SU1738821A1 - Method of producing light drilling mud - Google Patents

Description

3173

reducing the density and increasing the stability of the solutions.

The goal is achieved by the introduction of an aqueous solution of carboxymethylcellulose (CMC) into the well and in a viscous CMC solution of condensed fine chalk due to a chemical reaction between sodium carbonate and calcium chloride, then gassing by injection into a solution ammonium sulfate.

In contrast to the known method, the proposed method allows the process to be carried out at temperatures not higher than 90 ° C with the release of a gaseous agent — a fine chalk — in a polymer solution medium.

The goal is achieved due to the uniform generation of gas at positive temperatures no higher than 90 ° C in a polymer solution medium as a result of targeted chemical reactions.

The method is carried out as follows.

CMC is dissolved in water and, after it is completely dissolved, the calculated stoichiometric amount of calcium chloride and sodium carbonate is successively added, then the resulting solution is mixed in the well with a solution of aluminum sulfate. In a viscous polymer solution, calcium chloride reacts with sodium carbonate to form fine chalk, which is evenly distributed throughout the polymer solution. When adding aluminum sulphate fine chalk decomposition

with the formation of carbon dioxide. The overall process response is as follows:

3CaClЈ + 3NaiC03 + Al2 (S04) 5 + 3HiO- (OH) s + ZSazO + bybya + ZSOg.

Since the particles of chemically precipitated chalk are very small and evenly distributed in the solution, the bubbles of carbon dioxide formed are also small in size and evenly distributed in the viscous solution.

In a polymer solution, the rate of bubble rise is insignificant; therefore, this lightweight solution has a low density and high stability,

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Q 5

ABOUT

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The stoichiometric ratio of calcium chloride, sodium carbonate and aluminum sulfate in the solution should be 1.00: 1.00: 1.03.

At lower ratios, the above reaction does not pass to the end, some of the components are used irrationally and remain in excess.

A slight excess of aluminum sulfate has a positive effect on the properties of the solution due to the formation of microgel of aluminum hydroxide in the medium of the polymer solution.

Example. To prepare a solution containing,%: CMC 2; calcium chloride 2; sodium carbonate 2; aluminum sulphate 2, 20 g of CMC is dissolved in 920 ml of water. After the polymer has completely dissolved, 20 g of calcium chloride, 20 g of soda ash and 20 g of aluminum sulphate are successively added,

As a result of the reaction. Carbon dioxide is formed between the reagents, which is evenly distributed throughout the solution. The density of the lightweight solution is 890 kg / m3, the lifetime of the formed foam is more than 300 minutes. The experimental data on the effectiveness of the proposed method for preparing the solution are given in the table.

Analysis of the data presented allows us to conclude that the proposed method is more efficient than in comparison with. famous. Effective gassing is possible at positive temperatures no higher than 90 ° C. The resulting lightweight solutions have a significantly low density, therefore, they have a high ability to reduce the hydrostatic pressure in the well. According to the values of static shear stress, the high out-of-pocket and retention ability of the solutions prepared by the proposed method is obvious, due to the high stability of the foam, high-quality insulation is ensured, and the subsequent cleaning of the formation.

Claims (1)

The technical and economic efficiency of the proposed method is determined by the possibility of efficient gas generation at positive temperatures with small amounts of available reagents. Invention Formula The method of obtaining a lightweight drilling mud, including the sequential introduction into the well of gassing and aluminum sulphate, characterized in that, in order to increase the efficiency of the method due to uniform generation of gas at temperatures not exceeding 90 ° C while reducing density and increasing stability solution, before the introduction into the well 821 An aqueous solution of carboxymethylcellulose is prepared in which calcium chloride and gas evolution reagent are additionally introduced with stirring, sodium carbonate in stoichiometric ratio with calcium chloride being used as gas emission reagent. ten  At these temperatures, gas generation does not occur.