RU2740357C1 - Method for waterflooding of low-permeable and super-low-permeable reservoirs - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to development of oil and gas deposits and can be used in design and development of horizontal wells using multi-stage hydraulic formation fracturing—MHFF at sealing of horizontal wells with MHFF or drilling of offshoots—radial channels with horizontal section and MHFF. According to the method, the horizontal part of the production well is routed in the clay bed with ductility, providing protection of horizontal shaft from breakthrough in it of fractures of hydraulic fracturing of formation. Installation of horizontal part of injection well in productive formation is performed in parallel to horizontal part of production well. Ports are installed in the horizontal part of the injection well and multi-stage hydraulic fracturing of the formation is performed. Ports are installed in horizontal part of production well and performing multi-stage hydraulic fracturing of formation with provision of production well connection with productive formation or drilling of radial channels of production well with provision of connection of production well with productive formation. Ports are installed in horizontal part of production well. Perform multi-stage hydraulic fracturing of formation. Working fluid is pumped into injection well at pressure above formation hydraulic fracturing. Ports are installed in production well with offset relative to ports of injection well. Producing and injection wells are exploited by pumping liquid into injection well. Fluid is extracted from production well.

EFFECT: technical result is higher reliability of oil deposit development and increased oil recovery of formation.

9 cl, 1 tbl, 4 dwg

Description

The invention relates to the oil industry, namely to the field of development of oil and gas deposits, and can be used in the design and development of horizontal wells using multi-stage hydraulic fracturing (MSHF), in the infill drilling of horizontal wells with MSHF or drilling sidetracks (radial channels) with a horizontal section and multistage hydraulic fracturing.

From the prior art, a method is known for the development of an oil reservoir according to the RF patent for invention No. 2613713 (IPC: E21B 43/00, E21B 43/26, priority date: 03/31/2016, publication date: 03/21/2017), which includes drilling and alternation through one a row, placing at the first distance from each other, rows of horizontal production and rows of horizontal injection wells. The common features of the known from patent No. 2613713 and the claimed method of reservoir development is the drilling of injection and production (production) wells containing horizontal sections. The disadvantage of the known method according to the patent No. 2613713 of the development of an oil reservoir is a low coefficient of oil growth due to the absence of multi-stage hydraulic fracturing.

From patent document US9567842B2 (IPC: E21B43 / 305, priority date: 05/21/2013, publication date: 11/27/2014), a development method is known that includes drilling a plurality of horizontal production wells located at a first depth at the bottom or near the bottom of a hydrocarbon reservoir; a plurality of horizontal injection wells exiting at the same or less depth than the specified first depth; and a plurality of lateral wells originating from said plurality of horizontal production wells or said plurality of horizontal injection wells or both. The common features of the known method according to patent document US9567842B2 and the claimed method is the drilling of a production and injection wells at different depths (in formations located at different depths). In addition, a common feature with the claimed method according to an alternative feature is the drilling of radial channels from a horizontal production wellbore. The disadvantage of the known development method is the absence of multi-stage hydraulic fracturing, as well as the risk of auto-hydraulic fracturing (auto-hydraulic fracturing) from injection wells to producing wells with a decrease in fluid flow and an increase in water cut of the oil product.

From the patent document US9567842B2, a well configuration is known in which horizontal production wells are at a first depth, while horizontal injection wells are at a shallower depth than said first depth. At the same time, the production well contains many side wells. Common features of the known system of wells (patent US9567842B2) with a design method for reservoir development is a well configuration in which the trajectory of the horizontal production well is at the first depth, and the trajectory of the horizontal injection well is at a shallower (or greater) depth than the specified first depth. A common feature with the design method is also trajectory of horizontal boreholes (parts) of wells at different depths. The disadvantage of the known design method is the large total length of the wellbores, which increases the complexity of reservoir development, and also increases the risk of breakthrough of auto-hydraulic fractures into production wells, which leads to waterflooding and a decrease in the volume of fluid production.

