RU2555731C1 - Method of development of water-flooded oil reservoir with microwave electromagnetic effect (versions) - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: group of inventions relates to the field of oil industry and can be used for enhanced oil recovery of the reservoir in the development of water-flooded reservoirs with viscous oil and bitumen at a late stage of development. The method comprises opening the reservoir with the ability to transfer the production well into the injection one, the reservoir processing, keeping the hole without any influence, intake of oil from the reservoir. At that a system of microwave electromagnetic generators with radiation frequency of 2.5 GHz is lowered into the injection well, connected to the slot antenna using the feeder. The length of the slot antenna is selected equal to the thickness of the aquifer of the reservoir. In the mode of injection, the water injection into the reservoir is carried out with simultaneous influence on the reservoir with microwave electromagnetic field, the radiation power is determined by the time of heating of the water injected in the downhole to the desired temperature. When filling 5-10% of the volume of the pore space of the formation, the well is maintained, the well is transferred into the production well, and the liquid intake from the production well is carried out.

EFFECT: increase of the effectiveness and economical efficiency of development of water-flooded reservoirs of high-viscosity oil, intensification of oil production in water-flooded reservoirs of high-viscosity oil by increasing the coverage with influence to the reservoir with heating in the bottomhole area of the reservoir of the production wells.

2 cl, 3 dwg

Description

The invention relates to the field of the oil industry and can be used to increase oil recovery in the development of flooded deposits with viscous oil and bitumen at a late stage of development.

A known method of mining, including heating the formation with a high-frequency electromagnetic field through a production well during oil production (US patent 2757738, EV 43/00). High-frequency electromagnetic energy is transmitted from the wellhead to the bottom. A coaxial tubing system and casing are used as the transmission line. The energy and power interaction of high-frequency electromagnetic waves with the formation causes the occurrence of heat sources distributed over the volume of the formation, which leads to a decrease in the viscosity of the formation fluid.

The disadvantages of this method are the large energy losses during energy transfer from the wellhead to the bottom of the well, a small depth of penetration of electromagnetic waves, low coverage of the formation by heating. The specified method is not applicable when developing flooded deposits.

The closest in technical essence to the claimed method is a method involving exposure to the formation of a high-frequency electromagnetic field with simultaneous injection of a miscible agent - solvent (RF patent 2454532). The method involves exposure to a high-frequency electromagnetic field with simultaneous injection of solvent into the well. The formation is opened by at least one well, the production well is first put into the injection mode, then an exposure to a high-frequency electromagnetic field is carried out with the simultaneous injection of a mixed solvent to fill 5-10% of the pore space of the formation; then carry out the exposure of the well without any impact, the duration of which is determined by the relaxation time of pressure in the reservoir. Then, the well is put into production mode and the product is taken from the formation without high-frequency electromagnetic effects, the duration of the product selection is determined by the time of lowering the temperature at the bottom of the well not lower than the initial formation temperature, after which all work is repeated cyclically.

The disadvantage of this method is its inefficiency in the implementation of the method in flooded deposits with viscous oil and bitumen at a late stage of development, since high-frequency electromagnetic waves emitted in the deposits will be reflected from the water-oil and water-rock boundary, which in turn can lead to failure of equipment implementing the specified method.

The technical result of the invention is to increase the efficiency and profitability of the development of flooded deposits of highly viscous oil, the intensification of oil production in flooded deposits of highly viscous oil by increasing the coverage of the formation with heating in the bottom-hole zone of the reservoir of producing wells, maximizing the use of microwave energy of the electromagnetic field by additional heat transfer to the reservoir of the injected water.

The technical result can be achieved in two implementation options:

1) A system of microwave electromagnetic generators with a radiation frequency of 2.5 GHz, connected to the slot antenna by a feeder, is lowered into the injection well, the length of the slot antenna L is chosen equal to the thickness of the aquifer of the formation N, then the microwave is exposed to electromagnetic field with simultaneous injection of water. The radiation power is determined by the time of heating the injected water in the bottom of the well to the required temperature:

$$N=pC\Delta TQ\left(\mathrm{one}-\frac{r_c}{2R_n}\right),(\mathrm{one})$$

where ρ is the density of the injected water, kg / m ³ ; R _n is the radius of the bottomhole formation zone, which must be heated, m; C is the heat capacity of the injected water, J / kg * K; ΔТ is the difference between the final and initial temperatures of the bottom water, K; Q - flow rate of injected water, m ³ / s; r _c - well radius, m; then in the production well, fluid is sampled.

