RU2483206C1 - Development method of high-viscosity oil and bitumen deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in the development method of high-viscosity oil and bitumen deposit, which involves drilling of injection and production wells, heat carrier pumping through injection wells and extraction of the product through production wells, one pair of inclined production wells of similar length is drilled in parallel vertical planes with the distance of not less than 10 m between them and at an angle of 30-35° to the formation bottom towards each other. Then, three vertical injection wells are drilled symmetrically between them; at that, one of them is arranged in the middle of length of inclined production wells projected to a horizontal surface, and two others are arranged at equal distance to the right and to the left of it. Pumping of heat carrier to vertical injection wells is alternated with pumping of a hydrocarbon solvent. Heat carrier pumping cycle is performed till oil and bitumen viscosity in the productive formation is decreased to the value providing dilution of oil and bitumen in a chamber-solvent at further pumping of a hydrocarbon solvent, which is continued till maximum viscosity value of oil and bitumen, which provides dilution of oil and bitumen with the hydrocarbon solvent, is achieved; after that, pumping of hydrocarbon solvent to vertical injection wells are stopped and pumping of heat carrier is renewed to them. Oil and bitumen extraction from inclined production wells is performed constantly.

EFFECT: increasing displacement coefficient of high-viscosity oil and bitumen, and increasing the coverage of the formation with heat action both horizontally and vertically.

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Description

The invention relates to the oil industry and may find application in the development of deposits of high viscosity oil and bitumen.

A known method for the development of deposits of highly viscous oil (patent RU No. 2334095, IPC ЕВВ 43/24, published in Bulletin No. 26 of 09/20/2008), including drilling vertical injection wells and horizontal production wells, pumping a working agent through injection wells and selection of oil 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 the vertical part of the wellbore 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 well, while steam is used as a working agent in alternation with air.

The disadvantage of this method is the lack of uniformity in the coverage of the reservoir by heat, as a result of which oil recovery does not reach a high level, as well as the possibility of premature breakthrough of condensate and bottom formation water to the producing well.

The closest in technical essence and the achieved result is a method of developing deposits of highly viscous oil and bitumen (patent RU No. 2387820, IPC ЕВВ 43/24, published in Bulletin No. 12 of 04/27/2010), including drilling injection wells and horizontal producers wells, coolant injection through injection wells and product selection through production wells, while the horizontal production wellbore is placed near the bottom of the reservoir so that the distance from the entry point of the injection wellbore in the product the reservoir to the horizontal section of the production wellbore was 0.8 formation thicknesses, and the lower part of the injection wellbore is located at the same level as the horizontal production well at a distance of 5-10 m from each other, and the injection wells are drilled obliquely directionally at an angle of 45 ° to the bottom of the reservoir.

The disadvantages of this method are:

- firstly, the low coefficient of displacement of highly viscous oil and bitumen, since the displacement of highly viscous oil and bitumen is carried out only due to conductive heat transfer (formation of a vapor chamber) in the reservoir, obtained by pumping the coolant into the reservoir;

- secondly, the low efficiency of the development of deposits of highly viscous oil and bitumen due to continuous heat exposure (constant coolant injection into injection wells), which contributes to the breakthrough of condensate in the faces of production wells and premature flooding of produced products;

- thirdly, a small vertical coverage of the formation by the production well, since the production well is parallel to the bottom of the formation, which can lead to uneven thermal effects on the formation and, as a result, its incomplete production.

An object of the invention is to increase the displacement coefficient of highly viscous oil and bitumen in formations by eliminating the deposition of asphalt-resinous substances from highly viscous oil and bitumen, accelerating the destruction of water-oil emulsions, increasing the coverage of the formation by thermal effects both vertically and horizontally, and eliminating premature flooding of produced products.

The problem is solved by the method of developing deposits of highly viscous oil and bitumen, including drilling injection and producing wells, pumping coolant through injection wells and selecting products through production wells.

It is new that they drill one pair of producing directional wells of the same length in parallel vertical planes with a distance of at least 10 m between them and at an angle of 30-35 ° to the bottom of the formation, then three vertical injection wells are drilled symmetrically between them, with one of them are placed in the middle of the length of producing directional wells projected onto a horizontal surface, and the other two are placed at equidistant distances to the right and left of it, the coolant is pumped into vertical pumps oil wells alternate with the injection of a hydrocarbon solvent, the coolant injection cycle being carried out until the viscosity of oil and bitumen in the reservoir decreases to a value that ensures dilution of oil and bitumen in the solvent chamber during subsequent injection of the hydrocarbon solvent, which is continued until the maximum viscosity of oil and bitumen is reached providing liquefaction of oil and bitumen with a hydrocarbon solvent, after which the hydrocarbon solvent is injected into vertical injection wells Azhins stop and resume pumping coolant into them, while the selection of oil and bitumen from directionally directed production wells is ongoing.

The proposed method for the development of deposits of high viscosity oil and bitumen is implemented as follows.