From the prior art, a method is known for the development of a reservoir under the RF patent for invention No. 2613713 (IPC: E21B 43/00, E21B 43/26, priority date: 03/31/2016, publication date: 03/21/2017), in which the formation is drilled and alternated through one row, placing at a first distance from each other, rows of horizontal production (production) wells and rows of horizontal injection wells, at least two hydraulic fracturing ports are installed in the casing strings of injection and production wells, located at a second distance from each other and providing communication between the wells and the formation, through the hydraulic fracturing ports, multi-stage hydraulic fracturing is carried out in production wells and in injection wells, and the hydraulic fracturing cracks of the injection wells are displaced from the hydraulic fracturing cracks of the production wells by a third distance, the production and injection wells are put into operation by injecting fluid into the injection wells with controlled by adjusting the flow rate and / or volume of the injected fluid in such a way that the injection pressure was below the fracturing pressure. The general features of the method according to the patent of the Russian Federation No. 2613713 and the claimed method of developing a reservoir (formation) are drilling a horizontal production well, drilling a horizontal production well, arranging multistage hydraulic fracturing ports of one horizontal wellbore with an offset relative to the ports of a horizontal wellbore of another well. The disadvantage of the known development method according to RF patent No. 2613713 is an increase in the likelihood of auto-hydraulic fracturing breakthrough into a production well when compaction of horizontal sections of injection and production wells using hydraulic fracturing or when the pressure of the working fluid in the injection well is increased.

When designing according to the method described in the patent of the Russian Federation No. 2613713, in the case of modeling the occurrence of auto-hydraulic fracturing or a significant increase in the injection pressure, the fractures of the injection well will reach the main bore of the production well. Thus, injection should be simulated in a mode with a reduced pressure of the working fluid of the injection well in order to prevent the possibility of auto-fracturing, but this leads to a decrease in oil recovery of the productive formation.

The technical result of the claimed method of reservoir development is to increase the reliability of the development of oil deposits and increase oil recovery.

The technical result is achieved due to the fact that when using the method of developing reservoirs, the following is carried out:

- drilling the horizontal part of a production well in a shale formation;

- drilling the horizontal part of the injection well in the productive formation;

- installation of ports in the horizontal part of the injection well and carrying out multi-stage hydraulic fracturing;

- carrying out multi-stage hydraulic fracturing with the installation of ports in the horizontal part of the production well and ensuring the connection of the production well with the productive formation

or drilling radial channels of the production well to ensure the connection of the production well with the productive formation, installing ports in the horizontal part of the production well, carrying out a multi-stage hydraulic fracturing of the formation;

- while the installation of the ports of the production well is carried out with an offset relative to the ports of the injection well;

- operation of the production and injection wells by pumping fluid into the injection well and producing fluid from the production well.

The reliability of development is increased by minimizing the likelihood of flooding (breakthrough of the working fluid from the injection well into the production well) by protecting the production well with a plastic clay layer from hydraulic fractures of the injection well simultaneously with the dilution of the fracture plane of the production well (made from the wellbore or from the radial channels) and the plane hydraulic fractures of the injection well. Minimizing the likelihood of breakthrough of the working fluid of the injection well into the production well allows to increase the network and the total length of hydraulic fractures and, accordingly, increase the oil recovery of the productive formation.

In the absence of interlayers of a clayey non-reservoir with the same result, other types of interlayers (formations) can be used, which have equivalent mechanical properties, which can significantly reduce the development of a fracture that has arisen in a productive reservoir in the direction of a horizontal wellbore. For clay formations, the plasticity number (I _p ) must correspond to 7 or more.

Clay and productive strata can be adjacent, in contact with each other for a long or short area.

The reservoir can be located above or below the shale formation.

The installation of the production well ports can be carried out with an offset relative to the injection well ports, providing alternation of the injection well fracture plane through one, two or three production well fracture planes.

The installation of the injection well ports can be carried out with an offset relative to the production well ports, providing the alternation of the production well fracture plane through one, two or three injection well fracture planes.

The horizontal part of the injection well in the productive formation can be driven parallel to the horizontal part of the production well or largely parallel, which ensures the separation of the fracture planes.

The horizontal sections of the wells can be drilled perpendicular to the maximum formation stress or substantially perpendicularly.

Multistage fracturing can be carried out using high-viscosity gels based on guar, hydroxypropyl guar and other derivatives.

The technical result of the method for designing the development of low-permeability and ultra-low-permeability reservoirs by waterflooding is to build a hydrodynamic and geomechanical model to provide a more reliable method of reservoir development and enhanced oil recovery.

