Oil recovery method for casing leaked well and dual-tubing oil recovery string adopted therein

Abstract

The invention discloses an oil recovery method for a casing leaked well and a dual-tubing oil recovery string adopted therein. The method can be applied to part of casing leaked wells which have long sections, contain high-pressure water formations and have extremely poor leak point absorbance. According to the method, packer setting is conducted between the portion, below a leak point and above an oil reservoir, of a casing and an oil tube through a packer, and oil recovery is conducted by installing a small-diameter tubing pump in a small-diameter oil tube in the oil tube or by installing a rod type oil-well pump in a hollow sucker rod in the oil tube. The dual-tubing oil recovery string formed by the oil tube and the small-diameter oil tube or by the oil tube and the hollow sucker rod is adopted, and the small-diameter oil tube or the hollow sucker rod serves as a liquid channel, so that the casing damaged or leaked wells which have small-reducing leap-free casings, have long sections, contain high-pressure water formations and have extremely poor leak point absorbance are effectively managed. Management method is simple, investment cost is low, validity period is long, overhauling is not needed often, the problem of leakage of casings in any lengths can be solved, the yield of most casing leaked wells can be recovered, and economic benefits are remarkable.

Description

technical field [0001] The invention relates to a downhole oil recovery string of an oil production well in the petroleum industry, in particular to an oil recovery method for a casing leakage well and a double-pipe oil recovery string. The present invention can be used in casing leakage wells with problems such as long well sections, high-pressure water layers, and extremely poor suction at leakage points, so as to restore the production of the above-mentioned oil wells in the production process after well completion and slow down the rise of comprehensive water cut in the oil wells. Background technique [0002] In the middle and late stages of oil and gas field development, casing damage and casing leakage caused by various reasons are becoming more and more serious, resulting in increased water cut and declining production in oil wells, seriously restricting the sustainable and stable development of mature oil fields. According to statistics, about half of casing damage ...

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Problems solved by technology

[0004] 1. Packer string sticking process: simple operation and low cost, but the validity period is short, and sand is produced at the leak point, which is easy to cause overhaul. Because the original well tubing is still used for oil production, due to stuck leak, it is impossible to wash the well and measure the liquid level;

[0005] 2. Casing repair: It is not suitable for long well sections and operations corresponding to high-pressure water layers, the cost is high, and it is difficult to repair after failure;

[0006] 3. Small casing cementing: long effective period, but long operation period, high cost, difficult well cementing due to well depth, and difficult to repair again after casing breaks;

[0007] 4. Cement plugging process: Sometimes the construction pressure is too high, and the cement slurry is difficult to squeeze into the target layer continuously, which may easily cause overhaul; the leakage point has extremely poor suction, about ≦0.1m 3 / min, the conventional plugging agent cannot be squeezed into the leak point

[0008] In view of the above difficulties in the process of casing leakage treatment, conventional means can no longer meet the treatment requirements. Therefore, it has been developed to develop a production string for controlling casing leakage and casing damage wells that is simple to operate, low in cost, long in validity, and not easy to overhaul. very necessary

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