RU2681796C1 - Method for developing super-viscous oil reservoir with clay bridge - Google Patents

Abstract

FIELD: oil industry.SUBSTANCE: method of developing deposits of super-viscous oil with a clay bridge includes drilling in the reservoir a steam injection well and located below the horizontal production well, horizontal wells with a length L of the production and injection wells are placed in parallel in a vertical plane and at an angle of not more than 15° in the horizontal plane. In the absence of a hydrodynamic connection between the producing and injection wells, 1 or 2 vertical wells are drilled during steam injection for no more than 12 months, which are placed in a vertical plane at a distance (0.3–0.7)⋅L from the toe of the horizontal boreholes, and in the horizontal plane at a distance of not more than 0.2⋅L from horizontal boreholes. Research is conducted and the presence of a clay lintel, preventing the specified hydrodynamic connection, is determined. In these vertical wells, samples of rocks, including clays, are taken from the productive part, geomechanical studies are carried out, according to the results of which an optimal design, working fluids and a proppant for fracturing a clay web are selected. Fracturing of the clay bridge is carried out in such a way as to create both horizontal and vertical cracks. Vertical wells are mastered by steam injection for 1–6 months. Subsequently, these vertical wells are used to control and regulate the development of a section of the reservoir between the horizontal wells of the production and injection wells, as well as to supply chemical reagents in order to increase oil recovery and/or block irrigated areas of the reservoir.EFFECT: technical result is an increase in oil recovery from a super-viscous oil reservoir, an increase in the coverage ratio of a heterogeneous section of a reservoir due to the destruction of a clay bridge.1 cl, 1 dwg, 2 ex

Description

The invention relates to the oil industry and may find application in the development of deposits of extra-viscous oil or bitumen with a clay bridge and the use of steam gravity drainage.

A known method of developing deposits of highly viscous oil or bitumen, including drilling vertical injection wells and horizontal production wells, pumping a working agent (steam in alternation with air) through injection wells and oil extraction through production wells. The horizontal wellbore of the producing well is carried out at 1.5-2.5 m above the bottom of the reservoir, the horizontal well is perforated. Above the horizontal well of the producing well, 3.5-4.5 m is placed the bottom of the vertical injection well, perforated in the range of 0.5-1.5 m from the bottom. A vertical injection well is placed from a vertical wellbore of a producing well at a distance greater than 2/3 of the length of the horizontal section of the producing well, up to the end of the horizontal wellbore (RF patent No. 2334095, class E21B 43/24, published on September 20, 2008).

The disadvantage of this method is the low coverage of the reservoir by the action of the working agent and its rapid breakthrough to the horizontal wellbore of the producing well. In addition, in the presence of a clay bridge (impermeable layer), the effectiveness of the method is significantly reduced. As a result, oil recovery from the application of the known method remains low.

Closest to the technical nature of the proposed method is a method of developing deposits of highly viscous oil or bitumen using hydraulic fractures - hydraulic fracturing, including drilling of vertical injection and horizontal production wells in the reservoir, represented by the upper and lower parts of the reservoir, separated by an impermeable layer, fixing the vertical injection and horizontal production wells with casing strings, perforation of casing strings, coolant injection of a vertical injection well and the selection of products through the horizontal production well. A vertical injection well is drilled with an impermeable layer opened, a casing is perforated in the upper and lower parts of the reservoir and an impermeable layer, hydraulic fracturing is performed in a vertical injection well in the impermeable interval, the cracks are fixed, then the direction of the crack development in azimuth and the height of the fracture crack are determined , then additionally drill at least one vertical injection well at a distance of 150 m from the first vertical injection well wells perpendicular to the direction of the development of the fracture fracture, drilling of the horizontal production well is carried out at a distance of 5 m below the faces of the vertical injection wells and perpendicular to the direction of the fracture of the fracturing fracture, the coolant is pumped through the vertical injection wells and production is taken through the horizontal production well, while the flow rate is reduced by 50% from the initial value is carried out interval hydraulic fracturing from a horizontal production well in the intervals between vertical netatelnymi wells with opening to form a tight seam cracking, fracture crack is attached using weighted proppant (RF patent №2633887, Cl. E21B 43/267, E21B 43/24, publ. 10/19/2017 - prototype).