The technical result is achieved due to the fact that when using the design method for the development of reservoirs according to the first option, the following operations are performed:

- construction of the trajectory of the horizontal part of the production well in the clay formation;

- construction of the trajectory of the horizontal part of the injection well in the reservoir;

- modeling the installation of ports in the horizontal part of the injection well and carrying out multi-stage hydraulic fracturing;

- modeling of multi-stage hydraulic fracturing with the installation of ports in the horizontal part of the production well and ensuring the connection of the production well with the productive formation

or modeling the drilling of radial channels of the production well with the connection of the production well to the productive formation, modeling the installation of ports in the horizontal part of the production well and carrying out a multi-stage hydraulic fracturing of the formation;

- in this case, the installation of the production well ports is simulated with an offset relative to the injection well ports.

When using the design method for the development of reservoirs, it is possible to simulate the operation of the production and injection wells by determining the parameters of fluid injection into the injection well and the parameters of fluid production from the production well.

A clay formation is understood to be an impermeable (ultra-low-permeable) or low-permeable formation or other formation (a clay mineral formation), while having increased plasticity compared to a permeable formation.

Low-permeability reservoirs (formations) can be understood as rocks with permeability below 10 mD, and ultra-low-permeability - with permeability below
1 mD.

The claimed inventions are illustrated by the figures:

fig. 1 is a development scheme with one production and one injection wells;

fig. 2 is a development scheme with several production wells;

fig. 3 is a diagram for modeling the use of the development method;

fig. 4 is a graph of changes in the volumes of fluid production, on which are indicated:

1 - horizontal part of the production well;

2 - clay layer;

3 - productive formation;

4 - horizontal part of the injection well;

5 - radial channels;

6 - planes of multi-stage hydraulic fracturing of a production well;

7 - planes of fractures of multistage hydraulic fracturing of an injection well;

8 - the dependence of the change in fluid flow at an injection pressure of 40 MPa and the implementation of the horizontal parts of the production wells outside the clay formation;

9, 10, 11, 12 - dependences of changes in fluid inflow at injection pressure of 47 MPa, drilling of horizontal parts of production wells in a clay reservoir, but with different geological parameters of the reservoir being developed.

The application of the claimed method is as follows.

When using the reservoir development method (Fig. 1), the horizontal part of the production well 1 is drilled in the clay layer 2, located, for example, above the productive layer 3, the horizontal part of the injection well 4 is drawn in the productive layer 3, located, for example, under the clay layer 2 and adjacent to it. Further, for example, the radial channels 5 are drilled from the producing well 1 into the producing formation 3 in such a way that the connection of the producing well 1 with the producing formation is ensured. Then ports are installed (not shown in the figure) in the horizontal part of the production well 1 and ports (not shown in the figure) in the horizontal part of the injection well 4. In this case, the ports of the production well 1 are displaced relative to the ports of the horizontal part of the injection well 4. After which carry out a multi-stage hydraulic fracturing of the formation in the places where the ports of the production well 1 and the injection well 4 are installed, ensuring the alternation of the planes of the cracks 6 of the production well 1 and the planes of the cracks 7 of the injection well 4. The installation of ports in the wells 1 and 4 and carrying out the multistage hydraulic fracturing can be carried out simultaneously or sequentially in certain types of wells (first, in injection well 4, installing ports and carrying out multistage hydraulic fracturing, then in producing well 1, placing ports and conducting multistage hydraulic fracturing) This sequence does not affect the change in the technical result. Then, the production 1 and 4 injection wells are operated by injecting liquid into the injection well 4 and the production of fluid from the production well 1.

The development method is similar for many production wells (Fig. 2), the flow of fluid to which is provided by one injection well, as well as when drilling multiple injection wells.

The implementation of the development method without drilling the radial channels 5 is similar to the order of the steps described above, but the connection (hydraulic connection) of the clay formation with the productive formation is provided due to the fractures of the multi-stage hydraulic fracturing of the producing well 1 (Fig. 3).

Using the tNavigator hydrodynamic simulator, the oil recovery factor was predicted when using the method without drilling radial channels 5 (Fig. 3).

In developing the reservoir and design method for reservoir development, the following parameters were set in the simulation program.

