Foamable composition for removing liquids from gas wells

 

(57) Abstract:

The invention relates to the oil and gas industry, namely, foam compositions, and can be used to remove liquids from gas wells. Improving foaming properties of the composition and the intensification of the processes of removal of highly mineralized water and gas condensate from a gas well is achieved in that the composition contains urea 17,2 -17,9% wt. nitrite, an alkaline or alkaline-earth metal 48,7 50,7 wt. the Lewis acid 25,3 26,3 wt. the foam stabilizer of 0.2 -- 1.4 wt. the foaming agent is 0.7 to 2.2 wt. and water the rest. The composition used in the form of cylindrical pellets of the two brands on the basis of structure-forming water-soluble agents with a bulk density of 1.8-2.0 g/cm3upon receipt of the foam, the foam cements, penopolimer, obliczenia drilling fluids and cement slurries, with the elimination of sand tubes in the wells, washing and cleaning of bottom-hole formation zone with simultaneous depression at her and intensification of the processes of oil and gas. 2 C. p. F.-ly, 8 PL.

The invention relates to the oil and gas industry, in particular foaming compositions, and can be used to remove liquid from the gas squag the STN-active substance (surfactant), the corrosion inhibitor of pyridine KPI-I and gas-emitting agent dry ice [1] the Disadvantages of this structure are low foaming ability and low intensity removal of highly mineralized water and gas condensate.

Closest to the present invention is self-generating foam system for well completion, including urea, nitrite, alkali or alkaline earth metal, an acid, methenamine, a surfactant, and water [2] Foaming and gasanalysis agent in this system are carbon dioxide and gaseous nitrogen, which is formed due to chemical interaction between the source components.

The disadvantages of the known systems are: foam formation occurs immediately after mixing the starting components for any positive temperatures; for implementation of a process should foam system to be in the form of two solutions and each solution separately injected into the well. When mixing the two solutions foaming will occur in the upper part of the well, and when using the buffer fluid between the solutions of the probability of interaction of the starting components is very low.

Therefore, this foam with the solution foaming properties of the composition of the intensification of the processes of removal of highly mineralized water and gas condensate from a gas well.

The essence is that self-generating foam system containing urea, nitrite, alkali or alkaline earth metal, an acid, a surfactant, and water as acid contains a salt of a halide or sulfate of iron, aluminum and additionally the amendment carboxymethylcellulose (CMC) and polyacrylamide (PAA) in the following ratios, wt. Urea 17,2-17,9

Nitrite or alkaline

alkaline earth metal 48,7-50,7

The halide or sulfate of iron, aluminum 25,3-26,3 surfactant 0,7-2,2 CMC or PAA 0,2-1,4 Water the Rest

To protect the equipment against corrosion, it can optionally contain a corrosion inhibitor, for example, KPI-3, representing a 70% aqueous solution brown color with a faint odor, in an amount of 0.1-0.2 wt.

The original components of foam formulations in their interaction to form gaseous products and soluble in water connection through a number of intermediate chemical reactions.

As a result of hydrolysis of salts of iron or aluminum, formed from the remains weak hydroxides metal and a strong acid, the reaction medium has an acidic character.

The General scheme of the interaction of these salts with water imeem sulfate;

n and m indexes the chemical formula of the substance;

Me(OH)3poorly soluble in water and metal hydroxides;

HAn strong mineral acid.

The dependence of the acidity of an aqueous solution of certain salts of iron and aluminum are given in table. 1.

Poorly soluble in water and hydroxides of iron and aluminum, as well as insoluble salts of sulfates of alkaline earth metal improves the stability of foam.

Sulfates of alkaline-earth metals are formed in those cases, when the foamable composition contains nitrite, alkaline earth metal and a salt of sulfate of iron or aluminum, as well as in the interaction of highly mineralized water with high rigidity the same sulfates on the borehole bottom.

The interaction of the initial components of foam formulations in General form can be expressed as follows:

aMemAnn+ Kt(NO2)k+3(NH2)2CO __ 2Me(OH)3+

+ Kt(An) +6N2+3CO2+H2O

(2)

where Me iron or aluminium;

Kt cations of alkaline or alkaline-earth metal;

An anions of halides (Cl-, Br-I-or sulfate;

m, n, k indexes the chemical formula of the substance;

coefficie is all;

k 2 Kt alkaline-earth metal.

Gasanalysis highly mineralized water is carbon dioxide (carbon dioxide) and nitrogen.

Offer foamable composition for removing liquids from gas wells obtained as follows.

Prepare 5-25% aqueous solution of CMC or PAA and leave it to swell for 3-4 hours

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

first get at careful hashing urea, nitrite, alkaline or alkaline-earth metal powder or elastic-viscous surfactant solution CMC or PAA (mixture A). Mass content in the mixture "A" initial components are given in table. 2;

second when mixing the halide or sulfate of aluminium, iron with CMC solution or PAA (mixture B). The structure and boundary conditions of the components in the mixture "B" are given in table. 3, wt.

