A kind of chemical stimulation fluid for low permeability reservoir and preparation method thereof

Abstract

The invention provides a chemical stimulation fluid for low-permeability reservoirs and a preparation method thereof. Based on the total weight of the chemical stimulation fluid being 100 parts by weight, the chemical stimulation fluid comprises the following components by weight: 10.0-20.0 parts by weight of pressure-draining agent, 5.0-10.0 parts by weight of channel dredging agent, 2.0-4.0 parts by weight of waterproof locking agent and 2.0-2.5 parts by weight of clay stabilizer; the balance is water. The chemical stimulation fluid for low-permeability reservoirs provided by the present invention can obviously remove organic and / or inorganic scale plugging; has a certain degree of corrosion to reservoir cement; can obviously reduce the water saturation in the near-wellbore zone, and improve reservoir wetting. Moisture, prevent water lock, water sensitive damage.

Description

technical field [0001] The invention belongs to the field of petroleum drilling, and relates to a chemical stimulation fluid for low-permeability reservoirs and a preparation method thereof. Background technique [0002] The purpose of oil drilling is to discover oil and gas reservoirs, correctly evaluate oil and gas reservoirs, and maximize the development of oil and gas reservoirs. However, during the process from drilling the oil layer to cementing, perforating, oil testing, workover, coring, and stimulation measures such as fracturing, acidizing, and water injection, due to the invasion of foreign liquids and solids into the oil layer, and the clay and other substances in the oil layer Physicochemical effects occur, reducing the permeability of the oil layer around the wellbore to form a low-permeability zone, increasing oil flow resistance and reducing crude oil production, resulting in oil and gas damage. Due to oil layer damage, crude oil production decreases and the ...

AI Technical Summary

Problems solved by technology

Although the new type of low porosity and permeability reservoir protection drilling fluid system can well reduce the damage to the reservoir caused by liquid phase entry in the early drilling operation, it cannot completely solve the problem of filtrate intrusion into the reservoir. Drilling fluid filtrate, cement slurry filtrate The depth of the invasion of the reservoir far exceeds the depth of the perforation

Therefore, the perforation completion method cannot completely relieve the reservoir damage caused by the incompatibility of various filtrates.

[0006] 2) Various operating fluids, alkaline completion fluids, and formation water are seriously incompatible

The reason is that the cement slurry filtrate contains a large amount of Ca 2+ and other high-valent metal ions and high pH environment, while other operating fluids contain a large amount of organic anions, and formation water contains a large amount of CO 3 2- , SO 4 2- and other inorganic anions, therefore, their mixing will produce a large amount of organic and inorganic scale precipitation, which may cause serious damage to the reservoir

Severe incompatibility between drilling fluid filtrate, cement slurry filtrate, alkaline completion fluid and formation water, resulting in serious damage to reservoir permeability, the damage degree is as high as 30%-50%

[0007] 3) Polymer macromolecule pollution

The higher the concentration, the more serious the damage, and it will cause deep damage to the reservoir

[0008] To sum up, the fluid invasion in the early stage led to the increase of water saturation and the decrease of gas and oil saturation in the zone near the wellbore; There are still water locks, water sensitivity, inorganic scale, polymers and other pollution blockages in the zone, resulting in low or even no output after production

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