Figure 1 schematically shows a top view of a method for developing deposits of highly viscous oil and bitumen.

Figure 2 schematically shows in longitudinal section a method of developing deposits of high viscosity oil and bitumen.

By the method of developing deposits of high viscosity oil and bitumen, one pair of producing directional wells 1 and 2 of the same length is drilled - B (see Fig. 1) in parallel vertical planes 3 and 4, respectively, with a distance of at least 10 m between them and at an angle of 30 -35 ° (see figure 2) to the bottom of the reservoir 5.

Then between the trunks of producing directional wells 1 and 2 (see Fig. 1) at a distance of at least 5 m from the trunk of each of the production directional wells 1 and 2 with opening intervals 1 'and 2' (see figure 2) symmetrically drill three vertical injection wells 6, 7 and 8 (see figures 1 and 2).

Running production wells in an inclined direction increases the coverage of the formation by thermal effects both vertically and horizontally and allows for uniform thermal effects on the formation with its full development.

A distance of at least 5 m excludes direct breakthrough of the coolant into the trunks of producing directional wells 1 and 2 and is determined empirically.

The implementation of producing directional wells 1 and 2 of the same length B at an angle of 30-35 ° to the bottom of the reservoir 5 allows you to optimally increase the coverage of the reservoir by thermal effects both vertically and horizontally and to produce a uniform thermal effect on the reservoir 5, which is determined by experienced by way. One vertical injection well 6 is drilled in the middle of the length — L of producing directional wells projected onto a horizontal surface (not shown in FIGS. 1 and 2), i.e. at a distance of L / 2, and two other vertical injection wells 7 and 8 (see FIGS. 1 and 2), respectively, to the right and left of the first vertical injection well 6 at an equidistant distance (L / 4).

The coolant is pumped into the vertical injection wells 6, 7 and 8 alternating with the injection of a hydrocarbon solvent.

The opening intervals 6 ', 7' and 8 '(see figure 2) for pumping the coolant and hydrocarbon solvent of the reservoir 5 in the corresponding injection wells 6, 7 and 8 are performed as follows: 7', 8 ', respectively, in the wells 7 and 8 between the trunks of directional production wells 1 and 2, 6 'in the well 6 closer to the bottom of the formation 5.

The heat carrier used is: hot water, steam, hot polymer solution, etc. Nefras-S 150/200 according to TU 38.40125-82 or Nefras-Ar 120/200 according to TU 38.101809-80 can be used as a hydrocarbon solvent.

First, the coolant is injected into the formation 5, for example, steam through the opening intervals 6 ', 7' and 8 'of the corresponding vertical injection wells 6, 7 and 8. The injected steam breaks through to the upper part of the productive formation 5 due to the difference in density, creating an increase in dimensions of the steam chamber (not shown in FIGS. 1 and 2). At the interface between the steam chamber and cold oil-saturated thicknesses, a heat exchange process constantly occurs, as a result of which the steam condenses into water and, together with the heated oil, flows down to the bottom of the formation 5, and through the opening intervals 1 'and 2' (see Fig. 2) fall into the trunks of producing directional wells 1 and 2 under the action of gravity, from where they are selected by pumps (not shown in FIGS. 1 and 2). The growth of the steam chamber continues until it reaches the top of the formation 5, and then it begins to expand to the sides. In this case, oil is always in contact with a high-temperature steam chamber.

The coolant is pumped into the vertical injection wells 6, 7 and 8 (see FIGS. 1 and 2) until the viscosity of high-viscosity oil and bitumen in the reservoir 5 decreases (see FIG. 2) to a value that ensures dilution of oil and bitumen in the solvent chamber upon subsequent injection of a hydrocarbon solvent.

After that, the coolant is pumped into the vertical injection wells 6, 7 and 8 (see Figs. 1 and 2) and the cycle of pumping a hydrocarbon solvent, for example, nefras 150/300, into vertical injection wells 6, 7 and 8 is started, and the liquefied oil and bitumen, due to the diffusion of a hydrocarbon solvent, flows along the boundaries of the solvent chamber under the influence of gravitational forces into the trunks of directionally directed production wells 1 and 2, from which heated oil and bitumen are selected. At the same time, asphalt-resinous substances from high-viscosity oil and bitumen are not deposited due to the injection of a hydrocarbon solvent, the destruction of water-oil emulsions is accelerated, and premature flooding of produced products is eliminated by reducing the volume of condensate formed from the coolant due to the alternation of the coolant injection with the injection of a hydrocarbon solvent.

In the process of pumping a hydrocarbon solvent into vertical injection wells 6, 7 and 8 (see FIG. 2), the viscosity of oil and bitumen increases due to cooling of the steam chamber, which occurs due to the cessation of the injection of coolant into the reservoir 5.

