Microcapsule-encapsulated acid for oil field and preparation method thereof

Abstract

The invention discloses a microcapsule wrapping acid used for an oil field, which is prepared from basic acid, a curing filling material, a wrapping material, a surfactant and a solvent; and a preparation method comprises the steps of preparing materials, mixing, heating, fluidifying and wrapping. A macromolecule wrapping material is adopted for the microcapsule wrapping acid, which is carried todeep cracks of a stratum along with an injected liquid in the process of acid fracturing construction, and the situation of release of basic acid cannot occur when the material is in the shaft and just enters the cracks; H<+> can be released after the liquid enters the deep cracks of the stratum, thus breaking through the limitation of reaction conditions of conventional acidic rocks, greatly extending the effective acting distance of the acid liquor, and simplifying the construction flow and reducing the construction requirement; because wrapping treatment is performed on the basic acid, danger cannot be caused, and the wrapping acid can be stored for a long time; corrosion to a tubular column cannot be caused, and an acid fracturing flowback liquid produced subsequently is low in environment pollution damage, residue basically does not exist after acid fracturing, and secondary damage to the reservoir stratum can be avoided.

Description

technical field [0001] The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a microcapsule-encapsulated acid for oil fields and a preparation method thereof. Background technique [0002] Acid fracturing is an important production stimulation measure for carbonate oil and gas reservoirs, and its stimulation effect on oil and gas reservoirs is mainly determined by the conductivity of acid-etched fractures and the length of acid-etched fractures. The fracture conductivity mainly depends on the amount of acid-dissolved formation materials and the irregularity of the acid-etched fracture wall surface. The length of the acid-etched fracture is controlled by the acid fluid loss characteristics, the acid-rock reaction rate, and the acid fluid velocity in the fracture. In the conventional acid fracturing technology, the acid rock reaction is mainly limited by four conditions: ① H+ generation rate under chemical equil...

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Problems solved by technology

[0003] The solid acid in the early stage mainly used nitric acid, and the acid was solidified into granules through a curing agent. Without encapsulation measures, the solid nitric acid began to release nitric acid immediately after mixing with water. Nitric acid itself is a strong acid and has a strong oxidation effect. The blockage of organic matter in the formation has a strong lifting effect, but the etching effect on carbonate rock is relatively poor, and there is a danger to personnel caused by the release of nitric acid during use

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