RU2418156C1 - Development method of non-homogeneous oil formation - Google Patents

Abstract

FIELD: oil and gas industry. ^ SUBSTANCE: method involves pumping to the formation via injection wells of compound in the form of disperse polymer system at required concentration. Injection wells are pre-selected; they are interconnected with one comb of group pumping station (GPS). On mixing plant there prepared is disperse polymer system with concentration of components in water for each, which is determined by the formula. Disperse polymer system prepared at the plant is dosed to water flowing from GPS comb to chosen wells; and pumping of polymer system to them is performed in necessary concentration simultaneously or in series with shutting-in of well after completion of planned pumping volume and decrease of injection capacity by not less than 10% of initial one. ^ EFFECT: improving efficiency of the method owing to possible effective control of formation permeability, improving the processibility and reducing material and energy costs. ^ 2 ex, 2 tbl, 1 dwg

Description

The invention relates to the field of the oil industry, in particular to methods for developing oil fields by regulating the coverage of heterogeneous formations by water flooding using viscoelastic compositions based on polymers to increase oil recovery.

A known method of oil production by sequentially injecting portions of solutions of polyacrylamide and aluminum salt with a water buffer between them to conduct insulation work to align the injectivity profile of injection wells using viscoelastic compositions based on polyacrylamide (patent RU No. 2086757, ЕВВ 43/22. Publ. 08/10/1997).

The disadvantages of this method are the small penetration depth of the composition in the reservoir and the high concentration of expensive polymer. For gelation throughout the volume, it is necessary that the concentration of polymer in the solution be above a certain critical value to ensure that the individual macromolecules come into contact with each other.

In addition, when preparing a solution of polyacrylamide on the surface for injection into the well, it is necessary to completely dissolve the polyacrylamide in fresh water for 60 minutes, in wastewater 90 minutes.

A known method for oil production from a heterogeneous reservoir, comprising injecting a dispersed polymer system consisting of a mixture of an anionic polymer, a salt of a polyvalent cation and water, in the following ratio of components, wt.% (Patent RU No. 2215870, ЕВВ 43/22, publ. 10.11. 2003):

anionic polymer 0.001-0.08 polyvalent metal salt 0.0005-0.002 water rest

The composition is prepared by adding a solution of the cation salt to the polyacrylamide solution. As a result of the interaction of polyacrylamide (PAA) and a cation salt at an optimal ratio (the ratio of cation to anionic polymer unit of 0.01-1.07% and pH 4-10), two polymer segments are located at a certain distance from each other, resulting in a dispersion of colloidal particles is formed. The inner part of the colloidal particles contains water, and the shell consists of polymer molecules connected to each other by cations. Such polymer-gel capsules are freely located in the aqueous phase and are not connected with each other, as evidenced by the low dynamic viscosity of these systems, which differ little from the viscosity of polymer solutions that do not contain a crosslinker, and are easily pumped through pipes. However, the viscoelastic properties of encapsulated polymer systems increase in some cases by several orders of magnitude and, when moving in a porous medium, create significant filtering resistances.

The composition is prepared on the surface: first, a polymer solution is prepared separately in the water injected into the well from the cluster pump station (SPS) and a solution of a polyvalent metal salt in fresh water. The polymer solution with the addition of a salt solution by a high pressure pump is pumped from the wellhead into the well.

The disadvantage of using this method is that it is ineffective in highly permeable formations due to the insufficient polymer and salt of the polyvalent cation in the mixture. As a result, the number of encapsulated systems formed and their sizes are insufficient to clog highly permeable formation zones.

In addition, equipment and time are needed to prepare the polyacrylamide solution on the surface.

A known method for controlling the permeability of a heterogeneous oil reservoir (patent RU No. 2292450, ЕВВ 43/22, publ. 01/27/2007), in which the composition is injected in the form of a dispersed polymer system consisting of a suspension of colloidal particles of polyacrylamide with aluminum salts, the content of components, wt.%:

polyacrylamide 0.05-0.5 aluminum salt 0.0075-0.15 water rest

Preparation and injection of the composition is carried out by existing standard installations (UDR-32M, KUDR, Baker, etc.). The composition is prepared as follows. Polyacrylamide (PAA) in the form of a powder is dosed into the water entering the water from the cluster pump station (SPS) through a jet pump (ejector). When PAA is mixed with water, a suspension forms, which is fed into an intermediate tank. A solution of aluminum salt in the amount of 15-30% of the mass content of PAA is metered into the same container.

