Geothermal reactor well

Abstract

A geothermal reactor well system includes a closed-loop well coupled to one or more reactant sources. This closed-loop well includes a first surface well extending from the surface to a geothermal subsurface region and a second surface well extending from the surface to this region. Multiple connecting wells connect the first surface well to the second surface well. At least a portion of the connecting wells are sealed to prevent fluid from communicating with the surrounding geothermal subsurface region. A carrier fluid is placed within the closed-loop well. The closed-loop well is configured such that thermal energy from the geothermal subsurface region and / or the reaction of reactants within the well drives the fluid within the well to circulate by a thermosiphon, thereby transporting reactants through the well for reaction and transporting reaction products through the well for recovery.

Description

[Technical Field]

[0001] This disclosure relates to the production of chemical products from reactants circulating within wells, particularly in closed-loop wells in geothermal underground regions. [Background technology]

[0002] Valuable and essential products such as fuels can be produced by chemical reactions between reactive raw materials that occur over time under specific temperature and pressure ranges. Furthermore, some such processes may require catalysts and other substances to increase the rate or quantity of the product produced. Conventional reactor systems installed on the ground surface may be limited by cost, size, and other factors. [Overview of the project] [Means for solving the problem]

[0003] The concepts described herein encompass the production of chemical products from reactants circulating within boreholes, and particularly within closed-loop boreholes in geothermal underground regions.

[0004] In a particular embodiment, a geothermal reactor well system includes a closed-loop well coupled to one or more reactant sources. This closed-loop well includes a first surface well extending from the surface to a geothermal subsurface region and a second surface well extending from the surface to this region. Multiple connecting wells connect the first surface well to the second surface well. A carrier fluid is placed within the closed-loop well. The closed-loop well is configured such that thermal energy from the geothermal subsurface region and / or the reaction of reactants within the closed-loop well drives the fluid within the well to circulate by a thermosiphon, thereby transporting reactants through the closed-loop well for reaction and transporting reaction products through the closed-loop well for recovery.

[0005] In a particular embodiment, the method includes the step of introducing reactants into a closed-loop well from one or more reactant sources coupled to the well. The closed-loop well includes a first surface well extending from the ground surface to a geothermal subsurface region and a second surface well extending from the ground surface to a geothermal subsurface region. Multiple connecting wells connect the first surface well to the second surface well. A carrier fluid is circulated by thermal energy from the geothermal subsurface region and / or by a thermosiphon generated from the reaction of reactants in the closed-loop well, transporting the reactants through the closed well loop. The reaction products are then recovered from the closed-loop well.

[0006] The above embodiments may include, omit, or include some of the following features. For example, in certain examples, the reaction is partially driven by thermal energy from a geothermal underground region. A closed borehole loop may be configured such that the pressure and temperature within the closed borehole loop are within a specific pressure and temperature range for the reaction. At least a portion of the connecting borehole may be sealed to prevent the fluid from communicating with the surrounding geothermal underground region. The closed-loop well may include a catalyst bed located inside. The catalyst bed may include a slurry. In certain examples, the geothermal underground region has an intrinsic temperature of at least 200°C surrounding at least a portion of the connecting borehole. In certain examples, the products include fuel products, ammonia, and / or methanol. In certain examples, the reaction includes a Fischer-Tropsch synthesis.

[0007] Other embodiments will become apparent from the following drawings, detailed description and claims. [Brief explanation of the drawing]

[0008] [Figure 1A] This is a schematic side cross-sectional view of a closed-loop reactor well system according to the concepts described herein. [Figure 1B] This is a schematic side cross-sectional view of a closed-loop reactor well system according to the concepts described herein. [Figure 1C]This is a schematic side cross-sectional view of a closed-loop reactor well system according to the concepts described herein. [Figure 2] This is a schematic side cross-sectional view of a portion of a closed-loop reactor well in accordance with the concepts described herein. [Modes for carrying out the invention]

[0009] The same reference number used in the diagram refers to the same element.

[0010] In a geothermal reactor well system, a fluid containing one or more chemical components ("carrier fluid" or "working fluid") circulates within a closed-loop well underground. The carrier fluid and reactants are supplied to the closed-loop well, heated by the surrounding geological formation (e.g., bedrock), and then circulated to the surface. Because the well is a closed loop and does not substantially exchange fluid with the surrounding formation, the primary heat transfer from the soil surrounding the well is by conduction. In some examples, the well has two wellheads at the surface, namely an inlet wellhead and an outlet wellhead, which are connected by one or more connecting wellheads in the subsurface region. Wellheads can be sealed to prevent (completely or substantially) contact or flow between the fluid inside the well and the natural fluid in the formation (e.g., groundwater). In some examples, casing is installed over all or part of the wellhead to provide sealing. In some cases, sealant is circulated through the well to seal the well, and the well is not cased for all or part of its length.

