RU2250364C2 - Foam-forming compound for completing and washing wells and method for implementing said compound - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: compound including chlorine ammonium, sodium nitrite, reaction initiator, surfactant and water, as reaction initiator and surfactant has special alkylphosphate with following ratio of components in percents of mass: chlorine ammonium 5.0-28.0, sodium nitrite 5.0-28.0, alkylphosphate 0.5-5.0, water - the rest. Method for completing and washing wells and cleaning face zone of bed from pollutions, including pumping of foam-forming compound, pressing this into bed or to face, closing well, exposure for generation of nitrogen and forming of foam, then launch of well for self-drain, uses above-mentioned foam-forming compound, which is pressed by oil or mineralized water.

EFFECT: higher efficiency.

2 cl, 5 ex, 1 tbl

Description

The invention relates to the oil and gas industry, in particular to foam-forming compositions, and is intended for the development and washing of wells, as well as cleaning the bottom-hole formation zone from contamination.

A known method of opening a productive formation in a well, comprising preparing foam by introducing gas into a foaming agent solution, the gas being introduced in the perforation zone due to the chemical interaction of sodium nitrite, ammonium chloride and organic acid, while the organic acid is introduced into the perforation zone using a special container (USSR AS No. 1273508, Е 21 В 43/00, 11/30/1986).

The disadvantages of this method are:

a) when sulfamic, citric or acetic acid is used, even in very small quantities, the pH of the medium decreases (pH≤2), while the redox reaction between sodium nitrite and ammonium chloride is accompanied by the release of not only nitrogen, but also nitrogen oxides , including nitrogen dioxide (brown gas), under the influence of which there is rapid corrosion of downhole equipment and production casing. The release of nitrogen dioxide in the well can also lead to poisoning of working personnel in the implementation of well development technology;

b) the acid is fed into the perforation zone using a container, i.e. separately from the foaming composition, as gas evolution and foam formation occurs when the initial components are mixed with acid at any positive temperatures, which complicates the technology for conducting well development and cleaning the bottom-hole formation zone from contamination.

The closest analogues are a foaming composition for well development and washing, including, wt.%: Ammonium chloride 0-41.0, sodium nitrite 12.1-58.7, initiator of the reaction 0.2-24.3, surfactant Surfactants 0.1-1.5, carboxymethyl cellulose or polyacrylamide 0.1-1.5 and the rest water, and a method for developing and flushing wells and cleaning the bottom-hole formation zone from contaminants, including injecting this foam-forming composition, pushing it into the formation or before slaughter , shutting down the well, holding to generate nitrogen and foam, then start the wells for spouting (RF Patent №20085567, C 09 K 7/08, 07.27.1997).

The technical result of the invention is the creation of a foaming composition for the development and washing of wells, with the ability to regulate the process of redox reaction between sodium nitrite and ammonium chloride - ammonium chloride in order to minimize the formation of nitrogen oxides, simplifying the preparation of working compositions for implementing the technology.

Foaming composition for well development and washing, including ammonium chloride, sodium nitrite, a reaction initiator, a surfactant, surfactant and water, as a reaction initiator and a surfactant contains Himeko alkyl phosphate in the following ratio, wt.%: Ammonium chloride 5, 0-28.0, sodium nitrite 5.0-28.0, Himeko alkyl phosphate 0.5-5.0, the rest is water.

In the method of developing and washing wells and cleaning the bottom-hole zone of the formation from contaminants, including injecting a foaming composition, pushing it into the formation or before bottoming, shutting the well, holding for nitrogen generation and foam formation, then starting the well for self-discharge, use the above-mentioned foaming composition, its sale is carried out by oil or mineralized water.

The result is achieved by introducing into the composition containing sodium nitrite and ammonium chloride, a reaction initiator and a foaming agent - Himeko alkyl phosphate, which is a mixture of monophosphate and diesters of alkylphosphoric acids based on primary fatty, oxa and low molecular weight alcohols. Alkylphosphate "Himeko" is an anionic surfactant, therefore, in the proposed composition it is not only the initiator and regulator of the reaction of nitrogen evolution, but also a foaming agent. The introduction of this reagent makes it possible to withstand the pH in the foaming composition within narrow limits (pH 2-3), as a result of which the reaction between sodium nitrite and ammonium chloride proceeds with the predominant evolution of nitrogen, and since the introduced reagent is a foaming agent, foam is formed during the evolution of nitrogen.

The technology for the practical application of the proposed foaming composition involves dissolving sodium nitrite and ammonium chloride in water and introducing the Himeko alkyl phosphate into the resulting solution, followed by pumping the resulting solution into the well. A necessary condition of this technology is that the prepared solution must be pushed with oil or mineralized water into the reservoir or before the bottom, after which the well is closed for a reaction for at least 2 hours. Gas evolution occurs at a temperature not lower than 40 ° C.

For research were used:

1. Sodium nitrite, NaNO ₂ , technical, GOST 19906-74, is a white crystalline powder, the mass fraction of the main substance is not less than 98.5%, solubility in water at a temperature of 20 ° C - 82.9 g / 100 ml.

2. Ammonium chloride - ammonium chloride, NH ₄ Cl, GOST 2210-73, is a white powder, the mass fraction of the basic substance is not less than 99.6%, solubility in water at a temperature of 20 ° C - 37.2 g / 100 ml .

