CN107345480A - A kind of method of heating oil shale reservoir - Google Patents

Abstract

The invention relates to a method for heating an oil shale reservoir, comprising: respectively constructing a production well and a heating well in the oil shale area of the target reservoir; Pressurizing; injecting the pressurized heating medium into the medium heater to heat the heating medium to a predetermined temperature; injecting the heated heating medium into the oil shale area through the heating well to cool the oil shale area The oil shale is heated; the oil shale is heated by the heating medium to pyrolyze the oil shale to generate pyrolysis products, so that the pyrolysis products flow into the production well and are extracted to the ground; The pyrolysis products are separated to generate hydrocarbon gas that can heat the heating medium and heating medium that can be re-injected into the heating well for recycling after passing through the gas booster and medium heater in sequence. The method has the advantages of high recovery efficiency and large recovery scale.

Description

A method of heating an oil shale reservoir

technical field

The invention relates to the technical field of in-situ mining of oil shale, in particular to a method for heating an oil shale reservoir.

Background technique

In-situ mining of oil shale refers to heating the oil shale reservoir at a high temperature, generally at a temperature of about 350-500°C, converting the solid kerogen in the oil shale into liquid hydrocarbons, and then recovering oil through traditional oil and gas drilling Process The process of extracting liquid hydrocarbons from the ground. With the increasing pressure of environmental protection, the in-situ mining of oil shale is an inevitable trend of large-scale commercial development of oil shale in the future.

Oil shale in-situ mining technology can be divided into fluid heating, radiation heating and combustion heating according to heating methods. Among them, fluid heating technology has attracted wide attention due to its advantages of fast heating speed, short heating cycle and full use of retort gas.

At present, researches on heating technologies for in-situ mining of oil shale mainly include CRUSH technology of Chevron Corporation; CCR technology (Conduction, Convection, Reflux conduction, convection, reflux) ); IIST-VTPC Technology (Israel In-Situ Technology-Volume, Temperature, Pressure, Chemical Reactions) of Israel Asia Group.

The methods described by the above-mentioned companies are still in the conceptual design or indoor research stage for oil shale in-situ mining technology, and have not elaborated on how to realize the injection and circulation of high-temperature and high-pressure gas. Therefore, there is a need to provide an efficient, environmentally friendly, and economical method for heating oil shale reservoirs.

Contents of the invention

In view of the above problems, according to the present invention, a method for heating oil shale reservoirs is proposed, including: respectively constructing production wells and heating wells in the oil shale area of the target reservoir; heating the medium to pressurize the heating medium; injecting the pressurized heating medium into a medium heater to heat the heating medium to a predetermined temperature; passing the heated heating medium through the heating Injecting a well into the oil shale region to heat the oil shale in the oil shale region; heating the oil shale through the heating medium to pyrolyze the oil shale , so as to generate pyrolysis products, so that the pyrolysis products flow into the production well and are extracted to the surface; by separating the pyrolysis products produced in the production well, the heating medium capable of heating the heating medium is generated respectively The hydrocarbon gas and the heating medium that can be re-injected into the heating well for recycling after passing through the gas booster and the medium heater in sequence. According to the present application, using the method of the present application, the heating medium generated after the separation of the pyrolysis product can be returned to the ground to continue to be recycled, that is, it can be injected into the gas booster again for pressurization, and then injected into the Heating is carried out in the medium heater, so that it is injected into the oil shale region through the heater well to heat the oil shale in the oil shale region. In this way, resources are greatly saved, energy can be fully utilized, and a self-circulating system that does not require external energy supply is finally achieved.

In addition, the hydrocarbon gas separated from the pyrolysis product can heat the heating medium in the medium heater, thereby achieving the advantages of energy saving, low cost, strong operability, high recovery efficiency and large recovery scale.

In one embodiment, after the production well and the heating well are constructed, the production well and the heating well are respectively completed through thermal insulation sleeves. By setting the thermal insulation sleeves on the outer peripheral walls of the production well and the heating well, it can play the role of thermal insulation for the production well and the heating well, and avoid the heating medium in the production well and the heating well. The temperature drops too fast, resulting in serious disadvantages of heat loss.

In one embodiment, the method further includes increasing the porosity and permeability of the target reservoir by blasting or artificially stimulating the production well and the heater well.

In one embodiment, the pressure of the pressurized heating medium is greater than the reservoir pressure of the oil shale.

In one embodiment, the predetermined temperature of the heated heating medium is greater than the pyrolysis temperature of the oil shale.

In one embodiment, the production well and the heating well are exploded or artificially modified to construct fractures in the target reservoir, and the fractures can communicate with the production well and the heating well respectively. well.

