RU2421609C1 - Procedure for development of high viscous oil deposit - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: procedure consists in pumping fuel and oxidant into upper part of pay, in initiation of inter-layer ignition and in withdrawal of production from lower part of pay from section of well deflected relative to main section of borehole. According to the invention a borehole is drilled in form of two-wellhead bore with a deflected section rising from the sub-face of the pay to its top; the borehole is cased. This bore casing is equipped correspondingly with an upper and lower filters at the beginning and end of the deflected section. Overflow channels are located between the filters closer to the upper filter. Annular space between the lower filter and overflow channels and between the upper filter and the overflow channels is isolated during installation of casing. Further, the casing sting is cemented from the filters to wellheads. Internal space between the lower filter and overflow channels is sealed with a packer. A pump is lowered from one wellhead from the side of the lower filter, while a process string is lowered from another wellhead; its annular space is isolated between the overflow channels and the upper filter. ^ EFFECT: reduced financial expenditures for implementation of procedure, increased efficiency of utilisation of pay combustion due to control over temperature of withdrawn production along whole length of horizontal section of well, expanded coverage of pay with steam chamber. ^ 2 cl, 1 dwg

Description

The invention relates to the oil industry, in particular to the production of highly viscous heavy and bituminous oils.

The well-known "Method for the development of oil bitumen deposits" (patent RU No. 2287677, E21B 43/24, publ. Bull. No. 32 of 11/20/2006), including wiring in the reservoir of two horizontal shafts parallel to each other and injecting steam into the upper injection well and selection of products from the lower producing well.

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

Also known is the "Method for the development of high-viscosity oil or bitumen" (patent application No. 97107687, E21B 43/24, publ. 04/27/1999), 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 reservoir fluids through production wells, and after the creation of the combustion front, the boundary of the influence of the high-temperature zone moving along the formation is determined, after which a production well that is not covered by the thermal effect is selected, through which the annulus burning gases from the reservoir, while pumping gas to increase the reservoir temperature at the bottom of the producing well by 10-15 ° C.

The disadvantages of this method are the low efficiency of its application due to the inability to adjust the heating of the formation and the creation of a steam chamber, as well as a small coverage of the formation, since the heating of the formation and selection of production of the formation is pointwise.

The closest in technical essence and the achieved result is the "Method for the development of highly viscous oil or bitumen" (patent RU No. 2358099, E21B 43/24, publ. 10.06.2009), including the injection of oxidizing agent through injection wells, the organization of in-situ combustion and selection of products through producing wells, while horizontal wells with a horizontal wellbore in the bottom of the formation are used as producing wells, and vertical wells are placed in the wellbore and the end of the horizontal wellbore; they are pumped through the nearest vertical horizontal wells, and through remote ones — air; in this case, the bottomhole pressure of air injection in the well is set higher than the bottomhole pressure of fuel injection, while the injection of fuel into the closest vertical horizontal wells, and alternate with the remote injection of air with water injection into volumes that allow the maintenance of reservoir combustion.

The disadvantages of this method are:

- firstly, the low efficiency of its application due to the inability to control the temperature of the selected products along the entire length of the horizontal section of the producing well;

- secondly, the small area covered by the steam chamber of the formation due to the supply of air and fuel only through vertical wells, therefore, the heating of the formation and selection of production of the formation is pointwise;

- thirdly, significant financial costs for the implementation of the method, which is associated with the construction of several vertical wells. This is due to the fact that the injection of fuel (fuel) is carried out through the vertical wells closest to the horizontal, and air (oxidizing agent) is pumped through remote vertical wells.

The technical task of the proposed method is to reduce the financial costs of implementing the method and increase the efficiency of the use of reservoir combustion by controlling the temperature of the selected products along the entire length of the horizontal section of the well, as well as expanding the coverage of the formation with a steam chamber.