[0011] In certain examples of this disclosure, a closed-loop geothermal well system can be used as an underground reactor to produce products through chemical reactions between reactive components carried by a carrier fluid. The reactants can be injected into one of the surface wells, for example, the entrance well. The reaction products, by-products, and unreacted raw materials can be recovered to the surface through the other surface well. In certain examples, the carrier fluid may be inert to the reaction, or it may be reactants introduced into the reactor in excess (i.e., more than is needed for the reaction to produce the products). A thermosiphon driven by the thermal energy of the geothermal energy and / or the heat generated by the reaction can drive the circulation of the carrier fluid, reactants, and products without requiring pumping. In certain examples, the geothermal energy may additionally or alternatively be a propellant and / or catalyst of the reaction. The reactor well can provide a high-pressure and high-temperature environment for the reaction.

[0012] Figure 1A shows a schematic side section view of a geothermal reactor well system 100A according to the concepts of this specification. System 100A includes a well 102 drilled into the ground through a geothermal subsurface region 104 of interest. In certain cases, the geothermal subsurface region has an intrinsic temperature of 200°C or higher and surrounds at least a portion of the well 102. In certain cases, the subsurface region is one rock formation, a part of a rock formation, or multiple rock formations. In certain cases, the subsurface region 104 is dry and has little to no naturally occurring fluids. In certain cases, the subsurface region 104 is impermeable (bulk permeability coefficient of 0.1 millidarcy or less) or low permeability, i.e., bulk permeability coefficient of 100 millidarcy or less, 50 millidarcy or less, or 1 millidarcy or less. In certain cases, the subsurface region is in or is in a basement formation. In certain cases, the rock of the subsurface region is granite. In the illustrated example, well 102 includes an inlet surface well 120 and an outlet surface well 130, which extend in close proximity between the ground surface and the underground region 104. The inlet surface well 120 and the outlet surface well 130 are connected within the underground region 104 by one or more connecting wells 140. In the illustrated example, the connecting wells 140 define a multilateral well pattern including pairs of lateral wells 150, a subset of which kick off from the inlet well 120 and another subset which kick off from the outlet well 130. Each pair of lateral wells 150 intersects at their respective junctions 154, either at their tips or near them. Thus, the inlet well 120, the outlet well 130, and the connecting wells 140 define a closed loop.

[0013] The entrance borehole 120 and the exit borehole 130 can be drilled from the same drilling site and / or located at the same well site. In certain examples, the boreholes 120 and 130 are drilled within 10 meters, 25 meters, 50 meters, or 100 meters of each other. In other examples, the entrance surface borehole 120 and the exit surface borehole 130 may be separated by a longer distance. For example, Figure 1B, which will be discussed in more detail below, shows that the surface boreholes 120, 130, and the connecting borehole 140 define a U-shaped configuration. In certain examples, when the geothermal well 102 is configured in a U-shape, the entrance surface borehole 120 and the exit surface borehole 130 are drilled more than 3,000 meters apart.

[0014] In the illustrated example, the inlet surface borehole 120 and the outlet surface borehole 130 are vertical boreholes drilled substantially in a straight line (i.e., without the use of inclined drilling methods or equipment). In other examples, one or both of the surface boreholes may be other than vertical (e.g., inclined) and / or drilled using inclined drilling techniques. The connecting borehole 140 is drilled using inclined drilling techniques that penetrate the surface boreholes 120, 130 and includes a curved trajectory starting from the kick-off section 148 of the surface boreholes 120, 130.

[0015] Figure 1A shows a pair of parallel lateral wells 150 extending in the same direction (azimuth) from each of the surface wells 120 and 130. The lateral well 150 extending from the inlet surface well 120 is shown above the lateral well 150 extending from the outlet surface well 130. In some examples, the upper lateral wells 150 are located directly above them (the adjacent lower lateral wells 150), and in some cases directly above each of the lower lateral wells 150. In Figure 1A, each upper lateral well 150 rotates to intersect with its adjacent pair of lower lateral wells 150 at junction 154, connecting the surface wells 120 and 130. In other examples, one or more of the lower lateral wells 150 may intersect with the upper lateral wells 150. In any case, the configuration of the overlapping connecting boreholes 140 defines a layered borehole pattern having one subpattern of boreholes above and one subpattern of boreholes below. In a particular example, one or more additional layered patterns can be drilled from surface boreholes 120, 130 at different depths (i.e., at different kickoffs 148). In Figure 1A, the lower lateral borehole 150 extends downward beyond the junction 154 and defines the sump 152.