2) The formation is opened by at least one well, the producing well is first put into injection mode, the system of microwave electromagnetic generators with a radiation frequency of 2.5 GHz is lowered, connected to the slot antenna by means of a feeder, the length of the slot antenna L is chosen equal to the thickness of the aquifer of the formation N, then the microwave is exposed to the electromagnetic field with the simultaneous injection of water to fill 5-10% of the pore space of the formation, the radiation power is determined by the formula (1), then wells without any impact, the duration of which is determined by the pressure in the reservoir relaxation time:

$$t_p=\frac{R_{\mathrm{to}}^2}{\chi },t_{\mathrm{at}}<t_{\mathrm{at}}<t_R(2)$$

where t _p is the relaxation time, s, R _k is the distance to the well supply circuit, m, χ is the piezoelectric conductivity coefficient of the formation, m ² / s, t _c is the duration of the well exposure, s, t _y is the installation time for the equipment for taking fluid from layer

then the well is put into production mode and the product is taken from the formation without microwave electromagnetic effects, the duration of the product selection is determined by the time of lowering the temperature at the bottom of the well not lower than the initial reservoir temperature, after which all work is repeated cyclically.

Figure 1 shows the layout of the well of the first embodiment. Legend: 1 - a reservoir containing oil and water; 2 - injection well; 3 - a system of microwave electromagnetic generators; 4 - feeder; 5 - slot antenna; 6 - volumetric heat sources arising in the productive rock when exposed to microwave electromagnetic field; 7 - production well.

Figure 2 shows a diagram of the arrangement of the wells of the second embodiment. Legend: 1 - a reservoir containing oil and water; 2 - injection well; 3 - a system of microwave electromagnetic generators; 4 - feeder; 5 - slot antenna; 6 - volumetric heat sources arising in the productive rock when exposed to microwave electromagnetic field.

Figure 3 shows the dynamics of temperature changes in the bottom-hole zone of the formation when the microwave is exposed to the electromagnetic field and the water is injected together at different points in time (curve 1 after 30 minutes of exposure; curve 2 after 3 hours of exposure; curve 3 after 12 hours exposure; curve 4 - after 24 hours of exposure).

The method is carried out in the following sequence.

I implementation option.

A system of microwave electromagnetic generators 3 with a radiation frequency of 2.5 GHz, connected to the slot antenna by a feeder, is lowered into the injection well 1. The length of the slot antenna L is chosen equal to the thickness of the aquifer of the formation N. The microwave is exposed to an electromagnetic field with simultaneous injection of water. At the same time, they include a system of microwave electromagnetic generators and emit electromagnetic waves into the bottomhole zone of the formation. The radiation power is determined by the time of heating the injected water in the bottom of the well to a predetermined temperature according to formula (1). Due to dielectric losses in the formation 5, microwave electromagnetic energy is converted into thermal energy, volumetric thermal sources of heat appear in the formation 5. Water injected into the formation transfers heat deeper into the formation 5. Due to heating of the formation fluid, the mobility of the formation fluid and the coverage of the formation by heat are increased. In the production well 4, fluid is sampled.

II implementation option.

Production well 1 is transferred to the injection mode. A system of microwave electromagnetic generators 3 with a radiation frequency of 2.5 GHz, connected to the slot antenna by a feeder, is lowered into the injection well 1. The length of the slot antenna L is chosen equal to the thickness of the aquifer of formation N. Water is pumped into the formation through a tubing. At the same time, they include a system of microwave electromagnetic generators and emit electromagnetic waves with a radiation frequency of 2.5 GHz into the bottomhole zone of the formation. The radiation power is determined by the time of heating the injected water in the bottom of the well to a predetermined temperature according to formula (1). Due to dielectric losses in the formation 5, microwave electromagnetic energy is converted into thermal energy, volumetric thermal sources of heat appear in the formation 5. Water injected into the formation transfers heat deeper into the formation 5. Due to heating of the formation fluid, the mobility of the formation fluid and the coverage of the formation by heat are increased. The microwave exposure to the electromagnetic field and water injection continues until 5-10% of the volume of the reservoir’s first space is filled with water.

Then stop the impact on the formation and carry out the "exposure" of the well 1. In the formation 5 is a redistribution of pressure and temperature. With the redistribution of pressure in the reservoir 5, the accumulation of reservoir energy occurs due to an increase in reservoir pressure, which subsequently increases the amount of withdrawn oil. The exposure time t _in is estimated from the relaxation time of the reservoir pressure (during which it is assumed to install equipment for taking fluid from the reservoir 5 and reverse transfer of the well 1 to production) according to formula (2).

