Blocking remover for augmented injection of oilfield polymer-injected wells

Abstract

The invention provides a blocking remover for augmented injection of oilfield polymer-injected wells. The blocking remover is prepared from the following raw materials in parts by volume: a. 1.0-5.0 parts of crude oil cleaning agent, b. 0.1-1.0 part of oxidation-reduction system and c. 2.0-4.0 parts of clay stabilizer, wherein the oxidation-reduction system is prepared from an oxidant and a reducer which are in the parts-by-mass proportioning ratio of 1: (0.2-0.5); and the clay stabilizer means KCl, NH4Cl, a polyquaternary ammonium salt or a quaternary ammonium salt. According to the blocking remover, the oxidation-reduction system serves as a main agent, and a polymer-injected-converted water-flooding well blocking remover is prepared from the crude oil cleaning agent, the clay stabilizer, and the like; oxygen gas generated by the oxidant is converted into hydroxyl radicals by the oxidation-reduction system, so that no gas is generated in constructed reservoirs; and meanwhile, the system is non-corrosive, thereby being a safe, environment-friendly and high-pertinency blocking removal system.

Description

Technical field: [0001] The invention relates to a booster injection system aimed at water wells which are difficult to inject water after subsequent water flooding of polymer injection wells in the tertiary oil recovery process of oil fields. It is especially aimed at the depressurization and injection enhancement system of water injection wells using polyacrylamide and its derivatives as oil displacement polymers. Background technique: [0002] Tertiary oil recovery is one of the important development methods of oilfields at present. Polymer injection has been carried out in a large number of water injection wells, and good development results have been achieved. However, during the subsequent water flooding process of polymer injection, water injection wells generally experience increased water injection pressure, difficulty in injection, and difficulty in reaching the injection volume. Based on the analysis of on-site well washing and sand washing, the blockages are comp...

AI Technical Summary

Problems solved by technology

However, during the subsequent water flooding process of polymer injection, water injection wells generally experience increased water injection pressure, difficulty in injection, and difficulty in reaching the injection volume. Based on the analysis of on-site well washing and sand washing, the blockages are complex, including polymer aggregates. And reservoir sediment and various scale samples, complex plugging and plugging mechanism make the unblocking process difficult

At present, the plugging removal of such under-injection wells is mainly based on acidification and filling. Due to the lack of pertinence, single process and poor effect, it is difficult to solve on-site problems. It is urgent to carry out relevant process technology research to solve the problem of water injection in polymer injection wells

[0003] Conventional acidification, filling and other processes carry out plugging removal work, the effect is poor, and the validity period is short; using chlorine dioxide, hydrogen peroxide and other strong oxidants as plugging agents has a certain effect, but the safety is poor, and it is not suitable for storage and transportation and on-site construction

Cannot meet safety and environmental protection requirements

The reported plugging removal technologies for such wells can be divided into two categories. The first type uses strong oxidants such as chlorine dioxide and hydrogen peroxide to unblock reservoirs. However, due to their strong corrosiveness, Explosive gas can be produced during transportation and construction, which has caused great difficulties and potential safety hazards in the construction process; Hao Zhanyuan et al. (CN1435464) utilize sodium chlorite or sodium chlorate to react with phosphoric acid or citric acid to produce chlorine dioxide underground; Zhao Yingqiu et al. (CN1247734C, CN102925128A) invented a composite plugging removal process, which mainly consists of a mixture of calcium peroxide and tert-butanol peroxide for polymer plugging removal; Hu Xinsuo et al. Unblocking method of catalyst ADS; Lin Aiguo et al. invented a block-removing agent formula mainly composed of double-base curing cracking agent, dispersant, self-generated gas foaming and energy-enhancing diffusing agent

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