In one embodiment, the pyrolysis product is transported to the surface of the target reservoir by an oil pump, and after cooling, the pyrolysis product is passed to a three-phase separator to separate the pyrolysis product Thus, oil, gas and water are generated, and the oil, water and gas mixture are generated by separating the oil, gas and water.

In one embodiment, the pyrolysis product flows into the production well through the fracture.

In one embodiment, said gas mixture comprises said heating medium and said hydrocarbon gas.

In one embodiment, the method further includes selecting the corresponding gas-generating equipment according to the difference of the heating medium.

Compared with the prior art, according to the present application, the heating medium generated after the separation of the pyrolysis product can be returned to the ground to continue to be recycled, that is, it can be injected into the gas booster again pressurized, and then injected into the medium heater for heating, so as to inject into the oil shale area of the target reservoir through the heater well to heat the oil shale in the oil shale area. In this way, resources are greatly saved, energy can be fully utilized, and a self-circulating system that does not require external energy supply is finally achieved.

In addition, the hydrocarbon gas separated from the pyrolysis product can heat the heating medium in the medium heater, thereby achieving the advantages of energy saving, low cost, strong operability, high recovery efficiency and large recovery scale.

Description of drawings

Hereinafter, the present invention will be described in more detail based on the embodiments with reference to the accompanying drawings. In the picture:

Fig. 1 is a schematic flowchart of steps of a method for heating an oil shale reservoir according to an embodiment of the present application.

Fig. 2 is a schematic structural diagram of the heated oil shale reservoir of the present application.

In the figures, the same parts are given the same reference numerals. The drawings are not drawn to true scale.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

There is no record in the prior art on how to inject high-temperature and high-pressure gas into oil shale, and make the high-temperature and high-pressure gas returned to the ground continue to be recycled. Therefore, this application is aimed at this technical problem A method for heating oil shale reservoirs is presented. Next, the specific steps of the method will be described in detail.

The temperature range of the above-mentioned high-temperature and high-pressure gas is greater than or equal to 350 degrees and less than or equal to 500 degrees, and the range of the gas pressure of the high-temperature and high-pressure gas is greater than or equal to 2 MPa (megapascals) and less than or equal to 5 MPa (megapascals).

As shown in Figure 1 and Figure 2, wherein, Figure 1 schematically shows that the method includes:

Step S410, respectively constructing production wells 2 and heating wells 3 in the oil shale area 11 of the target reservoir 1. Wherein, the production well 2 and the heating well 3 are both vertical wells and are drilled from the surface of the corresponding oil shale area 11 of the target reservoir 1 from top to bottom.

In one embodiment, the target reservoir 1 may be an oil shale reservoir.

Step S420 , injecting the heating medium 100 into the gas increasing machine 5 through the gas making equipment 4 to pressurize the heating medium 100 .

In one embodiment, the heating medium 100 may be nitrogen or carbon dioxide. The heating medium 100 is mainly used to heat the oil shale in the target reservoir 1, that is, by injecting a high-temperature and high-pressure heating medium 100 into the heating well 3 as described below, to heat the oil shale in the target reservoir 1 rock 7, so that the immature solid kerogen in the oil shale 7 is converted into liquid hydrocarbons due to pyrolysis, and then the liquid hydrocarbons are extracted from the ground through the production well 2 through the oil and gas drilling and recovery process.

In a specific example, when the heating medium 100 is nitrogen, the pressure swing adsorption nitrogen production method can be used to produce nitrogen, so as to ensure that the purity of nitrogen can be 98%. The pressure of the nitrogen gas is 0.7MPa (megapascal), and the temperature is 40 degrees.

When the heating medium 100 is carbon dioxide, it is usually transported in a liquid form, and since the liquid carbon dioxide needs to be heated, it is usually transported in a gas cylinder at normal temperature and pressure.

In step S420, the volume of nitrogen injected into the gas booster 5 by the gas-making equipment 4 may be 3000Nm ³ /h (standard square/hour), that is, the nitrogen is injected into the gas booster 5 under the standard state The injected volume may be 3000 cubic meters per hour.

In step S420, since the temperature resistance of the gas booster 5 is low, the heating medium 100 produced by the gas production equipment 4 should first be pressurized by the gas booster 5, when the heating medium 100 After pressurizing to a predetermined pressure, the heating medium 100 is heated.

In addition, since the pressurized heating medium 100 needs to be heated, the gas booster 5 does not need to be cooled after the last stage of compression.

