RU2574085C1 - Viscous oil development method and device for its implementation (versions) - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: viscous oil development method includes generation of high pore pressure zone in the formation by supply of preheated water into injecting well and product export from the production casing installed in the developed deposit. At that water is heated up to critical temperature. Device intended for viscous oil development comprises production string, water tank, water pump, water heated connected to the pump output. At that output of the heater is connected to discharge line with the injecting well. At that the discharge line is connected to casing string of the injecting well or to flexible coil tubing and the water heater comprises a nozzle. The production casing is connected by a pipeline to input of the separator having three outputs - the first one for oil, the second one for water and the third one for gas; at that the third separator output is connected to the nozzle.

EFFECT: simplified circuit and design of the device, improved efficiency factor of the process and ensured safety.

10 cl, 13 dwg, 1 tbl

Description

The group of inventions relates to the oil industry and can be used in the development of viscous oil, shale oil, paraffin oil, oil containing kerogen, bitumen, oil from sand and clay rocks of oil-containing deposits. It is also possible to produce oil and gas in offshore fields and in permafrost.

Highly viscous and heavy oil are included in the category of hard-to-recover reserves, which today account for about 36% of the total oil production in the Russian Federation, and experts predict that by 2020 this figure will increase to 77% of all production. To produce one ton of highly viscous or heavy oil, it is necessary to put into development two to five times more hard-to-recover reserves and to drill two to five times more wells in comparison with active reserves. The extraction coefficient of high viscosity and heavy oil, as a rule, is 2-3 times lower than the recovery ratio of oil related to active reserves.

Another equally significant challenge for the Russian oil industry is the organization of industrial oil production from the Bazhenov formation. The Bazhenov Formation is represented by the source rock, in which the processes of conversion of kerogen to hydrocarbons have not yet been completed. Highly saturated clay deposits of the Bazhenov Formation are almost ubiquitous within the West Siberian Lowland over an area of more than 1 million square kilometers. The total geological oil reserves in them are estimated at between 0.8 and 2.1 trillion tons, and the growth potential of recoverable oil reserves is estimated at no less than 30-40 billion tons. The depth of the Bazhenov Formation is 2500-3000 meters. The thickness of the layer is 10-40 meters. The temperature of the reservoir is 80-130 degrees Celsius. Due to the fact that the rock of the Bazhenov formation has complex capacitive and filtration properties, the coefficient of oil recovery from the Bazhenov formation during its development by traditional methods does not exceed 3-5 percent. With the use of new technologies theoretically reaches 49%.

There is a method of developing an oil deposit by injecting an oxygen-containing mixture into the formation, in which to increase the efficiency of oil recovery and the safety of work, a coolant is pumped into the bottom-hole zone of the injection well with a temperature and volume that ensures the full consumption of the oxidizing agent at the process initiation stage (USSR AS No. 1090060).

This method guarantees the safety of the process only at the stage of its initiation. When a heat wave moves through a formation under low-viscosity oil conditions and the fuel deficit associated with this circumstance, oxygen can penetrate into unheated sections of the formation, up to the trunks of production wells. All this provokes an explosive situation at the development site.

In addition, in all known development methods, the natural energy of the field is not taken into account when choosing the object of influence, and at the stage of the initiation of the process, it is assumed that the thermodynamics of the bottom-hole zone are changed by introducing energy from the outside (from the surface), which does not contribute to the achievement of the maximum possible oil recovery and significantly impairs the cost-effectiveness of known ways.

A known method of developing an oil field according to the patent of the Russian Federation for the invention No. 2139421, IPC publ. 2010, in which, in order to increase oil recovery of light oil fields, it is planned to use thermogas treatment.