[0016] The connecting borehole 140 in Figure 1A is inclined downward, i.e., has a slope 160 from the vertical. In some examples, part or all of the connecting borehole may be horizontal (i.e., slope 160 is about 90 degrees) or substantially horizontal. In some examples, the connecting borehole 140 may have a steeper inclination, as shown in Figure 1B; i.e., the slope 160 may be smaller than the slope shown in Figure 1B, or it may be vertical (slope 160 is zero) or substantially vertical. In some examples, the connecting borehole 140 is aligned with the geological inclination of the strata in the subsurface region. In some examples, the lateral borehole 150 may have a length of 2,000 meters to 10,000 meters or more and may reach a depth of 1,000 meters to 8,000 meters or more.

[0017] Figure 1C shows another embodiment of the geothermal reactor well system-100C- in which lateral wells 150 extend toward each other from the inlet surface well 120 and the outlet surface well 130, respectively. The pair of lateral wells 150, when intersecting, together with the inlet well 120 and the outlet well 130, define a roughly U-shape. The configuration of connecting wells 140 defines a pattern of wells on the same plane in certain examples. In certain examples, one or more additional connecting well patterns can be drilled between the surface wells 120, 130 at different depths (i.e., at different kickoffs 148).

[0018] Referring collectively to Figures 1A-1C, in some examples, surface boreholes 120 and 130 are cased (at least partially or completely), while connecting borehole 140, including the connection of kickoff 148, is bare (i.e., without casing or liner or junction liner). In some examples, connecting borehole 140 may be at least partially lined (e.g., including liner or casing in areas where the subsurface region 104 is fractured, prone to collapse, unconsolidated, or otherwise requires liner).

[0019] Some or a part of the connecting wellbore 140, including the connections to the inlet surface wellbore 120 and the outlet surface wellbore 130, can be (fully or substantially) sealed with a sealant against fluid exchange with the surrounding subterranean region 104 without requiring a casing or liner within the wellbore or a portion of the wellbore. In some examples, the sealant may be in the form of a fluid sealant (such as an alkali silicate fluid) that flows through the wellbore. The sealant is designed such that all or substantially all of the carrier fluid circulating through the wellbore 102 during operation is recovered to the surface, little or no naturally occurring fluid from the subterranean region 104 is recovered, and little or no fluid from the wellbore flows into the subterranean region. In other words, the resulting wellbore 102 is a closed loop. In certain examples, during drilling of the connecting wellbore 140, the sealant can be applied to the wellbore, for example by being included in the drilling fluid and / or supplied as a separate fluid slug separate from the drilling fluid. Alternatively or additionally, the sealant may be applied after drilling and / or during operation of the wellbore. In certain examples, the sealant can be included in the carrier fluid and / or supplied as a fluid slug separate from the carrier fluid. In certain examples, the multilateral wellbore is lined with casing, cemented, and / or lined with liner, such that the carrier fluid, reaction fluid, and catalyst are isolated from the formation and formation fluids. The casing and / or liner may be steel, another metal alloy, and / or another type of casing material.

[0020] In the illustrated example, facility 110 is connected to an inlet surface well 120 and / or an outlet surface well 130. In certain examples, facility 110 includes one or more sources of reactants (e.g., tanks or pipelines) and a source of carrier fluid, which can be connected to the well 102 by valves or pumps to inject the reactants and carrier fluid into the well. In some examples, facility 110 is located on or near the surface of the formation; in other examples, facility 110 may be located partially or completely in an underground location. Facility 110 does not have to be located in one place, but can be divided into one or more separate locations (shown as facilities 110a, 110b) connected by piping, for example, as shown in Figure 1C. Facility 110 is configured to allow for the extraction of products from the reaction and the recovery, separation, and reuse of the carrier fluid.

[0021] Figure 2 is a schematic diagram of an underground reactor well 200 according to the concepts of this specification. The underground reactor well 200 is a closed-loop well similar to well systems 100A, 100B, or 100C, in which an inlet surface well 120 and an outlet surface well 130 are connected by one or more connecting wells 140 within the underground region 104. Although Figure 2 shows a relatively simple configuration of the reactor well 200 for convenience of explanation, the configuration of the reactor well 200 may differ and may be more complex and / or U-shaped, as described above in relation to well systems 100A, 100B, or 100C.

