Oil pool development method

FIELD: oil and gas production.

SUBSTANCE: invention provides a method of developing oil pool allowing production of oil from water-rich oil reservoir under difficult geological-tectonic conditions in the last development stage. In the method, neutral salt of carbonic acid and acid solution are forced into formation through injecting well with water generated in gas-liquid fringe created in formation. After pumping of neutral salt of carbonic acid, acid solution is pumped by portions alternating with water pumping. Before pumping of acid solution portions beginning by at least second portion, selective insulation of high-permeable formation intervals is performed. Aforesaid neutral salt of carbonic acid utilized is sodium carbonate aqueous solution or aqueous suspension of calcium carbonate and aforesaid acid solution is aqueous hydrochloric acid solution. Selective insulation of high-permeable formation intervals involves use of freshly prepared controllable viscoelastic composition containing water-soluble acrylic polymer, cross-linking agent, thermal stabilizer, surfactant, and water. Summary concentration of acid solution is determined from concentration of neutral salt of carbonic acid on the base of stoichiometric proportions.

EFFECT: increased efficiency of maintaining formation pressure and thereby oil recovery of formation due to leveled displacement front and reduced probability of the rupture of formation rock backbone, and simplified control of phase state of gas-liquid fringe by changing pressure of pumped acid solution portions.

8 cl

 

The invention relates to the oil industry, and in particular to a method of developing oil deposits, allowing to extract the oil from flooding the reservoir with complex geological and tectonic conditions at a late stage of development.

With the aim of improving sweep flooding in various stages of oil field development and the displacement of residual oil from flooded areas, as a rule, are widely used aqueous solutions of various chemicals. It is established that the extraction of residual oil from flooding the reservoir provides mixing displacement, which is achieved ultra-low interphase tension at the phase boundary. Such conditions occur when the displacement of oil by agents that virtually eliminate the negative effects of capillary forces on the displacement of oil.

It is known that the most promising method of increasing oil recovery at different development systems is injected into the reservoir rim carbon dioxide (CO2).

Especially important is the fact that the injection of carbon dioxide can be effectively used in a wide range of geological and technological conditions for the extraction of both light and heavy or high-viscosity oil.

During physico-chemical studies of the properties of carbon dioxide is found that in certain thermobaric the mini-conditions namely, when a strong contraction of the gas and its subsequent heating occurs a sharp increase in the density of CO2dozens of times, thus the density is close to the density of the liquid, and the viscosity remains almost like gas. This state of the gas is called “supercritical fluid”. The obtained solution “supercritical fluid” is an ideal reagent for use in the processes of oil and gas production, because thermodynamic regime, supported in situ, can be used to control the solvent properties of these fluids. The large density changes “solvent” is achieved approximately at the critical point of the solvent, in which the compressibility of the solvent is greater, and a small pressure changes cause large changes in the density.

The introduction of technologies based on the use of carbon dioxide, it is established that:

- when dissolved in water 5-10% CO2there is an increase in the viscosity of 20-30%decrease in the parameter of mobility in 2-3 times;

- when dissolved in oil CO2decreases the interfacial tension between the oil-water, there is a decrease in the viscosity of the oil at 1.5 to 2.5 times and increase oil recovery by 10-15%;

- when dissolved in oil and water CO2there is an increase in the volume of oil (volume effect) and on the washout of residual oil.

However, there were some shortcomings technology injection of CO2from land-based communications to increase oil recovery, including:

- breakthrough CO2in producing wells;

- minor changes thermobaric conditions, including stops wells, there is a decrease in the concentration of CO2in oil, which leads to coagulation and precipitation of asphaltenes and resins in the sediment. This, in turn, indicates preferential adsorption on the rock resinous components of oil, leading to the formation on a solid surface high-viscosity oil film, not washed at regular flooding;

- corrosion of oilfield equipment;

- problems of transporting large volumes of carbon dioxide;

- lack of necessary machinery and equipment, ensuring safe storage and use of CO2;

- high cost technologies;

- and finally, the absence in many oil producing areas of CO2in sufficient quantities for implementation in oil production.

In this regard, there is a need for such technology using carbon dioxide, which would preserve all the positive effects, and on the other hand, would have prevented the negative effects observed with the injection of CO2from n the terrestrial communications.

There is a method of developing oil deposits, consisting in pushing the water in the reservoir rim carbon dioxide created by the injection of a mixture of medium salts of carbonic acid (sodium bicarbonate) with citric acid [1].

