Foamable composition for well development

 

(57) Abstract:

The invention relates to the oil and gas industry, namely the foaming compositions for completion. Foamable composition for completion contains urea, nitrite, alkaline or alkaline-earth metal initiator reaction hydrolittoral, foaming, ammonium chloride, dispersant-foam stabilizer and water. Foamable composition can be used both in solid and in liquid state and apply it to other processes of intensification of oil and gas. 2 C.p. f-crystals, 5 PL.

The invention relates to the oil industry, in particular foaming compositions for completion.

The known method of thermal treatment of bottom-hole formation zone [1] due to the exothermic heat of reaction of the chemical interaction of sodium nitride and ammonium chloride in the presence of initiator, the reaction of organic acids.

The disadvantages of using this method of obtaining thermal energy is the high complexity of the process (production of special containers and use them for descent organic acid initiator of the reaction in the well).

The aim of the invention is to reduce costs and increase the effectiveness of development wells due to depression on a layer with simultaneous inoperability and heat treatment of bottom-hole formation zone (PPP), as well as flushing and cleaning of the bottom hole from mechanical impurities, sand, corrosion products and asphalt substances and removing them on the surface due to the flotation forces of the foam.

This goal is achieved by the fact that well-known self-generating foam system for mastering wells containing urea, a nitride of alkaline or alkaline-earth metal, an acid (reaction initiator), a surfactant, and water, further comprises ammonium chloride, foam stabilizer (flotation) carboxymethylcellulose (CMC) or polyacrylamide (PAA), and as an initiator of the reaction pinacolato hydrolittoral or Gex is arid alkaline or alkaline-earth metal 12,1 58,7

Pinacolato 0,2 24,3

Ammonium chloride 0 41,0

CMC or PAA 0,1 1,5

SURFACTANT IS 0.1 TO 1.5

Water the rest.

Gassing and foaming occurs spontaneously upon mixing the starting components for any positive temperature.

The initiator (catalyst) chemical interaction is pinacolato.

Foamable composition not containing the initiator of the reaction, its efficiency is also at the temperature of the reaction medium 80oC, initiating a chemical reaction occurs due to thermal catalysis. The dependence of the rate of chemical reaction of ammonium chloride with sodium nitrite concentration of hydrohloride ammonia at a temperature of 20oC are given in table. 1. The concentration of surfactant (OP-10) 0.5. in solution, the reaction initiator is introduced into the reaction mixture in the form of a cylindrical briquettes (rods) made of a pasty mixture comprising by weight. hydrolittoral ammonium 96,0; foam stabilizer (structure-forming agent) CMC 0,4; water the rest.

The chemical interaction of these compounds has the following form:

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or General scheme:

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where

a, b coefficients of chemical uravnenija instantly allocates a large amount of heat, about 300 kJ/mol.

The increase in initiator concentration of a chemical reaction speeds up the process of foam formation (PL. 1).

The minimum concentration of glyoxylate, in which the efficiency of the proposed composition is satisfactory depends on the mass ratio of ammonium chloride and glyoxylate, therefore, the coefficients a and b in the chemical equation (II).

The ratio of a and b must be less than or equal to 100.0, otherwise, the composition exhibits a low efficiency. The lower threshold concentration of ammonium chloride in the composition is equal to 9.0 wt. below this concentration the efficiency of the composition is maintained with increasing concentration of initiator in the reaction (table. PP 3 of 6).

Excess nitrous acid formed by the equation (6) or (8 and 11), it can be eliminated by introduction of the urea, which reacts with nitrous acid with the release of additional quantities of gaseous products and water:

(NH2)2CO+2HNO2_ 2N2+CO2+3H2O (12)

A General scheme of the interaction of the source components in the proposed structure will have the following form:

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where

a and b are the coefficients of a chemical equation;

m index hee is as glyoxylate in the proposed composition is ammonium hexafluorosilicate the General scheme is:

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Consider the partial case of equation (13), when a is 1; b is 0; m is 1; Me is Na, then the chemical equation takes the form:

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According to equation (15) selection teplofizicheskoi energy minimum, as most of thermal energy [1] is formed by the interaction of ammonium chloride with a metal nitrite in the presence of a catalyst of glyoxylate by the equation (10).

Glyoxylate as a result of hydrolysis (2) forms hydrofluoric (HF) acid, which reacts and dissolves carbonate and clay-containing rock formation. In table. 2 shows the results of laboratory tests showing the ability of an aqueous solution of hydrovhloride ammonium dissolving clay-containing rock and bentonitovuju clay at a temperature of 20oC.

Introduction the proposed composition of the surfactant and water-soluble polymeric compounds of the type CMC or PAA improve the stability and flotation properties of the foam. These physico-chemical properties of the foam are significantly improved when the content in the foam composition of polymer compounds in amounts of 0.05 to 1.5 wt. and when the surfactant concentration is 0.1 to 1.5 wt. In addition, they contribute to decrease the rate of absorption of water by the formation rock, the reduction razbuhavshie processing bottom-hole formation zone.

Technology is the practical application of the foam composition provides several ways of implementing technological operations on the well completion.