The known method allows only partially destroy the impermeable layer, because deposits of high viscosity oil or bitumen in most cases occur at a depth of 100-300 m and hydraulic fractures propagate in the horizontal plane. In addition, vertical injection wells lead to a low coverage of the formation by steam pressure. Thus, the oil recovery coefficient from the application of the known method remains low.

The proposed invention solves the problem of increasing oil recovery deposits of viscous oil.

The problem is solved in that in a method for developing a super-viscous oil deposit with a clay bridge, comprising drilling a horizontal injection well in a producing formation and a horizontal production well below, conducting hydraulic fracturing, injecting steam into the injection well and selecting products from the producing well, according to of the invention, horizontal trunks with a length L of production and injection wells are placed in parallel in a vertical plane and at an angle of not more than 15 ° in a horizontal -th plane, in the absence of a hydrodynamic connection between the production and injection wells during steam injection for no more than 12 months, 1-2 vertical wells are drilled, which are placed in a vertical plane - at a distance of (0.3-0.7) ⋅L from sock of horizontal wellbores, and in the horizontal plane at a distance of no more than 0.2⋅L from horizontal wellbores, conduct research and determine the presence of a clay bridge that impedes the indicated hydrodynamic connection in these vertical wells from the product At the same time, rock samples, including clays, are taken, geomechanical studies are carried out, according to the results of which they select the optimal design, working fluids and proppant for hydraulic fracture of the bridge, hydraulic fracture of the bridge is carried out in such a way as to create both horizontal and vertical cracks, then vertical wells are mastered by steam injection for 1-6 months; subsequently, these vertical wells are used to control and regulate the development of the reservoir section between horizontal oxen production and injection wells, as well as for feeding chemical reagents to enhance oil recovery and / or block formation sections watered. SUMMARY OF THE INVENTION

Overbinding is understood to mean oil with a viscosity of at least 10,000 cps. The technology of steam gravity drainage is widely used to develop deposits of super-viscous oil. However, in the presence of a clay bridge (impermeable layer or lens), the coverage of the formation by the action on the side of the vapor is insignificant, because it is not possible to create a hydrodynamic connection between the horizontal shafts of the producing and injection wells. As a result, there is a lack of development of residual oil reserves and, accordingly, the oil recovery of the reservoir remains low. Existing technical solutions do not fully allow us to solve this problem. The proposed invention solves the problem of increasing oil recovery deposits of viscous oil. The problem is solved as follows.

The figure shows a schematic illustration of a section of a super-viscous oil reservoir with the placement of wells.

Designations: 1 - productive formation of a super-viscous oil deposit, 2 - horizontal production well, 3 - horizontal steam injection well, 4 - vertical wells, 5 - clay bridge, hydraulic fracturing, hydraulic fracturing, L - lengths of horizontal boreholes 2 and 3.

The method is implemented as follows.

In productive formation 1, super-viscous oil deposits drill a horizontal production well 2, a horizontal well of length L which is drilled in the lower part of productive formation 1 (when viewed in a vertical plane).

Above the production well 2, a horizontal steam injection well 3 is drilled with a horizontal well length L. Horizontal shafts of producing 2 and injection 3 wells are placed in parallel in a vertical plane and at an angle of no more than 15 ° in a horizontal plane. According to calculations, the parallel placement of horizontal shafts in the vertical plane allows to reduce the watering rate of producing well 2. When the angle between the horizontal shafts of wells 2 and 3 is more than 15 ° in the horizontal plane, oil recovery is reduced due to a decrease in the coverage of the productive formation 1 by steam.