In this technology due to the fact that the reagents are pumped into the reservoir in the form of responsive mixture, the carbon dioxide will be formed in the well and be localized in the bottomhole formation zone. In addition, the method does not allow for the isolation of highly conducting layers. This will lead to uneven distribution of carbon dioxide in the pores of the formation, which may lead to a breakthrough of gas through the high-permeability layers.

There is a method of developing oil deposits. Its essence lies in the fact that in the reservoir creates a fringe of carbon dioxide, which is generated in situ in the reaction are alternately injected into the reservoir gas-producing and gas-emitting chemicals. In particular, as a gas-forming reagent is used acid solution, and as gas-emitting - medium salt of carbonic acid. The resulting gas-liquid slug is pushed along the layer of water [2].

Part of the carbon dioxide dissolved in the oil, creating a surround effect and provides washout of residual not the ti, moreover, under certain temperature conditions, the carbon dioxide generated directly in the reservoir, can be mixed with oil in unlimited proportions.

Part of the carbon dioxide dissolved in the water, increasing the viscosity of water, contributes to the alignment of the displacement front and increase coverage of the formation eviction.

In the known method the compliance of conditions of full saturation with carbon dioxide generated fringe provides odnofaznogo and nonequilibrium get rims, which significantly increases the efficiency of the method in contrast to existing methods that overload dioxide is dwuhfaznosti rim and, as a consequence, anticipating a breakthrough gas producing wells, and when nedorazumenii carbon dioxide properties rims do not differ from the properties of water.

Known technology of the development of oil deposits, providing for generating a gas-liquid rim directly in situ, does not provide for selective isolation of high permeability and washed out sections of the reservoir, especially in the process of alternately pumping gas-producing and gas-emitting solutions, which reduces the efficiency of the process of displacement. In addition, when the injection of the acid solution into the formation, folded carbonate rocks may be produced is Outi destruction of rock matrix of the formation.

The technical result of the claimed invention is to increase the efficiency of the system maintain reservoir pressure and, accordingly, the oil recovery by equalizing the displacement front, reduce the likelihood of destruction of the skeleton of the reservoir rock, the simplification of the regulation of the phase state of gas-liquid rim by the pressure change of the injection portions acid solution.

This result is achieved by the fact that the way of the development of oil deposits, consisting in pushing water generated in the liquid reservoir rim, created in the reservoir alternately injected into the formation via the injection well an average salt of carbonic acid and the acid solution, after the injection medium salts of carbonic acid acid solution pumped portions, alternating with water injection, while before download portions acid solution, starting at least from the second portion to produce selective isolation of high-permeability intervals of the formation.

In addition:

as the average salt of carbonic acid pumped into the reservoir an aqueous solution of sodium carbonate or aqueous suspension of calcium carbonate as the acid solution is an aqueous solution of hydrochloric acid;

selective isolation of high-permeability intervals of the reservoir produce freshly prepared adjustable voskop whim composition; adjustable viscoelastic composition contains a water-soluble polymer of acrylic series, stapler, thermo stabilizer, surfactant and water.

The total mass concentration of the acid solution is determined based on the mass concentration average salt of carbonic acid derived from the stoichiometric ratio.

The method is as follows.

Into the formation via the injection well pump the aqueous solution or aqueous suspension of a salt of carbonic acid. Then pumped into the reservoir portions acid solution, alternating injection of water as a buffer.

In the reaction medium salts of carbonic acid and a portion of the acid solution in the reservoir are formed of high-permeability channels, it can cause breakthrough subsequent portions acid solution. To align the displacement front before download portions acid solution, starting at least from the second portion to produce selective isolation of high-permeability channels adjustable viscoelastic composition. The resulting gas-liquid slug is pushed by reservoir water displacing oil from the reservoir.

The required volumes and concentrations injected into the formation reagents are based on the required volume of the rim, size of reservoir pressure and temperature conditions of full saturation from the rocky carbon dioxide. The total mass concentration of the acid solution is determined on the basis of the mass concentration average salt of carbonic acid derived from the stoichiometric ratio.

The phase state of the rim is adjusted by changing the pressure of the injection portions acid solution.

The required volume of a portion of the acid solution is determined from the condition VK.R.0,5Vp.cwhere VK.R.- volume of a portion of the acid solution, m3; Vp.c- volume of aqueous solution or aqueous suspension medium salts of carbonic acid, m3.

Thus, if pump acid solution in two portions, VK.R.=0.5 Vp.c.if three portions - VK.R.=0,33 VRSetc.