Aluminum salts are aluminum sulfate, aluminum polyoxychloride, potassium alum, aluminum ammonium alum (A2 (SO4) 3 · 8H2O; AlCl3 · 6H2O; AlK (SO4) 2 · 12H2O; Al (NH4) (SO4) 2 · 12H2O).

During the interaction of aluminum ions with PAA molecules, a suspension of colloidal particles is formed. Then, the composition in the form of a suspension of PAA and aluminum salt in water from the intermediate tank is pumped into the injection well from a high pressure pump. Preparation and injection of the composition are carried out from the wellhead.

The disadvantage of this method is the high concentration of PAA (0.05% and higher), which either does not allow the method to be used for medium-moderate and low permeabilities or leads to a large consumption of expensive PAA.

The closest in technical essence and the achieved result is a method for controlling the permeability of an inhomogeneous oil reservoir (patent RU No. 2298088, ЕВВ 43/22, С09К 8/88, publ. 04/27/2007), in which a dispersed polymer system is injected into the reservoir in the form an aqueous dispersion of colloidal particles of various polymers: polyacrylamide, or polysaccharide, or cellulose ether with a wider concentration range, and aluminum polyoxychloride is used as the polyvalent metal. The composition is injected at the following component concentrations, wt.%:

polyacrylamide, or polysaccharide, or   cellulose ether 0.005-0.5 aluminum polyoxychloride 0.0015-0.1 water rest

The preparation and injection of the composition is carried out by the existing standard settings (see previous analogue). The technical process of pumping a dispersed polymer system is carried out without first dissolving the polymer. Powder of polyacrylamide, or polysaccharide, or cellulose ether with a screw batcher is fed into a jet pump (ejector), where it is mixed with water and in the form of a suspension enters a mixing tank, where it is mixed with aluminum polyoxide chloride solution, and is pumped through a pressure line into an injection well. Preparation and injection of the composition is carried out from the mouth of one well.

The disadvantage of all analogues is the need to inject reagents separately into each well from its wellhead, for which it is necessary to stop the water injection from the pumping station in each well in succession, bring equipment for dosing reagents and injection to it, as well as deliver reagents to each well, and connect the equipment to the wellhead well reinforcement and inject reagents with subsequent exposure, then dismantle the equipment and move to another well with repetition of operations. Considering the fact that the wells are far away, large non-production material costs are required to perform transportation, strapping and commissioning operations. At the same time, when working with each well, interference (mutual influence) of the wells during the injection process is not taken into account, which requires a reagent to be pumped with a “reserve” to obtain a positive result and, as a result, additional financial costs for the reagents.

An object of the invention is to increase the efficiency of the method by controlling the permeability of the formation by parallel injection of a composition in the form of a dispersed polymer system, which is a polymer dispersion containing salts of a polyvalent metal, into a group of injection wells, as well as improving the processability and reducing material and energy costs.

The technical problem is solved by the method of developing a heterogeneous oil reservoir, including injecting into the reservoir through injection wells a composition in the form of a dispersed polymer system, which is a polymer dispersion containing salts of a polyvalent metal, at the required concentration (C _well ).

New is that pre-selected injection wells communicated with one comb of a cluster pump station (SPS), a dispersed polymer system with a concentration of components (C _mouth ) in water for each, determined by the formula, is prepared at the mixing plant

where C _mouth - the concentration of the components of the polymer system prepared on the installation;

_SLE — the required concentration of the components of the polymer system pumped into the wells;

V _SLE - total injectivity of working wells, m ³ / day;

V _mouth - the performance of the mixing plant, m ³ / day,

and the dispersed polymer system prepared at the installation is dosed into the water flowing from the SPS comb to the selected wells, the polymer system is injected into them with the required concentration (C _well ) simultaneously or sequentially with the wells being shut off when the planned injection volume is completed and the injectivity is reduced by no less than 10% of the original.