According to the known method, the essence of thermogas exposure is that an oxygen-containing mixture is pumped into the formation through an injection well - air, which, as a result of spontaneous in-situ oxidation processes, is transformed into a highly effective displacing agent, partially or completely mixed with the displaced oil. Such a transformation is ensured both due to the formation of CO ₂ as a result of in-situ oxidation processes, and due to the transition of light fractions into the gas phase under the influence of thermal energy released as a result of in-situ oxidation processes. An important criterion for the implementation of thermogas exposure is the level of the initial reservoir temperature, which according to the above method should exceed 65 ° C. The need to comply with this condition is determined by the fact that the intensity of spontaneous in-situ oxidation processes ensures almost complete consumption of oxygen injected into the formation in the zone, the dimensions of which are several times less than the distance between the wells. This means that the injection of an oxygen-containing mixture provides not only the in-situ formation of a displacing agent miscible with the displaced oil, but also the safety of the process.

Thus, the conditions provided for by the known method for the implementation of the thermogas development method make it possible to provide high efficiency for the displacement of light oil from the covered drained zones of oil-bearing rocks.

However, according to the non-trivial features of the filtration-capacitive properties of the rocks of the Bazhenov formation and the hydrocarbon content in them, the traditional approach to the formation of a development system with any method of exposure cannot provide effective oil recovery. In this regard, it should first of all be pointed out to the extremely wide range of filtration-capacitive characteristics of lithotypes of rocks of the Bazhenov formation noted above, the unevenness of their development both laterally and vertically. The consequence of such heterogeneity of the reservoir properties of the rocks of the Bazhenov formation is the uneven distribution of drainage zones, often the unpredictable nature of their hydrodynamic connection.

It can be assumed that such a non-trivial nature of the reservoir of the Bazhenov formation is one of the main reasons for the unsatisfactory performance of the fields of the Bazhenov formation in the previous three decades. That is why traditional waterflooding is also assessed as an unpromising way to develop such deposits.

In this regard, it should be noted the important feature of the Bazhenov formation deposits noted above, according to which the light oil contained in the matrix (microcracked part of the rocks) can hardly be extracted using traditional development methods (natural mode, water flooding). It is also obvious that these methods cannot involve hydrocarbon resources of organic matter - kerogen.

The technology of the thermogas method for developing light oil fields with conventional reservoirs according to the aforementioned method provides for the formation of an effective displacing agent miscible with oil in the formation due to spontaneous in-situ oxidation processes when air is injected into the formation. Therefore, the main criterion for the implementation of this technology is the initial reservoir temperature, the level of which should be above 65 ° C.

Field domestic and international experience has confirmed that the injection of air into such reservoirs actually leads to the formation of an effective displacing agent in the reservoir, which ensures oil recovery up to 60% and higher in fields with low permeability reservoirs.

Obviously, the implementation of thermogas exposure in the fields of the Bazhenov formation can also increase the efficiency of oil recovery from drained zones. However, according to the above, this is not enough, because for the effective development of deposits of the Bazhenov formation it is necessary to provide the solution of the following problems:

- to ensure the maximum possible extraction of light oil from the non-drained matrix, as well as hydrocarbons from kerogen, contained in both non-drained and drained rocks;

- to ensure the maximum possible development of the drainage zone not only in the matrix, but also in macrocrack rocks;

- to ensure effective displacement of light oil from drained areas.

To solve these problems, the technology of thermogas impact on the rocks of the Bazhenov formation should be characterized by the following parameters:

- in-situ oxidation processes should ensure the formation in the drained lithotypes of rocks moving zones of heat generation;

- the dimensions of the heat generation zone, the speed of its movement to the producing wells, as well as the temperature level in it should provide the maximum possible volume of oil-containing non-draining matrix to a temperature of at least 250-350 ° C, at which at least 40-50% is extracted according to generalized experimental data contained in the light oil matrix.

In this regard, it should be emphasized that with the increase in the size of the thermal rim, the size of the heating zone of the non-drained zone also increases. Simultaneously with an increase in the speed of movement of the thermal rim in the drained zone, the heating depth of the adjacent non-drained zone decreases.

In turn, the size of the heat-generating rim in the drained zone and its speed of movement are largely determined by the rate of injection of the oxygen-containing mixture, in particular air and water, and the air-water ratio. Moreover, if the rate of injection of working agents leads to an increase in the size of the heat generation zone, then the water-air ratio can lead to both its increase and its reduction.

