RU2582251C1 - Development method of layer-by-zonal heterogeneous superviscous oil or bitumen - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to oil industry and can be used in developing layer by layer-zonal non-uniform high-viscosity oil or bitumen accumulation. Development method for layer-by-zonal non-uniform high-viscosity oil or bitumen accumulation involves determination of two productive formations separated by aquitard interlayer. Horizontal production well is constructed in the lower formation above water-oil contact. In the upper productive formation, injection well is built with additional down shafts, from which additional plotted by shafts through sections of beds with low permeability with opening of the low permeable interlayer and additional by shafts through sections of formations with high permeability to hydrodynamic message or connection to the production well. Distance between additional down shafts is determined considering technological capabilities of drilling equipment for wiring, as well as with possibility to place between them filters with adjustable transmission lowered into injection well on pipe string located opposite additional shafts not linked with production well and packers insulating annular space of injection well between additional shafts and above filters. Number of pumped heat carrier and extracted product is determined from the properties of enter formations in each additional shaft due to controlled filters.

EFFECT: proposed development method for layer-by-zonal non-uniform high-viscosity oil or bitumen accumulation allows involvement of low-productive formations with thickness less than 10 m, increasing efficiency of oil recovery due to more even heating of productive formations, as well as reducing material costs, since it is possible to disconnect mined-out areas of productive formations, herewith volume of pumped heat carrier is getting reduced.

1 cl, 2 dwg

Description

The proposal relates to the oil industry, and may find application in the development of a layer-zone-heterogeneous reservoir of highly viscous oil or bitumen.

A known method of thermal displacement of oil from a horizontal well (patent RU No. 2067168, IPC ⁶ E21B 43/24, publ. 09/27/1996), including drilling a well with a horizontal well, installing a casing and cementing the annulus above a horizontal well, perforating the casing the columns along the annular generators in the terminal part and at the beginning of the horizontal section directly in front of the cement plug, after which the tubing string is lowered, the casing is centered in the casing with the help of a packer, which th is installed behind the first group of perforations, the coolant is supplied through the tubing, and the product is taken through the second group of perforations and transported along the annular annular space.

The disadvantage of this method is the low efficiency of oil recovery, since in the conditions of a layered-zonal-heterogeneous formation, its exposure vertically and in area is extremely small, which leads to a long duration of coverage of the entire volume of the formation by exposure and low rates of selection.

The closest in technical essence and the achieved result is a method of developing a layer-zone-heterogeneous reservoir of highly viscous oil or bitumen (patent RU No. 2295030, IPC E21B 43/24, published March 10, 2007), including the construction of a producing multi-well horizontal well with additional lateral shafts passing under a clay interlayer and above it parallel to the producing multi-mouth horizontal well of an injection two-mouth horizontal well with additional ascending branched shafts and, which are passed through a clay interlayer, creating a permeable zone between the wells by injecting the water coolant into both wells, and at first steam of a low degree of dryness (with a higher gas content) is pumped to increase the injectivity of the injection multi-well horizontal well and the proportion of associated water in the selected product, and then steam with a high degree of dryness (low fat gas) is pumped, the volume of which is determined by increasing the discharge pressure, which is maintained not exceeding the opening pressure of vertical fractures, after creating a permeable zone, the coolant is supplied only to the injection multi-mouth horizontal well, and production is selected from the horizontal multi-mouth well, the products are taken from the horizontal multi-mouth well until the full formation is produced, in addition, vertical wells passing through clay are additionally drilled interlayers, moreover, they are used both as a transport channel for filtering steam (gas) above the bed I have clay interlayers and create a steam (gas) oil bath, and for supplying selected products down.

The disadvantages of this method:

- the inability to engage in the development of low-power productive formations with a thickness of less than 10 m, since it is difficult to conduct a couple of wells in them;

- insufficient oil recovery efficiency, since the probability of a coolant breakthrough through one or more additional ascending branches passing through the most permeable sections of the reservoir is high, while other sections are not sufficiently warmed up;

- the inability to turn off the developed sections of productive formations, which leads to additional material costs, as they continue to pump coolant.

