RU2513791C1 - Development method of multilayer oil deposit using hydraulic fracturing of formation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to development of multilayer oil deposits and can be used in oil and gas industry. The concept of the invention is as follows: the method includes pumping of displacement agent through injection wells, extraction of formation fluids through producing wells, performance of formation fracturing with obtainment of effective created fracture. According to the invention permeability is determined for each productive formation penetrated by the well. Productive formations are classified by permeability degree. Depending on permeability of the productive formation perforation is carried out in producing and injection wells. Injection wells are injected while in producing wells hydraulic fracturing is made in all productive formations. At that in productive formations with permeability less than 10 mD hydraulic fracturing is made with created fractures of fixed half-length more than 100 m and fixed width in the productive part from 1.5 up to 3 mm. In productive formations with permeability more than 100 mD hydraulic fracturing is made with created fractures of fixed half-length more than 40 m and fixed width in the productive part from 5 up to 20 mm. In productive formations with permeability from 10 up to 100 mD hydraulic fracturing is made with created fractures of fixed half-length from 40 up to 100 m and fixed width in the productive part from 3 up to 7 mm.

EFFECT: simplifying and cheapening of the development method for multilayer oil deposits, improving efficiency of the method usage at oil deposits consisting of productive formations with different permeability and porosity properties and decreasing the time period for development of multilayer oil deposits.

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Description

The invention relates to the field of development of multilayer oil fields and can be used in the oil and gas industry.

A known method of developing oil deposits with layer-by-layer heterogeneity (patent RU No. 2443855, IPC ЕВВ 43/20, published on 02.27.2012, bull. No. 6), including drilling on any of the known grids of vertical, horizontal and deviated wells, determining the boundaries zones with different permeability, installing a packer in the wells at the border of the zones, injecting displacing fluid into each zone through injection wells and producing reservoir products from each zone through injection wells, determining the thickness of the effective oil saturation for the reservoir, compaction of the grid with important wells with additional wells up to 1-4 ha / well, drilling additional wells with an inclined length of a deposit equal to 2-3 thicknesses of effective oil saturation, determining a zone with different permeability, in the zone of a reservoir with lower permeability, carrying out acid treatment, pumping fluid through injection wells and selection of products through production wells above and below the boundary of zones with different permeability, drilling additional wells with a smaller diameter than other wells.

The disadvantages of this method are the complexity and complexity of its implementation, associated with the need to drill additional deviated wells.

Also known is a method of developing an oil and gas reservoir using hydraulic fracturing (patent RU No. 2135750, IPC ЕВВ 43/20, published on 08.27.1999), including artificial contour impact on the development object by injecting water and / or gas through injection wells, and / or other displacing agent, the selection of reservoir fluids through production wells, the implementation of hydraulic fracturing in a comprehensive manner on the entire set of injection and production wells, designing and implementing hydraulic fracturing based on continuous information about the mechanical properties of the rocks of the sections of injection and production wells, which is consistent with geophysical studies, setting the direction to hydraulic fractures by selecting anti-aircraft and azimuthal angles of injection and production wells to calculate the elimination of heterogeneity of filtration flows, increasing the period of effective operation of hydraulic fractures injection into them of compositions of physicochemical substances dissolving clay and other minerals s substance filling hydraulic fracture.

The disadvantage of this method is the low efficiency of its use in oil deposits, composed of productive formations with various filtration-capacitive properties (FES).

The closest in technical essence is the method of developing a multilayer oil reservoir in the presence of a highly permeable interlayer using hydraulic fracturing (patent RU No. 2374435, IPC ЕВВ 43/16, published on November 27, 2009, bull. No. 33), including injection of a displacing agent through injection wells, selection of formation fluids through production wells, the implementation of hydraulic fracturing selectively, first in the zone of low permeability formations, excluding perforation of a highly permeable formation with a permeability of three and more times higher than the average for the reservoirs, after the project selection of oil reserves, perforation of the highly permeable reservoir with subsequent exploitation of the latter, execution of the barrel with vertical entry into the production facility to ensure the maximum fracture pressure gradient and create the optimal hydraulic fracture, while simultaneously conducting hydraulic injection in the well stock fracturing in intervals with low permeability, and to create vertical filtration between highly permeable roplastkom, imperforate, and low-permeability carried lateral horizontal barrel in low range-wise, followed by hydraulic fracturing.

