Hydrogen production and sulfur-carbon sequestration

Abstract

An embodiment of the invention relates to producing hydrogen from a subterranean formation by injecting a reactant into the subterranean formation and reacting the reactant with the subterranean formation to form at least one of hydrogen gas or a mineralization product within the subterranean formation. The hydrogen produced is collected or one or more components of the reactant are sequestered to form a mineralization product in the subterranean formation. Another embodiment of the invention relates to producing hydrogen by injecting a thermal fluid into a subterranean rock formation, the thermal fluid including a reactant. The reactant reacts with components in the subterranean formation to form at least one of hydrogen gas, mineralized sulfur, or mineralized carbon.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Application No. 63 / 330,216, filed April 12, 2022, U.S. Provisional Application No. 63 / 330,220, filed April 12, 2022, and U.S. Provisional Application No. 63 / 330,223, filed April 12, 2022, the disclosures of which are incorporated herein by reference in their entireties. [Background technology]

[0002] The use of hydrogen as an alternative chemical feedstock and fuel source to hydrocarbons and other fossil fuels is a long-term yet unrealized goal of society. This dream of a hydrogen economy remains unrealized due to the long-standing problem of obtaining hydrogen in the quantities and at the cost required for a viable hydrogen economy. Furthermore, current methods of hydrogen synthesis are highly carbon and energy intensive. However, once produced, hydrogen provides a clean energy source that eliminates the greenhouse gases generated from the use of hydrocarbons, e.g., gas and oil, as energy sources. As a result, various mechanisms for the production of low-carbon or negative-carbon or "green" hydrogen are being explored in various industrial sectors. Hydrogen is a very important chemical used in various industries and can be extracted from underground rock formations.

[0003] Subsurface rock formations may contain other materials that can be utilized for energy production. For example, the formations may be rich in elements such as iron or minerals and fluids. The rock formations may also contain pores that hold or store various products or fluids. By-products of the process may be stored or sequestered in the subsurface formations for long periods of time. For example, over time, carbon dioxide may be mineralized into a solid and removed from the atmosphere on geological timescales. Sequestration may be an option for climate change mitigation in short and long term scenarios. [Brief description of the drawings]

[0004] The drawings illustrate several embodiments of the present invention, with the same reference numbers referring to the same or similar elements or features in different views or embodiments shown in the drawings.

[0005] [Figure 1] 1 illustrates a cross section of mafic rock that can be accessed for thermally assisted enhanced hydrogen production, sulfur enhanced hydrogen production, or sulfur-carbon mixture enhanced hydrogen production, according to one embodiment. [Diagram 2] 1 is a schematic diagram of sulfur enhanced hydrogen production in a subterranean formation, according to one embodiment. [Diagram 3] 1 is a schematic diagram of sulfur-carbon mixture enhanced hydrogen production in a subterranean formation, according to one embodiment. [Figure 4] 1 is a flow chart of a method for carrying out sulfur enhanced hydrogen production and sulfur-carbon mixture enhanced hydrogen production, according to one embodiment. [Diagram 5] 1 is a schematic diagram of thermally assisted enhanced hydrogen production with an embodiment of carbon or sulfur sequestration in subterranean formations, according to one embodiment. [Figure 6] 4 is a flow chart of a method for thermally assisted enhanced hydrogen production enhancement, according to one embodiment. [Figure 7] 1 is a schematic diagram of thermally assisted enhanced hydrogen production in subterranean formations, according to one embodiment. Summary of the Invention [Problem to be solved by the invention]

[0006] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to the fields of energy extraction, geology, or geophysics. Some embodiments disclose methods for producing hydrogen from underground rock formations. Some embodiments include sulfur sequestration through mineralization of dihydrogen sulfide and carbon sequestration through mineralization of carbon dioxide. [Means for solving the problem]

[0007] In one embodiment, a method of producing hydrogen from a subterranean formation may include injecting a reactant into the subterranean formation and reacting the reactant with the subterranean formation to form at least one of hydrogen gas or a mineralization product within the subterranean formation. The method may further include recovering hydrogen produced from the reaction of the reactant with the subterranean formation or sequestering one or more components of the reactant to form mineralized sulfur or mineralized carbon. In some embodiments, the reactant may include at least one of dihydrogen sulfide, carbon dioxide, water, steam, brine, geothermal fluid, or waste heat fluid. The subsurface formation may include at least one of iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-containing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich deposit. In some examples, the subsurface formation includes porous, faulted, or geologically or primarily fractured rock formations. In some embodiments, the subsurface rock formation includes a natural geothermal system.