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

Thus obtained the estimated number of terminals consistently throw inside the tubing through the gland-bast who live in the reaction and incubated for 20-60 min, then gradually release the pressure through the tubing or annulus, carry out the removal of fluid from the well. The well is ready for use.

The efficiency of removal of liquids from gas wells proposed foaming composition is due to the fact that interaction on hole formed gaseous agents are nitrogen and carbon dioxide;

the chemical reaction of the interaction between the source components of foam formulations irreversible because of the formation of poorly soluble in water connections gaseous products and water;

the aluminum hydroxide or iron, CMC or PAA increase the stability of the foam and its yielding ability of highly mineralized water and gas condensate.

The content of the briquettes B basic substance (halide or sulfate of aluminium, iron) from 90 to 98% of the rest aqueous solution of CMC or PAA (table. 3).

The greatest amount of water, CMC or PAA foamable composition contains, when briquettes "B" main ingredient is a salt of aluminum. Aluminum compounds in the composition is less soluble in water than iron salts, therefore, the briquettes produced on the same conc is ing slowly swell and dissolve in water, have a lower bulk density than briquettes "B" based on iron compounds.

A foaming composition containing aluminium salts are less effective at low temperatures of formation (below the 50about(C) require more time to implement a single well operations (30-60 min).

Foamable composition for removing liquids from gas wells, containing a salt of iron, allows for more efficient and faster to make the process of removal of highly mineralized water with higher density of 1.20 g/cm3in the presence of condensate at the temperature of the reservoir below the 50aboutC.

The solubility and swelling of briquettes in water depends on the content of the amendment CMC or PAA. Briquettes made in more concentrated solutions of the amendment, which is slower (worse) dissolved and further swell and Vice versa.

The concentration of the amendment, for example, in the briquette "B" defines and allows you to adjust the speed of foaming at the well bottom and the duration of the technological process (PL. 4).

Offer foamable composition for removing liquids from gas wells allows to obtain a foam with regulirue products.

P R I m m e R. Foamable composition test in a laboratory setup, which represents the model well.

Prepare a saline aqueous solution of a mixture of salts of potassium chloride and calcium chloride with a density of 1.20 g/cm3. Prepare rods (briquettes) on the basis of the doughy mixture "A", containing 6% aqueous solution of CMC. Doughy mixture contains simple stoichiometric ratio of the source gas-emitting substance (PL. 2), wt. Urea 28,2 sodium Nitrite 64.8 Sultanol NP-3 2,0 CMC 0,3 Water 4,7

Briquettes "B" is prepared on the basis of a 20% aqueous solution of CMC in the following ratios, wt. (PL. 3): the ferric Chloride 98,0 CM 0,4 Water 1,6

When the weight ratio of briquettes "a" and "B" (example of a specific implementation and table. 6):

100:

100 52,08

1,92 1,00

Foamable composition will have original content of all components, wt. Urea 18.5 sodium Nitrite 42,6 ferric Chloride 33,6 NP-3 1,3 CMC 0,3 Water 3,7

Laboratory results are shown in table. 5, from which it follows that:

for complete removal of highly mineralized water with a density of 1.20 g/cm3and hydrocarbon liquid fuel with a density of 0.82 g/cm3it takes less than 20 minutes at ivalsa at the interface of water and kerosene and plays the role of a loose piston when removing the hydrocarbon liquids;

the chemical reaction of the gas goes through the entire thickness of highly mineralized water and foam, if foamable composition (rods) has a bulk density of 10-15% higher than the density of the removed liquid, otherwise the rods emerge to section liquid phases, and the process of foam formation and removal of the fluid is less efficient;

for complete removal of liquid required quantity of foam formulations should not be less than 6% of the weight removed by saline water and kerosene (without taking into account the force of pressure of the produced gas).

The results of laboratory tests, it follows that using the proposed foamable composition, a tenfold increase in the intensity of the removal of liquids from gas wells compared with other known compositions and methods.

P R I m m e R. Gas well is cased 168 mm column temperature reservoir 60aboutC, pressure of 40 ATM. Work well complicated because of the presence of the liquid column, consisting of highly mineralized water with a density of 1.12 g/cm3and gas condensate with a density of 0.75 g/cm3. The liquid column height 260,0 and 190,0 m consists of water, the rest gas conden is it "a" and "B" (PL. 2 and 3).

A mixture of "A" on the basis of a 10% aqueous solution of CMC and containing urea, potassium nitrite, surfactant OP-10, in the following ratio of components (PL. 2), wt. Urea 24.5 Nitrite potassium 69,5 OP-10 1,0 CMC Water 0,5 4,5

Briquette "B" NAT basis of a 20% aqueous solution of CMC and aluminium chloride containing, by weight. Aluminium chloride 90,0 CMC 2,0 Water 8,0

For removing liquid from a gas well throw in sequence until the bottom hole through the seal-lubricator mounted on the wellhead, the estimated number of briquettes first grade "a" then "B".