The technical problem is solved by the method of developing a highly viscous oil field, including injecting fuel and an oxidizing agent into the upper part of the reservoir with the organization of in-situ combustion and selecting products from the lower part of the reservoir from the well section deviated relative to the main section of the wellbore.

What is new is that the well is drilled in the form of a double-well well with a deviated section rising from the bottom of the productive formation to its roof and equipped with a casing string, equipped at the beginning and end of the deviated section with upper and lower filters, respectively, between which the transfer channels are located closer to the upper filter , when installing the casing, the annulus between the lower filter and the transfer channels and between the upper filter and the transfer channels is isolated, after which the casing from the fil it is cemented to the mouths, the inner space between the lower filter and the transfer channels is sealed with a packer, the pump is lowered from one mouth on the lower filter side, and the production string is insulated from the other mouth, the pipe annulus between the transfer channels and the upper filter is isolated, and the fuel is pumped the column, and the oxidizer - by its annulus, while the selection of products is carried out by a pump.

Also new is that the injection of the oxidizing agent is alternated with the injection of water to control the temperature during in-situ combustion.

The drawing shows a layer in section, passing in the plane of horizontal wells.

The method is as follows.

In a field with high viscosity oil, a well is drilled in the form of a two-well well 1 with a deviated section 2 rising from the bottom of the productive formation 3 of high viscosity oil to its roof. After that, the double-mouth well 1 is equipped with a casing 4, while at the beginning and end of the deviated section 2, the casing 4 is equipped with upper 5 and lower 6 filters, between which transfer channels 7 are located closer to the upper filter 5.

When installing the casing 4 in the double-well bore 1, the annular space between the lower filter 6 and the transfer channels 7 and between the upper filter and the transfer channels 7 is isolated by any known method, for example, using inflatable packers 8; 8'; 8 '', after which the casing from the filters 5 and 6, respectively, to the mouths of the double-mouth well 1 is cemented.

The inner space between the lower filter 6 and the overflow channels 7 is sealed with a packer 9, from one mouth on the side of the lower filter 6 a pump 10 is lowered on the tubing string 11, and from the other mouth the process string 12, the annular space 13 of which between the overflow channels 7 and the upper filter 5 is isolated using a packer 14. As water use wastewater with a density of 1100-1180 kg / m ³ . The fuel used is, for example, hydrocarbon gas, associated gas, heating oil or the like.

After warming up with the steam-moving installation of the near-barrel part of the productive formation 3 of the two-well well 1, the required amount of fuel is injected through the production string 12 through transfer channels 7 into the productive formation 3.

Next, through the annulus of the process column 12, that is, the annular space 13 through the upper filter 5 into the reservoir 3, air (oxidizer) is injected and, under the design pressure, the reservoir 3 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 start 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 hydrocarbon dioxide, water vapor and nitrogen) are formed. The ignition temperature of methane in air is from 545 to 850 ° C. Since reservoir water 2 is contained in the reservoir 2, the water turns into steam during the combustion process. Nitrogen air creates the steam moves through the reservoir 2. As you move through the reservoir 2, combustion zones 15 and steam 16 are formed.

Since steam and nitrogen have a specific gravity less than oil, a vapor zone (steam chamber) 16 is formed in the roofing part of formation 2, due to gravitational forces, oil flows into the bottom of the productive formation 3 and is taken to the surface along the tubing string 11 from the double-well well 1 using any known pump 10 (for example, screw).

Created a localized combustion zone 15 allows you to generate steam in the reservoir 3, which allows for the displacement of both the section and the area. The fuel injection pressure is produced at a pressure above the pressure of the opening of vertical cracks, which allows to increase the permeability of the productive formation 2 and to carry out intensive selection of highly viscous oil, including from formations with low permeability.

Temperature sensors (not shown) are lowered into the double-wellbore 1 on the fiber-optic cable from the side of the mouth of the double-wellbore 1 through which the pump 10 is lowered on the tubing string 11 and placed in the casing 4 along the entire length from the mouth to the packer 9 (for example, at a distance of 2-7 meters). Temperature sensors monitor the temperature of the selected products (high viscosity heavy and bituminous oil) with an increase or decrease in temperature of the selected products.

