drill collar is susceptible to corrosion, which not only affects the drilling efficiency, but also greatly shortens the service life of the drill collar. In order to deal with this problem, scientists and engineers have developed a variety of anti-corrosion methods to extend the service life of the drill collar and reduce drilling costs. This article will introduce in detail an advanced anti-corrosion method for the inner wall of oil
drill collars and its practical application effect.
Overview of drill collar anti-corrosion method
This anti-corrosion method prevents the inner wall from being corroded by spraying an anti-corrosion coating on the inner wall of the drill collar. The entire spraying process is divided into four main steps: thread cleaning, inner wall rust removal, coating spraying, and anti-corrosion coating detection. Each step is crucial to ensure that a firm and uniform anti-corrosion coating is finally formed.
A) Thread cleaning
The first step is thread cleaning. Remove the thread protectors at both ends of the drill collar to be treated, and then use a cleaning agent to thoroughly clean the oil on the thread. The purpose of this step is to ensure that there is no oil interference in the subsequent steps and to ensure the adhesion of the coating.
B) Rust removal of the inner wall
The inner wall rust removal adopts a three-step rust removal method:
High-pressure water sandblasting: Use high-pressure water sandblasting equipment to treat the oxide layer on the inner wall of the drill collar to expose the smooth metal surface of the inner wall. This step can effectively remove the oxide layer and rust to ensure the cleanliness of the inner wall.
Drying treatment: Place the drill collar in a drying furnace to dry the moisture to prevent the residual moisture in the subsequent steps from affecting the adhesion and curing of the coating.
Pneumatic sandblasting: Use pneumatic sandblasting equipment to sandblast the inner wall of the drill collar again to remove rust, and thoroughly blow away the dust on the inner wall. This step further refines the inner wall surface and lays a good foundation for coating spraying.
C) Coating spraying
Use two-layer spraying process to spray TK34 epoxy phenolic coating on the inner wall of drill collar:
Base coating spraying: Use high-pressure centrifugal spraying equipment to spray the base coating. After spraying, send the whole drill collar into the preheating furnace and take it out of the furnace after the coating is dried. The preheating furnace is equipped with 2 burners and 4 circulating fans to achieve heating and forced circulation of air in the furnace. The circulating hot air can play a role in uniformly heating the bottom layer.
Surface coating spraying: After the drill collar cools down, the surface coating is sprayed. After spraying, the drill collar is sent to the baking furnace for baking to solidify the coating. The baking temperature is 220-250℃. At this temperature, the bottom layer and the surface layer of coating undergo cross-linking reaction to form a firm anti-corrosion coating.
D) Anti-corrosion coating detection
The anti-corrosion coating is detected, and the drill collar with incomplete anti-corrosion coating is returned to the inner wall rust removal step for rework. Through strict inspection and rework, it is ensured that the inner wall of each drill collar has a high-quality anti-corrosion coating.
Technical advantages
The beneficial effect of the above technical solution is that this method can make the inner wall of the drill collar have a firm anti-corrosion coating with a smooth surface. On the one hand, this can increase the flow rate of drilling fluid in the drill collar; on the other hand, it can also effectively slow down the corrosion of the inner wall of the drill collar by corrosive media such as H2S, CO2, and Cl-. Practice has proved that this anti-corrosion coating can increase the life of the drill collar by more than three times, greatly reducing the cost of drilling, and has a very significant effect.
Improvements in practical applications
In practical applications, in order to further optimize the anti-corrosion effect and coating quality, the following improvements can be made:
Improvements in preheating furnace and baking furnace: The preheating furnace and baking furnace in step C both use hot air circulation heating to evenly heat the bottom layer and the surface layer to ensure the uniformity and firmness of the coating.
Anti-corrosion coating thickness control: The thickness of the anti-corrosion coating is controlled between 175 and 225 microns. The coating thickness within this range can provide the best anti-corrosion effect and mechanical properties.
Anti-corrosion of drill pipe and casing pipe
In addition to drill collars, drill pipes and casings also need to be treated with anti-corrosion in oil drilling.
Drill pipes and casing pipes will also be exposed to corrosive media during drilling, so anti-corrosion treatment is also crucial. Drill pipes and
casing pipe can also use the inner wall rust removal method of drill collars, just make appropriate adjustments according to their size and structure.
In general, anti-corrosion treatment is an important technical means to extend the service life of drilling tools and improve drilling efficiency. With the continuous advancement of technology, it is believed that in the future, more efficient and environmentally friendly anti-corrosion methods will be developed to further promote the development of oil drilling technology.
Conclusion
Through the above detailed anti-corrosion methods, the service life of oil drill collars can be significantly improved and drilling costs can be reduced. In practical applications, strictly following each step and improving it in combination with actual conditions can ensure the best anti-corrosion effect. Anti-corrosion technology is not only applicable to drill collars, but also to other drilling tools such as drill pipes and casings. It is an indispensable and important technology in the field of oil drilling.