Foamable composition for well development

 

(57) Abstract:

The invention relates to the oil industry, namely, foam compositions, and is intended for the call flow of the liquid from the reservoir during the development wells. Reduce corrosion of equipment and increase the effectiveness of well development due to the simultaneous mud acid treatment of bottomhole formation zone is achieved by the fact that the foamable composition contains urea, 10,4 10,7 wt. nitrite of an alkali metal or alkaline-earth metal 59,0 60,7 wt. the Lewis acid of 23.7 24.4 wt. the foam stabilizer is 0.1 to 1.3 wt. surfactant 0,4 0,8 wt. and water the rest. The Lewis acid increases effektivnosti well development due to its dissolving ability of carbonate and clay-containing rocks on the bottom hole. The composition is prepared in the form of a cylindrical briquettes brands on the basis of structure-forming water-soluble agents with a bulk density of 1.8-2.0 g/cm38 table.

The invention relates to the oil industry, in particular foaming compositions, and is intended for call flow of fluid from the formation with the well completion.

Known composition for stimulation of zidkostej solution is carried out by thermal hydrolysis of urea according to the scheme:

CO(NH2)2+H2O __ CO2+2NH3< / BR>
(1)

The disadvantages of this structure are:

limited thermal conditions (temperature in the borehole must be above 105aboutC);

corrosion of oilfield equipment, especially from non-ferrous metals and their alloys in the presence of ammonia.

Known self-generating foam system containing urea, surfactant, nitrites of alkali or alkaline earth metals, acid, methenamine and water.

As gasanalysis agent in this composition are carbon dioxide and nitrogen gas, resulting from the interaction of initial components:

NaNO2+HCl NaCl+HNO2< / BR>
(2)

(NH2)2CO+2HNO2__ 2N2+CO2+3H2O

(3)

The disadvantages of this structure are that:

in the interaction of acids and salts of nitrite at pH 4.0 is highlighted brown gas, which causes corrosion of the equipment. When the temperature of the composition above the 20aboutWith nitrous acid decomposes with evolution dioxide and nitrous oxide. Nitrogen dioxide (brown gas) when interacting with water forms nitric acid according to the following scheme:
R>(5)

2NO2+H2O HNO3+HNO2< / BR>
(6) and in the presence of an oxidant and free oxygen:

4NO2+2H2O+O24HNO3< / BR>
(7)

methenamine decomposes with evolution of formaldehyde and ammonia in an acid environment.

The product of decomposition of urotropine and the acid are corrosive agents;

foaming occurs at any positive temperature immediately after mixing the starting components and has an explosive character.

The aim of the invention is to reduce corrosion of equipment and increasing the efficiency of exploration wells due to the simultaneous mud acid treatment of bottomhole formation zone (PPP).

This is achieved by the fact that well-known self-generating foam system for mastering wells containing urea, nitrite, alkaline or alkaline-earth metal, surface-active substances (SAS), an acid and water, the acid contains hydrofloric ammonium and further comprises structure-forming agent is carboxymethylcellulose (CMC) or polyacrylamide (PAA) in the following ratio, wt. Urea of 10.4 to 10.7

Nitrite or alkaline

alkaline-earth metal 59,0-60,7 Hydrofloric Ammon the formation conditions occurs spontaneously through a number of intermediate chemical reactions. The General scheme of interaction of reagents:

(NH2)2CO+2NH4HF+aMe(NO2)m__ aMeFm+4N2+CO2+7H2O

(8)

where a stoichiometric ratio;

m index the chemical formula of the substance;

IU alkali or alkaline earth metal;

a 4; m is 1 when IU alkali metal;

a 2, m 2, when IU alkaline-earth metal.

The reaction of formation of gaseous products completely shifted to the right and irreversible in accordance with rule Le Chatelier.

The irreversibility of the chemical interaction due to the formation of gaseous products, water and poorly soluble in water, alkaline and alkaline-earth metals except potassium fluoride.

The solubility of these salts in 100 g of water are presented in table.1.

Additionally introduced hydrofloric ammonium as acid allows to obtain a gaseous product and the foam under relatively mild conditions (pH 4.0 to 5.0). The rate of foaming depends on and is controlled by the concentration of the starting components, in particular the content in the foaming composition of the structure-forming agent.

Hydrofloric ammonium salt is formed from the remains weak hydrofluoric KIS is the first solution in small amounts are formed fluoride-hydrogen acid and ammonium hydroxide.

The salt solution has a slightly acid reaction (pH 5.0) due to the dissociation of hydrofluoric acid, which dissociated hydrogen ions in water at 10.5 times greater than that of hydroxide, ammonium hydroxide ions. The dependence of pH on the concentration of hydrohloride ammonium in water at a temperature of 20aboutListed in the table.2.

From the data table.2 shows that the concentration of hydrogen ions in aqueous solution hydrophoria much lower than in hydrochloric acid solution.

