CA3121320A1 - Geothermal renewable energy from deep earth - Google Patents

Abstract

A constructible Geothermal Renewable Energy Deep Earth energy collection system (GeoREDE) composed of novel shaped drilled horizontal spiral deep wells and liners, novel deep thermal energy spiral flow guides and recovery tubes and commercially available heat exchangers and turbines that are capable of generating energy &
capacity from the renewable energy (heat) deep in the earth. The primary or any residual heat collected can be used as a direct heat source for urban or industrial geothermal heating systems (i.e. district heating). The goal of this invention is to create an economic and virtually invisible and environmentally friendly renewable energy generating station package comprised in major part of commercially available technology and components using the novel deep thermal energy recovery spiral drilled wells with spiral flow guides and system described herein.
This invention uses closed loop EGS geothermal technology with an innovative method to increase the time the fluid stays in the heating zone.
Energy capacity and duration is limited only by the depth, size and number of the wells drilled & developed and the mass flow through the system. These plants could be located close to load centers, such as cities, in any areas that require energy and capacity.

Description

TECHNICAL FIELD
This invention relates to the field of geothermal energy extraction and more specifically to the process of extracting heat from wells drilled into the Earth and using the extracted heat for an industrial process, such as the generation of electricity, provide a heat source (district heating) or to drive a chemical or other manufacturing process.

2 of 23 Date Recue/Date Received 2021-06-05 BACKGROUND OF INVENTION
[001] Geothermal power is a reliable, clean, renewable source of power that can provide base-load electricity 24/7 rain or shine. If required Geothermal can also provide load following to support other renewables (i.e. wind, solar). Geothermal power plants have the least down time of any source of power including coal, gas, oil, hydro, solar, wind, or nuclear.
[002] Standard hydrothermal technologies depend on permeable aquifers that allow the flow of water through them to produce hot water. However, at the greater depths to which we anticipate we will be drilling, while the temperatures will be higher the granitic basement rock is less porous and natural water flow is restricted.

[003] Emerging (or Engineered) Geothermal Systems (EGS) is a newer type of geothermal power technology. EGS does not require naturally occurring permeable rock or existing in-situ thermal water reservoirs. Instead, this quickly evolving technology is used to capture the heat stored in high temperature rocks at great depth. The "closed loop" system of Geothermal EGS involves the creation of an artificial heat exchange system in the deep hot rock. Successful development of EGS technology promises to greatly broaden the regions with geothermal electrical generation and thermal energy potential.

[004] The closed loop EGS approach uses binary or flash power plants to produce power from the fluid that is used to capture the renewable heat of the earth. As there is no natural flow of fluid, the fluid has to be re-injected into the system to keep the pressure and production stable. EGS systems have significant advantages over conventional 3 of 23 Date Recue/Date Received 2021-06-05 hydrothermal systems that must be located near easily accessible subsurface hot water resources.

[005] Should economics allow it is also possible that by drilling even deeper than currently envisioned we can get into areas of rock over 400 degrees C and move into the Super-Hot development of EGS Geothermal. This results in greater energy generation from smaller areas and with fewer holes drilled.

[006] In any system part of the geothermal fluid can also be tapped off as a direct heat source for urban or industrial geothermal heating systems (i.e. district heating). This could prompt the local development of other industries with need of the heat, such as food drying, aquaculture. Greenhouse and vertical farming.

[007] Most forms of EGS require water for development, but that water can be of compromised quality. Thus, any accessible wastewater streams in the area (domestic or industrial) can be repurposed as feedstock for development of the EGS. Using wastewater can both save the project the effort of developing a water supply as well as potentially providing value in a remedial solution for removal and disposal of that wastewater.

[008] Some EGS developments are being examined with the use of a higher heat transfer fluid as the working fluid such as Carbon Dioxide (CO2), liquid salts or even Nitrous Oxide.

[009] The use of these other fluids could increase the capacity and efficiency of the Project depending on the temperatures found at depth and heat flow of the rock.

[010] The development of deep closed loop geothermal EGS Projects is accelerating in areas around the globe. Part of any economic evaluation of a Project should include the 4 of 23 Date Recue/Date Received 2021-06-05 positive impact these Geothermal Projects would have on lowering carbon and other greenhouse gas emissions which occur from other types of heat production and electricity generation the geothermal can replace.