After the development of wells 2 and 3 are put into operation. In the absence of hydrodynamic connection between the trunks of producing 2 and injection 3 wells when steam is injected for no more than 12 months, wells 2 and 3 are stopped. 1-2 vertical wells are drilled 4. These vertical wells 4 are placed in a vertical plane - at a distance of (0.3-0.7) ⋅ L from the toe of the horizontal wellbores 2 and 3, and in a horizontal plane - at a distance of not more than 0, 2⋅L from horizontal boreholes 2 and 3. According to studies, a hydrodynamic connection, depending on the geological and physical characteristics of reservoir 1, can be established for a sufficiently long time, but not more than a year. Therefore, there is no need to inject steam for more than 12 months if there is no reaction from the producing well 2. Drilling more than two vertical wells 4 in most cases is not economically justified, because 1-2 wells 4 are enough to reveal an impenetrable clay jumper 5. Obviously, if the dimensions of such a jumper 5 are small, then in 12 months the reaction of production well 2 from steam injection will occur and, accordingly, there is no need to drill vertical wells 4. When placing vertical wells 4 at a distance of less than 0.3⋅L and / or more than 0.7⋅L in the vertical plane from the toe of the horizontal wellbores 2 and 3, subsequent hydraulic fracturing does not allow to effectively create a hydrodynamic connection between production 2 and 3 wells, which leads to low oil recovery. Similarly, it is not possible to create an effective hydrodynamic connection between production 2 and injection 3 wells when placing vertical wells 4 at a distance of more than 0.2⋅L in the horizontal plane from horizontal boreholes 2 and 3.

Then, in vertical wells 4, geophysical studies are carried out and the presence of a clay bridge 5, which impedes the indicated hydrodynamic connection, is determined. In these vertical wells 4, rock samples, including clays, are taken from the productive part of the formation 1, and geomechanical studies are carried out. Based on the results of geomechanical studies, the optimal design, working fluids and proppant for hydraulic fracturing of the clay bridge 5 are selected.

Hydraulic fracturing of the clay bridge 5 is carried out in such a way as to create both horizontal and vertical cracks. Because the deposits of super-viscous oils are mostly shallow, then with hydraulic fracturing of the productive formation 1, mainly horizontal cracks form. To create vertical cracks, it is necessary to additionally pump deflectors.

Then, vertical wells 4 are mastered by steam injection for 1-6 months to accelerate the creation of a hydrodynamic connection between wells 2 and 3. At the same time, wells 2 and 3 are put into operation. According to studies, when steam is injected into vertical wells 4 for more than 6 months, the oil production rate are declining.

Subsequently, vertical wells 4 are used to control and regulate the development of a section of the productive formation 1 between the horizontal shafts of the producing 2 and injection 3 wells, as well as for supplying chemical reagents in order to increase oil recovery and / or blocking waterlogged sections of the productive formation 1.

Development is carried out until a fully economically viable production of super-viscous oil deposits.

The result of the implementation of this method is to increase oil recovery deposits of viscous oil.

Examples of specific performance of the method.

Example 1

Productive layer 1 of a super-viscous oil deposit is represented by terrigenous deposits. The average oil-saturated thickness is 17 m, the depth of the formation roof is 190 m, the initial reservoir pressure is 1.9 MPa, the viscosity of the oil under reservoir conditions is 16000 mPa⋅s, the initial reservoir temperature is 8 ° C.

In the productive formation 1, a horizontal production well 2 is drilled, a horizontal well with a length of L = 300 m is drilled in the lower part of the productive formation 1 (when viewed in a vertical plane).

Above producing well 2, a horizontal steam injection well 3 is drilled with a horizontal wellbore length of L = 300 m. Horizontal shafts of producing 2 and injection 3 wells are placed parallel in the vertical plane and at an angle of 15 ° in the horizontal plane.

After the development of wells 2 and 3 are put into operation. For 12 months, during the injection of steam, there was no hydrodynamic connection between the trunks of producing 2 and injection 3 wells. Wells 2 and 3 stop. Drill one vertical well 4, which is placed in a vertical plane - at a distance of 0.3⋅L from the toe of the horizontal wellbores 2 and 3, and in a horizontal plane - at a distance of 0.2⋅L from the horizontal wellbores 2 and 3.

