A kind of polymer injection plugging well slug combined unblocking agent, preparation method and application

Abstract

The invention discloses a combined blocking remover for a polymer injection blocking well section plug and a preparation method and application of the combined blocking remover, belonging to the technical field of tertiary oil recovery. The blocking remover comprises a blocking remover for an oxidizing and gel breaking section plug consisting of the following components in percentage by weight: 10-20 percent of sodium percarbonate, 1-2 percent of active agent, 0.5-2 percent of corrosion inhibitor, 2-5 percent of mutual solvent and the balance of water. According to the combined blocking remover for the polymer injection blocking well section plug, the blocking remover for the oxidizing and gel breaking section plug has the characteristics of high oxidizing and gel breaking rate, low corrosion and high safety. The oxidative decomposition and gel breaking rate on polyacrylamide and a cross-linking polymer gel system thereof which are commonly used in oilfield polymer flooding is over 96 percent, and the corrosion rate detected by adopting an N80 steel sheet standard test piece is 1g / m2.h below. After the polymer injection well blockage is decomposed and subjected to gel breaking, the original viscous black blockage is changed into a transparent aqueous solution, the blocking remover is high in liquidity and low in residue rate, the polymer injection well formation plugging can be efficiently removed, and the aims of removing blockage and increasing injection are achieved.

Description

technical field [0001] The invention specifically relates to a polymer injection blocked well slug combined plugging removal agent, and a preparation method and application of the combined plugging removal agent, belonging to the technical field of tertiary oil recovery. Background technique [0002] Polymer flooding technology is the leading technical measure to suppress the decline of crude oil production and further enhance the oil recovery in the later stage of oilfield water flooding development. However, in the process of polymer flooding, due to the adsorption, retention and mechanical trapping of polymers in the formation porous media, it is very easy to cause formation blockage of polymer injection wells. In order to suppress polymer channeling and expand the swept volume of polymer during polymer flooding, polymer gel is usually used for profile control at different stages such as before, during and after polymer flooding, which further aggravates the The formatio...

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Problems solved by technology

[0004] In addition, an effective polymer injection well usually injects polymer solution for 3 to 4 years or even longer. During the long injection process, the adsorption, retention and mechanical trapping of polymer in the formation porous Penetrating deep into the formation, causing deep formation plugging, at the same time, the whole process profile control measures widely used in the process of polymer flooding to inhibit polymer channeling further aggravated the deep formation plugging, which requires the solution of polymer injection plugged wells The blocking radius must reach a certain depth

[0005] At present, the plugging removal technology of polymer injection wells adopted in China generally has the following technical problems: First, the complexity of plugging in polymer injection wells is ignored, and only focus on the development of chemical agents for polymer and its cross-linked gel plugging removal and application, ignoring that oil pollution and various inorganic plugs are also important causes of formation plugging, or not considering the differences in physical and chemical properties of various plugs, injecting various plugging agents in general to remove plugs, chemical agents and corresponding plugs It is difficult to effectively contact and react, and the plugging removal effect is usually far from that of the laboratory test; the second is the inertial thinking of plugging removal near the wellbore, and the plugging removal radius is usually designed at 2 to 3 meters, ignoring the deep plugging of polymer injection plugging wells characteristics, unable to achieve the purpose of deep plugging removal

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