Near-neutral working fluid for improving permeability of high-temperature sandstone reservoir and preparation method of near-neutral working fluid

Abstract

The invention discloses a near-neutral working solution for improving the permeability of a high-temperature sandstone reservoir. The near-neutral working solution is prepared from 5-15 parts of organic carboxylic ester, 1-10 parts of inorganic fluoride, 0.5-1 part of an iron ion stabilizer, 0.2-0.5 part of a discharge aiding agent, 0.5-1 part of an anti-swelling agent, 1-3 parts of a complexing agent and 69.5-91.8 parts of water. The invention discloses a preparation method of a near-neutral working solution for improving the permeability of a high-temperature sandstone reservoir. The preparation method comprises the following steps: (1) preparing organic carboxylic ester; and (2) sequentially adding the organic carboxylate, the inorganic fluoride, the cleanup additive, the anti-swelling agent, the iron ion stabilizer and the complexing agent into water, and uniformly stirring. Compared with the prior art, the working fluid has the following beneficial effects: 1, when the working fluid is used in the transformation of a sandstone reservoir with the temperature exceeding 120 DEG C, the pH value of a working fluid system is 6.0-7.0, the pH value of residual liquid after the working fluid reacts with stratum rocks is 6.5-7.5, and the working fluid is small in corrosion to equipment, safe in construction and good in water solubility; 2, the on-site preparation is simple, and the construction difficulty is low;

Description

technical field [0001] The invention relates to a near-neutral working fluid for improving the permeability of high-temperature sandstone reservoirs and a preparation method thereof, belonging to the technical field of oil field chemical industry. Background technique [0002] In oilfield development, the acidizing process is usually used to increase the permeability of the near-wellbore zone of low-permeability sandstone reservoirs and increase the production of oil and gas wells. Sandstone is composed of sand grains and intergranular cements. The sand grains are mainly quartz and feldspar, and the cements are mainly clay and carbonates. The oil and gas storage space and seepage channels of sandstones are not completely filled by cements between sand grains. of pores. The acidizing treatment of sandstone is to dissolve the cement and some sand grains between the sand grains by acid liquid, or dissolve the mud plugs in the pores, or other scales to restore and increase the ...

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Problems solved by technology

[0005] For high-temperature sandstone reservoirs, due to the high temperature of the reservoir and the large amount of additives used in the acid solution, the cost of the acid solution is high, and the acid solution is easily consumed near the wellbore, and the action distance of the acid solution is short, which limits the effect of acidizing stimulation

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