A structure and method for preventing corrosion damage of downhole aluminum alloy-carbon steel pipe column

Abstract

The invention discloses a structure and method for preventing corrosion damage of underground aluminum alloy-carbon steel pipe columns, and belongs to the technical field of production pipe columns of oil field gas wells. The surface of an inner ring hook groove of an aluminum alloy cover is octagonal, an inner flange of a correspondingly assembled carbon steel is octagonal, and the two are assembled through an insulation sleeve to effectively prevent the rotating crankle loose buckling between upper and lower pipe columns so as to improve the joint insulation performance; the anodic oxidation treatment is performed for corresponding engagement surfaces of the aluminum alloy cover and the periphery of the inner flange of the carbon steel; a hook sleeve of the aluminum alloy cover is connected with the cover by a straight thread; after an insulation joint is assembled from bottom to top, epoxy resins are filled, the hook sleeve is tightened, and finally, a thermal shrinking cover serves as a joint protective cover; a righter is arranged and distributed as follows: the righter adopts a plastic insulation pipe; four convex edges are arranged at the periphery of a bone pipe; guide grooves are formed between the convex edges; and a plug is connected to the lowermost end of an aluminum alloy pipe.

Description

technical field [0001] The invention relates to a structure and a method for preventing corrosion damage of an aluminum alloy-carbon steel pipe column in a downhole, and belongs to the technical field of oil field gas well production pipe strings. Background technique [0002] The demand and application proportion of natural gas mining in my country is increasing. In order to reduce production costs and improve efficiency, oil and gas production enterprises must adopt economical downhole pipes suitable for well conditions. [0003] Changqing Oilfield is a typical (extra) low-permeability oil and gas field, which is characterized by low production of natural gas wells and deeper wells. The domestic CT70 coiled tubing is used as the velocity string in the drainage gas production process, and its cost is high. Therefore, a new type of velocity string composed of downhole "medium carbon steel + aluminum alloy tube" was developed. The economical and effective development of low-...

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Problems solved by technology

[0009] The second is that the aluminum oxide film has high hardness and high brittleness, and is not suitable for use in the environment of mechanical action. The high-strength impact force at the joint thread can easily cause microcracks

[0010] In the anoxic environment of high-temperature and high-pressure gas wells, the thermal (micro) cracks of the aluminum alloy anode cannot be completely self-healed in time. Cracks can directly lead to joint damage and failure, and gas well production will pose a great safety risk

[0011] The use of galvanic corrosion pipe string combination in the wellbore has always been a taboo in the industry. The general method to prevent galvanic corrosion is to use high-standard pipes of the same grade as much as possible. For the safety first consideration, this method is very important for the development of high-yield corrosion gas wells. It is a completely risk-free measure, but it is very uneconomical for gas fields with low production gas wells and deep gas layers. It is very necessary to find an economical, effective and reliable method to prevent galvanic corrosion of aluminum alloy tubes

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