RU2358099C1 - Procedure for development of high viscous oil - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: at development of oil field there is performed pumping of oxidant via pressure wells, in-situ combustion and withdrawing of production through producing wells. As producing wells there are used horizontal wells with a horizontal borehole in a sub-face of the oil reservoir. Vertical pressure wells are placed in the cross section and end part of the horizontal borehole. Pumping of fuel is carried out through the nearest to a horizontal vertical wells, while air is pumped via the remote wells. Bottomhole pressure of air pumped into well is set above the bottomhole pressure of pumped fuel. Pumping of fuel to the nearest to horizontal vertical wells and air into the remote ones is alternated with pumping of water in volumes allowing maintaining of reservoir combustion.

EFFECT: increased efficiency of process of replacement of high viscous oil by means of increased vertical sweep with effecting agent due to successive development of whole reservoir.

1 ex, 1 tbl, 2 dwg, 2 cl

Description

The invention relates to the oil industry and may find application in the development of a highly viscous oil field.

A known method of developing a bitumen deposit, including wiring two horizontal shafts in the formation parallel to each other and injecting steam into the upper injection well, and selecting products from the lower producing well (RF patent No. 2287677, class E21B 43/24, publ. 2006.11.20) .

The main disadvantage of this method is the low efficiency of the process, especially in thin formations due to large heat losses.

Closest to the proposed invention in technical essence is a method of developing a deposit of highly viscous oil or bitumen, including the injection of an oxidizing agent through an injection well, the creation of a straight-through combustion front, control of its progress and production of formation fluids through production wells. After the creation of the combustion front, the boundary of the influence of the high-temperature zone moving through the formation is determined, after which a production well not covered by the heat is selected, through which the combustion gases are evacuated from the formation through the annulus, while the gas is evacuated until the formation temperature at the bottom of the production well increases by 10- 15 ° C (application for the invention of the Russian Federation No. 97107687/03, publ. 1999.04.27 - prototype).

The main disadvantage of this method is the low efficiency of the unregulated heating process. In addition, in the absence of a highly permeable formation and a weak hydrodynamic connection between wells, heating the formation is not possible. Oil recovery is reduced.

The invention solves the problem of enhanced oil recovery, i.e. the effectiveness of the process of displacing high-viscosity oil by increasing the coverage of the formation with an exposure agent due to the consistent development of the entire formation.

The problem is solved in that in the method of developing a highly viscous oil field, including the injection of an oxidizing agent through injection wells, the organization of in-situ combustion and production selection through production wells, according to the invention, horizontal wells with a horizontal wellbore in the bottom of the formation are used as production wells, and vertical injection wells placed in the alignment and the end of the horizontal trunk, pump through the closest to horizontal vertical wells of fuel, and through remote - of air, while the bottomhole pressure of air injection in the well is set above the bottomhole pressure of fuel injection.

Injection of fuel into the vertical wells closest to the horizontal, and in remote injection of air, alternate with the injection of water in volumes that allow maintaining formation combustion.

The features of the invention are:

1) injection of oxidizer through injection wells;

2) organization of in-situ combustion;

3) selection of products through production wells;

4) the use of horizontal wells with a horizontal wellbore in the bottom of the formation as production wells;

5) the placement of vertical injection wells in the alignment and the end of the horizontal wellbore;

6) injection of fuel through the closest to horizontal vertical wells;

7) injection through remote vertical air wells;

8) the bottomhole pressure of air injection in the well above the bottomhole pressure of fuel injection;

9) the alternation of injection in the fuel closest to the horizontal vertical wells, and in remote air injection with water injection in volumes that allow the maintenance of reservoir combustion.

Signs 1-3 are common with the prototype, signs 4-8 are the salient features of the invention, sign 9 is a particular feature of the invention.

SUMMARY OF THE INVENTION

The development of high-viscosity oil fields by in-situ combustion is accompanied by a low efficiency of the unregulated heating process, and with low permeability of the formation and weak hydrodynamic connection between the wells, heating of the formation becomes practically impossible. In this case, oil recovery is significantly reduced. The proposed method solves the problem of increasing the efficiency of the process of displacement of highly viscous oil, i.e. enhanced oil recovery by increasing the coverage of the formation with an impact agent due to the sequential development of the entire formation.

Figure 1 and 2 presents a diagram of the implementation of the proposed method: figure 1 is a top view, figure 2 is a sectional view. Legend: 1 - horizontal well; 2 - vertical well for fuel injection; 3 - vertical well for air injection; 4 - hot water advancement zone; 5 - steam chamber; 6 - combustion zone; 7 - oil reservoir.

The method is carried out in the following sequence.

A well with a horizontal well is drilled in a field with high viscosity oil. Drilling a horizontal section is carried out in the bottom of the reservoir 1 (Fig.1, 2). In the end part of the horizontal well, a vertical well 2 is drilled for injecting fuel, for example, hydrocarbon gas, associated gas, heating oil, and the like into the formation. At a distance from the drilled vertical, another vertical well is drilled to inject air 3 into the reservoir 7.