[0008] In some embodiments, the method may further include heating the reactants prior to injecting the thermal fluid into the subterranean formation. The reactants may be heated from a heat source external to the subterranean rock formation. In some embodiments, the method may include fracturing the subterranean formation. The reaction may include one or more of a serpentinization reaction, a pyritization reaction, or a decarbonation reaction.

[0009] In some embodiments, a method of sequestering carbon dioxide or dihydrogen sulfide in a subterranean rock formation may include injecting a fluid comprising at least one of carbon dioxide and dihydrogen sulfide into the subterranean rock formation and reacting the fluid with elements of the subterranean rock formation to form at least one of hydrogen gas, mineralized carbon, or mineralized sulfur. In some embodiments, the subterranean rock formation may comprise one or more of iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-containing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentine minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich deposit in the subterranean rock formation to form hydrogen gas and mineralize carbon from the carbon dioxide. The subterranean rock formation may include a porous, faulted, geologically or initially fractured rock formation, or a natural geothermal system. In some embodiments, the method may further include heating the fluid prior to injecting the thermal fluid into the subterranean formation. The fluid may be heated by a heat source external to the subterranean rock formation. In some embodiments, reacting the fluid with elements of the subterranean rock formation may include one or more of a serpentinization reaction, a pyritization reaction, or a decarbonation reaction. The method may further include recovering hydrogen gas formed by reacting the fluid with elements of the subterranean rock formation.

[0010] In some embodiments, a method of producing hydrogen from a subterranean rock formation may include injecting a thermal fluid into the subterranean rock formation. The thermal fluid may include reactants and may be heated by a heat source external to the subterranean rock formation, the reactants may include one or more of dihydrogen sulfide or carbon dioxide. The method may further include reacting the reactants with components of the subterranean formation to form at least one of hydrogen gas, mineralized sulfur, or carbon, and recovering hydrogen produced from the reaction of the reactants with the subterranean formation or sequestering the mineralized sulfur or carbon within the subterranean formation. In some embodiments, the subsurface rock formation may include one of iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-containing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich deposit. The subsurface rock formation may include porous, faulted, geologically or primarily fractured rock formations, or natural geothermal systems. In some embodiments, the thermal fluid includes at least one of water, steam, saline water, geothermal fluid, waste heat fluid, or supercritical fluid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] FIELD OF THE DISCLOSURE Embodiments of the present disclosure generally relate to the fields of energy extraction, geology, or geophysics. Some embodiments disclose methods for producing hydrogen from underground rock formations. The underground rock formations may include porous, faulted, or geologically or primarily fractured rock formations. More specifically, the present disclosure relates to methods for producing and extracting hydrogen underground. Other embodiments disclose methods for hydrogen production and recovery, sulfur sequestration through dihydrogen sulfide mineralization, and carbon sequestration through carbon dioxide mineralization.

[0012] 1 shows a cross section of in situ mafic rock 100 that may be accessed for thermally assisted enhanced hydrogen production, sulfur enhanced hydrogen production, or sulfur-carbon mixture enhanced hydrogen production according to one embodiment. In some embodiments, hydrogen production may occur from terrains that have been limited by a lack of key reactants (i.e., water, heat, carbon dioxide, or dihydrogen sulfide) or where economically viable mineralization has not been possible, or where economically viable mineralization of sulfur and carbon has not been possible. However, the hydrogen production methods described herein may find applicability and provide improvements and benefits in terrains with excess geothermal heat (e.g., geothermal gradients greater than 20° C. / km), etc.