[0022] Geothermal heat from the subterranean formation 104 can provide the heat necessary to drive, catalyze, and / or initiate chemical reactants to produce a desired product. In addition, when the fluid flowing downward through the inlet surface wellbore 120 has a higher density than the high-temperature fluid heated by the subterranean formation 104 and flowing upward through the outlet surface wellbore 130, a thermosiphon effect occurs. In certain examples, when the reaction is exothermic, the heat of reaction is transferred to the mixture of carrier fluid, reactants, and products, further increasing the temperature of the mixture and contributing to enhancing the thermosiphon. In certain examples, this effect may cause the maximum temperature of the mixture of carrier fluid, reactants, and products to exceed the maximum rock temperature of the subterranean formation 104. The density difference creates a pressure difference between the fluid in the inlet surface wellbore 120 and the fluid in the outlet surface wellbore 130, which helps drive the fluid through the well 200 to the surface. The pressure in the outlet surface wellbore 130 can be controlled (e.g., by one or more valves located in and / or at other locations within the surface facility 110) to thereby control the pressure of the reaction fluid in the connecting wellbore 140. In certain examples, the thermosiphon can drive fluid through the reactor well 200 without additional assistance. In certain examples, the thermosiphon can be initiated and / or boosted by one or more pumps (e.g., pumps located within the surface facility 110 or at other locations).

[0023] In certain cases, reactor well 200 is constructed specifically as reactor well 200. However, in certain cases, reactor well 200 is an existing closed-loop geothermal well that has been repurposed and functions as an underground reactor, permanently or temporarily. For example, in a geothermal well site with one or more geothermal wells, one or more geothermal wells can be repurposed and operated as reactor well 200. The remaining geothermal wells can continue to be operated to generate heat and / or electricity, and some or all of the geothermal wells at the same site can be operated to generate electricity to supplement production from reactor well 200. Even if reactor well 200 is constructed specifically for this purpose, it can reside at the same site as the geothermal wells, and in certain cases, the site may include geothermal wells used for generating heat or electricity. The electricity can be used, for example, to drive pumps, compressors, and other components of the reactor well system.

[0024] As shown in Figure 2, the carrier fluid 202 flows downward through the surface inlet borehole 120 while carrying the reactants 204. The carrier fluid 202 and reactants 204 may be in the form of a homogeneous or heterogeneous mixture of the carrier fluid and reactants, or as alternating slags. The carrier fluid 202 can also carry the reaction products 206 (along with by-products and unreacted reactants) to the outlet surface borehole 130 for recovery (e.g., by a valve in a surface facility). In certain examples, it is desirable that the carrier fluid 202 be inert or inert to reaction with reactants 204. In some examples, the carrier fluid 202 may contain impurities or other substances that are not inert themselves but are present in small amounts such that the carrier fluid remains substantially inert (unreactive) to the desired degree. In some examples, an inert phase-change material ("PCM") carrier fluid that absorbs the heat of reaction as latent heat can be used, thereby improving thermosiphon drive as the PCM carrier fluid is heavier in the inlet borehole 120 where the reactants are lightest and lighter in the outlet borehole 130 where the reaction products are heaviest. In some examples, the carrier fluid is a reactant in the desired chemical reaction and is introduced into the system in excess, i.e., in more than is required for the reaction. Whether reactant, inert to the reaction, or generally inert, the carrier fluid can be selected based on its density to achieve the desired pressure in the multilateral section of the well system and / or based on geomechanical considerations to maintain well stability. In some examples, the average density of the carrier fluid in the well system is >500 kg / m³ 3 >1000kg / m 3 , or >1250kg / m 3In some examples, a solid weighting agent (e.g., barite) is introduced into the carrier fluid to maintain this density. In some examples, the carrier fluid includes n-pentane, isopentane, cyclopentane, R1234zEe, R1233zdE, R227ea, dimethyl ether, R1234yf, R1234zeZ, isobutane, butane, propane, hexane, toluene, R152a, R1243zf, propylene, R1243zf, naphtha, ethylene glycol, water, carbon dioxide, or one or more of the following solvents, diluents, or chemical reactants.

