Foamable composition for enhanced oil recovery

 

(57) Abstract:

The invention relates to the oil and gas industry, in particular foaming compositions for enhanced recovery in the later stages of field development. The enhanced oil recovery by increasing coverage nefteproduktov reservoir flooding or coolant is achieved in that the foamable composition contains the following components, wt.%: urea 1,5 - 4,0; nitrite, alkaline or alkaline-earth metal 5,2 - 13,8; acid 0,9 - 2,4; surfactant 0.2 to 1.0; hydrofoil ammonium 2,8 - 7,6; water the rest. Hydrofloric ammonium form as a result of hydrolysis of hydrofluoric acid, which reacts with carbonate and clay-containing rocks of the formation of poorly soluble in water fluorides of alkali and alkaline-earth metal, which clog the most permeable pores of the reservoir for water or steam, is involved in the process of gas saturation of the solution, additional gaseous nitrogen. Foamable composition is injected into the well and forced into the reservoir in the form of fringe before injection into the well water or coolant (steam, hot water and so on) table 2.

The invention apply the ists in the later stages of field development.

Known composition for enhanced oil recovery reservoir containing a surface-active substance (surfactant), ammonium nitrate, urea and water.

Gasanalysis solution is carried out by thermal hydrolysis of urea scheme

(NH2)2CO+H2O __ CO2+2NH3(1)

The disadvantage of this structure is the limited thermal condition, the temperature of the reservoir should be above 80aboutC.

Known foam system for mastering wells containing urea, surfactants, nitrite, alkali or alkaline earth metal, an acid, methenamine and water.

As gas agent in this composition are carbon dioxide and gaseous nitrogen formed at any positive temperature according to the following scheme:

(NH2)2CO+2H++ Me (NO2)n; 2N2+CO2+3H2O+ Men+, (2) where Me is an alkaline or alkaline earth metal;

n index the chemical formula of a molecule of a substance.

The disadvantage of this composition is low bridging action of the high-permeability layers and low dissolving ability of rocks, therefore, a lack of full coverage nefteproduktov Platania coverage nefteproduktov reservoir flooding or coolant.

The objective is achieved by the fact that the known foam system containing urea, surfactants, nitrite, alkali or alkaline earth metal, an acid and water optionally contain hydrofloric ammonium and used to create a foam rim in the reservoir prior to injection into the well water or coolant (steam, hot water and so on).

Offer foamable composition as the acid may contain a Lewis acid, salts formed from the remnants of a strong acid and a weak base, such as ferric chloride.

As a result of hydrolysis of these salts are formed acid and low in the water hydroxides of metals. For example, aluminium chloride ionic equation for the hydrolysis can be written in the following form:

Al3++3HOH __ Al(OH)+3H+(3)

Foaming in situ occurs spontaneously through a number of intermediate chemical reactions between the source components on diagram

2(NH2)2CO+2NH4HF2+2H++a+ Me(NO2)n__

__ aMeF + Men++6N2+2CO2+aH2O, (4) where Me is an alkaline or alkaline earth metal;

and the ratio of chemical equations;

n the index chemical Faure is lachesillidae metal clog the most permeable pores of the reservoir for water or steam and help to increase coverage of the productive layer with water or coolant. Additionally introduced hydrofloric of ammonia by hydrolysis forms hydrofluoric acid, which reacts and dissolves carbonate and clay-containing rock formation.

In table. 1 shows the results of laboratory tests showing the dissolution rate clay-containing rocks (claystone) and bentonite clay, depending on the concentration of hydrohloride ammonium in the water. A more concentrated aqueous solution of hydrohloride ammonium react with samples of rocks dissolves and destroys them due to disjoining pressure.

The use of volatile acids (hydrochloric acid, formic acid, etc. and their salts, as well as hydrohloride ammonium in the foaming composition can increase the depth of coverage of the productive formation of foam rim.

For example, physico-chemical properties of hydrogen chloride (hydrochloric acid), which has a critical temperature Tkr=51,4aboutC and critical pressure Pkr= 81,5 ATM at formation conditions of the majority of fields, as well as by thermal method of improving oil is in the gas phase.

Volatile acid (hydrogen chloride and peristylium able to cover the foam composition layer with a large radius of influence.

To confirm oil-driving properties penoobrazuyuschaya composition of experimental studies were performed.

The relative increase in recovery factor was determined on artificial cores using foam rims compared to simple flooding.

Research oil-driving properties of the composition were performed on linear models of the reservoir with a length of 1.0 m and a diameter of 0.15 m as the porous medium used quartz sand. Artificial core was saturated with a natural oil with a viscosity 8,42 cSt and density 0,848 g/cm3, further oil was replaced poptodorova water from the same reservoir with a total mineralization of 8.0 g/l so that the total amount of squeezing liquid was 130 ml.