A known method and device for the development of viscous oil according to the patent of the Russian Federation for the invention No. 2418944, IPC EV 43/04, publ. 05/20/2011

The essence of the method is that they create zones of in-situ oxidative and thermodynamic processes in the formation by introducing a downhole gas generator into the horizontal part of the casing of the casing and igniting the fuel in it and mixing water into the combustion products,

The device comprises a water heater, fuel tanks and an oxidizing agent on the surface, a gas generator installed in the horizontal part of the casing of the heating well, connected by pipelines to the oxidizing tanks, fuel tanks and a water heater.

The principal feature of the proposed development method is that the value of the air-water ratio of the water and air injected into the drained lithotypes of the rocks of the Bazhenov formation, the rate and pressure of their injection are established from the condition that it is necessary to warm up to temperatures not lower than 250 ° C of the maximum possible volume of the oil-containing impenetrable matrix surrounding drainage heat-generating zones of the reservoir. The implementation of such regulation makes it possible to ensure not only effective miscible displacement of light oil from drained zones, but also the introduction into active development of oil-containing micropermeable zones.

In this regard, it should be emphasized that the injection of a water-air mixture allows us to realize not only in-situ oxidation processes, as provided for in a known manner, but also provide on this basis a miscible displacement of light oil and thermal effects, but also hydraulic action. As noted above, this effect allows to increase the drainage zone due to the creation of additional new cracks and partial opening of existing microcracks. It is obvious that the simultaneous thermal and hydraulic effects should lead to a synergistic result in the expansion of the drainage zone and a significant increase in its filtration characteristics.

The disadvantages of this method and device are the complexity of the circuit and design.

A known method and device for the development of viscous oil according to US Pat. The Russian Federation for utility model No. 90492, IPC Е21В 43/24, publ. 01/10/2010, a prototype of the method and device.

A method for developing viscous oil fields involves creating a zone of in-situ high pressure in the formation by introducing preheated water into the injection well and pumping the produced product out of the production string installed in the developed field.

A device for developing a viscous oil field contains a production casing, a water tank, a water pump, a water heater connected to the output of the pump, while the output of the heater is connected by an injection pipe to an injection well.

The disadvantages of this method and device are the complexity of the circuit and design and high energy costs.

The task of creating a group of inventions is to simplify the circuit and design of the device and reduce energy costs in oil production.

Due to the pressure of the water column in the supply pipe, the height of which can be several kilometers, additional pressure of the coolant - water will be formed.

The solution of these problems was achieved in the method of developing viscous oil fields, including the creation of an in-situ high pressure zone in the reservoir by introducing preheated water into the injection well and pumping the produced product out of the production string installed in the developed field by heating the water to a critical temperature. The water pressure at the outlet of the water pump is set so that, taking into account the hydrostatic pressure of the water in the well in the bottomhole, its pressure exceeds the critical pressure of the water. Water is heated using gas produced in the field being developed. Water is heated with the help of gas condensate produced in the developed field.

The solution of these problems was achieved in a device for developing a viscous oil field containing a production string, a water tank, a water pump, a water heater connected to the pump outlet, while the heater outlet is connected by a discharge pipe to an injection well, so that the injection pipe is connected to the casing injection well, the water heater contains a nozzle, and the production string is connected by a pipe to the entrance to the separator having three exits, the first for oil, in the second for water and the third for gas, while the third outlet of the separator is connected to the nozzle.

The solution of these problems was achieved in a device for developing a viscous oil field containing a production casing, a water tank, a water pump, a water heater connected to the pump outlet, while the outlet of the water heater is connected by an injection pipe to an injection well so that the injection pipe is connected to a flexible pipe coiled tubing and lowered into the casing of the injection well, the water heater contains a nozzle, and the production string is connected by a pipe to the inlet into a separator having three exits, the first for oil, the second for water and the third for gas, while the third outlet of the separator is connected to the nozzle. A device for developing a viscous oil field may include a control unit connected by electrical connections to the drives. A device for developing viscous oil fields may include a control unit connected by electrical connections to the actuators, and pressure, temperature and water flow sensors at the outlet of the heater, connected by electrical connections to the control unit. The control unit may comprise a computer. The computer may be configured to automatically maintain a predetermined pressure at the bottom of the well.

