A high-viscosity and strong-corrosion acid system for tight oil reservoirs

Abstract

A high-viscosity strong corrosion acid solution system for tight oil reservoirs, comprising: 6%-12% hydrochloric acid, 1%-3% betaine, 4%-8% enhancer, 0.05%-0.2% citric acid, 0.5%-2% ammonium chloride, 0.5%-2% corrosion inhibitor, 0.1%-0.4% drainage aid, 0.05%-0.2% demulsifier, the balance is water, the sum of the above components is 100%; During the acidification of the acid solution system of the present invention, the increase of the viscosity of the acid solution reduces the fluid loss of the acid solution, forces more fresh acid to enter the deep part of the formation, and increases the effective distance of the acid solution. After the acidification, the high-viscosity fluid encounters When crude oil is in the formation, it will automatically break the gel and turn it into a low-viscosity fluid, so that the formation will not be damaged again.

Description

technical field [0001] The invention relates to an acidizing and plugging-removing acid solution in oil and gas field development technology, in particular to a high-viscosity and strong-corrosion acid solution system for tight oil reservoirs. Background technique [0002] With the increase of oil field development, the increase of water flooding energy, and the fracturing process and the water flooding process may cause some damage to the reservoir, which will bring some new problems in the long-term production of oil wells, such as The water flooding process often causes the migration of fine sand bodies in the formation to block the oil outlet channels, and formation scaling pollutes the oil outlet channels, resulting in blockage and pollution of the oil outlet channels. For these reasons, the skin factor of oil wells increases, resulting in a reduction in the production of some oil wells. [0003] For this reason, it is necessary to acidify oil-bearing reservoirs (fract...

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Problems solved by technology

[0004] From the current effect of acidification plugging removal measures, the effect of increasing production and increasing injection is not ideal. It is not that the acid solution has a poor effect on plugging and plugging. The main reason is that the acid solution is not completely as expected due to the "fingering" phenomenon. It is envisaged to enter the clogging zone for unblocking, but to enter the high-permeability layer with low seepage resistance to improve its matrix, the clogging cannot be completely removed, and the clogging in the reservoir will aggravate scaling and reduce production, thus shortening the effective period of acidification measures

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