[0025] At the surface, the products, reactants, and carrier fluid are separated, and the remaining reactants and carrier fluid are recycled and reintroduced into a closed-loop well reactor. The excess thermal energy from the generated mixture can be used in the organic Rankine cycle, the steam Rankine cycle, or as input energy for another process, and then the mixture is cooled. If the reactants (and recycled carrier fluid) enter the well at low temperatures, it is beneficial (in increasing the thermosiphon drive force and maintaining the geodynamic balance of the well), but it needs to be heated to a temperature sufficient to initiate certain reactions that exhibit commercially viable reaction rates at higher temperatures. In some cases, "low temperature" refers to an inlet temperature below 100°C, but may be below 50°C. In some cases, the "initiation heat" is supplied from high-temperature bedrock (geothermal energy). In some cases, other techniques such as electromagnetic heating (microwave heating and radiofrequency heating, etc.) and electric resistance heaters are used to supplement the geothermal energy to initiate the reaction. Once the threshold temperature for an exothermic reaction is reached, the reaction can become self-sustaining as the temperature of the carrier fluid, reactants, and product mixture increases due to heat from the geological formation, and the reaction rate further increases as the conversion rate rises. In certain cases, the chemical reaction is endothermic, and the required input energy is supplied by geothermal energy and can be supplemented by external heating methods.

[0026] In some examples, the system is designed to cool the carrier fluid to a liquid or supercritical liquid (above critical pressure but below critical temperature). In certain examples, the carrier fluid of the reactants may be a solvent. Using a supercritical solvent carrier fluid can increase heat transfer and make the local temperature within the catalyst bed more stable. Among many other considerations for this design parameter, furthermore, the carrier fluid can be maintained at a ratio that achieves a specific density in the inlet borehole 120 to promote thermosiphoning (other considerations are the partial pressure of the reactants and heat transfer from the exothermic reaction). In certain examples, a carrier fluid with a mole fraction of at least 50% is usable. In other examples, the mole fraction of the carrier fluid relative to the total mixture is at least 60%, 70%, 80%, 90%, or at least 95%. System 200 is also designed to have sufficient exothermic and operating temperatures to produce a fluid with a lower density in the outlet borehole 130. Since the reaction products are typically much heavier than the reactants in the inlet borehole 120, the density reduction due to high temperature is important in creating the thermosiphon effect. The proportion of solvent can also significantly affect this value. In certain examples, system 200 is configured such that the carrier fluid is liquid or supercritical (below critical temperature) at the top of the inlet well 120 and transitions to a supercritical fluid within the reaction / catalysis portion of the well, i.e., within the connecting well 140. As mentioned above, in some examples, a sump 152 can be formed at the junction of the lateral well 150. The sump 152 provides a place for debris or precipitates and by-products resulting from the reaction to accumulate outside the well channel.

[0027] In some examples, the reactor well 200 includes a catalyst bed 208 containing one or more catalysts that can increase the reaction rate of the reactants, within the well, in a connecting well 140, or in multiple connecting well 140s. When the reactants are introduced downward from the inlet surface well 120, they can react in the catalyst bed 208 as they pass through the high temperatures of the connecting well 140 and the subsurface region 104.

[0028] In certain cases, the catalyst is completely packed up to the top of the connecting well 140. To achieve the desired high porosity and permeability (e.g., tens to hundreds of darci), large catalyst particles can be used. Alternatively, in the reactor well 200, a slurry in which small catalyst particles are suspended in a fluid can be used. Small catalyst particles have a large surface area and can reduce pressure loss across the catalyst bed. In some cases, the effectiveness of the catalyst can be improved by using a PCM carrier fluid that can create an isothermal state within the well. Another approach is to use a carrier fluid with a high molar percentage and a high flow rate to suppress runaway temperature changes and maintain the reaction within an optimal temperature range (based on catalytic activity and desired reaction rate).

[0029] In some cases, the catalyst can be placed in a manner similar to sand in a fracturing process, and the borehole can be "screened out" with the catalyst. This can be done by placing gravel-sized catalyst at the beginning of the lateral of the connecting borehole 140 in the outlet borehole 130, essentially just allowing the gravel-sized catalyst to fall by gravity and form a gravel plug. The viscous fluid, entrained with the sand-sized catalyst, is then pumped from the inlet borehole 120 to the outlet borehole 130. The sand-sized catalyst blocks and screens out with the gravel plug, and the fluid continues to pass through the borehole until all the catalyst is in place. A surface separator can be used to remove catalyst particles that may flow to the surface. For example, if it is desirable to remove the catalyst in order to replace it when the catalyst has reached the end of its service life, the catalyst can be removed by drilling through the catalyst bed using a drill string and drill bit.