The pH on the concentration of hydrohloride in the range of pH 4-5 and depends on the degree of hydrolysis, the higher the concentration of hydrohloride in the water, the fewer hydrogen ions in aqueous solution and Vice versa.

In the proposed foaming composition hydrofloric ammonium acts as acidity regulator, which in turn affects the processes associated with the corrosion of the equipment.

At pH > 4.0 of the reaction mixture does not form corrosive nitrogen dioxide (brown gas) according to the scheme of chemical reactions (4).

Corrosivity of hydrohloride ammonium was tested in a laboratory setup in static conditions (table.3). The corrosion rate in the same conditions was determined for the Ah hydrohloride much lower than in solution eingeborenen hydrochloric acid, and not above, when hydrochloric acid contains a corrosion inhibitor.

Weak hydrofluoric acid is formed due to hydrolysis hydrophoria ammonium able to react and dissolve the clay-containing rock formation, thereby contributes to the effectiveness of development wells.

In table.3 shows the results of laboratory studies showing the dissolving ability of hydrohloride ammonium clay-containing rocks (claystone) and bentonite clay. A more concentrated aqueous solution of hydrohloride ammonium react with samples of rocks dissolves and destroys them due to disjoining pressure.

Method of preparation of the proposed foaming composition:

prepare 3-25% aqueous solution of CMC or PAA and leave it to swell for 3-4 hours

Crushed original components separately to powder and make two pasty mixture:

first get at careful hashing urea, nitrite, alkali or alkaline earth metal, powder or viscoelastic surfactants (surfactant) with 3-25% water dissolve or PAA (mixture B).

Doughy mixture is formed into the form of rods (cylindrical briquettes) and dried.

Made so the estimated number of terminals consistently throw inside the tubing (tubing) through the gland-lubricator installed on the wellhead.

Last injected rods made from a mixture of "B". Well close to the reaction and incubated for 20-60 min, then gradually release the pressure through the tubing or the annulus is carried out, the call flow of fluid from the reservoir.

The duration of the technological process and the amount of depression on the layer depend on the amount of typing cylindrical briquettes to the borehole bottom, from the initial content of the amendment in the briquettes B and reservoir temperature.

The high content of structure-forming agents CMC or PAA briquettes increases the time of their dissolution and influence the interaction process between the source components and the speed of gas saturation of the solution and Vice versa.

In table. 4 shows the time of dissolution of briquettes "B" from the mass content of the structure-forming agent CMC at a temperature of 40aboutC.

In formation conditions for increasing the speed of their chemical interaction (thermal catalysis) and foaming at the well bottom.

Offer foamable composition to completion allows you to obtain a foam with adjustable speed gas release up to 100 l/s and 200 m3gaseous products consisting of 80% nitrogen and 20% carbon dioxide, 1 ton of briquettes "a" and "B".

The content in the briquette "And" urea, nitrite, alkaline or alkaline-earth metal, surfactants, structure-forming agent and water (wt.) are given in table.5.

The greatest amount of water and structure-forming agent have the briquettes "And" composed of less water-soluble nitrites of alkali-earth metals, their solubility in 100 g of water of less than 50 g at a temperature of 20aboutC.

The briquettes B are 90-98% of hydrohloride ammonium rest of 15-25% aqueous solution of CMC or PAA.

In order to increase the effectiveness of development wells due to the simultaneous mud acid treatment of bottomhole formation zone, briquettes "B" to enter the borehole bottom 20% more than estimated.

The weight ratio of briquettes "a" and "B" for the full implementation of a process should be at the level of those values, which are given in table.6 and 7.

P R I m m e R. Foamable composition is tested in a laboratory setup, Prora CMC strictly stoichiometric ratios of the starting components, wt. Urea 17,1 sodium Nitrite 78,4 Sultanol NP-3 1,0 CMC 0,2 Water 3,3.

The briquette B prepare a 15% solution of CMC in the following ratios, wt. Hydrofloric ammonium 96,0 CMC 0,6 Water 3,4 When the weight ratio of briquettes "a" and "B" (see specific example) and taking into account the excess hydrohloride ammonium 20%

100:

100 40,6 or 2,46 1,00 foamable composition will have original content of all components, wt. Urea 12,2 sodium Nitrite 55,9 Hydrofloric ammonium 27,7 NP-3 0,7 CMC 0,3 Water 3,2

Laboratory results are shown in table.8, from which it follows that:

gasanalysis and intensively foaming occurs at a temperature of 25aboutIf the specific consumption of briquettes above 100 kg per ton of the liquid at the bottom of the borehole;

the briquettes B, with 0.6% CMC and 3.4% of water, swell and completely dissolve within 20 min;

as a result of chemical interaction between the components of the foamable composition, selection and formation of nitrogen dioxide (brown gas) is not observed.

Based on the results of laboratory tests foaming composition for completion in the form of briquettes at the same intensity of foaming compared to the prototype of the smaller korrozionnostojkoj, due to the replacement of acidifying agent salt, formed from the remnants of the weak base ammonium hydroxide and a weak hydrofluoric (HF) acid. Hydrofloric ammonium able to dissolve and loosen genocodeine species, thereby influencing the efficiency of development wells.