[011] Prior art, for example US10,527,026 B2 from January 2020, appears to allow for the use of a single drilled well for collection of the heat stored deep in the earth. The prior art in this patent requires the use of some amount of existing brine to be present while our current disclosure does not require any amount of natural fluid. This and other prior art systems use only an outer tube and inner tube and they do not envision the novel arrangement used to create the spiral flow used in the current disclosure to lengthen the duration of fluid exposure to the heat source, or the method of construction, operation and efficiency as described herein.

[012] An example of the prior art that is somewhat similar to an embodiment of this invention is patent US7,343,753 B2. This prior art varies from this current invention by having the spiral the full length of the tube and well, along with the outer tube being designed to be integral with the inner tube then inserted into the well. The focus of this prior art seems to be on small size and use with ground source heat pump systems. In fact, some variations are made with plastic. This prior art does not envision the extreme depth, pressure and heat of our novel system nor the method of construction, operation and efficiency as described herein.

[013] Another example of the prior art that is similar to this invention is Chinese patent CN210772840 U. This prior art varies from this current invention by having the spiral flow formed from twisted pipe, along with the outer tube being designed to be integral of 23 Date Recue/Date Received 2021-06-05 with the inner tube then inserted into the well. The focus of this prior art seems to be on small size and use with ground source heat pump systems. This prior art does not envision the extreme depth, pressure and heat of our novel system nor the method of construction, operation and efficiency as described herein.

[014] These and other prior art do not use our novel lower casing machining and possible in-situ reaming of only the bottom sections of the well casing to provide the tight fit required to the outer edge of the spiral flow directors and center flow return tube when it is separately inserted while turning into the well. Prior art does not use the layout and logarithmic design of our horizontal collection wells with internal spiral flow directors, both designed to increase the time the fluid stays in the high heat zone.

[015] The available other reviewed and searched similar prior art patents and commercial devices/techniques disclosed in the public domain do not utilize the novel combination of elements arranged and configured as disclosed and claimed herein.

[016] Accordingly, the primary object of this invention is to provide a Geothermal Renewable Energy Deep Earth Energy Collection system composed of straight and horizontal logarithmic spiral drilled wells and liners, proprietary deep thermal energy recovery spiral flow guide and the method of construction of these flow guides along with commercially available heat exchangers and turbines that are capable of generating energy & capacity from the renewable energy (heat) deep in the earth. Another aspect is to use multi-megawatt turbines or an array of wells and turbines that are capable of economically and efficiently generating power and energy.
6 of 23 Date Recue/Date Received 2021-06-05 To create an economically viable and constructible renewable energy generating and thermal energy supply system composed of commercially available components and techniques or techniques that are close to commercial development.
7 of 23 Date Recue/Date Received 2021-06-05 SUMMARY OF INVENTION

[017] A deep earth renewable energy collection system is disclosed which offers a novel extended spiral flow area at the base of the well which enables the fluid to stay longer and collect greater energy in the heat zone. The system offers an advantage that the generating units can be located in close proximity to a load center.

[018] Assuming the average earth heat gradient is 0.025 degrees C per meter of depth and if the average surface temperature of an area is 15 degrees C, we would need to drill 6000m depth to obtain temperatures of greater than 165 degrees C.

[019] In areas where the average earth heat gradient is 0.030 degrees C per meter of depth and if the average surface temperature of an area is 15 degrees C, we would need to drill 8000m depth to obtain temperatures of greater than 255 degrees C.

[020] In many areas the temperature gradient of the earth is not linear but increases as we go deeper due to fault areas in the bedrock. These areas are the prime target areas for investigation of rock temperature, deep heat flow & possible development.

[021] The Geothermal Renewable Energy Deep Earth Energy Collection system and method disclosed herein is a single (or multi) well closed loop system used to generate electrical energy & capacity. Benefits of this system include;
= No risk of earthquakes since no hydraulic fracturing needed.
= Uses commercially available methods of deep well drilling and casing.
8 of 23 Date Recue/Date Received 2021-06-05 = Does not fully rely on Geologic conditions for location, but most efficient and economical in fault areas where high heat & heat flow is closer to the surface.
= Can be located very close to load centers as needed. Can use brownfield land, quarries, etc.
= Suitable for use anywhere in North America, or worldwide as required simply by changing the drilled well depth.
= System provides for very high plant capacity factors ¨ generally over 90%
= There is a small surface development footprint especially when a thermal heat user is nearby.
= Uses proven mechanical equipment for generation.
= Can generate very efficiently at partial load points.
= Modular and scalable (Capacity from 1 MW or less to 100's of MW).
= Can provide a local source of power, energy & thermal heat/cool for isolated communities, mines or other industrial/commercial users = No fuel involved - no emissions from operation.
= Closed cycle system of fluid use ¨ after initial filling no fluid consumed.