[0030] Depending on the costs of removal and installation of a new catalyst, regenerating the catalyst may be preferable. For example, carbon contamination of a catalyst can be regenerated by reduction with H2 at temperatures above 350°C. System cleaning using solvents (supercritical CO2, organic fluids) can be performed to remove contaminants from the catalyst surface. Using a slurry form of the catalyst can also help with continuous catalyst regeneration on the ground.

[0031] A closed-loop well can be used as a reactor well 200 to apply high pressure to the fluid. In certain cases, the reactor pressure can range from 40 to 200 MPa (approximately two orders of magnitude (100 ×) larger than the maximum of a typical surface reactor). According to Le Chatelier's principle, increasing the reaction pressure in a particular reaction increases the reaction selectivity to mitigate the effects of high pressure. High pressure in a closed-loop well may also contribute to the autocatalysis of certain chemical reactions, thereby reducing the amount of catalyst required, or even eliminating the need for a catalyst in the well system. As an example, the synthesis of ammonia from gaseous hydrogen and nitrogen can begin autocatalysis at pressures >100 to 200 MPa. In certain cases, the volume of the connecting well 140 is 2500 m³. 3 As described above, the volume can be larger than that of a typical surface reactor, and therefore the yield per reactor can be higher (e.g., an order of magnitude higher). Furthermore, the residence time of a closed-loop well reactor operated by a thermosiphon can be several hours to tens of hours, while most surface reactor vessels operate with resistance times of several seconds to several minutes. Both the larger reactor volume (and longer resistance time) and the higher reactor pressure enable high single-pass conversion in certain chemical reactions, reducing the required surface infrastructure (improving capital efficiency), improving energy efficiency, and reducing the required catalytic activity. Achieving a high single-pass conversion is advantageous because it reduces the size of the equipment required for the recycling stream, such as heat exchangers, compressors, pumps, separators, refrigeration units, and other equipment. This lowers the overall capital cost of the plant and improves the energy efficiency of the process by reducing the power / energy demand of process machinery and equipment.

[0032] Because chemical plants and processes benefit greatly from economies of scale, most general-purpose chemical plants are typically large-scale. For example, a 3,300-ton-per-day ammonia plant may achieve a specific cost 11% lower than a conventional 2,000-ton-per-day plant. However, increasing the size of the reaction vessel to support higher plant capacity is difficult due to transportation and site limitations, and vessel size is a significant constraint in scaling up new facilities. Closed-loop well reactors eliminate these logistical constraints, thereby enabling large-scale chemical facilities with improved capital efficiency.

[0033] In some cases, a closed-loop well as reactor well 200 can be operated in a batch rather than continuous manner. This batch method involves circulating a high-density fluid composition and a low-density fluid composition within the loop. The low-density fluid contains the reactants and / or catalysts required for the reaction. The high-density fluid follows, ensuring that the low-density fluid remains within the multilateral reactor. During the reaction phase, the hydrostatic pressure generated by the denser fluid creates a high-pressure reactor region. Circulation can be stopped or slowed to allow sufficient time for the reaction to complete. A pump can be used to circulate the fluid from the closed-loop well for further processing. This circulation process can be repeated. This operating method is most advantageous when very high pressure and / or longer residence times are required.

[0034] The well systems described herein can be used to produce many different products and can be optimized to maximize the yield of a particular product or a mixture of certain products. In some examples, reactor well 200 can be used to produce fuels such as jet fuel, gasoline, or diesel. For example, in some examples, reactor well 200 can be used in Fischer-Tropsch synthesis via either the direct CO2 route or the CO route as shown below: nCO2 + (3n+1)H2 → C n H 2n+2 +2nH2O (2n+1)H2+nCO → C n H (2n+2) +nH2O

[0035] For the purpose of Fischer-Tropsch synthesis, the catalyst bed 208 may include catalyst materials based on, for example, Fe, Co, Cu, ZnO, and / or Al2O3. The Fischer-Tropsch process can be operated in a temperature range of 150–300°C. Higher temperatures increase the reaction rate and conversion rate, but also tend to promote methane production. For this reason, in low-pressure applications, the temperature can be maintained in the low to medium range. Increasing the pressure increases the conversion rate and promotes the formation of long-chain alkanes, both of which may be desirable. Typical pressures can range from 1 atmosphere to several tens of atmospheres. In certain examples, the reactor well 200 allows for pressures to be increased to approximately 400–2000 atmospheres and high temperatures, resulting in higher conversion rates and higher yields of long-chain alkanes than can be achieved with conventional surface reactors.

