Direct electricity generation at the bottom of a geothermal well

Abstract

The systems and methods of this disclosure relate to the generation of electricity by pumping a fluid (114) through a thermoelectric conduit (106) extending into a geothermal reservoir (105). One method comprises pumping fluid through at least one thermoelectric conduit extending into the geothermal reservoir. The method further comprises generating electricity with the thermoelectric conduit due to a temperature differential between the fluid and the geothermal reservoir.

Description

Title of the invention: Direct downhole electricity generation in a geothermal well

[0001] CONTEXT

[0002] Renewable energy includes geothermal energy, such as the heat that is continuously generated within the Earth's core. Geothermal energy is an important element in the transition to clean, renewable energy. It can replace nuclear power and fossil fuels for electricity generation. Current efforts in geothermal energy are mainly focused on how to extract geothermal energy from an underground formation and transport it to power plants to generate electricity or for other purposes (e.g., hot water, heating).

[0003] The typical process involves pumping cold water into a hot zone of the underground formation, bringing the heated water to the surface, and then transporting the hot water or steam to power plants to generate electricity. A significant amount of heat is lost during surface transport due to the associated infrastructure. Brief description of the drawings

[0004] These drawings illustrate certain aspects of certain examples in this disclosure and should not be used to limit or define the disclosure.

[0005] Fig. 1 A illustrates an operating environment for generating downhole electricity using geothermal energy, according to examples in this disclosure;

[0006] Figure [1B] illustrates a cross-sectional view of a thermoelectric conduit, according to examples in this disclosure;

[0007] Figure 2 illustrates a cross-sectional view of a geothermal reservoir comprising multiple U-shaped conduits connected in parallel flow configurations, according to examples in the present disclosure;

[0008] Figure 3 illustrates a side view of helical conduit(s), according to examples in this disclosure;

[0009] Figure 4 illustrates a cross-sectional view of the geothermal reservoir which includes multiple helical conduits, according to examples in the present disclosure;

[0010] Figure 5 illustrates a cross-sectional view of the geothermal reservoir comprising a first conduit disposed within a second conduit, according to examples in this disclosure; and

[0011] Figure 6 illustrates an operating sequence for generating underground electricity with one or more thermoelectric conduits, according to examples in this disclosure. DETAILED DESCRIPTION

[0012] This disclosure relates to downhole electricity generation using geothermal energy. More specifically, the step of transporting heat from the downhole to power plants is eliminated to improve energy conversion rates and further reduce the carbon footprint. A thermoelectric device / material can be implemented to generate electricity due to a temperature differential (e.g., 5° to 10°) across the device.

[0013] In geothermal energy applications, the temperature differential across the thermoelectric material can be relatively constant or otherwise maintained. In some examples, a continuous flow of electricity can be produced via a thermoelectric conduit / pipe that has an external diameter (ED) exposed to a heat source (e.g., a geothermal reservoir) and an internal diameter (ID) exposed to a cold source (e.g., water). In some examples, a thermoelectric pipe may be at least partially made of a thermoelectric material. In some examples, the thermoelectric material may have a coating and / or plating. In some examples, the thermoelectric material may be embedded in a casing. In some examples, the thermoelectric material may be included / embedded with another metal such as steel, for example.In some examples, the thermoelectric material may be included along the entire length of the conduit. In other examples, the thermoelectric material may be included in at least 5 feet, 10 feet, 15 feet, or 20 feet of the conduit. In some examples, the cold source may be at least 5° or 10° cooler than the heat source. The heat source may be, for example, at least 5° or 10° warmer than the cold source. The thermoelectric conduit may be placed in a heat reservoir (for example, a geothermal well), and cold water may be pumped through the thermoelectric conduit to maintain a cold temperature on the inner diameter of the conduit. The outer diameter of the conduit may remain warm due to the unlimited heat source of the geothermal well (within its production lifetime).

[0014] The temperature difference between the hot and cold sides of the conduit / pipe results in the continuous generation of electricity with the continuous flow of cold water through the conduit. When the hot fluid around the thermoelectric pipe cools due to energy transfer, convection occurs and the cooler fluid falls to the bottom of the well, where a constant heat source exists. The hot fluid from the bottom of the well / zone rises to the well surface.

