RU2047639C1 - Froth-forming composition for hole development - Google Patents

Abstract

FIELD: oil and gas mining industry. SUBSTANCE: froth-forming composition has, wt.-% ammonium chloride 30.0-35.4; alkaline or alkaline-earth metal nitrite, reaction starter iron or aluminium halide or sulfate, surface-active substance 0.04-0.05; КМЦ or ПАА 0.3-0.8, and water the rest. Froth-forming composition can be used both in solid and liquid state, for preparing foam, froth-material, alleviated drilling fluids, etc. EFFECT: increased effectiveness at layer permeability recovery, decreased cost at hole development. 8 tbl

Description

 The invention relates to the oil and gas industry, in particular to foaming compositions, and is intended for well development and inducing fluid flow from the reservoir.

 A known composition for isolating water inflow into a well, containing hydrolyzed polyacrylamide, potassium alum, sodium nitrite, ammonium chloride and water. The disadvantage of this structure is the low efficiency in well development.

 Known self-generating foam system containing ammonium chloride, nitrite of an alkali or alkaline earth metal, the initiator of the reaction is organic acid, surfactant and water [1] The disadvantage of using this system is the low recovery efficiency of the permeability of the formation, high costs when developing wells.

The purpose of the invention is to increase the efficiency of restoring the permeability of the formation, reducing costs when developing wells. This is achieved by the fact that the known self-generating foam system containing ammonium chloride, alkali metal or alkaline earth metal nitrite, a surfactant, a reaction initiator organic acid and water, additionally contains a water-soluble structure-forming agent carboxymethyl cellulose (CMC) or polyacrylamide (PAA), and as a initiator of the halogen reaction or sulfate of iron, aluminum in the following ratio, wt. Ammonium Chloride 30.0-35.4
Alkali nitrite or
alkaline earth metal 38.8-45.7
Iron, aluminum halide or sulfate 11.2-22.5 CMC or PAA 0.3-0.8 surfactant 0.04-0.50 Water Else
Gas evolution and foam formation occurs spontaneously due to the thermal energy of the formation through a series of intermediate reactions.

The general scheme of interaction of gas-emitting components is as follows:
nNH ₄ Cl + Me (NO ₂ ) _n __ → nN ₂ + MeCl _n + 2nH ₂ O
(1) where Me is an alkaline or alkaline earth metal;
n is the index of the chemical formula of a substance molecule

The gas saturation of the solution and the formation of foam during the interaction of ammonium chloride and nitrite of an alkali or alkaline earth metal according to scheme (1) proceeds at a temperature of the reaction medium above 80 ^about C.

 In order to increase the rate of this chemical reaction and to regulate the temperature regime of the foam system, a reaction initiator (catalyst) is additionally introduced into the reaction mixture.

Fe(OH)₃+3HCl
(2)
Соляная кислота играет роль катализатора при реагировании газовыделяющих реагентов по схеме (1) следующим образом:
Me(NO₂)_n+nHCl

MeCl_n+nHNO₂
(3)
nNH₄Cl+nHNO₂

nNH₄NO₂+nHCl
(4)

(5)
Зависимость рН среды от концентрации хлоридов железа и алюминия в воде при температуре 20^оС приведены в табл.1.In the proposed composition, the initiator of the chemical reaction is Lewis acid, salts formed from residues of a strong acid and a weak base. These salts are hydrolyzed in an aqueous solution and form acids and slightly soluble metal hydroxides in water. For example, iron (III) chloride reacts with water to form hydrochloric acid and iron (III) hydroxide according to the chemical equation of equilibrium:
FeCl ₃ + 3H ₂ O

Fe (OH) ₃ + 3HCl
(2)
Hydrochloric acid plays the role of a catalyst in the reaction of gas-releasing reagents according to scheme (1) as follows:
Me (NO ₂ ) _n + nHCl

MeCl _n + nHNO ₂
(3)
nNH ₄ Cl + nHNO ₂

nNH ₄ NO ₂ + nHCl
(4)

(5)
PH Dependence on the concentration of iron and aluminum chloride in water ^at 20 ° C are presented in Table 1.

 The introduction into the reaction medium of even a small amount of the initiator of the reaction helps to increase the multiplicity of the foam (chemical reaction rate) and reduce the pH of the solution environment.

 The dependence of the efficiency of the foaming composition on the concentration of the initiators of the reaction are given in table.2.