The technical objectives of the proposed method are the involvement in the development of low-power productive formations with a thickness of less than 10 m, an increase in oil recovery efficiency due to more uniform heating of the productive formations, as well as a reduction in material costs, since it is possible to turn off the developed sections of the productive formations, while the volume of pumped coolant is reduced.

Technical problems are solved by the method of developing a layer-zonal inhomogeneous reservoir of highly viscous oil or bitumen, including determining two productive formations in the reservoir separated by a low-permeable layer, constructing a horizontal production well in the lower layer above the oil-water contact, above which an injection well is constructed with additional shafts that open the low-permeable interlayers, coolant injection into both wells before heating of the interwell space of productive formations, injections from the coolant to the injection well and the selection of products from the producing well.

What is new is that an injection well is built in the upper producing formation, from which additional descending trunks are built through sections of low-permeability formations with opening of a low-permeable layer and additional descending trunks through sections of reservoirs with high permeability to hydrodynamic communication or connection with the producing well, while the distance between additional descending shafts is determined taking into account the technological capabilities of drilling equipment for their wiring, as well as with the possibility of placing between them filters with controlled transmission, lowered into the injection well on a string of pipes located opposite additional shafts not connected to the producing well, and packers that isolate the annular space of the injection well between the additional shafts and above the filters, the amount of coolant being pumped and taken products are determined from the properties of the exposed formations in each additional wellbore due to adjustable filters.

In FIG. 1 shows the injection of coolant into the formation through a horizontal injection well with additional descending shafts revealing a poorly productive interlayer and producing a horizontal well.

In FIG. Figure 2 shows the injection of coolant into the formation through a horizontal injection well with additional descending shafts revealing a poorly productive interlayer and product selection from the producing horizontal well and additional descending shafts drilled before hydrodynamic communication or connection with the producing well.

The method is as follows.

On the layer-zonal inhomogeneous deposits of highly viscous oil or bitumen, the upper 1 (Fig. 1, 2) and lower 2 productive formations are distinguished. The upper 1 and lower 2 productive formations are separated by a poorly productive layer 3. In the upper 1 productive stratum, an injection horizontal well 4 is drilled. In the lower productive stratum 2, a horizontal production well 5 is drilled above the oil-water contact (not shown in Fig.).

Due to the fact that within any formation the injectivity of individual sections can significantly differ from each other, there is an uneven development of the steam chamber, which leads to a decrease in the effectiveness of the impact on the formation. Using the hydrodynamic model, the injectivity of individual sections is calculated and the shape of the steam chamber is determined based on the results of temperature and pressure measurements in neighboring wells. After that, in order to increase the injectivity of areas with low permeability and align the shape of the steam chamber, additional downward shafts 6 are constructed from an injection horizontal well 4 through sections of formations 1, 2 with low injectivity, revealing a poorly permeable layer 3, and additional downward shafts 7 through sections of formations 1 , 2 with high permeability to hydrodynamic communication or connection with the producing horizontal well 5. When choosing the distance between the additional downstream The drawer shafts 6 and 7 take into account the technological capabilities of the drilling equipment (not shown in Fig.) for their wiring, for example, it is necessary to exclude the likelihood of getting into the neighboring well when drilling the next well with a downhole motor with a skew angle, to exclude the possibility of breakage of drill pipes when drilling additional ascending shafts to ensure leaching of drill cuttings while drilling additional ascending trunks and so on. In addition, consider the possibility of placing between them filters 8 with adjustable transmission, for example, RF patent No. 2485290, launched on the pipe string 9 and located opposite the additional shafts 6, as well as packers 10, which isolate the annular space 11 of the injection well 4 between the additional shafts 6 and above filters 8.