[0015] The cold fluid can be pumped into a well, and minimal energy is required to maintain the flow. The thermoelectric conduit uses an integrated temperature differential to generate electricity. The absence of moving parts enhances durability. Furthermore, there is no need to bring heat from the underground formation to the surface, thus reducing the carbon footprint of geothermal wells.

[0016] To increase electricity production, the surface area of ​​the thermoelectric pipe can be increased. For example, several U-shaped pipes can be connected in parallel flow configurations, where multiple U-shaped thermoelectric pipes are located in a single underground heat reservoir. Helical pipes can also be used to increase the surface area of ​​each thermoelectric generator. Multiple helical thermoelectric pipes can be connected so that the flow through them is also parallel. In some examples, the helical thermoelectric pipes can be connected separately or one inside the other. Parallel connections allow for increased electricity production.

[0017] Figure 1A illustrates an example of a well system 100 for generating downhole electricity using geothermal energy, according to examples in this disclosure. The well system 100 may include a borehole 102 drilled in a subsurface formation 104. The borehole 102 may be a vertical borehole as illustrated, or it may be a horizontal and / or directional borehole. While the well system 100 may be illustrated as being onshore, it should be understood that the present techniques may also be applicable in offshore applications. The subsurface formation 104 may be composed of several geological layers and include one or more geothermal reservoirs 105 with temperatures ranging, for example, from 70 °F to 350 °F or higher.

[0018] A conduit 106 can extend through the borehole 102 from the surface 108. The conduit 106 can have an inlet 110 and an outlet 112 at the surface 108. The conduit 106 can extend downward from the inlet 110, through the geothermal reservoir(s) 105, and back up to the surface 108 via the outlet 112. A pump 113 can be coupled to the inlet 110 to pump the fluid 114 into the conduit 106. A fluid source 115 can supply the fluid 114 to the pump 113 via a pipe 116. The fluid 114 can exit the conduit 106 from the outlet 112 to be recycled back into the conduit 106, or for further processing.

[0019] With further reference to [Fig. 1B] (a cross-sectional view of the conduit 106), the conduit 106 can be made of a thermoelectric material 107 (for example, bismuth telluride). A Seebeck effect generates a voltage with the thermoelectric material 107 from a temperature difference encountered in the subsurface formation (for example, pumped cold water coming into contact with the hot subsurface geothermal zone). The internal diameter of the conduit 106 has a lower temperature due to the pumped cooling fluid 114 being in contact with the internal diameter.

[0020] The external diameter of the conduit 106 has a higher temperature due to the geothermal reservoir 105. The fluid 114 may consist of cold water or water at room temperature, or water that is at least 5 °F or at least 10 °F colder than the geothermal reservoir(s) 105. The temperature difference is sufficient to produce energy via the thermoelectric material 107. Referring again to [Fig. 1A], one or more cables 118 (for example, wires) may extend from the conduit 106 to transfer the electricity generated from the conduit 106 to an electrical network 120 and / or a battery 122, for example.

[0021] Cold water can be pumped into the thermoelectric conduit 106 to maintain a cold temperature on the inner diameter of the pipe. The outer diameter of the pipe can remain hot due to the unlimited heat source of the geothermal well (during its production life).

[0022] The temperature difference between the hot and cold sides of the pipe results in the continuous generation of electricity with a continuous flow of cold water. When the hot fluid around the thermoelectric pipe cools slightly due to energy transfer, convection occurs and the cooler fluid sinks to the bottom of the well, where a constant heat source exists. The hot fluid from the bottom of the well / zone then rises to the surface.

[0023] The cold fluid can be pumped downwards, but little energy is required to maintain the flow. The thermoelectric pipe uses an integrated temperature differential to generate electricity. The absence of moving parts improves durability. Furthermore, there is no need to bring heat from the underground formation to the surface, thus reducing the carbon footprint of geothermal wells. To increase electricity production, the surface area of ​​the conduit 106 can be increased.