The method can be used the following reagents:

as water-soluble salts of carbonic acid - any water-soluble salt of carbonic acid, but it is preferable to use the best available sodium carbonate /PA2CO3/,

as the water-insoluble salt calcium carbonate /caso3/;

as the acid solution is preferable to use an aqueous solution of hydrochloric acid;

as the water-soluble polymer of acrylic series, for example, is hydrolyzed polyacrylonitrile /GIPAN/, copolymer of methacrylic acid and methacrylamide /METAS/, polyacrylamide /PAA/and others. Preferably you should use the most effective water-soluble polymers having high molecular weight, in particular polyacrylamide. Polyacrylamide is produced in the form of a gel /TU 6-16-01-1040-76/ and in the form of dry powder /TU 6-16-157-78/. Imported brand KOGYO” (Japan), “FP-301” /France/, “Praestol” /Germany/ etc.;

as the staple - bichromate sodium /Na2Cr2O7/, bichromate of potassium /K2CR2O7/, as well as chlorides and sulfates of iron, aluminum, chromium, copper, mainly sodium bichromate or potassium bichromate;

as thermo stabilizer - lignosulfonate, which not only gives the stability of the viscoelastic composition at high formation temperatures, but also performs the function of the stapler;

as surface-active substances (surfactants) - nonionic and anion active surfactants, in particular sulfonic acid - anion surface-active substance is a mixture of sodium salts of alkylbenzenesulfonic with alkyl residue, reagent OP-10 - nonionic, highly active surfactant - monoalkylphenol ether of polyethylene glycol, and others;

as regulated viscoelastic composition can be used, for example, the composition containing as a water-soluble polymer of acrylic number of polyacrylamide as a staple - for example, sodium bichromate, as thermosta the lyst - lignosulfonate, as surface-active substances - sulfonic acid in the following ratio of components, wt.%:

polyacrylamide 0,1-1,0

the bichromate of sodium 0,4-0,8

lignosulfonate 0,2-0,5

the sulfonic acid of 0.1-0.3

water the rest

A specific example of the method

For example, the oil reservoir with the reservoir pressure of 5 MPa, the reservoir temperature 40° developed With the proposed method, with the creation of liquid in the reservoir rim in the amount of 0.1 pore volume (pore volume is 5000 m3). Thus, the amount of fringe should be 500 m3. For complete saturation 1 m3water containing sodium chloride at a temperature of 40° and a pressure of 5 MPa will require about 13 Nm3the carbon dioxide. Then for saturation of 500 m3under given conditions will need to 6500 Nm3carbon dioxide.

Given that 1 ton of sodium carbonate in contact with 0.7 tons of hydrochloric acid produces 210 Nm3carbon dioxide, it turns out that sodium carbonate will need a 31 ton, hydrochloric acid 22 tons. Taking volumes of aqueous solutions of sodium carbonate and acid solution are equal (i.e. 250 m3each), it turns out that the mass concentration of sodium carbonate in aqueous solution will be 12.5%, and the concentration of hydrochloric acid in aqueous solution will be 9%.

Connectivity via the injection well into the reservoir was pumped the entire volume of 12.5% aqueous solution of sodium carbonate, that is 250 m3the portion (125 m3) 9% aqueous solution of hydrochloric acid and 3 m3water at a pressure of 6.5 MPa. Next was prepared and injected into the reservoir adjustable viscoelastic composition containing components in mass %: PAA - 1.0; sodium bichromate - 0,5; sulfonic acid - 0.3 and water - level 98.2 in the volume V=4 m3. Next was pumped water buffer, the second portion (125 m3) 9% aqueous solution of hydrochloric acid and 5 m3water at a pressure of 8.5 MPa. Then was carried out displacement of the rim with water.

As a result, the selection of oil by reacting 3 production wells within 6 months increased by 10-15%.

The above operations may be repeated in the same sequence.

The method of using water-insoluble salts of carbonic acid in aqueous suspension is carried out in the same sequence and the same conditions as when using water-soluble salt of carbonic acid.

Thus, the application of the described method allows to significantly increase the oil recovery factor.

Sources of information

1. US No. 4523642, E 21 In 43/022, 1985

2. RU # 2142557, E 21 IN 43/20, 1999

1. The way of the development of oil deposits, consisting in pushing water generated in the liquid reservoir rim, created alternate injection into the formation via the injection well an average salt coal KIS is the notes and acid solution, characterized in that after injection the average salt of carbonic acid acid solution pumped portions, alternating with water injection, while before download portions acid solution, starting at least from the second portion to produce selective isolation of high-permeability intervals of the formation.

