Multi-formation acidification water injection string

Abstract

The invention relates to a multi-formation acidification water injection string. The multi-formation acidification water injection string comprises an upper eccentric water distributor, a middle eccentric water distributor and a lower eccentric water distributor corresponding to an upper water injection layer, a middle injection layer and a lower water injection layer, wherein a centralizer and afirst packer are arranged between the upper eccentric water distributor and the middle eccentric water distributor, an intelligent acid injection valve and a second packer are arranged between the middle eccentric water distributor and the lower eccentric water distributor, a switching valve is arranged above the upper eccentric water distributor, an intermediate oil pipe is arranged under the eccentric water distributor, an acidification single-flow valve is connected under the intermediate oil pipe in a screwing mode, a screen pipe is connected to the lower end of the acidification single-flow valve in a screwing mode, an oil pipe holder is arranged under the screen pipe, a paint oil pipe is connected under the oil pipe holder, and a screw plug is connected to the lower end of the paintoil pipe in a screwing mode. A sliding sleeve ball seat is arranged in the middle section of an inner cavity of a lower joint of the acidification single-flow valve, a pressure ring is arranged on theupper part of the lower joint, and a sealing ball seat is arranged at the top of the pressure ring. The multi-formation acidification water injection string can be acidized layer by layer from bottomto top by being pulled out only once, no residual acid is required to be discharged, and after acidizing is ended and a throw-in test is completed, water can be injected directly.

Description

technical field [0001] The invention relates to a water injection well string, in particular to a multi-layer acidification water injection string, which belongs to the technical field of water injection well devices. Background technique [0002] After a period of development of water injection wells, especially in the late stage of oilfield development, the water injection pressure of most water injection wells will increase greatly, and it will show a trend of increasing year by year, resulting in less and less water injection, which will affect the water injection development effect. Severe impact, ultimately greatly reducing oil field production. [0003] Acidizing is a measure to remove plugging and increase injection that is often taken on the formation. It uses the chemical dissolution of acid liquid and the hydraulic action when squeezing acid into the formation to dissolve formation blockages and some formation minerals, expand, extend, and communicate formation fr...

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Problems solved by technology

[0005] The traditional acidizing plugging removal process mainly has the following problems: (1) Due to the pressure relief or liquid drainage after acidizing, the oil layer may be excited, causing particle migration and causing damage to the reservoir, and there is a certain risk; (2) After acidizing plugging removal, it is necessary to Long-term flowback treatment takes up a long time in the well; (3) There are many construction procedures, long periods, and many tools are used, which increases the operating cost; (4) During the swabbing and drainage process, in order to prevent the coating damage of the paint tubing under the screen, it is necessary to A new set of ordinary oil pipes is used for acidification and liquid drainage construction, which increases the cost of materials; (5) The acid liquid discharged from the return cannot be discharged on site, and needs to be transported to a designated place by special vehicles for treatment, which increases subsequent treatment costs

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