3. Himeko alkylphosphate is a mixture of mono- and diesters of alkylphosphoric acids based on primary fatty, oxa and low molecular weight alcohols, TU 400MP "X-2075-227-001-93", a mobile liquid from colorless to light brown in color, mass the proportion of the basic substance is not less than 95.0%; when dissolved in water, it forms a translucent micellar solution.

Since the molar mass of ammonium chloride is 53.5 g / mol, and sodium nitrite is 69.0 g / mol, the reaction described by the equation:

NH ₄ Cl + NaNO ₂ → N ₂ ↑ + NaCl + 2H ₂ O

the amount of sodium nitrite should be 1.29 times greater than the amount of ammonium chloride. However, the reaction is more complete in the event of an excess of one of the components, therefore, equal concentrations of reagents are taken in the proposed composition, which suggests an excess of ammonium chloride. The lowest salt concentrations are determined by the ability to obtain a sufficient amount of gas for well development, and the maximum concentration by the difficulty of dissolving the salts. The lowest concentration of Himeko alkyl phosphate is determined by the ability to form a foam, and the maximum concentration is determined by economic feasibility.

Examples of the preparation of foaming compositions

Example 1

5.0 g of sodium nitrite, 5.0 g of ammonium chloride and 0.5 g of Himeko alkylphosphate were successively dissolved in 89.5 ml of water with stirring.

Example 4

17.0 g of sodium nitrite, 17.0 g of ammonium chloride and 2.0 g of Himeko alkylphosphate were successively dissolved in 64.0 ml of water with stirring.

Example 7

In 39 ml of water, 28.0 g of sodium nitrite, 28.0 g of ammonium chloride and 5.0 g of Himeko alkylphosphate were successively dissolved with stirring.

Example 10 (known)

In 54.9 ml of water, 19.4 g of ammonium chloride, 23.6 g of sodium nitrite and 2.1 g of a foaming agent (sulfanol) were successively dissolved with stirring, after which, during the study, 0.029 wt.% Sulfamic acid was added to the resulting composition.

Example 11 (known)

In 54.5 ml of water, 20.0 g of ammonium chloride, 23.2 g of sodium nitrite and 2.3 g of a foaming agent (sulfanol) were successively dissolved with stirring, after which 0.0028 wt.% Acetic acid was added to the resulting composition in the form of a 5% solution.

The resulting compositions were investigated as follows.

The prepared compositions were loaded into a 1 liter glass cylinder, the latter was placed in a water bath at a temperature of 45-95 ° С, a circle of filter paper was placed on top of the cylinder to record the release of nitrogen dioxide, because When nitrogen dioxide was released, a brown coating appeared on the paper. In the process of heating the foaming composition, gas evolution and foam formation began. During the experiment, the multiplicity of the foam was determined - the ratio of the volume of the foam to the volume of the foaming solution and the release of nitrogen dioxide was recorded. The research results are presented in the table.

Table No. p / p The content in the foaming composition, wt.% Test temperature Foam ratio Brown plaque Ammonium chloride Sodium nitrite Alkyl phosphate "Himeko" Acid Sulfanol 1.* 5,0 5,0 0.5 - - 45 2 not 2. * 5,0 5,0 0.5 - - 70 2,5 not 3. * 5,0 5.0 0.5 - - 95 3 not 4.* 17.0 17.0 2.0 - - 45 7 not 5.* 17.0 17.0 2.0 - - 70 8 not 6. * 17.0 17.0 2.0 - - 95 10 not 7. * 28.0 28.0 5,0 - - 45 10 not 8.* 28.0 28.0 5,0 - - 70 12 not 9.* 28.0 28.0 5,0 - - 95 fifteen not 10.* 19,4 23.6 sulfamic 0.029 2.1 45 5 there is eleven.* 20,0 23,2 vinegar 0.0028 2,3 95 6 there is * - the remaining water content is up to 100%

As follows from the table, the proposed composition has a higher foam ratio even at lower concentrations of salts and surfactants (op 4-6), does not emit nitrogen dioxide, and additional acid is not required to initiate the reaction.

The method of developing and washing wells and cleaning the bottom of the formation from contamination involves injecting the specified foaming composition into the well, pumping it with oil or mineralized water into the formation or before the bottom, after which the well is closed and kept to generate nitrogen and foam, and then the well is launched self-effusive.

A new set of claimed essential features allows to achieve a technical result, namely, to create an effective foaming composition for developing and washing wells, as well as a method for developing and washing wells and cleaning the bottom-hole formation zone from contamination with its use.

Claims (2)

1. Foaming composition for well development and washing, including ammonium chloride, sodium nitrite, a reaction initiator, a surfactant and water, characterized in that it contains Himeko alkyl phosphate as a reaction initiator and surfactant in the following ratio of components , wt.%: Ammonium chloride 5.0-28.0 Sodium nitrite 5.0-28.0 Alkylphosphate "Himeko" 0.5-5.0 Water Else 2. A method of developing and washing wells and cleaning the bottom of the formation from contamination, including injecting a foaming composition including ammonium chloride, sodium nitrite, a initiator of the reaction, surfactant and water, pushing it into the formation or before the bottom, shutting the well, holding for nitrogen generation and the formation of foam, then the start of the well on a self-discharge, characterized in that as the specified foaming composition, the foaming composition according to claim 1 is used, it is sold with oil or mineralized water.