The development system contains two production wells 1 and one injection well 4. The distance between the horizontal parts of the wells is 500 m. The length of each horizontal wellbore of production wells 1 is 1000m. The length of the horizontal wellbore of injection well 4 is also 1000m. At the same time, the permeability of the clay formation = 0 mD, the permeability of the productive formation = 0.4 mD, the initial half-length of the multi-stage hydraulic fractures of producing 1 and injection 4 wells is 120 m, the distance between fracture ports is 100 m.

Using the tNavigator hydrodynamic simulator, it was revealed that with the above parameters, several scenarios of oil production are possible, due to the presence of uncertainties in predicting the growth of fractures due to geological heterogeneity of the reservoir:

1) When drilling production wells 1 outside a clay formation, the maximum injection pressure is limited to a value below the fracturing pressure (40 MPa). At the same time, the growth of auto-hydraulic fracturing fractures in injection wells 4 is limited. As a result, over 10 years, an oil recovery factor (ORF) of 7.7% will be achieved (Fig. 4, dependence 8). This development option is currently used in real fields as a baseline.

2) When drilling production wells 1 in clay reservoir 2, the injection pressure is maintained above the fracturing pressure (equal to 47 MPa), while the half-length of the auto-hydraulic fracturing fractures in injection well 4 does not change. As a result, over 10 years ORF = 8.8%, the relative increase in ORF = 15% (Fig. 4, dependence 9).

3) Also, when drilling production wells 1 in shale formation 2 and injection pressure higher than the hydraulic fracturing pressure (47 MPa) with other geological parameters, the half-length of only one auto-hydraulic fracture fracture in injection well 4 increases to 400 m and passes between hydraulic fracturing fractures of production wells 1, with This does not change the length of the remaining auto-hydraulic fractures in injection well 4. As a result, over 10 years ORF = 9.7%, the relative increase in ORF is 26% (Fig. 4, dependence10).

4) When drilling production wells 1 in clay layer 2 and the injection pressure is higher than the hydraulic fracturing pressure (47 MPa) and third geological parameters, the half-length of four auto-hydraulic fractures in injection well 4 grows to 400 m and passes between the hydraulic fractures of production wells 1, the length of one fracture does not change. As a result, over 10 years the oil recovery factor is 11.3%, the relative increase in oil recovery factor is 46% (Fig. 4, dependence 11).

5) In the most optimistic scenario, when drilling production wells 1 in shale formation 2 and the injection pressure is higher than the hydraulic fracturing pressure (47 MPa), the half-length of all auto-fracturing fractures in injection well 4 increases to 400 m and passes between the hydraulic fractures of production wells 1. As a result, In 10 years, the recovery factor reached 15.3%, the relative increase in recovery factor = 99% (Fig. 4, dependence 12).

Thus, the maximum oil recovery factor will be achieved at a maximum hydraulic fracturing pressure of 47 MPa and a maximum increase in the length of all auto-hydraulic fracturing fractures in injection well 4. For better achievement of the technical result, clay 2 and productive layer 3 can directly contact or be separated by layers of other geological characteristics, but in this case, the connection of the production well with the productive formation should be ensured using auto-hydraulic fracturing.

The results of applying the claimed method are shown in the table.

Table

No. Stage description Cumulative production over 10 years, m ³ OR for 10 years,% Oil recovery factor, rel.% one. No growth of auto-hydraulic fractures,
P discharge 40MPa (dependence 8) 146237 7.7% 0% 2. No growth of auto-hydraulic fractures,
P discharge 47 MPa (dependence 9) 167575 8.8% 15% 3. Growth of one auto-hydraulic fracture up to 400 m, injection P 47 MPa (dependence 10) 200141 9.7% 26% 4. Growth of four auto-hydraulic fractures up to 400 m, injection P 47 MPa (dependence 11) 213977 11.3% 46% 5. Growth of all auto-hydraulic fractures more than 400 m, injection P 47 MPa (dependence 12) 290374 15.3% 99%

Thus, the maximum oil recovery factor and the most complete development of the formation will be achieved with the most developed fractures (with a significant increase in the length of the fractures), while the horizontal part of the production well 1 is located in the clay layer 2, i.e. surrounded (protected) by elastic material (mineral). When providing natural protection of the horizontal wellbore of the production well from the breakthrough into it of auto-hydraulic fracturing (when carrying out multi-stage hydraulic fracturing) of injection well 4, the maximum increase in oil recovery factor is achieved.