Then, in a vertical well 4, geophysical studies are carried out and the presence of a clay bridge 5, which impedes the indicated hydrodynamic connection, is determined. In these vertical wells 4, rock samples, including clays, are taken from the productive part of the formation 1, and geomechanical studies are carried out. Based on the results of geomechanical studies, the optimal design, working fluids and proppant for hydraulic fracturing of the clay bridge 5 are selected. SlickWater is used as hydraulic fracturing fluid, 16/20 mesh quartz sand is used as proppant.

Hydraulic fracturing of the clay bridge 5 is carried out in such a way as to create both horizontal and vertical cracks. To create vertical cracks in the process of hydraulic fracturing of the reservoir 1 and fixing the proppant cracks, deflectors are periodically pumped - viscous compositions based on polymers (for example, polyacrylamide).

Then the vertical well 4 is mastered by injection of steam for 1 month. At the same time, wells 2 and 3 are put into operation. Subsequently, vertical well 4 is used to control and regulate the development of a section of productive formation 1 between the horizontal shafts of producing 2 and injection 3 wells, as well as for supplying chemicals to increase oil recovery (for example, aromatic hydrocarbons) and / or blocking waterlogged areas of the reservoir 1 (e.g., gelling formulations).

Development is carried out until a fully economically viable production of super-viscous oil deposits.

As a result of the development, which was limited to reaching the water well of the production well to 98% while reducing the oil production rate to 0.5 tons / day, 41.6 thousand tons of oil were produced, the oil recovery factor (CIN) was 0.394 units. According to the prototype, ceteris paribus, 37.8 thousand tons of oil was produced, oil recovery factor - oil recovery factor was 0.358 units. The increase in recovery factor by the proposed method is 0.036 units

Example 2

Perform as example 1. The reservoir is characterized by other geological and physical characteristics. Two vertical wells are drilled 4. One of the wells 4 is placed in a vertical plane - at a distance of 0.7⋅L, and the other - at a distance of 0.3⋅L from the toe of the horizontal boreholes 2 and 3. After the hydraulic fracturing of the reservoir 1, the vertical wells 4 are mastered by steam injection for 6 months.

The proposed method allows to increase the coverage coefficient of an inhomogeneous section of a super-viscous oil deposit due to the destruction of the clay bridge by hydraulic fracturing of the reservoir and, as a result, to increase the oil recovery coefficient.

The application of the proposed method will solve the problem of increasing oil recovery deposits of viscous oil.

Claims (1)

A method for developing a super-viscous oil reservoir with a clay bridge, comprising drilling a horizontal injection well in the reservoir and located below the horizontal production well, conducting hydraulic fracturing, injecting steam into the injection well and selecting products from the production well, characterized in that the horizontal trunks are of production length L and injection wells are placed in parallel in a vertical plane and at an angle of not more than 15 ° in a horizontal plane, in the absence of When the steam is injected for no more than 12 months, 1 or 2 vertical wells are placed in the vertical plane at a distance of (0.3-0.7) ⋅L from the toe of the horizontal wellbores, and in horizontal plane at a distance of not more than 0.2⋅L from horizontal wellbores, conduct research and determine the presence of a clay bridge that impedes the indicated hydrodynamic connection, in these vertical wells, an image is taken from the productive part Samples of rocks, including clays, conduct geomechanical studies, according to the results of which they select the optimal design, working fluids and proppants for hydraulic fracturing of the clay bridge, hydraulic fracturing of the clay bridge is carried out in such a way as to create both horizontal and vertical fractures, then vertical wells are developed by injection steam for 1-6 months, subsequently, these vertical wells are used to control and regulate the development of a section of the reservoir between horizontal production wells guide and injection wells, as well as for feeding chemical reagents to enhance oil recovery and / or blocking portions watered producing formation.

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