An increase in the concentration of the initiator of the reaction accelerates the process of foam formation and increases the concentration of nitrous acid in the reaction mixture according to chemical equation (4), which in turn affects the temperature regime of the foaming composition. For example, the introduction of iron chloride in the reaction medium in an amount of 0.27 wt. formed foam multiplicity of 3 or greater at ⁷⁰ ° C to obtain a foam of the same characteristics to the composition which does not contain a reaction initiator, it is necessary to maintain the temperature conditions at 95-100 ° ^C.

Gas saturation of the solution is carried out with gaseous nitrogen according to equation (5) and a large amount of heat is released, about 300 kJ per mole of NH ₄ NO ₂ . The decomposition of ammonium nitrate occurs almost instantly, and the released nitrogen multiplies the volume of the mixture.

 The application technology of the proposed foaming composition provides for two ways to implement the technological operation for well development.

 The first way. Prepare an aqueous solution containing ammonium chloride, nitrite of an alkaline or alkaline earth metal, surfactant and bring it to the bottom of the well. The initiator of the reaction is prepared in the form of cylindrical briquettes made of a pasty mixture containing a 100% aqueous solution of a structure-forming agent and a catalyst. The estimated number of briquettes is successively thrown into the inside of tubing (tubing) through a gland-lubricator installed at the wellhead.

The second way. A 3-10% aqueous solution of a structure-forming agent is prepared and left to swell for 3-4 hours. The initial components are crushed individually to a powder and three dough mixtures are made on the basis of a 3-10% solution of a structure-forming agent:
mixture "A" is obtained by stirring nitrite of an alkali or alkaline earth metal and surfactant in a solution of a structure-forming agent;
mixture "B" contains ammonium chloride;
mixture "B" initiator of the reaction.

 The resulting mixture is formed and pressed in the form of cylindrical briquettes (rods) and dried. The calculated quantities of briquettes made in this way are brought to the bottom of the well in the same way as in the first method, the initiator of the reaction. Briquettes containing a reaction initiator are last introduced.

 The preparation of a mixture containing simultaneously ammonium chloride and nitrite of an alkaline or alkaline earth metal is not excluded, but the manufacture of briquettes from this mixture and storage of finished products will entail certain difficulties. When heated and any reaction initiator gets into these briquettes, they can explode and cause irreparable damage.

 The well is closed for response and held for 20-60 minutes, then gradually release the pressure through the tubing or annulus, and a flow of fluid from the reservoir is called up.

The proposed composition for well development allows you to get foam with a controlled gas release rate of up to 100 l / s or at least 120.0 m ^{3 of} gaseous product at the bottom of the well for 1 ton of briquettes "A" and "B".

 Table 3 shows the content of the components in the mixture "A".

 The greatest amount of water are those mixtures that contain less soluble in water nitrites of alkaline earth metals.

 The mixture "B" consists of 90.0 wt. from ammonium chloride, the rest is a 3-10% aqueous solution of a structure-forming agent.

 The mixture "B" contains 90.0 wt. the initiator of the reaction, 1.0 wt. structure-forming agent, the rest is water.

EXAMPLE EXAMPLE 1 The foaming composition tested in a laboratory, which is a model of the well, at a temperature of 60 ^C. A solution comprising ammonium chloride, with sodium nitrite in their stoichiometric ratio according to equation (1), surfactant, and water, wt. Ammonium chloride 15.0 Sodium nitrite 19.4 Surfactant 1.0 Water 64.6
The initiator of the reaction is pressed in the form of cylindrical briquettes from a pasty mixture containing, by weight. Aluminum chloride 90.0 Water 9.0 CMC 1.0
20.0 ml of the gas-emitting solution are placed at the bottom of the well model and the reaction initiator is introduced in the form of rods.

 The results of laboratory tests are given in table.4.

 From the data table. 4 it follows that intensive foam formation occurs when the concentration of aluminum chloride is above 0.9%. Foaming is quite active when the content of ammonium chloride in the foaming composition is 6.7 wt. and sodium nitrite 8.6 wt. below these concentrations, the gas saturation efficiency of the solution is not satisfactory.

The upper boundary conditions proportions of starting components for the liquid formulation determines the solubility of ammonium chloride at ²⁰ ° C, 100 g of water was dissolved 37.2 g of ammonium chloride.

PRI me R 2. Prepare three types of rods based on a 5% and 10% aqueous solution of CMC. The rod "A" contains sodium nitrite, surfactants (sulfanol NP-3), CMC and water in the following ratios of components, wt. Sodium nitrite 94.5 surfactant 0.5 CMC 0.2 Water 4.8
The core "B" consists of 90.0 wt. from ammonium chloride, the rest is 5% aqueous solution of CMC.

 The core "B" contains in its composition 90.0% aluminum chloride, 1.0% CMC and the rest is water.