For example, if the temperature of the sampled product rises above a predetermined one, if the set temperature of production sampling from horizontal well 1, equal to 60 ° C, rises to 75 ° C, to which one or more temperature sensors react.

The oxidizer (air) is pumped through another mouth of the double-mouth well 1, namely, into the annular space of the well 13, and the water supply to the annular space 13 is stopped and water flows from the annular space 13 through the upper filter 5 into the vapor zone 16 and combustion 15, as a result of which water is mixed with fuel (fuel) in the combustion zone 15, while the parallel injection of fuel (fuel) into the process pipe string 12 through transfer channels 7 to the combustion zone 15 is carried out constantly.

As a result of water injection, the temperature of the products taken by the pump 10 decreases, as indicated by one or more temperature sensors launched into the double-well hole 1 on the fiber-optic cable from the side of the pump 10.

For example, a decrease in the temperature of the selected product reached 45 ° C, that is, the temperature at which the product was taken was lower than the set value, equal to 60 ° C. Then, the injection of water through another mouth of the double-mouth well 1, namely, into the annular space of the well 13, is stopped and the flow of oxidizer (air) into the annular space 13 is started.

The oxidizer from the annulus 13 through the upper filter 5 enters the zones of steam 16 and combustion 15, as a result of which the oxidizer is mixed with the fuel (fuel) in the combustion zone 15, while the parallel injection of fuel (fuel) into the process pipe 12 through the transfer channels 7 in the combustion zone 15 are constantly.

As a result of the injection of the oxidizing agent, the temperature of the products taken by the pump 10 increases, as indicated by one or more temperature sensors, lowered into the double-well hole 1 on the fiber-optic cable from the pump side 10. If the temperature of the selected products is further higher than the permissible temperature, one or several sensors react to this temperature, the process described above is repeated.

Thus, the injection of the oxidizing agent is alternated with the injection of water, while monitoring the temperature during in-situ combustion.

The implementation of this method requires significantly lower financial costs in comparison with the prototype, since it allows to avoid the construction of several injection wells, and the process of product selection along with the injection of fuel and oxidizer is solved using one double-well.

Due to the fact that the well is drilled in the form of a double-well well with a deviated section rising from the bottom of the formation to its roof, the coverage area of the productive formation by the steam chamber is significantly expanded, therefore, the efficiency of heating the formation is improved and, as a result, the volume of selected products increases. In addition, the in-situ combustion process is controlled by alternating the injection of oxidizing agent and water, and the temperature of the sampled products is controlled by temperature sensors launched into the double-mouth well on the fiber-optic cable from the side of the pump that performs the production selection.

Claims (2)

1. A method of developing a highly viscous oil field, including injecting fuel and an oxidizing agent into the upper part of the reservoir with the organization of in-situ combustion and selecting products from the lower part of the reservoir from the well section deviated relative to the main section of the wellbore, characterized in that the well is drilled in the form of a double well with a deviated section rising from the bottom of the reservoir to its roof and equipped with a casing, at the beginning and end of the deviated section equipped with the upper and lower filters, between which the transfer channels are located closer to the upper filter, when installing the casing, the annular space between the lower filter and the transfer channels and between the upper filter and the transfer channels is insulated, after which the casing from the filters to the mouths is cemented, the inner space between the bottom filter and transfer channels are sealed with a packer, a pump is lowered from one mouth on the bottom filter side, and a process string, annulus which is isolated between the transfer channels and the upper filter, and the fuel is injected through the process column, and the oxidizer is produced through its annulus, while the selection of products is carried out by a pump. 2. The method of developing a highly viscous oil field according to claim 1, characterized in that the injection of the oxidizing agent is alternated with the injection of water to control the temperature during in-situ combustion.

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