[022] This system allows multiple, modular units to be used. Wells can be drilled to depth and as long as they remain at least 25m apart at depth, they will not influence each other.
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[023] Most previous single well geothermal designs in other prior art systems use only an outer tube and inner tube and they do not envision the novel arrangement used to create the spiral flow used in the current disclosure to lengthen the duration of fluid exposure to the heat source, or the method of construction, operation and efficiency as described herein.

[024] Construction of the single well system would start with drilling a deep well into the surface of the earth and extending that well down to a depth of over 1000 meters such that the temperature of the rock and the heat flow of the rock meets or exceeds the design requirements of the Project.

[025] Such a well to be lined with a steel well casing at least in the bottom 1/4 length of the total hole depth. This casing to be grouted in place with a thermally conductive grout.
This is the major heat zone.

[026] The inside of these bottom well casing sections to be machined before installation with a novel axial spiral groove to match the novel spiral extended flow guide which will be mounted on the end of a sectional long central return flow tube and then inserted, while turning, into the spiral groove in the steel casing.

[027] The spiral extended flow guide could also be designed such that it can machine the spiral groove into the well casing as it is lowered in place while turning.

[028] The central return flow tube sections above the spiral extended flow guide sections will have at least 3 sets of radial arms equally spaced around the diameter at 2 elevations to keep the tube centered in the well.
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[029] The top sections of the central return flow tube above the spiral extended flow guide sections could be insulated to limit heat loss.

[030] Fluid will be inserted in the space between the well walls and flow down the well, absorbing some heat, until the fluid reaches the novel spiral flow guide. At this point the fluid will enter the flow guide and absorb the high heat from the outside casing while descending in a spiral down the flow guide.

[031] The fluid will exit the bottom end of the flow guide at the base of the well casing and then the heated fluid will return to the surface up the central return flow tube. The heat will be extracted from the fluid at the surface and used to create energy. It is possible this fluid return could be via a thermosiphon effect.

[032] When the desired amount of energy has been extracted from the fluid at the surface, the fluid will be returned down the well to repeat the cycle.

[033] Power cables will carry the generated energy from the generator to inverters, converters, transformers, switchgear etc. as required located on the Project site and then into the electricity grid.

[034] Another embodiment of the system would use multiple smaller diameter drilled deep inlet wells leading to a central main collection well to return the collected heat to the surface.

[035] To minimize surface footprint these inlet wells would be slightly angled vertically to required depth then have a novel horizontal logarithmic spiral shape which will include the liner and novel spiral flow guide tubes to extend the time the fluid is in the high heat zone.
11 of 23 Date Recue/Date Received 2021-06-05

[036] These wells will all be located at the same diameter from, and concentric to a single drilled vertical return well. To better enable intersection with the return well, the inlet wells will feed into a larger diameter collection zone created at the bottom of the central well.

[037] The collection zone will be about 500m in length. The multiple inlet wells will intersect near the top of the collection zone while the single return well extends to the bottom of the collection zone to collect the heated fluid and return to the surface for use.
12 of 23 Date Recue/Date Received 2021-06-05 DETAILED DESCRIPTION

[038] A specific object is to provide a system for generating power which is composed of drilled deep wells and liner, proprietary deep thermal energy spiral extended flow guides and commercially available heat exchangers and turbines that are capable of generating energy & capacity from the renewable energy (heat) deep in the earth. Mostly modular construction and provides a high cycle efficiency at relatively low cost.

[039] Still another object is the ability to provide a battery of mutually supporting power-generating turbines and deep heat collection well systems that are disposed in support of one another.

[040] Described briefly one typical construction of the single well system functions in the following manner. Please refer to figures 1 to 5 for clarity;

[041] Drilling a deep well into the surface of the earth and extending that well down to a depth of over 1000 meters such that the temperature of the rock and the heat flow of the rock meets or exceeds the design requirements of the Project.

[042] Such a well to be lined with a steel well casing (1) at least in the bottom 1/4 length of the total hole depth. This casing to be grouted in place with a thermally conductive grout. This is the major heat zone.

[043] The inside of these bottom well casing sections to be machined before installation with a novel axial spiral groove to match the novel spiral extended flow guide sections (2) which will be mounted on the end of the long central return flow tube sections (3) and then inserted, while turning, into the spiral groove in the steel casing.
13 of 23 Date Recue/Date Received 2021-06-05

[044] Each of the central return flow tube sections will have at least 3 sets of radial arms, equally spaced radially and vertically, to keep the tube sections centered in the well.