The disadvantages of this method are the complexity and complexity of its implementation, inherent in the above counterparts, as well as the delayed development of a multilayer field associated with the phased introduction into the development of formations with various reservoir properties.

The technical objectives of the invention are to simplify and reduce the cost of the method of developing a multilayer oil reservoir, increasing the efficiency of its use in oil deposits stacked by productive formations with various reservoir properties, as well as accelerating the development time of a multilayer reservoir.

The stated technical problems are solved by the method of developing a multilayer oil reservoir using hydraulic fracturing, including pumping a displacing agent through injection wells, selecting reservoir fluids through production wells, and performing hydraulic fracturing to produce an effective fracture.

New is that they determine the permeability of each reservoir opened by the well, classify the reservoir by permeability, depending on the permeability of the reservoir, perforate in production and injection wells, injection wells are injected, and in production wells hydraulic fracturing is performed in all production formations, and in productive formations with a permeability of less than 10 mD, hydraulic fracturing is carried out with the creation of hydraulic fractures with a fixed floor with a length exceeding 100 m and a fixed width in the productive part from 1.5 to 3 mm, hydraulic fracturing is carried out in productive formations with permeabilities of more than 100 mD with the creation of hydraulic fractures with a fixed half length of up to 40 m and a fixed width of 5 to 20 mm, and in productive formations with a permeability of 10 to 100 mD, hydraulic fracturing is carried out with the creation of hydraulic fractures with a fixed floor length of 40 to 100 m and a fixed width of 3 to 7 mm.

Also new is the fact that for the effective development of a multilayer oil reservoir in production wells, equipment for simultaneous and separate operation is used.

Figure 1 schematically shows the profiles of the width and half length of hydraulic fractures. Figure 2, 3, 4 presents the sequence of implementation of the proposed method.

The proposed method is as follows.

A network of vertical and / or directional production and injection wells is built on a multilayer oil reservoir. During the construction of a network of vertical and / or directional production and injection wells, a complex of geophysical well surveys (GIS) is carried out in them, in particular, the permeability of each productive formation of a multilayer oil reservoir uncovered by a well is determined. Productive formations are classified by permeability into three main groups. The first group includes productive formations 1 (Figs. 1-4) with permeability of up to 10 mD, the second - productive formations 2 with permeability of 10 to 100 mD, and the third - productive formations 3 with permeability of more than 100 mD.

In production and injection wells, perforation of 4 productive formations is performed depending on the permeability, moreover, to achieve uniform injectivity of all productive formations uncovered by the injection well, as well as to improve the hydrodynamic connection of the well with the productive formation during hydraulic fracturing in production wells, perforation is carried out with different densities perforations per 1 m of the reservoir. The greater the permeability of the reservoir, the lower the density of perforations per 1 m of the reservoir.

It was experimentally established that the optimal density of perforations per 1 m of productive thickness of a reservoir with a permeability of 10 to 100 mD is 10 holes. Accordingly, productive formations of the third group with a permeability of more than 100 mD are perforated with a lower density of perforations, for example 5 perforations per 1 m of productive thickness of the productive formation. Productive formations of the first group with a permeability of less than 10 mD are perforated with a higher density of perforations, for example 20 perforations per 1 m of productive thickness of the productive formation.

Injection wells are injected, and in production wells, hydraulic fracturing is performed, and hydraulic fracturing is performed in all productive formations of a multilayer oil reservoir.

It is well known that the effectiveness of a hydraulic fracture as a conductive channel from the reservoir into the wellbore is determined by its dimensionless permeability. The dimensionless permeability of a fracture is a value that shows the ratio of the permeability of the reservoir to the permeability of the fracture itself. The permeability of a fracture should be 1.2-1.4 times greater than the permeability of the reservoir. With this ratio of permeabilities, the hydraulic fracturing performed will be most effective.

For example, in order to achieve such a ratio of permeabilities in productive formations with a permeability of less than 10 mD, it is necessary to create hydraulic fractures with a fixed half-length of more than 100 m and a fixed width in the productive part of 1.5 to 3 mm, in productive formations with a permeability of more than 100 mD it is necessary to create hydraulic fractures with a fixed half-length of up to 40 m and a fixed width of 5 to 20 mm, and in productive formations with a permeability of 10 to 100 mD, it is necessary to create hydraulic fractures with a fixed half-length from 40 to 100 m and a fixed width of 3 to 7 mm.

