A kind of nano temporary plugging liquid and its preparation method and a kind of plugging removal liquid

Abstract

The invention provides nanometer temporary blocking liquid, which is prepared from 2 to 4 percent of bentonite, 0.2 to 0.8 percent of clay dispersing agents, 0.2 to 0.5 percent of tackifiers, 0.05 to 0.1 percent of anti-swelling agents, 0.1 to 1.0 percent of temporary blocking nanometer materials, 0.1 to 0.2 percent of nanometer material dispersion stabilizers and 0.1 to 0.2 percent of pH regulators. The invention also provides a preparation method of the nanometer temporary blocking liquid. The method comprises the following steps of (1), adding the bentonite, the clay dispersing agents and the pH regulators into water; uniformly stirring the materials; (2) sequentially adding the anti-swelling agents and the tackifiers; sufficiently stirring the materials to obtain a bentonite dispersing system; (3) preparing the temporary blocking nanometer materials into high-concentration nanometer dispersion glue liquid; (4) mixing the nanometer dispersion glue liquid and the bentonite dispersion system; adding the nanometer material dispersion stabilizers; then, performing sufficient stirring dispersion. The invention also provides unblocking liquid, which is prepared from 0.2 to 0.5 percent of gel breakers and 10 to 15 percent of acid liquid.

Description

technical field [0001] The invention relates to the field of exploration, in particular to a nano temporary plugging fluid, a preparation method thereof and a plugging removal fluid. Background technique [0002] The positive pressure difference formed between the drilling fluid and the formation during the drilling process can cause a large number of solid particles and foreign liquids to enter the reservoir, reducing the permeability of the formation and reducing the productivity of oil and gas wells. Experimental research shows that the damage rate of solids to the reservoir during drilling can be as high as 90%, the penetration depth can reach 1.5m, the damage rate of filtrate to the reservoir can reach 40%, and the damage radius can reach 4.0m. It is difficult to relieve by perforation. The so-called shielding and temporary plugging technology is: the key to designing a harmless drilling fluid that prevents the intrusion of filtrate and solid particles is to bridge the...

AI Technical Summary

Problems solved by technology

A large number of nanoscale pores will be formed between the micron-scale particles after bridging. The diameter of these nanoscale pores can often reach 100-200nm. Completion fluid filtrate still continues to invade, causing reservoir damage

[0005] On the other hand, conventional shielding and temporary plugging reservoir protection methods mainly rely on natural flowback and matrix acidification for plugging removal.

Natural flowback is mainly through the reverse displacement of formation fluid pressure to discharge the temporary plugging material in the pores. This method has the disadvantages of long flowback time, incomplete flowback, and low permeability recovery rate; It is by injecting a certain amount of hydrochloric acid (concentration 15%) or earth acid (10% HCl+3% HF) into the reservoir. The two often induce acid sensitivity, sand production, and secondary precipitation of the reservoir while removing plugging. A series of negative effects, resulting in low recovery rate of reservoir permeability (generally 50%-80%)

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