The hydrocarbon solvent is pumped into the vertical injection wells 6, 7 and 8 until the maximum viscosity of oil and bitumen is reached, which ensures the dilution of oil and bitumen with a hydrocarbon solvent, after which the hydrocarbon solvent is pumped into the vertical injection wells 6, 7 and 8 and the injection is resumed. coolant to reduce viscosity, as described above. The selection of oil and bitumen from directional production wells 1 and 2 are constantly conducted.

An example of a specific implementation.

A highly viscous oil and bitumen deposit is being developed with a production density of 985 kg / m ³ located at a depth of 100 m with a reservoir thickness (h) of 25 m, with a porosity of 35%, with an oil saturation of 0.75 units, and a permeability of 0.29 microns.

Drill one pair of producing directional wells 1 and 2 (see Fig. 1) of the same length B = 400 m in parallel vertical planes 3 and 4 with a distance of at least 10 m between them and at an angle of 30 ° to the bottom of the formation, then between the shafts producing directional wells 1 and 2 symmetrically, i.e. Three vertical injection wells are drilled at a distance of at least 5 m from each well of a producing directional well: 6, 7, and 8.

Projected onto a horizontal surface, the lengths - L of directional production wells 1 and 2 are:

L = V · cos 30 ° = 400 m · 0.866 = 346 m.

The distance where the first vertical injection well 6 is drilled is the middle of the production of directional wells and is L / 2 = 346 m / 2 = 173 m. The distance from the vertical injection well 6 to the vertical injection wells 7 and 8 is: L / 4 = 216 / 4 = 86.5 m.

The coolant is pumped into the vertical injection wells 6, 7 and 8 alternating with the injection of a hydrocarbon solvent.

Next, the development of a deposit of highly viscous oil and bitumen begins, with the first coolant being pumped: steam, for example, water with a temperature of 200-220 ° C in vertical injection wells 6, 7 and 8 (see Figs. 1 and 2) with the formation of a steam chamber in productive formation 5 and enter into the development of directional production wells 1 and 2, which select products.

The coolant injection cycle with the formation of a vapor chamber (not shown in FIGS. 1 and 2) is performed until the viscosity of oil and bitumen in the reservoir 5 decreases to a value that ensures dilution of oil and bitumen in the solvent chamber during subsequent injection of the hydrocarbon solvent, for example, to reduce the viscosity up to µ = 150 MPa · s, a hydrocarbon solvent, such as ethane, is injected into the vertical injection wells 6, 7 and 8 (see FIGS. 1 and 2). In this case, liquefied oil and bitumen having a viscosity, as indicated above, μ = 150 MPa · s, due to the diffusion of a hydrocarbon solvent, flows along the boundaries of the solvent chamber under the influence of gravitational forces into the trunks of directional production wells 1 and 2, from which the preheated oil and bitumen. In the process of pumping a hydrocarbon solvent into vertical injection wells 6, 7 and 8, the viscosity of high viscosity oil and bitumen increases due to cooling of the steam chamber, which occurs due to the termination of the injection of coolant into the reservoir 5.

The hydrocarbon solvent is pumped into the vertical injection wells 6, 7 and 8 until the maximum viscosity of oil and bitumen is reached, for example, to a value of µ = 3000 MPa · s, at which (extreme value) liquefaction of highly viscous oil and bitumen with a hydrocarbon solvent is still ensured, after whereby the injection of the hydrocarbon solvent into the vertical injection wells 6, 7 and 8 is stopped and the injection of the coolant into them is resumed until the viscosity decreases, as indicated above, to μ = 150 MPa · s. Thus, the cycles of pumping the coolant and hydrocarbon solvent alternate, as described above.

The proposed method for the development of deposits of highly viscous oil and bitumen is quite effective, since the coefficient of oil and bitumen displacement increases by an average of 10-15% due to the combination of conductive heat transfer in the reservoir and diffusion of the hydrocarbon solvent in oil and bitumen, and the coverage of the formation with thermal exposure also increases both horizontally and vertically.

Claims (1)

A method for developing deposits of high viscosity oil and bitumen, including drilling injection and producing wells, pumping coolant through injection wells and selecting products through production wells, characterized in that they drill one pair of producing directionally directed wells of the same length in parallel vertical planes with a distance of at least 10 m between them and at an angle of 30-35 ° to the bottom of the formation towards each other, then three vertical injection wells are drilled symmetrically between them, while one of them placed in the middle of the length of producing directional wells projected onto a horizontal surface, and the other two at equidistant distances to the right and to the left of it, the coolant is pumped into vertical injection wells with the injection of hydrocarbon solvent, and the coolant is injected to reduce the viscosity of oil and bitumen in the reservoir to a value that ensures the dilution of oil and bitumen in the solvent chamber during the subsequent injection of a hydrocarbon solvent, which Continually to achieve maximum viscosity oil and bitumen, providing oil and bitumen dilution with a hydrocarbon solvent, and then download a hydrocarbon solvent into the vertical injection wells is stopped and restarted download coolant therein, wherein the selection of oil and bitumen from the slant are constantly producing wells.

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