The described system of preparation, dosing and injection of the composition allows you to naturally control the injection of the composition into the wells and in the whole site, taking into account the prevailing waterflooding system with SPS. The injection volumes of the composition into the wells are determined by the injectivity of the wells in the conditions of the existing injection system.

The choice of the required concentration of the injected composition is determined by the permeability of the highly permeable interlayer of a layered-heterogeneous or highly permeable zone of a zone-heterogeneous formation.

According to the proposed method, the injected water from the pumping station is used for pumping the composition (to supply the composition to the wells), and the installation is used to prepare and dispense the composition.

This allows, in addition to reducing the cost of injecting the composition, to naturally regulate the coverage of formations by water flooding due to the interference of wells and the distribution of volumes of injected water among injection wells instead of artificially planned volumes when injected from the wellhead into one well. This technology of influencing the oil reservoir is much more effective than treating individual wells according to the prototype, as it provides a self-regulating flow of the composition into the reservoir through the reservoir pressure maintenance system. This is achieved by the fact that the amount of composition entering the formation through a specific injection well is proportional to its injectivity. Consequently, a larger amount of composition will enter the most highly permeable and watered zones of the formation than in oil-saturated and low-drainage zones.

New in the proposed method is also that the injection into the group of wells is carried out sequentially, starting with the most injection wells, with their subsequent shutdown while reducing the injectivity of each injection well to a predetermined value, which is not less than 10% less than the initial one, and connecting the following wells .

The technical result of the invention is more effective control of the permeability of the formation by injecting an aqueous dispersed polymer system into a group of injection wells, which leads to a redistribution of the filtration flow of the oil-displacing fluid and to an increase in the oil displacement coefficient, as well as the technological effectiveness of the method. Compared with the prototype provides a reduction in material and energy costs.

The drawing shows the installation diagram and its strapping with the comb unit.

The installation contains containers with reagents (not shown) connected to a reagent control and dosing complex (CUDR), consisting of a dosing and reagent supply control unit (BDU) 1, into which reagents are supplied for mixing with water and obtaining a disperse system, and an electric pump unit (ENB) 2 KUDR, which pumps the prepared dispersed system into the comb block (BG) 3, which distributes the flow of water flowing through conduit 4 from the pump station to wells (not shown). The BDU used in practice consists of an inlet pipe 5 connected through a control valve 6 to a supply conduit 4, which supplies water from the pumping station to the BG 3, a jet pump 7, to which polymer is fed through a funnel 8 through a funnel 9. The jet pump 7 delivers a suspension of polymer in water into the mixing tank 10, where reagents (for example, salts of a polyvalent metal) are fed from the tank 11 by the metering pump 12. The number of containers 11 and metering pumps 12 that supply reagents to the mixing tank 10 may be several - by the number of components added to this tank 10. The dispersed system obtained after mixing the PAA suspension with a solution of a salt of a polyvalent metal from the mixing tank 10 is fed to the inlet of the high pressure pumps 13 ENB 2, which pump this system through high-pressure pipe 14 into boreholes (whiskers) 15. For autonomous operation, the KUDR is equipped with an electric generator 17. The prepared volume of the dispersed system in KUDR is distributed in proportion to the flow of water (injectivity) into the wells through the pipelines 15 through the valves 16.

The essence of the method is as follows.

Select injection wells with an injection rate of at least 100 m ³ / day, which are under water injection from one BG SPS. To do this, an analysis is made of the development status of sections of selected injection wells according to geophysical and field data. The injectivity profile of the injection wells is determined. The reservoir properties of the formation (porosity, permeability, oil-saturated thickness), development indicators (production rates of oil and liquid wells, water cut), hydrodynamic relationship between injection and production wells are considered. According to the results of the analysis, injection wells for injection of a dispersed polymer system are finally determined. The number of wells used for simultaneous injection of the composition according to the proposed method depends on the number of wells on the BG and is from practice 2-15 units, preferably 3 or more wells.