[045] Fluid will be inserted in the space between the well walls and flow down the well (4), absorbing some heat, until the fluid reaches the novel spiral flow guide.

[046] At this point the fluid will enter the flow guide and absorb the high heat from the outside casing while descending in a spiral down the flow guide (5).

[047] The fluid will exit the bottom end of the flow guide at the base of the well casing and then the heated fluid will return to the surface up the central return flow tube (6).

[048] The heat will be extracted from the hot fluid at the surface and then be used to create energy (7).

[049] When the desired amount of energy has been extracted from the fluid at the surface, the fluid will be returned down the well to repeat the cycle (8).

[050] Described briefly one typical construction of the multi-well GeoREDE
system functions in the following manner. Please refer to figures 6 to 8 for clarity;

[051] Drilling a central deep well vertically into the surface of the earth and extending that well down to a depth of over 1000 meters such that the temperature of the rock and the heat flow of the rock meets or exceeds the design requirements of the Project.

[052] Such a well to be lined with a steel well casing. This casing to be grouted in place with a thermally insulating grout. This is the heated fluid return well (13).
14 of 23 Date Recue/Date Received 2021-06-05

[053] Create in the final 500m depth of the fluid return well a fluid collection area (12) with an extended diameter of at least 10 times the well diameter. This entire area will be designed porous to allow fluid flow from top to bottom with minimum restrictions.

[054] The fluid return well casing will extend to the bottom of the fluid collection area and be perforated in at least the bottom 25m to allow for the hot fluid to enter the fluid return well and transfer the geothermal heat collected to the surface.

[055] Drill to the required depth for the multiple inlet wells (9). To minimize surface footprint while increasing the diameter at depth, these inlet wells will be slightly angled vertically outwards to the required depth then transition to the novel horizontal logarithmic spiral (10) shape which will include the liner and novel integral spiral flow guide tubes (11) designed to extend the time the fluid is in the high heat zone.

[056] These inlet wells (1) will all be located equidistantly spaced at the same diameter from, and concentric to the hot fluid return well (13). To better enable intersection of the inlet wells with the return well, the inlet wells will feed into the top of the larger diameter collection area (12) created at the bottom of the central well.

[057] Fluid will be inserted in the space between the inlet well (9) walls and flow down the well, absorbing some heat, until the fluid reaches the novel horizontal logarithmic spiral section (10) with integral spiral flow guide (11).

[058] At this point the fluid will enter the flow guide and absorb the high heat from the outside casing while advancing along the spiral flow guide towards the fluid collection area (12).
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[059] The heated fluid will exit the end of the flow guide into the fluid collection area (12) and then travel down the collection area absorbing more heat until reaching the perforated lower section of the central return well where the heated fluid from all inlet wells will return to the surface up the central return well (13).

[060] The collected heat will be extracted from the hot fluid at the surface and used to create energy.

[061] When the desired amount of energy has been extracted from the fluid at the surface, the fluid will be returned down the inlet wells to repeat the cycle.

[062] It also is to be appreciated that the extracted heat can be used for an industrial process, such as the generation of electricity, provide a commercial heat source (district heating) or to drive a chemical or other manufacturing process.

[063] It is to be understood that the invention and techniques disclosed herein are to illustrate the preferred setup. Still other modifications will be obvious to persons skilled in the art.
16 of 23 Date Recue/Date Received 2021-06-05