The invention is illustrated in the drawings of FIG. 1 ... 13, where:

- in FIG. 1 shows a diagram of a first embodiment of the device,

- in FIG. 2 shows a diagram of a second embodiment of the device,

- in FIG. 3 shows a diagram of a third embodiment of the device

- in FIG. 4 shows the design of a water pump with a drive in the form of an electric motor,

- in FIG. 5 shows the design of a water pump with a drive in the form of an internal combustion engine,

- in FIG. 6 shows the control and management diagram,

- in FIG. 7 shows a control circuit using a computer,

- in FIG. 8 is a diagram of the state of water,

- in FIG. 9 change in water pressure depending on the depth of the well,

- in FIG. 10 change in water pressure depending on the depth of the well,

- in FIG. 11 change in water pressure depending on the depth of the well,

- in FIG. 12 shows an algorithm for automatically adjusting water pressure in a well,

- in FIG. 13 shows a diagram of oil and gas production from a production casing and their separation and purification.

A device for developing viscous oil (Fig. 1 ... 13) contains an injection well 1, in which a casing 2 is installed, having a cavity 3, vertical and horizontal sections 4 and 5, respectively. Perforation 6 was performed on the entire horizontal section 5. In the bottom of the horizontal section 5 of the casing 2, a shoe 7 with an axial hole 8 was installed. The horizontal section 5 is located within the oil reservoir 9. In the upper part of the casing 2, i.e. above the surface 10 of the rock 11, the collector 12 is made with a cavity 13 inside it.

The device has the following equipment (Fig. 1) mounted on the surface 10: a water tank 14 with a pipe 15 connected to it with a pump 16 having a drive 17, the output of which is connected to a water heater 18, the output of which is connected by a pipe 19 to the cavity 13 of the collector 12 .

The water heater 18 comprises a housing 20 to which an exhaust pipe 21 is connected. A section of the heat exchanger 23 is installed in the cavity 22 of the housing 20 and a nozzle 24 to which a fuel pipe 25 is connected with a fuel pump 26 having a drive 27.

In FIG. 2 shows a second variant of the device, which additionally contains a tubing string 28 having a perforation 29 in the lower part (within the horizontal section).

The third version of the device (Fig. 3) instead of the tubing string 28 contains coiled tubing 30 with a flexible pipe 31, at the end of which a receiver 32 is attached with holes 33 over the entire surface.

In FIG. 4 shows in more detail the design of the water pump 16 with the drive 17. The water pump 16 contains an inlet housing 34, a screw 35 and a centrifugal impeller 36 mounted on the shaft 37, an output housing 38, a support 39 and a seal 40. As a drive 17 can be used an electric motor 41 (Fig. 4), which is connected by an electric wire 42 through a switch 43 to a power source 44.

Perhaps the use as a drive 17 of the internal combustion engine 45 (Fig. 5).

CONTROL AND MANAGEMENT SYSTEM

The control system is shown in FIG. 6 and comprises a water flow regulator 46 and a valve 47.

The control system includes a water pressure sensor 48, a water flow sensor 49, a water temperature sensor 50.

The device comprises a control unit 51, which is electrically connected 52 to sensors 48 ... 50 and to a water flow controller 46. In addition, the control unit 51 is electrically connected 52 to actuators 17 and 27.

In FIG. 7 shows a control circuit using a computer 53 to which a monitor 54, a keyboard 55, a mouse-type manipulator 56, a sensor controller 57 to which sensors 48 ... 50 are connected, and a control controller 58 to which electric drives 52 are connected are connected by electrical connections 52 17 and 27.