The gas pressure of the heating medium 100 after being pressurized by the gas booster 5 is 5 MPa, and the temperature is greater than or equal to 90 degrees and less than or equal to 110 degrees.

Step S430, injecting the pressurized heating medium 100 into the medium heater 6 to heat the heating medium 100 to a predetermined temperature.

The medium heater 6 can be a gas heater, the pressure resistance of the gas heater is 5 MPa, and the maximum heating temperature is 800 degrees, so as to meet the demand of injecting nitrogen gas into the oil shale area 11 in the target reservoir 1 .

After the heating medium 100 is heated by the medium heater 6 , the temperature of the heating medium 100 can reach about 500 degrees.

In step S440, the heated heating medium 100 is injected into the oil shale area 11 through the heating well 3, so as to heat the oil shale 7 in the oil shale area 11.

In step S450, the oil shale 7 is heated by the heating medium 100 to pyrolyze the oil shale 7 to generate a pyrolysis product 8, so that the pyrolysis product 8 flows into the production well 2 and is extracted to the surface.

In step S460, the pyrolysis product 8 in the production well 2 is separated to generate the hydrocarbon gas 81 capable of heating the heating medium 100 and the hydrocarbon gas 81 that can pass through the gas booster 5 and the medium heater 6 in sequence and reinject into the heating medium 100. The heating medium 100a is circulated in the well 3. It can be seen that the method of the present application can ensure that the oil shale 7 is developed at a lower cost under in-situ conditions. At the same time, the temperature, pressure and injection volume of the heating medium 100 can be controlled constantly on the surface of the target reservoir 1 (that is, on the ground), thereby greatly improving the quality of generated oil and gas.

In addition, the heating medium 100a generated after the pyrolysis product 8 is separated can be returned to the ground to continue to be recycled, that is, it can be injected into the gas booster 5 again for pressurization, and then injected into the medium heater 6 Heating is performed so that it is injected into the oil shale region 11 through the heater well 3 to heat the oil shale 7 . In this way, resources are greatly saved, energy can be fully utilized, and a self-circulating system that does not require external energy supply is finally achieved.

In addition, the hydrocarbon gas 81 separated from the pyrolysis product 8 can heat the heating medium 100 in the medium heater 6, thereby achieving energy saving, low cost, strong operability, high recovery efficiency and recovery scale Big plus.

As shown in FIG. 2 , after the production well 2 and the heating well 3 are manufactured, the production well 2 and the heating well 3 are respectively completed through the thermal insulation casing 9 . Specifically, by setting the thermal insulation sleeves 9 on the outer peripheral walls of the production well 2 and the heating well 3 respectively, it can play the role of thermal insulation for the production well 2 and the heating well 3, and avoid heating The temperature of the medium 100 in the production well 2 and the heating well 3 drops too fast, which leads to serious disadvantages of heat loss.

The method of the present application also includes blasting or artificially transforming the production well 2 and the heating well 3 to increase the porosity and permeability of the target reservoir 1 . Among them, the above-mentioned artificial transformation methods can be acidification or hydraulic fracturing. However, since the above-mentioned artificial modification method is well known to those skilled in the art, for the sake of space saving, no detailed description is given here.

As shown in FIG. 2 , the pressure of the pressurized heating medium 100 is greater than the reservoir pressure of the oil shale 7 . In this way, since the pressure of the heating medium 100 is greater than the reservoir pressure of the oil shale 7, the heating medium 100 can be successfully injected into the area corresponding to the oil shale 7 of the heating well 3, so that the oil shale 7 is heating.

The predetermined temperature of the heated heating medium 100 is greater than the pyrolysis temperature of the oil shale 7 . In this way, the oil shale 7 can be pyrolyzed smoothly. In addition, due to the long route from the medium heating 6 to the heating well 3, considering the heat loss along the course during the injection of the heating medium 100, it is necessary to make the predetermined temperature of the heating medium 100 higher than that of the oil shale 7. pyrolysis temperature.

In one embodiment, the predetermined temperature may be 500 degrees.

As shown in FIG. 2 , the above-mentioned hydraulic fracturing is performed on the production well 2 and the heating well 3 to construct fractures 12 in the target reservoir 1 , and make the fractures 12 communicate with the production well 2 and the heating well 3 respectively. It can be seen that the formation of the crack 12 provides a flow channel for the flow direction of the pyrolysis product 8 .

In a specific embodiment, the fracture 12 can be one or more fractures 12 with different lengths, widths and heights left in the target reservoir 1, so that the production well 2 and heating in the target reservoir 1 A new fluid channel is established between wells 3. It can be seen that the formation of the fracture 12 greatly improves the production of the oil and gas well.