Claims

Claims Some aspects of the present disclosure use methods of construction or equipment that are currently in use or under development by others and we are not attempting to claim exclusive property or privilege of these methods or equipment.
The deep drilling of the wells, casing and grouting of the wells will be done utilizing the most economic design and method to keep development and construction cost low.
There are presently various commercial systems along with a few near commercial or under development methods for very deep drilling. Present systems that have drilled over 6000m and will be able to drill to the depths we envision are conventional rotary drill heads, water powered hammers (Strada Global) and air powered hammers (NUMA) or a combination of the three. Under development are high power laser, plasma flare, electro-pulse boring, sonic drilling, microwave drilling and ram accelerator systems.
There may be other methods under development we are not currently aware of.
The physical design and shape of the major part of the straight well, the casing materials and whether the well is stepped in size with depth or straight bore size are other aspects of the disclosure we are not attempting to claim as exclusive property or privilege, only the spiral groove in the bottom casing section design , the spiral flow guide heat collection system and the novel horizontal logarithmic spiral wells with integral spiral flow guide heat collection system design used in the multiple well embodiment.
Also not claimed but included in the disclosure is using the hot fluid brought to the surface to generate electricity using a commercially available apparatus comprised of at least one heat exchanger, turbine and electric generator set, piping connecting the heat 17 of 23 Date Recue/Date Received 2021-06-05 exchangers and the turbine along with a control system to operate the apparatus all contained in a structure, or structures, to hold said heat exchangers, turbine and generator, piping and control system along with electrical control and distribution equipment connected to the conductors of the generator to receive the energy generated therein and re-transmit elsewhere via a power conduit.
The embodiments of the disclosed invention in which an exclusive property or privilege is claimed are defined as follows;
[Claim 01] For use in collecting then transferring with fluid the deep heat energy within the earth to the surface a method as follows;
Drilling a deep well into the surface of the earth and extending that well down to a depth of over 1000 meters such that the temperature of the rock and the heat flow of the rock meets or exceeds the design requirements of the Project. Such a well to be lined with a steel well casing at least in the bottom 1/4 length of the total hole depth.
This casing to be grouted in place with a thermally conductive grout. This is the major heat zone.
The inside of this bottom well casing to be machined before installation with a novel axial spiral groove to match the novel spiral extended flow guide sections which will be mounted on the end of a long central return flow tube sections and then inserted, while turning, into the spiral groove in the steel casing. Each of the central return flow tube sections will have at least 3 sets of radial vanes, equally spaced radially and vertically, to keep the tube sections centered in the well.
Fluid will be inserted in the space between the well walls and flow down the well, absorbing some heat, until the fluid reaches the novel spiral flow guide. At this point the 18 of 23 Date Recue/Date Received 2021-06-05 fluid will enter the flow guide and absorb the high heat from the outside casing while descending in a spiral down the flow guide.
The fluid will exit the bottom end of the flow guide at the base of the well casing and then the heated fluid will return to the surface up the central return flow tube. The heat will be extracted from the fluid at the surface and be used to create energy.
When the desired amount of energy has been extracted from the fluid at the surface, the fluid will be returned down the well to repeat the cycle.
[Claim 02] Apparatus as claimed in claim 1 in which the spiral extended flow guide is designed such that it can machine the spiral groove into the well casing as it is lowered in place while turning.
[Claim 03] Apparatus as claimed in claim 1 in which the central return flow tube is insulated.
[Claim 04] For use in collecting then transferring with fluid the deep heat energy within the earth to the surface a method as follows;
Drilling a central deep well vertically into the surface of the earth and extending that well down to a depth of over 1000 meters such that the temperature of the rock and the heat flow of the rock meets or exceeds the design requirements of the Project. Such a well to be lined with a steel well casing. This casing to be grouted in place with a thermally insulating grout. This is the heated fluid return well.
Create in the final 500m depth of the fluid return well a fluid collection area with an extended diameter of at least 10 times the well diameter. This entire area will be designed porous to allow fluid flow from top to bottom with minimum restrictions. The fluid return 19 of 23 Date Recue/Date Received 2021-06-05 well casing will extend to the bottom of the fluid collection area and be perforated in at least the bottom 25m to allow for the hot fluid to enter the return well.
Drill to the required depth for the multiple inlet wells. To minimize surface footprint while increasing the diameter at depth, these inlet wells will be slightly angled vertically outwards to the required depth then transition to the novel horizontal logarithmic spiral shape which will include the liner and novel integral spiral flow guide tubes designed to extend the time the fluid is in the high heat zone.
These inlet wells will all be located equidistantly spaced at the same diameter from, and concentric to the hot fluid return well. To better enable intersection of the inlet wells with the return well, the inlet wells will feed into the top of the larger diameter collection area created at the bottom of the central well.
Fluid will be inserted in the space between the inlet well walls and flow down the well, absorbing some heat, until the fluid reaches the novel horizontal logarithmic spiral section with integral spiral flow guide. At this point the fluid will enter the flow guide and absorb the high heat from the outside casing while advancing along the spiral flow guide towards the fluid collection area.
The heated fluid will exit the end of the flow guide into the fluid collection area and then the heated fluid from all inlet wells will return to the surface up the larger central return well. The heat will be extracted from the fluid at the surface and be used to create energy.
When the desired amount of energy has been extracted from the fluid at the surface, the fluid will be returned down the inlet wells to repeat the cycle.
20 of 23 Date Recue/Date Received 2021-06-05 [claim 5] Apparatus as claimed in claim 4 in which the entire length of the vertical inlet well is insulated.
It is to be understood that the invention and techniques disclosed herein are to illustrate the preferred setup. Still other modifications will be obvious to persons skilled in the art.
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