2. The method according to claim 1, characterized in that the total mass concentration of the acid solution is determined on the basis of the mass concentration average salt of carbonic acid derived from the stoichiometric ratio.

3. The method according to claim 2, characterized in that the average salt of carbonic acid into the formation in the form of its aqueous solution.

4. The method according to claim 2, characterized in that the average salt of carbonic acid into the formation in the form of an aqueous suspension.

5. The method according to claim 3, characterized in that the reservoir is injected aqueous solution of sodium carbonate.

6. The method according to claim 4, characterized in that the reservoir is injected aqueous suspension of calcium carbonate.

7. The method according to claim 5 or 6, characterized in that the acid solution is pumped into the reservoir an aqueous solution of hydrochloric acid.

8. The method according to any one of claims 1 to 7, characterized in that the selective isolation of high-permeability intervals layer produced by injection of freshly prepared adjustable viscoelastic composition containing water-soluble polymer clay is acrylic series stapler, thermo stabilizer, surfactant and water.



 

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The invention relates to the oil industry

FIELD: oil and gas production.

SUBSTANCE: invention provides a method of developing oil pool allowing production of oil from water-rich oil reservoir under difficult geological-tectonic conditions in the last development stage. In the method, neutral salt of carbonic acid and acid solution are forced into formation through injecting well with water generated in gas-liquid fringe created in formation. After pumping of neutral salt of carbonic acid, acid solution is pumped by portions alternating with water pumping. Before pumping of acid solution portions beginning by at least second portion, selective insulation of high-permeable formation intervals is performed. Aforesaid neutral salt of carbonic acid utilized is sodium carbonate aqueous solution or aqueous suspension of calcium carbonate and aforesaid acid solution is aqueous hydrochloric acid solution. Selective insulation of high-permeable formation intervals involves use of freshly prepared controllable viscoelastic composition containing water-soluble acrylic polymer, cross-linking agent, thermal stabilizer, surfactant, and water. Summary concentration of acid solution is determined from concentration of neutral salt of carbonic acid on the base of stoichiometric proportions.

EFFECT: increased efficiency of maintaining formation pressure and thereby oil recovery of formation due to leveled displacement front and reduced probability of the rupture of formation rock backbone, and simplified control of phase state of gas-liquid fringe by changing pressure of pumped acid solution portions.

8 cl

FIELD: oil and gas production.

SUBSTANCE: invention aims at increasing productivity of oil- and gas-producing and injecting wells exposing high-temperature low-permeable oil reservoirs. In the treatment method according to invention including forcing enzyme substrate and separate enzyme into formation and creating conditions to enzymatically convert substrate into acid, geologic and productive characteristics for each interval of bottom zone are determined in order to pick out low-permeable intervals of oil reservoir for treatment, whereupon properties of enzyme substrate and separate enzyme as well as conditions for their pumping are chosen. Substrate utilized in the method is head fraction of methyl- and/or ethyl-, and/or butyl acetate production, to which aliphatic alcohols are added, and enzyme is an acid solution. Substrate is pumped simultaneously and/or before, and/or after pumping of enzyme, after which well is closed for some time and then opened and placed under predetermined operational conditions.

EFFECT: enhanced efficiency of acid treatment due to increased phase permeability for oil and deepness of active acid-treated zone of low-permeable oil reservoirs.

25 cl, 1 tbl, 3 ex

FIELD: oil and gas production.

SUBSTANCE: invention is intended for use during development of oil pools at different waterflooding phase for intensifying functioning of producing wells and increasing current oil recovery of formation. Composition contains, wt %: liquid hydrocarbon 10.0-20.0, oil-soluble surfactant 0.3-5.0, water-soluble or water-oil-soluble surfactant 0.1-1.0, superfine hydrophobic material 0.1-2.0, and water (the rest). Composition may further contain 0.3-5.0% calcium chloride. Oil recovery is increased owing to hydrophobization of formation structure, reduction of surface tension in water/rock/oil phase boundary, increase in detergent power of polluted surface, increase in composition viscosity, and increase of relative permeability of the formation for hydrocarbon phase as compared with water phase.

EFFECT: increased oil recovery.

2 cl, 2 tbl, 2 ex

FIELD: oil and gas production.

SUBSTANCE: composition contains 0.05-2.5% of hydrophobic power, 0.05-10% of ethylene/vinyl acetate copolymer, and organic solvent. Composition intensifies oil production owing to increased effective radius of formation bottom area treatment, prevention of moistening inversion effect upon fall of hydrophobic agent concentration, and, consequently, decreased volume of simultaneously produced water.