After the above-mentioned pyrolysis product 8 enters the production well 3, the pyrolysis product 8 is transported to the surface 13 (earth surface) of the target reservoir 1 by the pumping unit 10, and the pyrolysis product 8 is passed to the three-phase phase after cooling. The separator 20 separates the pyrolysis product 8 to generate oil, gas and water 30 , and generates oil 40 , water 50 and gas mixture 60 by separating the oil, gas and water 30 . Wherein, the gas mixture 60 includes a heating medium 100 a and a hydrocarbon gas 81 .

After the oil-gas-water 30 is transported to the surface by the pumping unit 10 , the oil-gas-water 30 is cooled and then separated and measured by the three-phase separator 20 . Wherein, the separated oil 40 and water 50 can be measured by a turbine flowmeter, and the hydrocarbon gas 81 and the heating medium 100a can be measured by an orifice flowmeter.

The above-mentioned turbine flowmeter and orifice flowmeter have the advantages of accurate measurement. In addition, because the structure and use of the turbine flowmeter and orifice flowmeter are well known to those skilled in the art, for the sake of saving space, this will not be described. detail.

The pyrolysis product 8 flows into the production well 2 through the fracture 12 .

In one embodiment, the method further includes selecting the corresponding gas generating equipment 4 according to the difference of the heating medium 100 . Specifically, the corresponding gas generating equipment 4 can be selected according to whether the heating medium 100 is nitrogen or carbon dioxide.

In summary, using the method of the present application, the heating medium 100a generated after the separation of the pyrolysis product 8 can be returned to the ground to continue to be recycled, that is, it can be injected into the gas booster 5 again for pressurization , and then injected into the medium heater 6 for heating, thereby injecting into the oil shale 7 through the heating well 3 to heat the oil shale 7 . In this way, resources are greatly saved, energy can be fully utilized, and a self-circulating system that does not require external energy supply is finally achieved.

In addition, the hydrocarbon gas 81 separated from the pyrolysis product 8 can heat the heating medium 100 in the medium heater 6, thereby achieving energy saving, low cost, strong operability, high recovery efficiency and recovery scale Big plus.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for parts thereof without departing from the scope of the invention. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims (10)

1. A method of heating an oil shale reservoir comprising: Construct production wells and heater wells respectively in the oil shale area of the target reservoir; Injecting a heating medium into the gas booster through the gas making equipment to pressurize the heating medium; injecting the pressurized heating medium into a medium heater to heat the heating medium to a predetermined temperature; injecting the heated heating medium into the oil shale area through the heating well to heat the oil shale in the oil shale area; heating the oil shale with the heating medium to pyrolyze the oil shale to generate a pyrolysis product, so that the pyrolysis product flows into the production well and is extracted to the ground; Separate the pyrolysis products produced in the production well to generate hydrocarbon gas capable of heating the heating medium and re-inject it after passing through the gas booster and the medium heater in sequence The heating medium that is circulated in the heating well. 2. the method for heating oil shale reservoir according to claim 1, it is characterized in that, after constructing described production well and described heating well, by thermal insulation sleeve pipe to respectively to described production well and described heating well The heater well is completed. 3. The method for heating oil shale reservoirs according to claim 2, characterized in that, the method also includes blasting or artificially transforming the production wells and the heating wells to increase the temperature of the target reservoirs. porosity and permeability. 4. The method for heating an oil shale reservoir according to claim 1, characterized in that the pressure of the pressurized heating medium is greater than the reservoir pressure of the oil shale. 5. The method for heating an oil shale reservoir according to claim 1, characterized in that, the predetermined temperature of the heated heating medium is greater than the pyrolysis temperature of the oil shale. 6. The method for heating an oil shale reservoir according to claim 3, characterized in that, by carrying out explosion or artificial transformation on the production well and the heating well, to construct fractures in the target reservoir, And make the fractures communicate with the production well and the heater well respectively. 7. The method for heating an oil shale reservoir according to claim 1, characterized in that, the pyrolysis product is transported to the surface of the target reservoir by an oil pump, and after cooling, the pyrolysis product is The product is passed to a three-phase separator to separate the pyrolysis products to produce oil, gas and water, which is separated to produce an oil, water and gas mixture. 8. The method for heating an oil shale reservoir according to claim 6, wherein the pyrolysis product flows into the production well through the fracture. 9. The method for heating an oil shale reservoir according to claim 7, wherein the gas mixture comprises the heating medium and the hydrocarbon gas. 10. The method for heating oil shale reservoirs according to claim 1, characterized in that the method further comprises selecting the corresponding gas-making equipment according to the difference of the heating medium.