The water from the water conduit 4 with the pumping station through the valve 6 of the pipeline 5 and the jet pump 7 is fed into the mixing tank 10. The polymer is dosed into it using the funnel 9 and the screw feeder 8 through the jet pump 7 and a concentrated polymer suspension is formed in the mixing tank 10 by stirring with a mixer. water. A polyvalent metal salt solution is supplied to the same container 10 by the metering pump 12 from the storage tank 11. As a result of mixing, an aqueous dispersed polymer system — a dispersed system — is obtained.

The concentration of the components prepared at the installation of the dispersed system is calculated by the formula [1].

From the tank 10 by one of the high pressure pumps 13 of the installation, the obtained disperse system is dosed through the valves 16 of the pipelines 14 into the water pumped from the pumping station through the BG 3 through the pipelines into the wells.

The volume of concentrated polymer system prepared at the installation (equal to the productivity of the installation) with a concentration of C _{mouth is} distributed (dosed) into pipelines 15 in proportion to the injectivity of the wells, and after dilution with water flowing from the pumping station to BG 3, the polymer system enters all wells with the same required concentration C _well

As the polymer, polyacrylamide, polysaccharide, cellulose ether can be used, and salts of polyvalent metals, in particular aluminum, can be used.

Moreover, the installation itself, which is usually used for the preparation and injection of reagents from the wellhead, is used as a mixer and dispenser in the proposed method, and pumping energy (not shown) of oil pump stations is used for injection.

The low dynamic viscosity of the composition, which at a maximum polymer concentration of 0.5%, has a viscosity of 20 MPa · s, makes it easy to pump the composition through water pipes to the well and through tubing in the well and eliminates the formation of plugs during shutdowns.

In the process of pumping the composition, the flow rate and pump pressure at the installation are constantly monitored according to the readings of the flow meter and manometer (not shown). The injectivity of the wells is determined by measuring the flow rate of the Panametrix overhead meter (not shown) on pipelines 15 BG 3, or if there are two or more wells on each pipeline 15, the flow meter is measured at the corresponding wellheads. Wellhead pressure is measured by pressure gauges (not shown).

Upon achievement of the planned (in accordance with the leading geologist of the reservoir pressure maintenance) injectivity of the well after injection of the composition, which should be at least 10% less than the initial one, it is shut off by shutting off the corresponding valve 16 from the injection of the composition and put into selling water through the corresponding pipeline 15 with SPS . The corresponding valve 16 opens to the injection of the composition and the next well is connected. Thus, all wells are sequentially processed.

With insufficient reduction in the injectivity of individual wells (for example, less than 10% of the original) at the end of the process, an additional injection of a composition with a higher concentration in the volume of 100-300 m ³ can be performed in them.

In the case of a significant difference in the initial injectivity of the wells (two or more times), the composition is injected with different concentrations. First, the composition is injected into more accelerated wells with a higher concentration. With a decrease in their injectivity (or shutdown when the required volume is injected), the concentration of the composition decreases and wells with low injectivity are connected to the injection.

Case Studies

Example 1. In this example, the results of injection of a dispersed system, which is a dispersion of polyacrylamide with aluminum salts, into five injection wells with a constant concentration of components are presented. In this case, the injection is first carried out in the four most receiving wells, and the fifth well is connected after completion of work on the first well with a decrease in injectivity to the required value for subsequent flooding (at least 10% lower than the initial one).

The site with five injection wells and ten production wells is located on the Sabanchinskoye field, the production object of which is the Lower Carboniferous formation, which lies at a depth of 1200 m. The formation has an oil-saturated thickness of 3.4-10 m, porosity 15.3-24.0%, permeability 1.0-2.4 μm ² . The viscosity of the oil in reservoir conditions of 15 MPa · s, the density of the injected water 1.1 g / cm ³ . The daily oil production in the wells of the site is from 1.2 to 16.4 tons / day with an average water cut of 92%.