[0024] Figure 2 illustrates a cross-sectional view (e.g., top view) of the geothermal reservoir 105 which has multiple U-shaped conduits 106 connected in parallel flow configurations, according to examples in this disclosure. For example, the multiple U-shaped conduits 106 are connected in parallel flow configurations in a heat reservoir A single underground conduit (for example, geothermal reservoir 105) is used to increase electricity production. Multiple U-shaped conduits 106 increase the surface area for the thermoelectric material, thus increasing electricity generation. Each conduit 106 has an inlet 110 and an outlet 112, as previously described.

[0025] Figure 3 illustrates a side view of the helical conduit(s) 106, according to examples in this disclosure. The helical shape is included to increase the surface area of ​​the thermoelectric material in the conduit 106. In some examples, a plurality of helical conduits 106 may be connected within a geothermal reservoir. The fluid 114 may be pumped down the helical conduit 106 via an inlet 110 and back up to the surface through a non-helical pipe 300 (or another helical conduit) and through the outlet 112, for example. The helical shape is included to increase power generation.

[0026] Figure 4 illustrates a cross-sectional view (for example, a top view) of the geothermal reservoir 105, which includes multiple helical conduits 106, as shown in the examples in this disclosure. The helical conduits 106 can be connected so that the flow through them is also parallel for increased surface area (i.e., increased electricity generation). Each conduit 106 has an inlet 110 and an outlet 112, as previously shown.

[0027] Figure 5 illustrates a cross-sectional view (e.g., a top view) of the geothermal reservoir 105, which has helical conduits 106a and 106b arranged one inside the other, as shown in the examples in this disclosure. The parallel connections in the geothermal reservoir 105 resulting from this configuration allow for increased electricity production. Each of the conduits 106a and 106b has an inlet 110 and an outlet 112, as previously shown. As depicted, a first conduit 106a (e.g., smaller in size) is arranged inside a second conduit 106b (e.g., larger in size). The entire conduit 106a is arranged in the inlet 110 of the second conduit 106b. This configuration increases the conduit area to improve electricity generation.

[0028] Figure 6 illustrates an operating sequence for generating electricity in an underground formation with thermoelectric conduits extending into a geothermal reservoir, according to examples in this disclosure. In step 600, the fluid is pumped from the surface into a conduit extending into an underground geothermal reservoir (for example, see Figure 1A). The conduit may have a shape to maximize the surface area in order to increase electricity generation. For example, the conduit(s) may include at least one U-shaped pipe (for example, see Figures 1A and 2), at least one helical pipe (for example, see Figures 3 and 4). 4), and / or at least one pipe arranged inside another pipe (for example, see [Fig. 5]). In some examples, the pipe configuration may include eccentric, concentric, and / or coaxial configurations.

[0029] In step 602, the temperature difference between the fluid and the geothermal reservoir generates electricity. The Seebeck effect generates the voltage with the thermoelectric material from the temperature difference encountered in the underground formation (for example, the pumped cold water coming into contact with the hot underground geothermal zone). The inner diameter of the conduit has a lower temperature due to the pumped cooling fluid being in contact with the inner diameter (for example, see [Fig. 1B]). The outer diameter of the conduit has a higher temperature due to the geothermal reservoir. The fluid may consist of cold water or water at room temperature, or water whose temperature is at least 5 °F or at least 10 °F colder than the geothermal reservoir(s). The temperature difference is sufficient to produce energy via the thermoelectric material.

[0030] In step 604, the generated electricity is recovered at the surface. For example, one or more cables (e.g., wires) may extend from the conduit to transfer the generated electricity from the conduit to an electrical network and / or a battery (e.g., see [Fig. 1A]).

[0031] Therefore, the systems and methods of this disclosure enable the generation of downhole electricity using geothermal energy. The systems and methods may include any of the various features disclosed herein, including one or more of the following statements.

[0032] Statement 1. A method comprising: pumping fluid into at least one thermoelectric conduit, the thermoelectric conduit extending into a geothermal reservoir; and generating electricity with the thermoelectric conduit due to a temperature differential between the fluid and the geothermal reservoir.