EFFECT: increased oil production, prolonged overhaul period, improved environmental safety, and lowered production expenses.

2 tbl, 3 ex

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes drilling product and force wells, forcing gas and water through force wells into separate zones of productive bed and extraction of hydrocarbons from product wells, forming separate gas, water and hydrocarbon saturated areas with major contents of respectively gas, collected therein for later use, water and hydrocarbons, periodical pumping of collected gas from formed gas saturated zones to water saturated zones, periodical pumping of water to gas saturated zones is performed. It is possible to pump collected gas to water saturated zones in form of gas-water mixture. It is possible to pump in passing gas of current deposit. It is possible to pump hydrocarbon or non-hydrocarbon gas from other sources. It is possible to pump water with admixture of specifically selected chemical reagents or compositions thereof. When gas content in water saturated zones reaches from 0.1 to 28% from water content in water saturated zones it is reasonable to generate resilient waves with frequency within range from 0.0001 to 45 KHz and amplitude within range from 0.02 to 2.8 MPa. It is reasonable to pump gas and water to separate areas of productive bed with concurrent generation of resilient waves in there with frequency within range from 0.0001 to 45 KHz and amplitude within limits from 0.02 to 2.8 MPa.

EFFECT: higher efficiency.

7 cl, 5 dwg

FIELD: oil extractive industry.

SUBSTANCE: method includes pumping of Sulfacella water dispersion into bed through force well and extraction of oil through extracting well, said dispersion additionally containing non-ionogenic surfactant AF9-12 with following ratio of components, in percents of mass: Sulfacella 0.5-1, AF9-12 0.01-0.1, water- the rest, while, before pumping of said dispersion mineralized water is pumped with total mineralization until 290 g/l in amount of 10% from volume of said dispersion, when pumping said dispersion prepared in fresh water, drain water is previously pumped, and when pumping said dispersion made from drain or bed water, bed water is previously pumped. For preparation of said dispersion fresh, drain or bed water is used with mineralization till 290 g/l.

EFFECT: higher efficiency.

2 cl, 2 tbl

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes examination of operation well for gas-condensation and periodical cleaning of face-adjacent well area from precipitating hydrocarbon condensate by pumping hydrocarbon condensate solvent into bed, exposure of well for period of condensate dissolution and following removal of received solution from face-adjacent area during well launch, as solvent binary mixture is used with unlimited mutual solubility of components, while at least one of them has unlimited mutual solubility with hydrocarbon condensate, and relation of binary mixture components is determined from previously built phase diagram of three-component system, formed during dissolution of hydrocarbon condensate. As binary mixture with unlimited mutual solubility of components a mixture of acetone and methanol is used, or chloroform and methanol, or chloroform and aniline, or chloroform and acetone.

EFFECT: higher productiveness.

2 cl, 3 ex, 6 tbl, 2 dwg

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes placing water solution of carnallite ore, either modified, concentrated, or mixtures thereof, said solution is used at maximal for well temperature conditions concentration and is pumped in amount, necessary and enough for forming a hydraulic column in well shaft above ceiling of productive bed and along remaining shaft height well is filled with water up to mouth. Carnallite ore used has composition, in percents of mass: potassium chloride 20.5-21.5; sodium chloride 19.5-22.5; magnesium chloride 24.0-27.0; crystallization water 29.5-30.5. Modified ore has composition, in percents of mass: potassium chloride 23.0-29.5; magnesium chloride 31.8-46.0; crystallization water - the rest. Said water solution is prepared by dissolving ore in fresh technical water, drained from oil preparation plants, or in bed water. In case of dissolving in bed water, the latter is pumped from well at temperature 60-90°C. During perforation of well, value of technological liquid hydraulic column above productive bed ceiling is taken equal to (1.03-1.07)-(1.05-1.1)Pb, where Pb - productive bed pressure. Water solution of carnallite ore is used at density 1.23-1.37 t/m3. During use of said solution as working body of force wells it is used at density 1.05-1.20 t/m3, and solution also contains swelling inhibitor for argillaceous component of oil and gas bearing bed, like oxyethylenedendiphosphone acid, in amount 0.05-0.15% of used dissolved ore mass.

EFFECT: higher efficiency.

1 cl, 4 ex

FIELD: oil industry.

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EFFECT: higher efficiency.

2 tbl, 2 ex

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EFFECT: increased yield of biogas to continuously effecting culturing of microorganisms.

1 dwg, 2 tbl

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