SS test in the form of rods held in a laboratory at a temperature of 25 ° ^C. The weight ratio of briquettes "A" and "B" in the tests should be 1.22 to 1.00 (example of a specific implementation of works), then the content of the briquettes components "A" and "B" at the bottom of the well will be, mac. Sodium nitrite 52.5 Ammonium chloride 40.5 Sulfanol NP-3 0.3 CMC 0.3 Water 6.4.

 The results of laboratory tests are given in table.5.

From which it follows that:
a foaming composition, made in the form of rods, exhibits its highest efficiency at a temperature of 25 ^{° C,} if the specific consumption per ton of liquid briquettes (cores) "A" and "B" above 60.0 kg, and briquettes "B" (reaction initiator ) not less than 15.0 kg;
the rods are completely dissolved in water in 20-40 minutes;
weight ratios of the gas-emitting composition (rods "A" and "B") and the initiator of the reaction (aluminum chloride) of the rods "C" should be at least 3.0-7.0;
foaming occurs throughout the thickness of the liquid and foam.

Based on the obtained laboratory test data, the following conclusions can be drawn that:
the proposed foaming composition exhibits not poor performance both in liquid and solid form;
the use of this composition is economically feasible in comparison with the known compositions with the same intensity of foaming;
the manufacture of PS in the form of cylindrical briquettes is feasible stationary or in the factory at any distance from the application;
the use of the composition in solid form is possible year-round, regardless of the ambient temperature;
the implementation of the process is characterized by its simplicity, low complexity and well development can be done at any positive temperature of the reservoir.

To call a fluid influx from the formation during the development of wells with 90% water cut reservoir pressure 60 atm, the temperature at the bottom 65 ^{° C} and equipped with 50-mm tubing, it is necessary to determine by calculation the amount of the foaming composition, made in the form of cylindrical pellets to obtain 50.0 m ^{3 of} gaseous product in the bottomhole formation zone for 20/30 minutes

 A foaming composition is prepared in the form of cylindrical briquettes of three grades.

Briquettes "A" from a pasty mixture containing, by weight. Sodium nitrite 94.0 surfactant (OP-10) 1.0 CMC 0.2 N ₂ About 4.0.

 Briquettes "B" based on a 4.0% aqueous solution of CMC containing ammonium chloride 90.0 wt.

Briquettes "B" initiator of the reaction, contains in its composition, wt. Aluminum chloride 90.0 CMC 1.0 Water 9.0
To develop the well, the calculated amount of the foaming composition in the form of briquettes into the tubing is successively thrown through the gland-lubricator installed at the wellhead.

 The order of input of briquettes “A” or “B” is not regulated; briquettes “B” are the last initiator of the reaction.

0,1829 л/г Для определения весовых соотношений брикетов А и Б находят соотношения молекулярных масс газовыделяющих компонентов:
NH₄Cl:NH₄Cl-

1,00
NaNO₂:NH₄Cl-

1,29
Следовательно, при содержании в брикете "А" нитрита натрия 94,0% а в брикете Б хлорид аммония 90,0% весовые соотношения брикетов должны быть:
A:Б 100:

A Б 1,23 1,00
Газовыделяющий состав при таком весовом соотношении брикетов будет содержат, мас. Хлорид аммония 40,4 Нитрит натрия 51,8 ПАВ 0,5 КМЦ 0,3 Вода 7,0
На 1 т брикетов А и Б образуется газообразного азота с объемом: Q (ГNH₄Cl + +ГNaNO₂) х 1000 х V, где ГNH₄Cl; ГNaNO₂ единичные доли газовыделяющих компонентов состав; V объем газа на 1 кг газовыделяющих компонентов состава, м³.Based on the general scheme (1) of the chemical interaction of the starting gas-emitting components, the chemical reaction equation is composed:
NH ₄ Cl + NaNO ₂ __ → N ₂ + NaCl + 2H ₂ O The molecular weights of the reacting substances are determined:
NH ₄ Cl 14 + 4 + 35.5 53.5 g / mol
NaNO ₂ 23 + 14 + 2 x 16 69.0 g / mol. Under normal conditions, 1 mol of gaseous nitrogen occupies a volume of 22.4 liters, then, in terms of 1 g of the starting substances, it will be released:
V

0.1829 l / g To determine the weight ratios of briquettes A and B, the ratios of molecular weights of the gas-emitting components are found:
NH ₄ Cl: NH ₄ Cl-