On the basis of the General scheme (2) interaction of the gas-emitting components comprise chemical equation:

2AlCl3+6KNO2+3(NH2)2CO __ 2Al(OH)+6N+6KCl+3CO+3H2O

Determine the molecular mass of the reacting substances:

for AlCl32(27+35,53) 265 g/mol

6KNO26(39+14+162) 510 g/mol

3(NH2)2CO 3(14+2)2+12+16

180 g/mol Under normal conditions 1 mol of gas occupies a volume equal to 22.4 l, then the total volume of gases:

V 22,4(6+3) 201,6 l or 1 g of the original substances: V 0,2111 l/g To determine the mass content of the source components (%) briquettes find the ratio of molecular masses of relatively UB>2)2CO: 3(NH2)2CO - 1,00 Therefore, when the content in the briquette "And" major substances 94% OP-10 1.0% and 5,5% aqueous CMC solution with a concentration of 10% must be a Mac. Urea 24.5 Nitrite potassium 69,5

Taking into account that the content in the briquette B aluminium chloride 90% and the ratio of the molecular masses of aluminium chloride and urea is 1,47 1,00, the weight ratio of briquettes "a" and "B" will be (PL. 5):

"A" "B"100 "A":"B" 100:

"A" "B" 2,50 1,00.

In table. 5 are given the weight ratio of briquettes "a" and "B", estimated volumes of gases which may be emitted as a result of chemical interaction under normal conditions of 1 g gas-emitting components of foam formulations and 1 ton of briquettes.

The volume of gases emitted as a result of chemical reactions 1 t foamable composition is 195,9 m3foamable composition will have a ratio of initial components, wt. Urea 17.5 Nitrite potassium 49,5 aluminium Chloride 25,7 OP-10 0,7 CMC 0,9 Water 5,5

Q 0,2111(175+495+257) 195,9 m3For complete removal of liquids from gas wells, based on 1 ton of liquid 70 kg foamable composition (table. 4), the total weight of the briquettes "a" and "B" should be (4,71+ +1,16) x 70 411,6 kg, where 4,71 weight mineralized water, t; gassing condition, that is completely the interaction of the components of the foamable composition occurs for 0.5 h (table. 4), the bottom hole will be about:

44,8 l/s where the speed getvideoentry, l/C;

0,928 content gas-emitting components in the foamable composition in unit fractions;

411,6 weight of the foamable composition in the form of pellets, kg;

0,2111 the amount of the produced gases at normal conditions per 1 kg of the starting compounds, m3. Well close to the reaction and incubated for 20-30 min, then release the pressure through the annulus. The well is ready for further operation.

Instead of potassium nitrate and aluminium chloride in the foaming composition can be used sodium nitrite or alkaline earth metal and other halides or aluminum sulfate, iron.

Technology to remove water from gas wells in this case is no different, the difference is only quantitative proportions of interacting components, which are determined from the equation of the chemical reaction (2).

In table. 7 and 8 shows the mass content of the source components, when the brick "And" in its composition contains an alkaline nitrite and briquettes "B" contains the minimum and maximum kolichani components in the foamable composition (wt.) to remove liquids from gas wells are in the table. 7 and 8.

The proposed method for the removal of liquids from gas wells-Intrusive and does not require large expenditures.

The preparation of the foamable composition in the form of a cylindrical briquettes (rods) can be made stationary or in the factory any distance from the applier.

The proposed structure can be used for obtaining foam, foam cements, penopolimer, lightweight drilling fluids and cement slurries to eliminate sand tubes in the wells, washing and cleaning of bottom-hole formation zone with simultaneous depression at him and intensification of the processes of oil and gas.

The original gas-emitting components and the foaming composition cheap and available, not corrosionprotection, do not require special conditions during the transportation and storage industry produces large and widely applied in various industries.

1. FOAMABLE COMPOSITION FOR REMOVING LIQUIDS FROM GAS WELLS, containing urea, nitrite, alkali or alkaline earth metal, an acid, a foaming agent and water, characterized in that it additionally contains a foam stabilizer, and the acid is about or alkaline earth metal 48,7 50,7

The Lewis acid 25,3 26,3

The foaming agent 0,7 2,2

Foam stabilizer 0,2 1,4

Water the Rest

2. Composition under item 1, characterized in that it as a Lewis acid contains aluminium salt or iron halide or sulfate of aluminum, iron, and as a foam stabilizer, water-soluble polymeric compound is carboxymethyl cellulose or polyacrylamide.

3. Composition under item 1, characterized in that it further comprises a corrosion inhibitor in an amount of 0.1 to 0.2 wt. from the composition.

 

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