The method of designing the development of reservoirs is similar to the method of developing reservoirs, but at the same time, the trajectory of the horizontal part of the production well 1 is built in the clay layer 2, the trajectory of the horizontal part of the injection well 4 is built in the productive formation 3. Then, the installation of ports in the horizontal part of the injection well 4 is simulated and carrying out multi-stage hydraulic fracturing. Then, simulation of multistage hydraulic fracturing is carried out with the installation of ports in the horizontal part of the production well 1 and ensuring the connection of the production well 1 with the productive formation 3 (Fig. 3) modeling the drilling of radial channels 5 of the production well 1 with the connection of the production well 1 with the productive formation 3 (Fig. 1, 2). After that, the installation of ports in the horizontal part of the production well 1 is simulated and the multi-stage hydraulic fracturing is carried out in it, while the installation of the ports of the production well 1 is modeled with an offset relative to the ports of the injection well 4.

As a result of using the claimed method of reservoir development, an increase in the reliability of the development of oil deposits and an increase in oil recovery are provided. As a result of using the method of designing the development of low-permeability and ultra-low-permeability reservoirs by waterflooding, the construction of a model is provided to provide a more reliable method of reservoir development and enhanced oil recovery.

Claims (22)

1. A method for the development of reservoirs, in which they carry out: - drilling the horizontal part of a production well in a clayey formation with plasticity, which protects the horizontal wellbore from breakthrough of auto-hydraulic fracturing cracks into it; - drilling the horizontal part of the injection well in the productive formation to a large extent parallel to the horizontal part of the production well; - installation of ports in the horizontal part of the injection well and carrying out multi-stage hydraulic fracturing; - installation of ports in the horizontal part of the production well and carrying out multi-stage hydraulic fracturing to ensure the connection of the production well with the productive formation or drilling the radial channels of the production well to ensure the connection of the production well to the productive formation, installing ports in the horizontal part of the production well, carrying out multi-stage hydraulic fracturing; - the pumping of the working fluid in the injection well is carried out at a pressure above the hydraulic fracturing of the formation; - installation of the production well ports is carried out with an offset relative to the injection well ports; - operation of the production and injection wells by pumping fluid into the injection well and producing fluid from the production well. 2. The method of developing reservoirs according to claim 1, wherein the argillaceous and productive formations are adjacent to each other. 3. The reservoir development method of claim 1, wherein the reservoir is located above or below the clay reservoir. 4. The method of reservoir development according to claim 1, wherein the installation of the production well ports is carried out with an offset relative to the injection well ports, providing alternation of the injection well fracture plane through one, two or three production well fracture planes. 5. The method of reservoir development according to claim 1, wherein the horizontal portions of the wells are drilled predominantly perpendicular to the maximum formation stress. 6. The method of reservoir development according to claim 1, wherein multistage hydraulic fracturing is performed using a highly viscous gel. 7. The method of reservoir development according to claim 1, wherein the plasticity of the clay formation is 7 or more. 8. Design method for reservoir development, in which the following operations are performed: - construction of the trajectory of the horizontal part of the production well in a clay formation with plasticity, which ensures the protection of the horizontal wellbore from breakthrough into it of auto-hydraulic fracturing cracks; - the construction of the trajectory of the horizontal part of the injection well in the productive formation is carried out largely perpendicular to the maximum stress of the formation; - modeling the installation of ports in the horizontal part of the injection well and carrying out multi-stage hydraulic fracturing; - modeling the installation of ports in the horizontal part of the production well and carrying out multi-stage hydraulic fracturing with the connection of the production well with the productive formation or drilling the radial channels of the production well with the connection of the production well with the productive formation, installation of ports in the horizontal part of the production well, carrying out multi-stage hydraulic fracturing; - in this case, the installation of the ports of the production well is carried out with an offset relative to the ports of the injection well; - modeling the operation of the production and injection wells by determining the parameters of fluid injection into the injection well and the parameters of the fluid production from the production well. 9. The design method for the development of reservoirs according to claim 8, in which the plasticity of the clay formation is 7 or more.

Images