Slow-release corrosion and scale inhibitor capsule for oil wells and preparation method thereof

Abstract

The invention provides a double-film controlled-release corrosion and scale inhibition capsule and a preparation method thereof. The preparation method comprises the following steps: uniformly mixinga corrosion and scale inhibition integrated agent, an inorganic carrier and a density weighting agent, kneading the mixture, and drying the mixture to obtain a loading integrated agent; kneading the integrated loading agent, an aqueous solution of a coating agent A and an aqueous solution of a cross-linking agent, then preparing a particle ball by adopting an extrusion method, and drying the particle ball to form a capsule core; and spraying and coating the capsule core with an aqueous solution of a coating agent B and an aqueous solution of a cross-linking agent to form a first layer of film,then spraying the aqueous solution of the coating agent A and the aqueous solution of the cross-linking agent to form a second layer of film, and performing drying to obtain the slow-release corrosion and scale inhibitor capsule for oil wells. The capsule anti-scaling particle filling process is simple, a tubular column is not moved, and the capsule anti-scaling particle can be put into a wellbore pocket through an oil sleeve annulus at a time. Meanwhile, the density of the added weighting agent is larger than that of water, the weighting agent does not flow away along with wellbore liquid soas to guarantee rapid sinking of the capsule, and the purpose of slow release is achieved by slowly dissolving the water-soluble capsule shell into water.

Description

technical field [0001] The invention relates to a slow-release corrosion and scale inhibitor capsule for oil wells and a preparation method thereof, belonging to the field of oil field chemistry. Background technique [0002] Oilfields are generally developed by water flooding. Since the injected water contains scale-forming ions such as sulfate and carbonate ions, and the formation water is rich in calcium, barium / strontium, etc., due to the incompatibility of the two water qualities, sulfate scales and carbonates are easily formed. Scale, resulting in surface pipelines, wellbore, stratum fouling blockage, a greater impact on oilfield production. Especially in recent years, with the development of the main block into the middle and high water cut stage, and the enhanced oil recovery (CO 2 Flooding, air foam flooding, etc.) process tests, resulting in frequent wellbore corrosion and scaling, seriously affecting the safe production and operation of the oilfield. [0003] Th...

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Problems solved by technology

[0002] Oilfields are generally developed by water flooding. Since the injected water contains scale-forming ions such as sulfate and carbonate ions, and the formation water is rich in calcium, barium / strontium, etc., due to the incompatibility of the two water qualities, sulfate scales and carbonates are easily formed. Scale, resulting in fouling of surface pipelines, wellbore, and strata, which has a great impact on oilfield production

Especially in recent years, with the development of the main block into the middle and high water cut stage, and the enhanced oil recovery (CO 2 Flooding, air foam flooding, etc.) process tests, resulting in frequent wellbore corrosion and scaling, seriously affecting the safe production and operation of the oilfield

[0003] The corrosion and scale inhibition of oil wells is usually added by adding corrosion inhibitors and scale inhibitor liquids. It is inconvenient to add them continuously on site. It is time-consuming and labor-intensive to add them manually. Moreover, the liquid corrosion and scale inhibitors flow away with the produced fluid or It adheres to the pipe wall and cannot reach the bottom of the well, and the action period is relatively short; there are also solid corrosion and scale inhibitors added at one time. Cast molding, put into the anti-scaling working cylinder, and connect to the lower part of the oil well pump and the upper part of the screen pipe. This method needs to shut down the well, and the process is complicated, which affects the production of the oil field.

At present, the hot spots are slow-release corrosion inhibitors and scale inhibitors. The production method is to uniformly mix scale inhibitors with fillers, adhesives, dispersants and other agents in a certain proportion, extrude them, then air-dry them, and crush them to form Particles of a certain size have achieved a certain sustained-release effect, but due to the rapid release of the drug, the effective period is short

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