Then, well 1 is put into production mode and oil is selected. The duration of selection t _in is determined by the time of the temperature decrease at the bottom of the well, which should not be lower than the initial reservoir temperature.

Example 1. The impact on the formation with a water cut of 70%, containing oil with a viscosity of 620 MPa * s at reservoir temperature of 21 ° C. The porosity of the formation of 0.29. Permeability 0.6 μm ² . The distance to the well supply loop is R = 92 m, the piezoelectric conductivity coefficient of the formation is 0,0003 m ² / s.

A system of microwave electromagnetic generators with a radiation frequency of 2.5 GHz, connected to the slot antenna by means of a feeder, was lowered into the injection well. The length of the slot antenna L was chosen equal to the thickness of the aquifer of the formation N equal to 6 m. After that, the microwave was applied by the electromagnetic field to the formation with simultaneous injection of water with a flow rate of 15 m ³ / day. The power of the system of microwave electromagnetic wave generators was 18 kW. Oil was extracted from the production well. At the same time, additional oil production amounted to 125 tons.

Example 2. The impact on the formation with a water cut of 65%, containing oil with a viscosity of 500 MPa * s at reservoir temperature of 18 ° C. The porosity of the formation of 0.32. Permeability 0.5 μm ² . The distance to the well supply loop is R = 115 m, the piezoelectric conductivity coefficient of the formation is 0,00025 m ² / s.

First, the production well was put into injection mode. A system of microwave electromagnetic generators with a radiation frequency of 2.5 GHz connected to the slot antenna via a feeder was lowered into well 1. The length of the slot antenna L was chosen equal to the thickness of the aquifer of the formation N equal to 12 m. After that, a microwave was applied to the formation with a microwave field while water was injected to fill 6.25% of the formation’s first space. The power of the system of microwave electromagnetic wave generators was 22 kW. The exposure time was 24 hours. Well exposure was carried out with a duration of 1 day. Further, oil was taken until the bottom temperature dropped to 18 ° C. At the same time, additional oil production amounted to 162 tons.

Using the claimed method in comparison with known methods will increase the coefficient of hydrocarbon recovery by 10-12%.

Claims (2)

1. The method of development of flooded microwave oil deposits by electromagnetic action, including opening the formation, treating the formation, taking oil from the formation, characterized in that a system of microwave electromagnetic generators with a radiation frequency of 2.5 GHz is lowered into the injection well and connected to the slot antenna by means of a feeder, the length of the slot antenna L is chosen equal to the thickness of the aquifer of the formation N and the microwave is exposed to the electromagnetic field with the simultaneous injection of water, the radiation power is determined by the time m heating the injected water in the bottom of the well to the required temperature:
$$N=\rho C\Delta TQ\left(\mathrm{one}-\frac{r_c}{2R_n}\right)$$

,
where ρ is the density of the injected water, kg / m ³ ; R _n is the radius of the bottomhole formation zone, which must be heated, m; C is the heat capacity of the injected water, J / kg * K; ΔТ is the difference between the final and initial temperatures of the bottom water, K; Q - flow rate of injected water, m ³ / s; r _c - well radius, m,
then in the production well, fluid is sampled. 2. A method of developing a flooded microwave oil reservoir by electromagnetic action, including opening a formation, transferring a producing well to an injection well, treating the formation, holding the well without any impact, taking oil from the formation, characterized in that the producing well is first put into injection mode, into the injection well is lowered by a system of microwave electromagnetic generators with a radiation frequency of 2.5 GHz, connected to the slot antenna by a feeder, the length of the slot antenna L is chosen equal to the thickness of the aquifer area of the reservoir N and in the injection mode, water is pumped into the reservoir with simultaneous exposure of the microwave to the reservoir by an electromagnetic field, the radiation power is determined by the time of heating the injected water in the bottom of the well to the required temperature:
$$N=\rho C\Delta TQ\left(\mathrm{one}-\frac{r_c}{2R_n}\right)$$

,
where ρ is the density of the injected water, kg / m ³ ; R _n is the radius of the bottomhole formation zone, which must be heated, m; C is the heat capacity of the injected water, J / kg * K; ΔТ is the difference between the final and initial temperatures of the bottom water, K; Q - flow rate of injected water, m ³ / s; r _c - well radius, m; when 5-10% of the volume of the pore space of the reservoir is filled, the well is exposed, the well is transferred to the producing well and fluid is taken from the producing well.

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