1.00
NaNO ₂ : NH ₄ Cl-

1.29
Therefore, when the content of sodium nitrite in briquette “A” is 94.0%, and in briquette B, ammonium chloride 90.0%, the weight ratios of the briquettes should be:
A: B 100:

A B 1.23 1.00
The gas-releasing composition with such a weight ratio of briquettes will contain, wt. Ammonium chloride 40.4 Sodium nitrite 51.8 Surfactant 0.5 CMC 0.3 Water 7.0
On 1 ton of briquettes A and B, nitrogen gas is formed with a volume of: Q (GNH ₄ Cl + + NaNO ₂ ) x 1000 x V, where GNH ₄ Cl; ГNaNO ₂ unit fractions of gas-emitting components composition; V gas volume per 1 kg of gas-emitting components of the composition, m ³ .

163,6 кг
Б

133,0 кг
Инициатора реакции необходимо для проведения данной технологической операции, при весовом соотношении газовыделяющего состава и брикета В 7,0 1,0 (табл.5):
B

42,4 кг
Таким образом, пенообразующий состав будет иметь соотношение исходных компонентов, мас. Хлорид аммония 35,3 Нитрит натрия 45,5 Хлорид алюминия 11,2 ПАВ (ОП-10) 0,4 КМЦ 0,5 Вода 7,1
Скорость газонасыщения раствора составит около
ω V/t где V объем газа по условиям задачи, л;
t время реагирования, с.Q (0.404 + 0.518) x 1000 x 0.1829
168.6 m ³ . To obtain, according to the conditions of the task, 50.0 m ^{3 of} gas at the bottom of the well, 296.6 kg of PS or briquettes A and B are required individually:
A

163.6 kg
B

133.0 kg
The initiator of the reaction is necessary for carrying out this technological operation, with the weight ratio of the gas-generating composition and briquette B 7.0 1.0 (Table 5):
B

42.4 kg
Thus, the foaming composition will have a ratio of the starting components, wt. Ammonium chloride 35.3 Sodium nitrite 45.5 Aluminum chloride 11.2 Surfactant (OP-10) 0.4 CMC 0.5 Water 7.1
The rate of gas saturation of the solution will be about
ω V / t where V is the volume of gas according to the conditions of the problem, l;
t response time, s.

27,8 л/с
Скважину закрывают на реагирование и выдерживают 20-30 мин, затем стравливают давление через затрубное пространство, осуществляют вызов приток жидкости из пласта.ω

27.8 l / s
The well is closed for response and held for 20-30 minutes, then the pressure is vented through the annulus, and a flow of fluid from the reservoir is called.

To develop a waterless well to the bottomhole formation zone complete 1.0-3.0 m ^{3 of} water.

 Instead of sodium nitrite, nitrites of other alkali or alkaline earth metals can be used, and instead of aluminum chloride, another reaction initiator (Lewis acid, etc.).

 The process of foam formation in these cases is no different from the interaction of nitrite with ammonium chloride. The difference is only in quantitative proportions, which are calculated according to the chemical reaction equation (1).

 Tables 6 and 7 show the mass ratios of the components of the foam-forming composition, the weight ratios of the briquettes, the calculated volumes of gases that are formed under normal conditions per unit of gas-generating components and the foam-forming composition, and the initiator of the reaction is aluminum chloride.

 Table 6 shows the data for the minimum content of gas-emitting component in briquettes A, and in table 7 for the maximum content of this component.

 Table 8 shows the ratios of the starting components for the foaming composition in the liquid state.

 The proposed method for producing a foaming composition for well development is not time-consuming and does not require the use of special equipment, which allows it to be used in the production of foam, foam cement, foam concrete, foamed polymers, lightweight drilling and cement slurries, for cleaning and washing the bottom-hole formation zone, completion of wells, and elimination of plugs in wells and the intensification of oil and gas production processes. This foaming composition can be used both in solid and in liquid state.

 The proposed starting reagents are cheap and affordable, do not require special conditions during transportation and storage, the industry produces large-tonnage and are widely used.

Claims (1)

 FOAM FORMING COMPOSITION FOR WELLS, including ammonium chloride, alkali or alkaline earth metal nitrite, a reaction initiator, a surfactant and water, characterized in that it further comprises a foam stabilizer carboxymethyl cellulose or polyacrylamide, and aluminum or aluminum sulfate as initiator of the reaction. in the following ratios of components, wt. Ammonium Chloride 30.0 35.4
Alkaline or alkaline earth metal nitrite 38.8 45.7
Iron or aluminum halide or sulfate 11.2 22.5
Carboxymethyl cellulose or polyacrylamide 0.3 0.8
Surfactant 0.04 0.5
Water Else

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