For example, to obtain a foam rim are two solution of 10.0 ml of the components of the foam system. The first solution contains urea, sodium nitrite and surfactant OP-10, the second contains strictly stoichiometric ratio of the solution hydrohloride ammonium in hydrochloric acid.

Prepared solutions consistently using a buffer fluid between them (oil with a volume of 10.0 ml) is injected into the formation model, the last solution hidrofor is,0 ml.

The discharge pressure and squeezing fluid fixes the gauge at the same speed expiration (0.5 ml/s) displacement of fluid for each experiment.

The results of the experimental determination of the efficiency of the proposed foaming composition shown in table.2.

From table. 2 that the foam rim increases the discharge pressure, therefore, the coverage of the productive formation by flooding and increases the relative increase in the recovery factor.

From the analysis of the survey results follows that the optimum content of the components in the foam of the following composition, wt. Urea 1,5-4,0

Nitrite or alkaline

alkaline earth metal 5,2-13,8 Hydrofloric ammonium 2,8-7,6 Acid 0,9-2,4 surfactant 0.2 to 1.0 Water the Rest

The use of gas-emitting components in the proposed formulation at concentrations greater or less than these values is impractical because of the relative increase in recovery factor does not satisfy the objectives. For example, when using the rim of 1.5% aqueous surfactant solution (OP-10) relative increase of the recovery factor is 32.9 per cent (table. 2), while the concentrations of the components in the foaming is rarest recovery factor of no more than 36% of the Concentration of surfactant should be in the range of 0.2-1.0 wt. Increasing the concentration above 1.0 wt. in the foaming composition leads to difficulties in preparing oil (unnecessarily high consumption of demulsifiers), and a decrease of less than 0.2 wt. below a low foaming ability of the composition.

An example of the preparation of the foamable composition in real conditions with a volume of 50.0 m3.

Prepared in two different tanks of solution by 25.0 m3.

The first solution contains 750 kg (3.0 wt.) urea, 2587,5 kg (10.4 wt. ), sodium nitrite, 125,0 (0.5 wt.) Surfactant (OP-10) and bring the volume of solution in the water to 25.0 m3.

In another vessel dissolve in water 1425,0 kg (5.7 wt.) hydrofloric ammonium and 457.5 kg (1.8 wt.) hydrochloric acid, calculated on the dry matter and bring the volume of solution in the water to 25.0 m3.

Prepared solutions using separating buffer fluid (oil with a volume of not less than 5.0 m3sequentially injected into the injection well and forced into the reservoir, last upload solution containing hydrofloric ammonium and acid. Well let by injection of water or brine.

Instead of sodium nitride can be used nitrides other alkaline or alkaline earth metals, and instead of the Sol is lots Lewis).

Examples of preparation and use of compositions in these cases is not fundamentally different.

The quantitative proportions of the interacting components are calculated according to the chemical equation (4).

Offer the source reagents are cheap and available, do not require special conditions during the transportation and storage industry produces large capacity and are widely used.

FOAMABLE COMPOSITION FOR enhanced oil RECOVERY, containing urea, nitrite, alkaline or alkaline-earth metal, an acid, a surfactant (surfactant) and water, characterized in that it further comprises hydrofloric ammonium in the following ratio, wt. %:

Urea - 1,5 - 4,0

Nitrite, an alkaline or alkaline-earth metal - 5,2 - 13,8

Hydrofloric ammonium - 2,8 - 7,6

Acid - 0,9 - 2,4

SURFACTANT - 0,2 - 1,0

Water - The Rest

 

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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.

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1 tbl

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EFFECT: improved fluid-carrying ability.

1 tbl

FIELD: oil and gas production industry, in particular two-phase foam forming composition for secondary development of clay grouted stratum with non-uniform permeability by perforation under abnormal law stratum pressure.

SUBSTANCE: claimed composition contains foam forming agent, inhibitor, solvent and water. Bone glue in amount of 4-6 mass % is used as foam forming agent and inhibitor, sodium or potassium hydroxide in amount of 0.2-0.5 % is used as solvent, and balance: water. Composition of present invention makes it possible to produce foam with increased order, stability, inhibiting properties, low filtration factor, improved holding properties and to keep integrity of casing string and cement ring.

EFFECT: increased efficiency of secondary stratum development by perforation.

9 ex

FIELD: oil and gas production industry, in particular two-phase foam forming composition for development of productive stratum under abnormal law stratum pressure.

SUBSTANCE: claimed composition contains foam forming agent, stabilizer, inhibitor, and processing water. Bone glue in amount of 3-5 mass % is used as foam forming agent, stabilizer and inhibitor, and balance: processing water. Composition of present invention makes it possible to produce foam with increased order, stability, inhibiting and geological properties, low filtration factor, improved holding properties.

EFFECT: increased efficiency of stratum development.

3 ex

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