Generally speaking, in productive formations with low permeability, hydraulic fractures should be narrow and extended, and in productive formations with high permeability, wide and short.

To create a hydraulic fracture with a given geometry in the reservoirs of the first and second groups, a hydraulic fracture is carried out with the injection of the fracture buffer fluid in a volume equal to 10-20% of the total volume of the fracture fluid, with an increase in the concentration of crack fixer - proppant in the mixture and constant flow rate of the fracture fluid (see, for example, the monograph by Konstantinov S.V., Gusev V.I., / Technique and technology of hydraulic fracturing abroad: - Overview, M., VNIIOENG, 1985 - 61 pp.). Moreover, the total volume of the fracturing fluid is determined based on field experience and using various computer modeling programs.

To create a hydraulic fracture in productive formations of the third group, hydraulic fracturing is carried out using end shielding technologies (for example, such as TSO or Frac-Pack - the company’s technology names) with the injection of the fracturing buffer fluid in a volume equal to 7-10% of the total fracturing fluid volume , with a stepwise increase in the concentration of proppant in the mixture and with a stepwise decrease in the flow rate of the fracturing fluid (see, for example, US Pat. Nos. 6,837,309 and US Pat. No. 6,938,693).

For example, in order to ensure that the hydraulic fracturing in the first group production layer of 5 m thickness and permeability up to 10 mD is optimal from the point of view of its effectiveness, it will be necessary to create a hydraulic fracture 9 with such parameters as: fixed half-length of the hydraulic fracture in the reservoir over 100 m , for example 110 m, and the fixed width in the reservoir from 1.5 to 3 mm, for example 3 mm (figure 1). For this, it will be necessary to pump 60-90 m ^{3 of} fracturing fluid and about 12-20 tons of crack proppant.

In order to ensure that the hydraulic fracturing in the second group reservoir 5 m thick and with a permeability of 10 to 100 mD is optimal from the point of view of its effectiveness, it will be necessary to create a hydraulic fracture 11 with such parameters as: fixed half-length of the hydraulic fracture in the reservoir from 40 to 100 m, for example 57 m, and the fixed width in the reservoir from 3 to 7 mm, for example 5 mm (figure 1). To do this, you need to pump 40-47 m ^{3 of} fracturing fluid and about 6-9 tons of crack proppant.

In order for the hydraulic fracturing in the third group production layer with a thickness of 5 m and a permeability of more than 100 mD to be optimal in terms of its effectiveness, it will be necessary to create a hydraulic fracture 10 with parameters such as: fixed half-length of the hydraulic fracture in the reservoir up to 40 m, for example 38 m, fixed width in the reservoir from 5 to 20 mm, for example 17 mm (Fig. 1). To do this, you need to pump 40-45 m ^{3 of} fracturing fluid and about 10-20 tons of crack proppant.

To ensure efficient development of a multilayer oil reservoir in production wells, equipment for simultaneous and separate operation is used.

Examples of practical application of the method.

Example 1

A network of production and injection wells was built on a multilayer oil reservoir, composed of productive formations with various reservoir properties.

In the process of building a network of vertical and / or directional production and injection wells, a GIS complex was carried out, in particular, the permeability of each productive formation of a multilayer oil reservoir discovered by a well was determined.

Productivity strata were classified by permeability into three main groups. The first group included productive formations 1 (Fig. 1) with a permeability of 8 mD (up to 10 mD), the second group included productive formations 2 with a permeability of 83 mD (10 to 100 mD), and the third group included productive formations 3 with a permeability of 320 mD (over 100 md).

In production and injection wells perforated 4 production intervals. Productive formations of the first group were perforated with a density of 20 holes per 1 m of productive thickness, productive formations of the second group with a density of 10 holes per 1 m of productive thickness, and productive formations of the third group with a density of 5 holes per 1 m of productive thickness.

The injection wells were injected, and hydraulic fracturing was carried out in the production wells. In production wells, hydraulic fracturing was carried out in the following sequence.