[0033] Statement 2. The process according to statement 1, further comprising the recovery of the fluid out of the thermoelectric conduit.

[0034] Statement 3. The process according to statement 1 or statement 2, further comprising the recovery of electricity at a surface of a well, the thermoelectric conduit extending into the well.

[0035] Statement 4. The process according to any one of statements 1 to 3, in which the fluid comprises water.

[0036] Statement 5. The method according to any one of statements 1 to 4, wherein the thermoelectric conduit has a U-shaped form to maximize the surface area for electricity generation.

[0037] Statement 6. The method according to any one of statements 1 to 5, wherein the thermoelectric conduit has a helical shape to maximize the surface area for electricity generation.

[0038] Statement 7. The method according to any one of statements 1 to 6, wherein a first thermoelectric conduit is arranged in a second thermoelectric conduit to maximize the surface area for electricity generation.

[0039] Statement 8. The process according to any one of statements 1 to 7, wherein a temperature of the fluid is lower than a temperature of the geothermal reservoir.

[0040] Statement 9. The method according to any one of statements 1 to 8, wherein an internal diameter of the thermoelectric conduit is colder than an external diameter of the thermoelectric conduit.

[0041] Statement 10. The method according to any one of statements 1 to 9, wherein a first thermoelectric conduit is disposed in an inlet of a second thermoelectric conduit to maximize the surface area for electricity generation.

[0042] Statement 11. A system comprising: a thermoelectric conduit extending into a geothermal reservoir; and a fluid source and a pump in communication with the thermoelectric conduit.

[0043] Statement 12. The system according to statement 11, in which the thermoelectric conduit is disposed in a borehole.

[0044] Statement 13. The system according to Statement 11 or Statement 12, wherein the thermoelectric conduit has a U-shaped form to maximize the surface area for electricity generation.

[0045] Statement 14. The system according to any one of statements 11 to 13, wherein the thermoelectric conduit has a helical shape to maximize the surface area for electricity generation.

[0046] Statement 15. The system according to any one of statements 11 to 14, wherein a first thermoelectric conduit is arranged in a second thermoelectric conduit to maximize the surface area for electricity generation.

[0047] Statement 16. The system according to any one of statements 11 to 15, in which an internal diameter of the thermoelectric conduit is colder than an external diameter of the thermoelectric conduit.

[0048] Statement 17. The system according to any one of statements 11 to 16, wherein a first thermoelectric conduit is disposed in an inlet of a second thermoelectric conduit to maximize the surface area for electricity generation.

[0049] Statement 18. The system according to any one of statements 11 to 17, in which the fluid comprises water.

[0050] Statement 19. The system according to any one of statements 11 to 18, wherein the thermoelectric conduit has an inlet at a surface of a well.

[0051] Statement 20. The system according to any one of statements 11 to 19, in which the thermoelectric conduit has an outlet at a surface of a well.

[0052] Although the present disclosure and its benefits have been described in detail, it should be understood that various changes, substitutions, and alterations may be made to it without departing from the spirit and scope of the disclosure as defined by the appended claims. The preceding description provides various examples of the systems and methods of use disclosed herein, which may contain different process steps and alternative combinations of components. It should be understood that, although individual examples may be discussed herein, the present disclosure covers all combinations of the disclosed examples, including, without limitation, different combinations of components, combinations of process steps, and system properties.It should be understood that compositions and processes are described as "comprising", "containing" or "encompassing" various components or steps, and compositions and processes may also "consist essentially of" or "be made up of" the different components and steps.

[0053] For the sake of brevity, only certain ranges are explicitly disclosed here. However, ranges from any lower limit may be combined with any upper limit to cite a range not explicitly cited; similarly, ranges from any lower limit may be combined with any other lower limit to cite a range not explicitly cited; likewise, ranges from any upper limit may be combined with any other upper limit to cite a range not explicitly cited. Furthermore, whenever a numeric range with a lower and upper limit is disclosed, any number and any range included within the range are specifically disclosed.In particular, each range of values ​​(of the form, "from about a to about b", or, equivalently, "approximately from a to b" or, equivalently, "approximately a-b") disclosed herein should be understood as stating every number and range contained within the larger range of values, even if not explicitly quoted. Thus, each individual point or value can constitute its own lower or upper bound when combined with any other individual point or value, or with any other lower or upper bound, to quote a range not explicitly quoted.