In FIG. 8 is a water state diagram showing a critical point: a critical pressure of 218.5 atmospheres and a critical temperature of 374 ° C. With these parameters, the difference between the liquid and gaseous states disappears.

In FIG. 9 shows the change in water pressure along the depth of the well pos. 59, it can be seen that the pressure increases due to the hydrostatic column, in FIG. 10 - change in water temperature along the depth of the well - pos. 60, which always falls, since superheated water gives off heat to the ground, and in FIG. 11 - change in the density of water (steam) along the depth of the well pos. 61.

In FIG. 12 shows an algorithm for automatically adjusting supercritical pressure at the bottom of a well, described in more detail below. In FIG. 13 is a diagram of oil and gas production and separation. Oil and gas are produced using production casing 62, in the upper part of which a manifold 63 is made. A separator 64 is connected to the manifold 63, which separates the produced product into oil, gas and water. The separator 64 is connected by the first outlet to the oil pipeline 65, the second exit - to a gas dryer 66, to the output of which a gas liquefaction unit 67 is connected. The first outlet 67 of this installation is connected to the oil pipeline 65. The second outlet 68 through the valve 69 is connected by a pipe 70 to the fuel pipe 25 for power preheater 18 with liquefied gas.

To supply the heater with non-liquefied gas, the outlet from the gas dryer 66 through the valve 71 is also connected to the fuel line 24. This will reduce the cost of heating the water, since imported fuel will be more expensive in any case.

To start the installation at the initial moment, you may need imported fuel.

DEVICE OPERATION

Before the work is completed, an injection well 1 is drilled (Fig. 1) and a casing 2 is installed in it. In this case, the horizontal part 4 of the casing 2 is completely perforated with holes 5 (Fig. 1). The drive 17 and 27 (Fig. 6) is launched, which rotates the centrifugal impeller 35 of the water pump 16. The heated water enters the cavity 3 and then through the openings 6 and the hole 8 in the shoe 7 into the injection well 1.

In the second embodiment, using coiled tubing 30 on a flexible pipe 31 into the casing 2 lower the receiver 32.

The drive 17 and 27 (Fig. 6) is launched which rotates the centrifugal impeller 35 of the water pump 16. The heated water enters the cavity 3 through the openings 33 of the receiver 32.

In all cases, the same thermodynamic processes occur. The pressure of the water column as the well deepens increases due to hydrostatic pressure (Fig. 9), and the temperature decreases (Fig. 10). The density of water increases (Fig. 11), and after injection it turns into steam and its density decreases several times.

Evaporated water vapor warms up the oil reservoir 9 and the heavy oil fractions contained therein, which are then pumped out.

The process is controlled (Fig. 6) automatically using the control unit 51 via electrical connections 52 received from sensors 48 ... 50 or manually.

It is possible to automatically set any supercritical pressure at the bottom of injection well 1 by changing the pressure P0 at the entrance to well 1. Measuring the water pressure in the lower part of the well and transmitting its value up is technically difficult due to high temperatures in this zone and poor rock permeability.

Using a computer 53 (FIG. 7) and initial data in the form of thermophysical properties of water and steam, the algorithm shown in FIG. eleven.

The desired value of p1 is set by introducing it into the memory of computer 53. Computer 53 calculates the calculated value of the same pressure P1i, which will differ from the set P1. The difference between the current and previous calculations is determined:

ΔP = P1i-P1

The design pressure at the well inlet 1 P0 is increased by this difference and the calculation is repeated many times until this difference P is less than 0.1 atm.

The power of the heater 16 is expediently carried out using gas produced by the production string 62, which is made next to the injection well 1, intended for heating the oil reservoir 9.

The comparison results of the proposed method for the production of viscous oil with the prototype are given in table. one

Superheated water is injected into the reservoir from the surface of the earth or from an offshore platform with a subcritical temperature higher than critical (above 374 degrees Celsius) and high overpressure, which allows reaching the indicated water temperatures without boiling and without steam formation directly on the surface, but with the formation of a large amount of steam in bottom-hole or bottom-hole zone of the well when delivering superheated water to a ground-based boiler plant.

