Producing well sleeve interior anti-corrosion method

Abstract

The invention provides a producing well sleeve interior anti-corrosion method. A pump hanging tail pipe is extended to the position, 1-2m from the upper end, of a perforation segment, thereby enablingoil water mixture of a sleeve and the space of an oil pipe ring between the flow liquid level and the tail end of the pump hanging tail pipe to become dead volume and oil water ratio to be increased,and a corrosion inhibitor is additionally filled in the oil water mixture of the sleeve and the space of the oil pipe ring. According to the producing well sleeve interior anti-corrosion method, liquid of the space of the flow liquid level and the tail pipe of the oil pipe ring becomes the dead volume by extending the pump hanging tail pipe, because the densities of oil and water of output liquidare different and the gravity theory exists, the oil and water are gradually separated, and crude oil occupies the upper space; output water moves downward, the part of dead volume from the flow liquid level to the space of the tail pipe of the oil pipe ring is occupied by the crude oil, the water content is greatly decreased, thereby greatly reducing corrosion for the interior of the sleeve; thecorrosion inhibitor is added in the space of the oil sleeve ring at the same time, since the part of the liquid is the dead volume, once the added corrosion inhibitor is dispersed in the part of theliquid, and the corrosion inhibitor can exist for a longtime without replenishing; and the dosage of the corrosion inhibitor and the personal cost can be greatly reduced.

Description

technical field [0001] The invention belongs to the technical field of anticorrosion in oil and gas fields, and in particular relates to an anticorrosion method for casing pipes in oil production wells. Background technique [0002] After the operation of the downhole pump for mechanical oil recovery is completed, air enters along with the liquid level in the annular space of casing pipe 2 in the wellbore continuously falling. In a humid environment, the inner wall of the casing 2 and the outer wall of the oil pipe 1 are continuously corroded, and the protective film such as the passivation film formed falls off under alternating and vibration loads and frequent operations, and the corrosion continues. Such a cycle makes the pipe The walls keep getting thinner. And every time the pipe wall becomes thinner by 1 mm, its tensile strength, external extrusion resistance, and internal pressure resistance will decrease by more than 118% for Φ73 mm oil pipe, 210% for Φ139.7 mm casi...

AI Technical Summary

Problems solved by technology

[0004] Due to the complexity of corrosion source components, mutual superposition and interaction, stress changes during well production and continuous destruction of passivation film and protective film during operation, the covering method can only partially alleviate the corrosion problem, and the common problems are high cost, The problem of poor performance

[0005] The method of adding corrosion inhibitors to the wellbore to reduce the corrosion rate has the following three disadvantages: First, continuous dosing is required, which not only requires a large amount of corrosion inhibitors, but also high labor costs; second, the effect of corrosion inhibitors is better in the early stage of oil well production , as the development progresses, the water content rises, and the corrosion inhibition effect becomes worse; the third is that adding corrosion inhibitors in severely corroded oil fields still cannot achieve the purpose of corrosion inhibition

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