During pilot works, polyacrylamide (PAA) grade DR 98177 with a molecular weight of 6.7 million units was used as a polymer, and alumina in accordance with GOST 12966-85 as aluminum salts: aluminum sulfate (aluminum sulfate). Preparation and dosage of the composition was carried out using the KUDR-1 unit with a capacity of V _mouth = 240 m ³ / day (10 m ³ / h).

The planned injection volumes and the required concentration of reagents for injection wells are presented in Table 1. The initial injection rate of wells is given there, which varies from 182 to 341 m ³ / day.

For the injection of the composition, four wells (wells 1, 2, 3, 4) with the highest injectivity were selected as the priority ones.

The download process consisted of two stages.

First step

Injection of the composition into four wells (wells 1, 2, 3, 4) within 3.8 days.

The initial total injectivity of four wells V _well = 1078 m ³ / day (44.9 m ³ / h).

From the initial total injectivity of the wells and the concentration of injected components of the composition into the wells, C _paqu = 0.1% and C _{Al squ} = 0.03%, the initial concentration of the components C _paust and C _{Al conv} , prepared at a concentrated composition unit, is determined by the formula [ one]:

C _paust = C _{paa squv} · V _well / V _mouth = 0.1 · 44.9 / 10 = 0.45%;

C _{Al mouth} = C _{Al well} · V _well / V _mouth = 0.03 · 44.9 / 10 = 0.135%.

The obtained concentrated dispersion of PAA with Al salts by a high-pressure pump is fed into water, pumped from the pumping station via a mustache into the wells, diluted with it, and fed into the wells with the required concentration of components C _pass = 0.1%; C _{Al SLE} = 0.03%.

In the future, periodically, with a change (decrease) in the total injectivity of working wells V _well , the dosage of PAA and Al salt after measuring injectivity is adjusted by recalculation according to the formula [1]. In this case, the concentrations of PAA and Al composition entering the wells remain constant and equal, respectively

C _{paa squr} = 0.1%; C _{Al SLE} = 0.03%.

After 6 days, the injectivity of well 1 decreased from 341 to 170 m ³ / day. The well is disconnected from the injection of the composition due to a decrease in injectivity to a value sufficient for subsequent flooding. The total injection volume of the composition into 4 wells at the 1st stage is 4950 m ³ .

Second phase

Connection to the injection of well 5 and the injection of the composition into four wells (wells 2, 3, 4, 5) for 5.5 days. In this case, the concentration of the components of the composition prepared at the facility is calculated at the beginning of the injection and periodically with a change in injectivity during the injection, in the same way as in the first stage, according to the formula [1].

Due to the decrease in injectivity to the value required for subsequent flooding, wells 2 and 4 are disconnected from the injection after 4.5 days (after the start of injection at the 2nd stage).

The total injection volume of the composition at the 2nd stage is 3550 m ³ .

The work was stopped after the implementation of the planned volume of injection of the composition into all wells in the amount of 8500 m ³ .

The total duration of the injection of the composition was 11.5 days: 1st stage - 6 days; 2nd - 5.5 days.

The result of the injection of the composition is a decrease in injectivity of wells by 34.8-57.9%. This indicates an increase in the filtration resistance of the formation due to a decrease in the permeability of the most permeable intervals of the formation and the inclusion of previously undisturbed interlayers in the water.

After the injection, oil production in the wells of the site increased by 10-50%, water cut decreased by 1.0-7.3%. Additional oil production during the manifestation of the effect was 9400 tons.

When carrying out the process according to the proposed method, 8500 m ^{3 of the} composition with a PAA concentration of 0.1% was pumped into the wells in 11.5 days; Al - 0.03%. For the preparation and dosage of the composition, the KUDR-1 unit with a productivity of 240 m ³ / day was used. In the case of using the same KUDR-1 unit for pumping 8500 m ^{3 of} the same composition according to the known method, it would take 35.4 days (8500: 240) separately from each well from the wellhead, i.e. three times more than the proposed method. In addition, time is required for dismantling the equipment, its transportation and installation during the transition from one well to another.