The first method. Develop well due to depression on a layer with simultaneous teplofizicheskoi processing PPP, flushing and cleaning of the borehole bottom.

Produced at the wellhead or stationary aqueous solution containing urea, ammonium chloride, nitrite, alkaline or alkaline-earth metal, a surfactant, and bring it to the borehole bottom. The reaction initiator is prepared in the form of a cylindrical briquettes, made from a doughy mixture containing 5,0 20,0% aqueous solution of CMC or PAA and pinacolato. The estimated number of briquettes consistently throw inside the tubing (tubing) through the gland-lubricator installed on the wellhead.

The second method. Develop well with simultaneous mud acid treatment of the PPP. Cook 3 10 solution of CMC or PAA and leave it to swell for 3 to 4 h Crushed original components separately to powder and are based on 3 to 10% aqueous solution of CMC or PAA two pasty mixture:

mixture "And" get with paramesh is about to be, wt. ammonium chloride 0 93,0; urea 1,0 33,8; pinacolato 2,0 - 64,2; CMC or PAA 0,1 1,0; water the rest;

mixture B contains a nitride of alkaline or alkaline-earth metal, a foam stabilizer and surfactant wt. the metal nitride 93,0 94,5; surfactant is 0.5 to 2.0; CMC or PAA 0,1 0,5; water the rest.

The obtained mixture is molded and pressed into the form of a cylindrical briquettes (rods) and dried. Made so the estimated number of briquettes is brought to the well bottom as in the first method, the initiator of the reaction.

Last injected briquettes grade "B".

The third way. The composition is prepared in the form of two solutions high density:

solution No. 1 is prepared in the form of a finely dispersed system containing pinacolato, ammonium chloride and a foam stabilizer (CMC or PAA) in an amount of from 1.0 to 3.0% with a density of more than 1,00 g/cm3;

a solution of N 2, containing urea, nitrite, metal, CMC or PAA concentration of 1.0 to 3.0% surfactant, with higher density of 1.00 g/cm3.

The obtained solutions sequentially with an interval of 1.0 to 1.5 h, adjusted to the borehole bottom. The loss of fluids to the well bottom is due to the difference of densities of solutions and well production, the higher this difference, the faster gravitate and injection wells in operation, and coming out drilling or after repairs.

Example. Foamable composition is prepared in the form of two solutions, and test it in a laboratory setup, which is a model of the well, at a temperature of 20oC.

Make up an aqueous solution of N 2 containing hydrolittoral ammonium, ammonium chloride and CMC concentration 1%

Solution No. 1 is prepared by dissolving in 1.0% aqueous surfactant solution (sulfinol NP-3), urea, sodium nitrite.

The stoichiometric ratio of initial components are calculated according to chemical equation (13) where the coefficients a and b are found from the weight ratio of ammonium chloride and hydrovhloride ammonium.

Weight content in grams and the ratio of initial components wt. in these solutions are given in table. 3.

In table. 3 shows also the weight ratio of solution No. 1 and 2, the results of laboratory tests (foam, the temperature change of the solution).

Before entering into the model well solutions No. 1 and 2, fill in the model by 10 to 15% of its height oil with a density of 0,86 g/cm or kerosene with a density of 0.82 g/cm3.

The boundary of the ratio of initial components depend on: the weight with the OTE or ammonium chloride. When the content in the original composition of ammonium chloride tends to zero, then the lower boundary condition for glyoxylate (hydrovhloride ammonium) is its concentration when iniciirovanie chemical reaction sufficient to produce a foam ratio of more than 4.0 at 20oC.

In table. 4 shows the results of laboratory tests of the proposed composition that does not contain ammonium chloride.

The concentration of hydrohloride of ammonia in the composition should be above 4.0%

Preparation of foamable composition of briquettes and solutions define the boundary conditions of the ratios of the components (table. 5). The weight ratio of glyoxylate to ammonium chloride should not exceed 47,0, otherwise, the composition exhibits a low efficiency (table. 1).

On the basis of the obtained results of the proposed foamable composition for completion is easy to perform technological operations, cost-effective and reasonable in comparison with other known methods of obtaining foam on the bottom of a well.

The proposed structure allows to use it both in the solid and in the liquid state.

For call flow of fluid from the reservoir is m, perforation interval 1595 1602 m and pump-compressor pipe with a diameter of 63 mm, at the end of which is funnel or the pen above the perforated interval is 100 m, it is necessary to determine the amount of liquid foaming composition and quantity of each component, if: a reaction initiator (ammonium hydrodifluoride) is brought to the borehole bottom in the form of a cylindrical briquettes; available aqueous solution of sodium nitrite with a density of 1.20 g/cm3; required to maximally raise the temperature at the bottom hole and to the volume of gas evolved was 20.0 volume wells.

This method of well completion includes:

replacement of fluid in the tubing and in the annulus oil with a volume of not less than 6.0 m3;

download after the oil through the tubing of the liquid portion of the composition and its displacement in the reservoir oil with a volume equal to the volume of the tubing;

bringing the solid parts of the composition of the inhibitor reaction to the borehole bottom, consistent throwing bricks into the tubing through the gland-lubricator;

closing wells and extract 1.0 1.5 h in order to dissolve the pellets and chemcial reaction gas. The process of gas saturation of the solution is controlled by increasing pressure on the mouth of squatinidae repair work to study the flow of a liquid.