[0036] In certain cases, reactor well 200 can facilitate a one-step conversion of CO2 and H2 to fuel. The concepts described herein can also be applied to reactions in which CO and H2 are the main reactants, which is a two-step process in which CO is produced from CO2 by a reverse water-gas shift (RWGS) reaction followed by a Fischer-Tropsch synthesis. Two-step reactions have low CO2 conversion rates, low selectivity for long-chain hydrocarbons, or both. Some catalysts have high CO2 conversion rates but low C5+ selectivity (e.g., FeNa), or low CO2 conversion rates but high C5+ selectivity (e.g., Na-Fe3O4 / HZSM-5). One-step reactions show improved conversion rates of reactants and selectivity for jet fuel-range hydrocarbons. For example, a one-step reaction can yield jet fuel products in a yield of about 19% and reduce unit capital costs by 50%.

[0037] In some examples, the wellbore systems and methods described herein can be used to produce other products. For example, the reactants nitrogen and hydrogen can be used as reactants 204 for ammonia production using the Haber-Bosch process: N 2(g) +3H 2(g) ↔ 2NH 3(g)

[0038] Currently, ammonia synthesis processes are typically operated at high temperatures greater than 400°C and pressures of 10 to 20 MPa. The typical single-pass conversion under these operating conditions is about 20%. Higher conversion is achieved at high pressure and low temperature, both of which are achievable in a closed-loop wellbore reactor. Lower conversion occurs at low pressure and high temperature, but low pressure and high temperature are currently used to optimize the reaction with respect to surface footprint, energy efficiency, and material constraints. Using a subsurface wellbore network allows high pressures (400 to 2000 atm) to be used economically, which can greatly increase the single-pass conversion. This may include relying on different or modified reaction pathways similar to the Claude process or Casale process. The long residence time of the closed-loop wellbore reactor allows less active (and less expensive) catalysts to be used economically without sacrificing selectivity or yield.

[0039] In some examples, to produce urea as product 206, ammonia and carbon dioxide can be injected as reactants 204 to produce ammonium carbamate, which is then decomposed to form urea: 2NH3+CO2↔ NH2COONH4 NH2COONH4↔ (NH2)2CO+H2O

[0040] In some examples, product 206 may be methanol produced from carbon monoxide or the reaction of carbon monoxide and hydrogen as reactants 204: CO+2H2→ CH3OH CO2+3H2→ CH3OH+H2O

[0041] In some examples, product 206 may be methanol produced by the direct reaction of CH4:

[0042]

number

[0043] In some examples, the reactions involve the conversion of methanol, ethanol, isobutanol, or other alcohols to acetic acid, formaldehyde, methyl tert-butyl ether, gasoline, olefins, kerosene, and / or other oligomerized products.

[0044] In some examples, the reaction can involve high-pressure polymerization.

[0045] In some examples, the reactions include methods for extracting important minerals and metals, including high-pressure acid leaching, pressurized oxidation, and other forms of pressurized leaching.

[0046] In some examples, the reactions involve the conversion of hydrocarbons, biomass, or biowaste raw materials into fuels through processes including hydrothermal liquefaction, hydrothermal carbonization, and supercritical fluid extraction.

[0047] In some examples, the reactions include hydrogenation reactions to modify hydrocarbons into higher-value products through processes such as supercritical water reforming.

[0048] As used herein, the term “uphole” means the direction along a borehole tubing string or borehole from its distal end (the end furthest from the surface) toward the surface, and as used herein, “downhole” means the direction along a tubing string or well toward its distal end. A downhole location means the location along the tubing string or well toward the downhole side from the surface.

[0049] This disclosure includes details of many specific embodiments, which should not be construed as limiting the subject matter or claims, but rather as descriptions of features specific to a particular embodiment. In relation to a separate embodiment, certain features described in this disclosure may also be implemented in combination or in a single embodiment. Conversely, various features described in relation to a single embodiment may also be implemented separately or in any preferred partial combination in multiple embodiments. Furthermore, the aforementioned features may be described as acting in a particular combination, and may even be claimed first as such a combination, but one or more features from the claimed combination may, in some cases, be extracted from the combination, and the claimed combination may be a partial combination or a variation of a partial combination.