At a high overpressure of 218.5 atmospheres, water can be heated to a critical point corresponding to a temperature of 374 ° C (Fig. 7). At the same time, the density of water during its heating to a critical point will remain almost unchanged from the original, which allows you to deliver it to the place of use - bottom-hole or bottom-hole zone of the well in a compact form with low heat loss due to high speed due to pressure difference - higher on the surface of the earth and lower in the well. At the same time, due to lower pressure in the well, water will boil and a large amount of steam will be ejected into the well.

Due to the pressure of the water column in the supply pipe, the height of which can be several kilometers, additional pressure of the heat carrier - water of the order of 100-300 atmospheres will be formed. This will unload the load on the water pump and reduce the energy costs of its drive.

Of significant interest is the so-called critical point of the substance, at which the difference between the liquid and its vapor disappears, and, therefore, the latent heat of vaporization is zero. The critical point is characterized by critical pressure and critical temperature.

Critical pressure is the pressure at which and above which the liquid cannot be converted into vapor by any increase in temperature. So, for water, the critical pressure is 221.3 bar (225.65 kgf / cm ² ). This means that water, when compressed to 221.3 bar (or higher), will never turn into steam!

And the water vapor obtained in the steam preheater of the boiler unit with a temperature of 374.15 ° C cannot be condensed, no matter how its pressure is increased.

The use of a group of inventions allowed:

1. To simplify the scheme for supplying hot water to the oil reservoir.

2. At the development site using the proposed method, oil recovery of 70% is achieved.

3. To reduce the warm-up time of the oil reservoir to 250 ° C from 14 months to 15 days compared with the prototype.

4. At the same time as oil production, produce and dispose of gaseous hydrocarbons.

5. Improve the ecology of the mining process.

Claims (10)

1. A method of developing viscous oil fields, including creating an in-situ high pressure zone in the reservoir by introducing preheated water into the injection well and pumping the produced product out of the production string installed in the developed field, characterized in that the water is heated to a critical temperature. 2. A method for developing a viscous oil field according to claim 1, characterized in that the water pressure at the outlet of the water pump is set such that, taking into account the hydrostatic pressure of the water in the well in the bottomhole, its pressure exceeds the critical water pressure. 3. The method of developing a viscous oil field according to claim 1 or 2, characterized in that the water is heated using gas produced in the field being developed. 4. A method for developing a viscous oil field according to claim 1 or 2, characterized in that the water is heated using gas condensate produced in the field being developed. 5. A device for developing a viscous oil field containing a production casing, a water tank, a water pump, a water heater connected to the pump outlet, wherein the heater outlet is connected by an injection pipe to an injection well, characterized in that the injection pipe is connected to an injection well casing , the water heater contains a nozzle, and the production casing is connected by a pipe to the inlet of the separator having three exits, the first for oil, the second for water and a third gas, wherein the third separator connected to the outlet nozzle. 6. A device for developing a viscous oil field containing a production casing, a water tank, a water pump, a water heater connected to the pump outlet, wherein the outlet of the water heater is connected by a discharge pipe to an injection well, characterized in that the injection pipe is connected to a flexible coiled tubing and lowered into the casing of the injection well, the water heater contains a nozzle, and the production string is connected by a pipe to the inlet of the separator having When output, the first - for oil and one for water and one for gas, wherein the third separator connected to the outlet nozzle. 7. A device for developing a viscous oil field according to claim 6, characterized in that it comprises a control unit connected by electrical connections to the drives. 8. A device for developing viscous oil fields according to claim 7, characterized in that it comprises a control unit connected by electrical connections to the actuators and pressure, temperature and water flow sensors at the outlet of the heater, connected by electrical connections to the control unit. 9. A device for developing a viscous oil field according to claim 8, characterized in that the control unit comprises a computer. 10. A device for developing a viscous oil field according to claim 9, characterized in that the computer is configured to automatically maintain a given pressure in the lower part of the well.

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