[0054] Consequently, the present examples are well suited to achieving the objectives and advantages mentioned, as well as those inherent therein. The particular examples disclosed above are purely illustrative and can be modified and implemented in different but equivalent ways obvious to a person skilled in the art who benefits from the teachings contained herein. Although individual examples are discussed, the invention covers all possible combinations of all The examples. Furthermore, no limitations are foreseen for the details of development or design provided herein, other than those described in the claims below. Moreover, the terms of the claims have a simple and ordinary meaning, unless explicitly and clearly stated otherwise by the patent holder. It is therefore understood that the particular illustrative examples disclosed above may be altered or modified, and all such variations are considered to be within the scope and spirit of those examples. In the event of a conflict in the uses of a word or term in this description and in one or more patents or other documents, the definitions consistent with this description shall prevail.

Claims

Demands

1. A method comprising: pumping a fluid (114) into an inlet of a first thermoelectric conduit (106a) and an inlet of a second thermoelectric conduit (106b), wherein the first thermoelectric conduit and the second thermoelectric conduit extend into a geothermal reservoir (105), wherein the first thermoelectric conduit and the second thermoelectric conduit comprise a helical portion, and wherein the first thermoelectric conduit is disposed in the second thermoelectric conduit; and generating electricity with the first thermoelectric conduit and the second thermoelectric conduit due to a temperature differential between the fluid and the geothermal reservoir.

2. A method according to claim 1, further comprising the recovery of the fluid from an outlet of the first thermoelectric conduit and an outlet of the second thermoelectric conduit and optionally, further comprising the recovery of electricity at a surface of a well, the first thermoelectric conduit and the second thermoelectric conduit extending into the well.

3. A method according to claim 1, wherein the fluid comprises water.

4. Method according to claim 1, wherein the first thermoelectric conduit further has a U-shaped form to maximize the surface area for electricity generation.

5. A method according to claim 1, wherein a fluid temperature is lower than a geothermal reservoir temperature.

6. Method according to claim 1, wherein an internal diameter of the first thermoelectric conduit is colder than an external diameter of the first thermoelectric conduit and optionally, wherein the first thermoelectric conduit (106a) is disposed in an inlet (110) of the second thermoelectric conduit (106b) to maximize the surface area for electricity generation.

7. System comprising: a first thermoelectric conduit (106) and a second thermoelectric conduit (106b) extending into a geothermal reservoir (105) in which the first thermoelectric conduit and the second thermoelectric conduit include a helical portion, in which the first thermoelectric conduit is disposed within the second thermoelectric conduit; and a fluid source (115) and a pump (113) in communication with the first thermoelectric conduit and the second thermoelectric conduit.

8. System according to claim 7, wherein the first thermoelectric conduit and the second thermoelectric conduit are arranged in a borehole and optionally, wherein the thermoelectric conduit further has a U-shape to maximize the surface area for electricity generation.

9. System according to claim 8, wherein an internal diameter of the first thermoelectric conduit is colder than an external diameter of the first thermoelectric conduit.

10. System according to claim 8, wherein the first thermoelectric conduit (106a) is disposed in an inlet (110) of the second thermoelectric conduit (106b) to maximize the surface area for electricity generation.

11. System according to claim 8, wherein the fluid comprises water.

12. System according to claim 8, wherein the first thermoelectric conduit has an inlet at a surface of a well and optionally, wherein the first thermoelectric conduit has an outlet at a surface of a well.

13. Method according to claim 2, wherein the first thermoelectric conduit comprises a non-helical return line fluidly coupled to a bottom of the helical portion of the first thermoelectric conduit and to the outlet of the first thermoelectric conduit.

Images