P R I m m e R. For call flow of fluid from the low-permeability layer of the production well, water content 40% pressure 70 at, the temperature at the bottom hole 60aboutC and equipped with 75 mm operating pump-compressor pipe you want to learn well foamable composition in the form of a cylindrical briquettes. You must determine the total number of briquettes for carrying out the process to get 90,0 m3gaseous products in the bottomhole formation zone for 20-30 minutes

Prepare foamable composition (stationary) in the form of two briquettes "a" and "B".

Briquette "And" from a doughy mixture on the basis of 10% aqueous CMC solution containing urea, potassium nitrite, OP-10, CMC and water in the following ratios, wt. (PL.5) Urea 14,2 Nitrite potassium 80,8 OP-10 1,0 CMC 0,4 Water 3,6

Briquette "B" on the basis of a 20% aqueous solution of CMC,mania 90,0 CMC 2, Water to 8.0. For development wells with simultaneous mud acid treatment consistently throw to the bottom of the borehole through the gland-lubricator mounted on the wellhead, the estimated number of first briquettes "A", and then briquettes "B".

On the basis of the General scheme (8) the interaction of gas-emitting components are the chemical equations:

(NHCO+2HF2+4 4KF+4N+CO+7H2O

Determine the molecular mass of the reacting substances: for

2NH4HF2__ 2(14+4+1+219) 114 g/mol

4KNO2__ 4(39+14+216) 340 g/mol

(NH2)2CO__ (14+2)2+12+16 60 g/mol Under normal conditions 1 mol of gas occupies a volume of 22.4 l, then the total volume of gases:

V 22,4 (4 + 1) 112,0 l or 1 g of the original substances: V 0,2179 l/,

To determine the mass content of the source component in the briquettes (wt.) find the ratio of molecular mass relative molecular mass of urea:

2NH4HF2:(NH2)2CO - 1,90

2KNO2:(NH2)2CO - 5,67

(NH2)2CO (NH2)2CO - 1,00 Therefore, when Soderini in the briquette "And" basic substance 95% surfactant (OP-10) of 1.0% and 4.0% aqueous CMC solution with a concentration of 10% must be a Mac.

Urea 14,2%

Nitrite potassium 8 is the compared molecular masses of hydrohloride ammonium and urea: 1,90:1,00, the weight ratio of briquettes "a" and "B" should be (PL.6):

"A":"B" 100,0:

"A" "B" 2,78 1,00. The volume of gases emitted as a result of chemical reactions 1 t foamable composition is equal for 194.3 m3and foamable composition will be the initial concentration, wt. Urea 10.4 Nitrite potassium 59,0 Hydrofloric ammonium 23,7 NP-3 0,7 CMC 0,8 4,4 Water

Q (104 + 590 + ) 0,2179 for 194.3 m3To obtain a gas with a volume 90,9 m3you 463,2 kg foaming composition or briquettes "a" and "B":

"A"- 340,7 kg

"B" is 122.5 kg Velocity of the gas at the well bottom will be about:

50 l/Well close to the reaction and incubated for 20-30 min, then release the pressure through the annular space shall call flow of fluid.

In the case of development of waterless well before bottom-hole formation zone pumps 0,5-3,0 m3water. Instead of potassium nitrite can be used nitrites other alkali and alkaline earth metals. The formation of foam in this case is no different from the interaction of nitrite of potassium with other components. The difference is only quantitative proportions, which are calculated by the equation of the chemical reaction.

In tables 6 and 7 shows maximalnych metals, the calculated volumes of gases that may develop under normal conditions of 1 g of starting compounds and 1 t foamable composition, the weight ratio of briquettes "a" and "B" at the minimum and maximum content in briquettes "B" hydrohloride ammonium.

The lower and upper boundary conditions in the foamable composition of the source components (wt.) there are also from the data table.6 and 7 (on p. 2).

The proposed method of producing a foaming composition for completion not time consuming and does not require special equipment that can be used for obtaining foam, foam cements, concrete, penopolimer, lightweight drilling fluids and cement slurries for cleaning and washing PPP, removal of sand tubes and for intensification of oil and gas.

Offer the source reagents are cheap and available, do not require special conditions during the transportation and storage industry produces large capacity and are used in various sectors of the economy.

1. FOAMABLE COMPOSITION FOR well DEVELOPMENT, including urea, nitrite, alkali or alkaline earth metal, an acid, a surfactant and voguish in the following ratio of components, wt.

Urea 10,4 10,7

Nitrite, an alkaline or alkaline earth metal 59,0 60,7

The Lewis acid 23,7 24,4

The foam stabilizer is 0.1 to 1.3

Surfactant 0,4 0,8

Water the Rest

2. Composition under item 1, characterized in that the Lewis acid it contains hydrofloric ammonium, and as a foam stabilizer is a water - soluble polymeric compound carboxylmethylcellulose or polyacrylamide.

 

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