After warming up with a steam-moving installation of the bottom-hole part of the formation 2, the required amount of fuel is injected, then air is injected into the end of the horizontal wellbore under the design pressure, the formation is ignited and a burning center is created.

The air contains nitrogen, which is not chemically involved in the combustion reactions, but is present in the combustion zone. Since the air contains 21% vol. oxygen and 79% vol. nitrogen, when burning air, one volume of oxygen accounts for 79: 21 = 3.76 volumes of nitrogen.

For example, the equation of the combustion reaction of natural gas (methane) in air can be written as follows:

CH ₄ + 2O ₂ + 2 · 3.76N ₂ = CO ₂ + H ₂ O + 2 · 3.76N ₂

The combustion process is organized according to this equation so that in the combustion zone 1 m ^{3 of} combustible gas accounts for 9.5 m ^{3 of} air, which contains the required 2 m ^{3 of} oxygen. A combustible mixture (or part thereof) is provided with a heat pulse of sufficient power to initiate a combustion reaction. As a result of complete combustion of 1 m ^{3 of} methane, 36,000 kJ of heat are released and more than 10.5 m ³ of combustion products (a mixture of carbon dioxide, water vapor and nitrogen) are formed. The ignition temperature of methane in air is from 545 to 850 ° C. Since formation water is contained in the formation, the water turns into steam during the combustion process. Nitrogen air created by the vapor moves through the reservoir. As you progress through the formation, various zones are formed: hot water, steam, and combustion. Since steam and nitrogen have a specific gravity less than oil, a vapor chamber is formed in the roofing part of the formation. Due to the forces of gravity, oil flows into the bottom of the formation and is taken to the surface through a horizontal well.

The created localized combustion zone allows generating steam in the reservoir, which allows for displacement both in the section and in the area; the sequence of development of the reservoir occurs from top to bottom and along the reservoir by supplying a displacing agent to the end of the trunk with subsequent selection.

Injection of fuel into the vertical wells nearest to the horizontal, and in remote injection of air, it is possible to alternate with the injection of water in volumes that allow the maintenance of reservoir combustion. This helps to reduce the cost of development without reducing oil recovery.

An example of a specific implementation.

A section of the Ashalchinskoye field of the Republic of Tatarstan is being developed. In the Ashalchinskoye field with highly viscous oil at a depth of 90 m, heterogeneous formations are 8-15 m thick with a temperature of 8 ° C, a pressure of 0.5 MPa, a water saturation of 0.34 units, a porosity of 30%, and a permeability of 0.365 μm ² , saturated with oil having a density of 956 kg / m ³ and a viscosity of 10206 MPa · s. Drill a horizontal well. Drilling a horizontal section with a length of 75 m is carried out in the plantar of the reservoir (Fig.1-2). At a distance of 10 m and 20 m from the end part, two vertical wells are drilled in the horizontal well section.

To ignite the formation, steam is injected with a temperature of 320 ° C into well 2. Then methane is pumped into the well to create a bottomhole pressure of 1.2 MPa. Air is pumped through well 3 to create a bottomhole pressure of 1.6 MPa.

Methane is produced at a rate of 10 thousand m ³ per day, and air is 95 thousand m ³ per day.

The exploitation of the site is designed to achieve the design oil recovery of 65%.

Due to the consistent development of the entire interval, the coverage of the formation increases by exposure and all sections of the formation around the well are uniformly produced and, as a result, oil recovery is significantly increased. Comparison of the effectiveness of the proposed method is shown in the table.

Comparison of the technical and economic effectiveness of the proposed method

Table Indicators Prototype The proposed method Balance reserves, thousand tons 9 9 The average oil flow rate, t / day one thirty The coefficient of coverage of the reservoir impact, unit 0.10 0.90 The coverage coefficient of the formation by water flooding, d.ed. 0.60 0.90 The displacement factor, unit 0.50 0.80 Oil recovery ratio, unit 0,03 0.65 Recoverable oil reserves, thousand tons 0.30 5.8 Additional oil production, thousand tons - 162.5 The value of additional oil production, million rubles - 94 Costs, million rubles - 50,0 National economic effect, million rubles - 44

From the table it follows that the application of the proposed method leads to additional oil production, i.e. to increase oil recovery.

The application of the proposed method will improve the recovery of high-viscosity oil deposits.

Claims (2)

1. A method of developing a highly viscous oil field, including the injection of an oxidizing agent through injection wells, the organization of in-situ combustion and the selection of products through production wells, characterized in that horizontal and horizontal boreholes in the bottom of the formation are used as production wells, and vertical injection wells are placed in the alignment and the end of the horizontal trunk, they inject fuel through the closest to the horizontal vertical wells, and through the remote into air, while the bottomhole pressure of air injection in the well is set above the bottomhole pressure of fuel injection. 2. The method according to claim 1, characterized in that the injection into the nearest vertical horizontal wells of fuel, and in the remote injection of air alternate with the injection of water in volumes that allow the maintenance of reservoir combustion.

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