On tubing 5 (FIG. 2) of brand “K” or “E” with a diameter of 89 mm according to GOST 633-80, a two-packer assembly 7 (for example, a two-packer assembly for selective hydraulic fracturing of 2PROK-GRPS-2 manufactured by LLC NPF “Packer”, Oktyabrsky, RB) with a filter installed between two packers 8. The two-packer arrangement allows reliable isolation of the interval subjected to hydraulic fracturing from higher and underlying reservoirs.

A two-packer arrangement was installed opposite the lowest perforated production formation 1 of the first group with a permeability of 8 mD and a massive hydraulic fracture was carried out in it.

A fracture buffer fluid was pumped into the well without a crack fixer — proppant — in a volume of 10 m ³ , then another 70 m ^{3 of} fracture fluid was mixed with proppant, and the proppant concentration in the mixture was increased from 200 to 1200 kg / m ³ . The total injected proppant mass in this case was 20 tons. The flow rate of the fracture fluid was constant and amounted to 2.5 m ³ / min. After that, the fracturing fluid was mixed with proppant into the reservoir using industrial water in a volume equal to 11.4 m ³ at a pressure of 37 MPa.

As a result, a hydraulic fracture 9 was created (Fig. 1) with such parameters as: fixed half-length - 110 m and fixed width in the productive part - 3 mm. The total hydraulic fracture length — the length of the fracture on both sides of the axis of the well — was 220 m, respectively.

After the pressure drop, the two-packer arrangement was raised and installed opposite the overlying reservoir 3 (Fig. 3), belonging to the third group with a permeability of 320 mD, and hydraulic fractured using TSO and Frac-Pack end shielding technologies.

A fracture buffer fluid was pumped into the well without a crack fixer - proppant - in a volume of 6 m ³ , then another 39 m ^{3 of} fracture fluid was pumped into the mixture with proppant, while the proppant mixed with fracture fluid was pumped sequentially in three stages. At the first stage, 600 kg of proppant were pumped in a mixture with a rupture fluid in a volume of 1 m ³ at a flow rate of 2.5 m ³ / min, the proppant concentration in the mixture was 600 kg / m ^3, respectively. Then, the injection rate was reduced to 0.5 m ³ / min for 2 minutes. Then, the injection rate was resumed to 2 m ³ / min and the remaining volume of the fracturing fluid in the mixture with proppant was pumped into the tubing, while the proppant concentration in the mixture was gradually increased from 600 to 1200 kg / m ³ . After that, the fracturing fluid was mixed with proppant into the reservoir using industrial water in a volume equal to 9.1 m ³ at a pressure of 27 MPa, while the injection rate was gradually reduced from 2 to 0.5 m ³ / min.

As a result, a hydraulic fracture 10 was created (FIG. 1) with such parameters as: fixed half-length of hydraulic fracture — 38 m, fixed hydraulic fracture width in the productive part of 20 mm (FIG. 1). The total hydraulic fracture length — the length of the fracture on both sides of the well axis — was 76 m, respectively.

After the pressure drop, the two-packer arrangement was raised and it was installed opposite the overlying productive formation 2 (Fig. 4), belonging to the second group with a permeability of 83 mD, and a conventional hydraulic fracturing was carried out in it.

A fracture buffer fluid was pumped into the well without a crack holder, proppant, in a volume of 7 m ³ , then another 40 m ^{3 of} fracture fluid was pumped into the mixture with proppant, while the proppant concentration in the mixture was increased from 200 to 1200 kg / m ³ . The total injected proppant mass in this case was 8 tons. The flow rate of the fracture fluid was constant and amounted to 2.1 m ³ / min. After that, the fracturing fluid in a mixture with proppant was pushed into the reservoir with industrial water in a volume equal to 7.6 m ³ at a pressure of 24 MPa.

As a result, a hydraulic fracture 11 was created (Fig. 1) with such parameters as: fixed half-length of hydraulic fracture - 40 m, fixed hydraulic fracture width in the productive part - 3 mm. The total hydraulic fracture length — the length of the fracture on both sides of the well axis — was 80 m, respectively.