If the injection is carried out according to the known method, then the planned volume of the composition indicated in Table 1 should be pumped into each well separately. From the same table it follows that the actual injection volumes of the composition into each well obtained by applying the proposed method differ from the planned ones.

The essence of the matter is that, according to the proposed method, the injected composition is distributed in the reservoir by filtration flows that occur with the existing waterflooding system, when water is pumped into all wells and into the reservoir with oil wells, and the composition is dosed into it. This technology of influencing the oil reservoir is much more effective than treating individual wells according to the known method, as it provides a self-regulating flow of the composition into the reservoir through the reservoir pressure maintenance system. This is achieved by the fact that the amount of composition entering the formation through a specific injection well is proportional to its injectivity. Consequently, a larger amount of composition will enter the most highly permeable and watered zones of the formation than in oil-saturated and low-drainage zones.

Example 2

The example shows the results of pumping a composition with different concentrations into four injection wells. Initially, the composition is injected with increased concentration into the two most receiving wells. After equalization of injectivity, the injection process continues simultaneously to all wells with the required concentration.

A site with four injection wells and fourteen production wells is located at the Bavlinskoye field, the production facility of which is the terrigenous reservoir of the D) Lower Devonian reservoir, which lies at a depth of 1800 m. The average thickness of the formation is 9.3 m; porosity 18.9-23.7%; permeability of 0.4-1.3 μm ² . The viscosity of the oil in reservoir conditions is 4 MPa · s, the density of the injected water is 1.1 g / cm. The daily oil production in the wells of the site was 1 to 7.9 tons / day with a water cut of 86.4-96.37%.

During the pilot works, we used polyacrylamide grade DR 98177 with a molecular weight of 6.7 million units, and aluminum salts - aluminum polyoxychloride (POHA) brand "Aqua-Aurat ™ -30" (TU-6-09-05- 1456-96).

Preparation and dosage of the composition was carried out using the KUDR-1 unit with a capacity of V _mouth = 240 m ³ / day (10 m ³ / h).

Planned injection volumes and concentration of reagents for injection wells are presented in Table 2. The initial injectivity of the wells is also given there.

The download process consisted of two stages.

First step

The composition is injected into the most receiving wells 1, 2 with an increased concentration of PAA - 0.15% and POHA - 0.03% in order to reduce their injectivity and equalize with the injectivity of wells 3, 4 for subsequent joint injection into all four wells. The total initial injectivity of wells 1 and 2 is 970 m ³ / day (510 + 460) or 40.4 m ³ / h.

Based on the total injectivity of the wells and the required concentration of injected components of the composition into the wells, C _paqu = 0.15% and C _{Al squ} = 0.03%, the initial concentration of the components C paust and ca [mouth, prepared on the installation of concentrated composition according to the formula [1 ]:

C _paust = C _paa-well · V _well / V _mouth = 0.15 · 40.4 / 10 = 0.606%;

C _{Al mouth} = C _{Al well} · V _well / V _mouth = 0.03 · 40.4 / 10 = 0.12%.

The resulting concentrated dispersion PAA Al salts with a high-pressure pump is supplied into the water pumped from the SPS mustache into the wells, diluted by it and enters the well at the desired concentration _{of PAA} component C = 0.15% _rms and _rms C _Al = 0.03%.

In the future, periodically, with a change in the total injectivity of working wells V _{well, the} concentration of components of the composition prepared at the installation is adjusted by recalculation according to the formula [1]. In this case, the concentrations of PAA and Al in the composition entering the wells remain constant and equal, respectively, with C _{paq SQR} = 0.15% and C _{Al cbq} = 0.03%.

During the day, 400 m ^{3 of the} composition was pumped into well ¹ with a decrease in injectivity from 510 to 300 m ³ / day; 370 m ^{3 of the} composition was pumped into well ² with a decrease in injectivity from 460 to 285 m ³ / day (Table 2).