[0050] Specific embodiments of the subject matter have been described. Nevertheless, it will be understood that various modifications, substitutions, and changes are possible. Although operations are shown in a specific order in the drawings or claims, this should not be understood as requiring that such operations be performed in a specific or sequential order shown, or that all illustrated operations be performed (some operations may be considered optional), in order to achieve the desired result. Accordingly, the above embodiments do not define or limit this disclosure. [Explanation of symbols]

[0051] 100A Geothermal Reactor Well System 100B Geothermal Reactor Well System 100C Geothermal Reactor Well System 102 Geothermal Well 104 Geothermal underground area 110 facilities 110a Facility 110b Facility 120 Inlet surface wellbore 130 Outlet surface wellbore 140 Connecting well boreholes 148 Kick-off 150 Lateral Boreholes 152 Samp 154 Junction 160 gradient 200 underground reactor wells 202 Carrier fluid 204 Reactants 206 Products of the reaction 208 Catalyst bed

Claims

1. A geothermal reactor well system, A closed-loop well coupled to one or more reactant sources, The first surface well extends from the ground surface to the geothermal underground region; A second surface well extending from the ground surface to the geothermal underground region; The closed-loop well includes; a plurality of connecting wells that connect the first surface well to the second surface well; and A geothermal reactor well system comprising a carrier fluid disposed within the closed-loop well, wherein the closed-loop well is driven by thermal energy from the geothermal underground region and / or the reaction of reactants within the closed-loop well to circulate the fluid within the closed-loop well by a thermosiphon, thereby transporting the reactants through the closed-loop well for the reaction and transporting the products of the reaction through the closed-loop well for recovery.

2. The geothermal reactor well system according to claim 1, wherein the reaction is partially driven by thermal energy from the geothermal underground region.

3. The geothermal reactor well system according to claim 1 or 2, wherein the closed well loop is configured such that the pressure and temperature within the closed well loop are within a specific pressure and temperature range for the reaction.

4. The geothermal reactor well system according to any one of claims 1 to 3, wherein the closed-loop well further includes a catalyst bed located inside.

5. The geothermal reactor well system according to claim 4, wherein the catalyst bed includes a slurry.

6. The geothermal reactor well system according to any one of claims 1 to 5, wherein the geothermal underground region has an intrinsic temperature of at least 200°C surrounding at least a portion of the connecting well.

7. The geothermal reactor well system according to any one of claims 1 to 6, wherein the product is a fuel product.

8. The geothermal reactor well system according to any one of claims 1 to 6, wherein the reaction comprises a Fischer-Tropsch synthesis.

9. The geothermal reactor well system according to any one of claims 1 to 6, wherein the product comprises ammonia.

10. The geothermal reactor well system according to any one of claims 1 to 6, wherein the product comprises methanol.

11. The geothermal reactor well system according to any one of claims 1 to 10, wherein at least a portion of the plurality of connecting well bores are sealed to prevent fluid communication between the connecting well bores and the surrounding geothermal underground region.

12. It is a method, A step of distributing reactants into a closed-loop well from one or more reactant sources coupled to the closed-loop well, wherein the closed-loop well is The first surface well extends from the ground surface to the geothermal underground region; A second surface well extending from the ground surface to the aforementioned geothermal underground region; A process comprising: a plurality of connecting wells that connect the first surface well to the second surface well; A step of placing the carrier fluid inside the closed-loop well; A step of circulating the carrier fluid to transport the reactants through the closed well loop, wherein the circulation is driven by thermal energy from the geothermal underground region and / or by a thermosiphon from the reaction of the reactants in the closed well loop; and A method comprising the step of recovering the products from the reaction of the reactants from the closed-loop well.

13. The method according to claim 12, wherein the reaction is partially driven by thermal energy from the geothermal underground region.

14. The method according to claim 12 or 13, further comprising the step of configuring the closed borehole loop such that the pressure and temperature within the closed borehole loop are within a specific pressure and temperature range for the reaction.

15. The method according to any one of claims 12 to 14, wherein the closed-loop well further comprises a catalyst bed located inside, and the circulation further comprises circulating the carrier fluid and the reactants through the catalyst bed.

16. The method according to claim 15, wherein the catalyst bed includes a slurry.

17. The method according to any one of claims 12 to 16, wherein the geothermal underground region has an intrinsic temperature of at least 200°C surrounding at least a portion of the connecting well.

18. The method according to any one of claims 12 to 17, wherein the product is a fuel product.

19. The method according to any one of claims 12 to 17, wherein the reaction comprises a Fischer-Tropsch synthesis.

20. The method according to any one of claims 12 to 17, wherein the product comprises ammonia.

21. The method according to any one of claims 12 to 17, wherein the product comprises methanol.

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