After completion of the full cycle of hydraulic fracturing of the productive formations in the well, a two-packer assembly was removed from the well. The descent of the technological tubing with a diameter of 73 mm (not shown in FIGS. 1-4) washed the well from the remnants of the fracturing fluid and proppant. The appropriate equipment was lowered into the well for simultaneous and separate reservoir exploitation and the well was put into operation.

Example 2

A network of production and injection wells was built on a multilayer oil reservoir, composed of productive formations with various reservoir properties.

In the process of building a network of vertical and / or directional production and injection wells, a GIS complex was carried out, in particular, the permeability of each productive formation of a multilayer oil reservoir discovered by a well was determined.

Productivity strata were classified by permeability into three main groups. The first group included productive formations 1 (Fig. 1) with a permeability of 5 mD, the second group included productive formations 2 with a permeability of 10 mD, and the third group included productive formations 3 with a permeability of 240 mD.

In production and injection wells perforated 4 production intervals. Productive formations of the first group were perforated with a density of 20 holes per 1 m of productive thickness, productive formations of the second group with a density of 10 holes per 1 m of productive thickness, and productive formations of the third group with a density of 5 holes per 1 m of productive thickness.

The injection wells were injected, and hydraulic fracturing was carried out in the production wells. In production wells, hydraulic fracturing was carried out in the following sequence.

On tubing 5 (FIG. 2) of brand “K” or “E” with a diameter of 89 mm according to GOST 633-80, a two-packer assembly 7 (for example, a two-packer assembly for selective hydraulic fracturing of 2PROK-GRPS-2 manufactured by LLC NPF “Packer”, Oktyabrsky, RB) with a filter installed between two packers 8. The two-packer arrangement allows reliable isolation of the interval subjected to hydraulic fracturing from higher and lower productive formations.

A two-packer arrangement was installed opposite the lowest perforated production formation 1 of the first group with a permeability of 5 mD and a massive hydraulic fracture was carried out in it.

A fracture buffer fluid was pumped into the well without a crack holder - proppant - in a volume of 8 m ³ , then another 73 m ^{3 of} fracture fluid was pumped into the mixture with proppant, while the proppant concentration in the mixture was increased from 200 to 1200 kg / m ³ . The total injected proppant mass was 18 tons. The flow rate of the fracture fluid was constant and amounted to 2.5 m ³ / min. After that, the fracturing fluid was mixed with proppant into the reservoir using industrial water in a volume equal to 11.4 m ³ at a pressure of 37 MPa.

As a result, a hydraulic fracture 9 was created (Fig. 1) with such parameters as: fixed half-length - 120 m and fixed width in the productive part - 2.2 mm. The total hydraulic fracture length — the length of the fracture on both sides of the axis of the well — was 240 m, respectively.

After the pressure drop, the two-packer arrangement was raised and it was installed opposite the overlying productive formation 3 (Fig. 3), belonging to the third group with a permeability of 240 mD, and hydraulic fractured using TSO and Frac-Pack end shielding technologies.

A fracture buffer fluid was pumped into the well without a crack fixer — proppant — in a volume of 5 m ³ , then another 40 m ^{3 of} fracture fluid was pumped into the mixture with proppant, while proppant mixed with the fracture fluid was pumped sequentially in three stages. At the first stage, 600 kg of proppant were pumped in a mixture with a rupture fluid in a volume of 1 m ³ at a flow rate of 2.5 m ³ / min, the proppant concentration in the mixture was 600 kg / m ^3, respectively. Then, the injection rate was reduced to 0.5 m ³ / min for 2 minutes. Then, the injection rate was resumed to 2 m ³ / min and the remaining volume of the fracturing fluid in the mixture with proppant was pumped into the tubing, while the proppant concentration in the mixture was gradually increased from 600 to 1200 kg / m ³ . After that, the fracturing fluid was mixed with proppant into the reservoir using industrial water in a volume equal to 9.1 m ³ at a pressure of 27 MPa, while the injection rate was gradually reduced from 2 to 0.5 m ³ / min.

As a result, a hydraulic fracture 10 was created (Fig. 1) with such parameters as: fixed half-length of the hydraulic fracture - 34 m, the fixed hydraulic fracture width in the productive part of 10 mm (Fig. 1). The total fracture length — the length of the fracture on both sides of the axis of the well — was 68 m, respectively.