Sodium nitrite with a density of 1.20 g/cm3has a concentration of 28.0 by Dissolving the calculated amount of urea, ammonium chloride and OP-10 in a solution of sodium nitrite prepared liquid part foamable composition.

Cylindrical briquettes (rod) is prepared from a doughy mixture containing 96,0 hydrolittoral ammonium, 4,0 aqueous CMC solution with a concentration of 20.0%

In order to raise the temperature in the reaction mixture, the weight content of ammonium chloride should be 47 times more weight content of hydrovhloride of ammonia in the composition.

On the basis of these conditions are the stoichiometric coefficients a and b in the chemical equation (13) provide for a particular case, the reaction equation and find the ratio of initial gas-forming components:

The coefficient a is 1; b, 100; m 1,0; Me Na

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Determine the molecular mass of the reacting substances, g:

Urea 60,0

Sodium nitrite 10469 7176,0

Hydrolittoral ammonium 257 114,0

Ammonium chloride 10053,5 5350,0

Under normal conditions, 1 g/mol of gas occupies a volume of 22.4 l, then the amount of emitted gases: V 22,4(102 + 1) 2352,0 l or 1 g source of blowing agents:

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To find the mass of content and soothes mass relative molecular mass, for example, urea:

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Taking into account that the conditions of the problem in the presence of a aqueous solution of sodium nitrite with a density equal to 1.20 g/cm3(28,0% concentration), then the ratios of the components are, Mac.

Urea 0,15

Sodium nitrite 18,53

Ammonium chloride 13,82

Hydrolittoral ammonium 0,29

OP-10 1,00

Water The Rest.

The volume of gases emitted by 1.0 t solution with the same ratio of components will be:

Q(1,5 + 185,3 + 138,2 + 2,9) 0,1852 60,7 m3< / BR>
The problem, to obtain a gaseous product with a volume equal to 20.0 volume of the well, should the amount of foamable composition:

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where

n necessary amount of a foaming composition, kg;

3,14

D diameter of the production string, m;

H is the depth of descent of the production string, m;

Q the volume of gas produced per ton, composition, m3;

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Or, respectively, of each component in the composition, kg:

Urea 18,1

Sodium nitrite 2233,1 or 6646,1 l 28

Ammonium chloride 1665,5

Hydrolittoral ammonium 34,9

OP-10 OF 120.5

Water the Rest

Given that hydrolittoral ammonia is a component of the cylindrical bre 36,3 kg

Thus, for a call flow of liquid from the reservoir portion of the foamable composition in an amount 12015,0 kg lead up to the bottom of the borehole in the form of a solution, and the rest (reaction initiator) into the number of 36.3 kg in the form of briquettes, which is 0.3 of the total quantity of the foam composition.

The proposed composition by mixing all components will have the following ratio of components, wt.

Urea 0,15

Sodium nitrite 18,53

Ammonium chloride 13,82

Hydrolittoral ammonium 0,29

SURFACTANT (OP-10) 1,00

CMC 0,01

Water the Rest

Instead of sodium nitrite can be used nitrites other alkaline or alkaline-earth metals, instead of hydrovhloride the ammonium hexafluorosilicate.

The formation of foam in these cases is no different. Examples of preparation and use foam composition is not fundamentally different, the difference is only in quantitative proportions of the interacting components of the scheme (13 and 14).

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 the plugs in wells and other processes of intensification of oil and gas.

1. Foamable composition for exploration wells containing donor nitrogen, nitrite, alkali or alkaline earth metal initiator of the reaction, foaming agent and water, characterized in that it further comprises a dispersant foam stabilizer, and as a donor of nitrogen ammonium chloride, and the reaction initiator ammonium hydrodifluoride in the following ratios, wt.

Nitrite, an alkaline or alkaline-earth metal 12,1 58,7

Hydrolittoral ammonium 0,2 24,3

Ammonium chloride 2,4 41,0

Dispersant-foam stabilizer of 0.1 to 1.5

The foaming agent is 0.1 to 1.5

Water the Rest

2. Composition under item 1, characterized in that it as a dispersant - foam stabilizer contains a water-soluble high-molecular compound is sodium carboxymethyl cellulose.

3. The composition according to PP.1 and 2, characterized in that it contains additional donor nitrogen urea in an amount of not more than 12.8 wt.

 

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FIELD: oil and gas production.

SUBSTANCE: solid foaming agent containing, wt %: carboxymethylcellulose 15-25, sodium sec-alkyl sulfate 5-15 and sodium sulfonate 25-35 (both anionic surfactants), additionally contains: sodium silicate 3-7, sodium carbonate 2-4, disodium ethylenediaminetetraacetate as complexone 1-3, and foaming-enhancing detergent - the rest.

EFFECT: increased efficiency in carrying over formation fluid from bottom of gas and gas condensate wells.

1 tbl

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