Second phase

Simultaneous injection of the composition in wells 1, 2, 3, 4 with a concentration of C _paa-well = 0.1%; C _{Al SLE} = 0.02%. The initial total flow rate of 4 wells V _well = 1085 m ³ / day (300 + 285 + 260 + 240) or 45.2 m ³ / h. The initial concentration of components C _paust and C _{Al mouth} prepared at the installation of a concentrated composition in accordance with the formula [1] is

C _paust = C _paa-well · V _well / V _mouth = 0.1 · 45.2 / 10 = 0.452%;

C _{Al mouth} = C _{Al well} · V _well / V _mouth = 0.02 · 45.2 / 10 = 0.09%.

As the composition is injected and the well injectivity decreases, the concentration of the composition components at the installation is adjusted in accordance with the formula [1].

The injection of the composition at the 2nd stage lasted 5 days. In this case, well 1 and well 3 are disconnected from the injection of the composition after 4.5 days upon reaching the required injectivity (well 1, 240 m ³ / day; well ^3, 170 m ³ / day) for subsequent flooding, and well 2 and well 4 are disabled after 5 days (Table 2).

The total duration of the injection of the composition was 6 days: 1st stage - 1 day; 2nd stage - 5 days.

The result of injection of the composition is a decrease in injectivity of wells by 43.9-69.0%, which indicates an increase in the filtration resistance of the formation due to a decrease in the permeability of the most permeable intervals.

After the injection, oil production in the wells of the area increased by 21-50.2% with a decrease in water cut by 1.6-9.0%. Additional oil production during the manifestation of the effect was 7900 tons.

When carrying out the process according to the proposed method, 5290 m ^{3 of the} composition were pumped into wells in 6 days. For the preparation and dosage of the composition, the KUDR-1 unit with a productivity of 240 m ³ / day was used. In the case of using the same KUDR-1 unit to inject 5290 m ^{3 of} the same composition according to the known method, it would take 22 days separately from each well from the wellhead (5290: 240), i.e. 3.7 times more time than the proposed method. In addition, time is required for dismantling the equipment, its transportation and installation during the transition from one well to another. The time to complete these works is saved at least 2 times (if you upload only to a group of 2 wells), that is, a multiple of the number of wells covered by the treatment with BG.

In the proposed method, the distribution of injection volumes by wells differs from the planned ones, which are pumped according to the prototype (Table 2). The technology of impacting an oil reservoir by simultaneous injection into a group of wells is more efficient than processing individual wells according to the prototype, as it provides a self-regulating flow of the composition into the reservoir through a reservoir pressure maintenance system. The technological advantage of the proposed method is that when the composition is injected into a group of wells, the formation coverage by water flooding is optimally controlled after it is injected due to the natural distribution of the volumes of the injected composition over the treated area. At the same time, a greater amount of composition will enter the most highly permeable and watered zones of the formation than in oil-saturated and poorly drained zones.

The application of the proposed method for developing an inhomogeneous formation allows to achieve more effective control of the permeability of the formation by injecting the composition in the form of a dispersed polymer system into a group of injection wells, which leads to a redistribution of the filtration flow of the oil-displacing fluid and to an increase in the oil displacement coefficient, as well as the technological effectiveness of the method. Compared to the prototype, material and energy costs are reduced.

Claims (1)

Method of developing an inhomogeneous oil formation comprising pumping into the formation through injection wells composition as a dispersed polymer system, which is a polymer dispersion containing polyvalent metal salt, with the desired concentration _{of SLE,} characterized in that the pre-selected injection wells communicated with a comb bush pump station - KNS, a dispersed polymer system with a concentration of C _mouth components in water for each, determined by the forms, is prepared at the mixing plant ole:
With _mouth = With _well · V _well · V _mouth ,
where C _mouth - the concentration of the components of the polymer system prepared on the installation;
_SLE — the required concentration of the components of the polymer system pumped into the wells;
V _SLE - total injectivity of working wells, m ³ / day;
V _mouth - Fitting mixing performance, m ³ / day and prepared for installation of a dispersed polymer system is metered into the water extending from the combs CND to selected wells, injecting in that the polymer system produced with the required concentration _{of SLE} contemporaneously or sequentially with disconnecting wells during completion the planned volume of injection and a decrease in injectivity of at least 10% of the original.

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