The coolant 12 (Fig. 1) is injected into wells 4 and 5. The amount of coolant 12 injected into the injection well 4 is carried out depending on the injectivity of the formation sections 1, 2 (the lower the injectivity, the more steam is injected, and vice versa) due to the adjustable filters 8. After warming up the productive formations 1, 2, the flow of coolant 12 is stopped in the producing horizontal well 5 and production 13 is taken from it (Fig. 2). In addition, the product 13 flows from the upper layer 1 into the producing well 5 along additional descending shafts 7 drilled before hydrodynamic communication or connection with it. In this case, the coolant 12 continues to be pumped into the horizontal injection well 4, which allows the upper 1 and lower 2 layers to continue to be heated. Thus, the coolant 12 (Fig. 1) is sequentially injected into wells 4, 5 and production 13 (Fig. 2) is taken from well 5 until the full production of upper 1 (Fig. 1, 2) and lower 2 layers. In this case, in the case of developing reserves of certain sections of the upper 1 and lower 2 layers, opened by additional descending shafts 6, or breaking through them coolant 12 (Fig. 1), the corresponding adjustable filters 8 are closed, and through others they continue to pump coolant 12.

Using a hydrodynamic model, a comparative assessment of the effectiveness of the proposed method and the method taken as a prototype. The following parameters are set for the model: the top 1 layer has a temperature of 20 ° C, pressure is 0.5 MPa, oil saturation is 0.77 units, porosity is 30%, permeability is 1.5 μm ² and is saturated with highly viscous oil or bitumen with a density of 956 kg / m ³ and a viscosity of 30,000 mPa · s, and the lower 2 layer - temperature 20 ° C, pressure - 0.5 MPa, oil saturation - 0.6 units, porosity - 30%, permeability - 1.5 μm ² and is saturated with high viscosity oil or bitumen with a density of 956 kg / m ³ and a viscosity of 30,000 mPa · s. The upper 1 and lower 2 productive formations are separated by a poorly productive interlayer 3 of a thickness of 3-5 m, having a temperature of 20 ° C, pressure - 0.5 MPa, oil saturation - 0.6 units, porosity - 17%, permeability - 0.1 μm ² . The sole of the bottom 2 of the reservoir is located at a depth of 90-95 m. In the top 1 of the reservoir, a horizontal injection well 4 is drilled 450-500 m long. In the bottom of the reservoir 2 a horizontal producer 5 is drilled 450-500 m long above the oil-water contact (in FIG. (not shown) not less than 2 m. In reservoirs 1 and 2, poorly permeable sections are defined according to the calculation results, through which additional descending trunks 6 are drilled, revealing a poorly permeable interlayer 3. Between each pair of descending additional trunks 6 additional shafts 7 were drilled before hydrodynamic communication or connection with the producing horizontal well 5 through sections with high permeability. The distance between the additional trunks 6 and 7 is 40-45 m. As a result of using the proposed method, it is possible to achieve a relative increase in the oil recovery coefficient by 16% and a decrease in steam consumption by 12%.

The proposed method for the development of a layer-zonal inhomogeneous reservoir of highly viscous oil or bitumen allows for the involvement of low-power productive formations with a thickness of less than 10 m, to increase the efficiency of oil recovery due to more uniform heating of the productive formations, and also to reduce material costs, since it is possible to turn off the developed sections of layers, while reducing the volume of injected coolant.

Claims (1)

A method for developing a layer-zone-heterogeneous reservoir of highly viscous oil or bitumen, comprising determining two reservoirs in the reservoir separated by a low-permeable layer, constructing a horizontal production well in the lower layer above the oil-water contact, above which an injection well with additional bores is opened to open the low-permeable layer, coolant in both wells to heat up the inter-well space of the reservoir, injection of coolant into the injection well and selection of products from the producing well, characterized in that an injection well is built in the upper producing formation, from which additional descending trunks are built through sections of low-permeability formations with opening of a low-permeable interlayer and additional descending trunks through sections of formations with high permeability to hydrodynamic communication or connections with the producing well, while the distance between the additional descending shafts is determined taking into account technological possibilities drilling equipment for their wiring, as well as with the possibility of placing between them filters with adjustable transmission, lowered into the injection well on a string of pipes located opposite additional shafts not connected to the producing well, and packers that isolate the annular space of the injection well between additional shafts and above the filters, and the amount of pumped coolant and selected products is determined from the properties of the exposed formations in each additional wellbore thanks I have adjustable filters.

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