After the pressure drop, the two-packer arrangement was raised and it was installed opposite the overlying productive formation 2 (Fig. 4), belonging to the second group with a permeability of 54 mD, and conducted a normal hydraulic fracture in it.

A fracture buffer fluid was pumped into the well without a crack holder, proppant, in a volume of 10 m ³ , then another 60 m ^{3 of} fracture fluid was pumped into the mixture with proppant, while the proppant concentration in the mixture was increased from 200 to 1200 kg / m ³ . The total injected proppant mass in this case was 12 tons. The flow rate of the fracture fluid was constant and amounted to 2.1 m ³ / min. After that, the fracturing fluid in a mixture with proppant was pushed into the reservoir with industrial water in a volume equal to 7.6 m ³ at a pressure of 24 MPa.

As a result, a hydraulic fracture 11 was created (Fig. 1) with such parameters as: fixed half-length of hydraulic fracture - 70 m, fixed hydraulic fracture width in the productive part - 5 mm. The total hydraulic fracture length — the length of the fracture on both sides of the axis of the well — was 140 m, respectively.

After completion of the full cycle of hydraulic fracturing of the productive formations in the well, a two-packer assembly was removed from the well. The descent of the technological tubing with a diameter of 73 mm (not shown in FIGS. 1-4) washed the well from the remnants of the fracturing fluid and proppant. The appropriate equipment was lowered into the well for simultaneous and separate reservoir exploitation and the well was put into operation.

Example 3

A network of production and injection wells was built on a multilayer oil reservoir, composed of productive formations with various reservoir properties.

In the process of building a network of vertical and / or directional production and injection wells, a GIS complex was carried out, in particular, the permeability of each productive formation of a multilayer oil reservoir discovered by a well was determined.

Productivity strata were classified by permeability into three main groups. The first group included productive formations 1 (Fig. 1) with a permeability of 2 mD, the second group included productive formations 2 with a permeability of 100 mD, and the third group included productive formations 3 with a permeability of 120 mD.

In production and injection wells perforated 4 production intervals. Productive formations of the first group were perforated with a density of 20 holes per 1 m of productive thickness, productive formations of the second group with a density of 10 holes per 1 m of productive thickness, and productive formations of the third group with a density of 5 holes per 1 m of productive thickness.

The injection wells were injected, and hydraulic fracturing was carried out in the production wells. In production wells, hydraulic fracturing was carried out in the following sequence.

On tubing 5 (FIG. 2) of brand “K” or “E” with a diameter of 89 mm according to GOST 633-80, a two-packer assembly 7 (for example, a two-packer assembly for selective hydraulic fracturing of 2PROK-GRPS-2 manufactured by LLC NPF “Packer”, Oktyabrsky, RB) with a filter installed between two packers 8. The two-packer arrangement allows reliable isolation of the interval subjected to hydraulic fracturing from higher and lower productive formations.

A two-packer arrangement was installed opposite the lowest perforated production formation 1 of the first group with a permeability of 2 mD and a massive hydraulic fracture was carried out in it.

A fracture buffer fluid was pumped into the well without a crack holder — proppant — in a volume of 15 m ³ , then another 90 m ^{3 of} fracture fluid was pumped into the mixture with proppant, while the proppant concentration in the mixture was increased from 200 to 1200 kg / m ³ . The total injected proppant mass in this case was 21 tons. The flow rate of the fracture fluid was constant and amounted to 2.5 m ³ / min. After that, the fracturing fluid was mixed with proppant into the reservoir using industrial water in a volume equal to 11.4 m ³ at a pressure of 37 MPa.

As a result, a hydraulic fracture 9 was created (Fig. 1) with such parameters as: fixed half-length - 150 m and fixed width in the productive part - 1.5 mm. The total hydraulic fracture length — the length of the fracture on both sides of the axis of the well — was 300 m, respectively.

After the pressure drop, the two-packer arrangement was raised and it was installed opposite the overlying reservoir 3 (Fig. 3), belonging to the third group with a permeability of 120 mD, and hydraulic fractured using TSO and Frac-Pack end shielding technologies.

A fracture buffer fluid was pumped into the well without a crack fixer — proppant — in a volume of 4 m ³ , then another 32 m ^{3 of} fracture fluid was mixed with proppant, while proppant mixed with fracture fluid was pumped sequentially in three stages. At the first stage, 600 kg of proppant were pumped in a mixture with a rupture fluid in a volume of 1 m ³ at a flow rate of 2.5 m ³ / min, the proppant concentration in the mixture was 600 kg / m ^3, respectively. Then, the injection rate was reduced to 0.5 m ³ / min for 2 minutes. Then, the injection rate was resumed to 2 m ³ / min and the remaining volume of the fracturing fluid in the mixture with proppant was pumped into the tubing, while the proppant concentration in the mixture was gradually increased from 600 to 1200 kg / m ³ . After that, the fracturing fluid was mixed with proppant into the reservoir using industrial water in a volume equal to 9.1 m ³ at a pressure of 27 MPa, while the injection rate was gradually reduced from 2 to 0.5 m ³ / min.

As a result, a hydraulic fracture 10 was created (FIG. 1) with such parameters as: fixed half-length of the hydraulic fracture — 31 m, fixed hydraulic fracture width in the productive part of 5 mm (FIG. 1). The total fracture length — the length of the fracture on both sides of the well axis — was 62 m, respectively.

After the pressure drop, the two-packer arrangement was raised and it was installed opposite the overlying productive formation 2 (Fig. 4), which belongs to the second group with a permeability of 30 mD, and conducted a normal hydraulic fracture in it.

A fracture buffer fluid was pumped into the well without cracks — proppant — in a volume of 8 m ³ , then another 45 m ^{3 of} fracture fluid was pumped into the mixture with proppant, while the proppant concentration in the mixture was increased from 200 to 1200 kg / m ³ . The total injected proppant mass in this case was 12 tons. The flow rate of the fracture fluid was constant and amounted to 2.1 m ³ / min. After that, the fracturing fluid in a mixture with proppant was pushed into the reservoir with industrial water in a volume equal to 7.6 m ³ at a pressure of 24 MPa.

As a result, a hydraulic fracture 11 was created (Fig. 1) with such parameters as: fixed half-length of hydraulic fracture - 100 m, fixed hydraulic fracture width in the productive part - 7 mm. The total hydraulic fracture length — the length of the fracture on both sides of the axis of the well — was 200 m, respectively.

After completion of the full cycle of hydraulic fracturing of the productive formations in the well, a two-packer assembly was removed from the well. The descent of the technological tubing with a diameter of 73 mm (not shown in FIGS. 1-4) washed the well from the remnants of the fracturing fluid and proppant. The appropriate equipment was lowered into the well for simultaneous and separate reservoir exploitation and the well was put into operation.

As a result of the application of the proposed method, it was possible to significantly increase the selection of reservoir fluids, accelerate the process of developing a multilayer oil reservoir, folded by productive formations with various reservoir properties, and also save significant material and technical resources.

The proposed method allows to simplify and reduce the cost of developing a multilayer oil reservoir, to increase the efficiency of developing multilayer oil reservoirs stacked by productive formations with various reservoir properties, and also to accelerate the development of such oil fields.

Claims (2)

1. A method of developing a multilayer oil reservoir using hydraulic fracturing, including pumping a displacing agent through injection wells, selecting reservoir fluids through production wells, effecting hydraulic fracturing to produce an effective fracturing fracture, characterized in that the permeability of each reservoir that is opened by a well is determined , productive formations are classified by permeability, depending on the permeability of the productive stratum, perforation is carried out in production and injection wells, injection wells are injected, and in production wells, hydraulic fracturing is performed in all productive formations, and in production reservoirs with a permeability of less than 10 mD, hydraulic fracturing is carried out with the creation of hydraulic fractures with a fixed half length of more than 100 m and a fixed width of the productive part from 1.5 to 3 mm, in the productive in the formations with permeability of more than 100 mD, hydraulic fracturing is carried out with the creation of hydraulic fractures with a fixed half-length of up to 40 m and akreplennoy width from 5 to 20 mm, and in reservoirs with permeability from 10 to 100 mD is conducted with the creation of a hydraulic fracture with a fixed hydraulic fracture half-length of 40 to 100 m and a fixed width from 3 mm to 7 mm. 2. The method according to claim 1, characterized in that for the effective development of a multilayer oil reservoir in production wells, equipment for simultaneous and separate operation is used.

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