[0013] In some embodiments, in the production of natural resources from underground formations, wells or boreholes may be drilled into the earth to the location where the natural resources are believed to be present. Similarly, in the injection of water or the sequestration of dihydrogen sulfide, carbon dioxide, or other greenhouse gases into underground formations, wells or boreholes may be drilled into the earth to the location where the water or these gases are injected, placed, and sequestered. These natural resources recovered may be hydrogen, helium, carbon dioxide, dihydrogen sulfide, methane or other hydrocarbon gases, dihydrogen sulfide reservoirs, hydrogen reservoirs, helium reservoirs, carbon dioxide reservoirs, dihydrogen sulfide rich reservoirs, hydrocarbon rich reservoirs, and the natural resources may be fresh water, brackish water, salt water, steam, which may be a heat source for geothermal energy, or some other natural resources may be mineral deposits, minerals, metals, underground gemstones.

[0014] The formations containing these resources may be hundreds, thousands, or tens of thousands of feet below the earth's surface, including below the bottom of a body of water, e.g., below the ocean floor, or below other natural resources, e.g., below an aquifer. In addition to being at various depths within the earth, these formations may span regional areas of different sizes, shapes, and volumes.

[0015] Typically, and as a common example, in drilling a water well, an initial borehole is drilled into the earth, e.g., at the land surface or at the seabed, followed by subsequent smaller diameter boreholes drilled into the earth to extend the overall depth of the borehole, thus decreasing in diameter as the overall borehole gets deeper, so that it may be envisioned as a telescoping assembly of holes with the largest diameter hole at the top of the borehole closest to the earth's surface.

[0016] The beginning stages of the subsea drilling process are generally described as follows: Once the drilling rig is at the surface in the area to be drilled, an initial borehole is formed by drilling a 36 inch hole to a depth of approximately 200-300 feet below the seafloor. A 30 inch casing is then inserted into the initial borehole. The 30 inch casing may be referred to as a conductor. The 30 inch casing may or may not be cemented into place. Risers are generally not used during this drilling operation, and cuttings from the borehole, such as earth material or other material removed from the borehole by the drilling activity, are returned to the seafloor. A 26 inch diameter borehole is then drilled into the 30 inch conductor to extend the borehole depth to approximately 1000-1500 feet. This drilling operation is performed without the use of a riser. A 20 inch casing is then inserted into the 30 inch conductor and the 26 inch borehole. The 20 inch casing is cemented into place. A wellhead is secured to the 20 inch casing. (In other operations, additional smaller diameter wellbore holes may be drilled, smaller diameter casing inserted into the wellbore, and the wellhead secured to the smaller diameter casing.) A BOP (blow out preventer) is then secured to the riser and lowered by the riser to the seabed where the BOP is secured to the wellhead. From this point, all drilling activity in the wellbore is conducted via the riser and BOP. Subsea drilling operations that do not use risers are also contemplated.

[0017] In the land drilling process, the steps are similar, but the large diameter tubulars of 20-30 inches are not typically used. Thus, generally, there is a surface casing, typically about 13 3 / 8 inches in diameter. This may extend from the surface, e.g., the wellhead and BOP, to a depth of tens to hundreds of feet. One of the purposes of the surface casing is to meet environmental concerns in groundwater protection and prevent surface casing discharge of greenhouse gases or flammable gases into the groundwater aquifer or atmosphere. The surface casing should have a large enough diameter to allow the passage of the drill string, production equipment such as electric submersible pumps (ESPs), and circulating mud. Beneath the casing, one or more intermediate casings of different diameters may be used. (Parts of the borehole are not cased, and are called open hole.) These may have diameters ranging from about 9 inches to about 7 inches, but larger or smaller sizes may also be used and may extend to depths of thousands to tens of thousands of feet. Inside the casing, the production pipe runs from the pay zone, or production zone, of the wellbore to and through the wellhead at the surface. There can be one production pipe in a wellbore, or multiple production pipes with each end at a different depth.

[0018] Fluid communication between the formation and the well can be greatly increased by the use of hydraulic fracturing techniques. The first use of hydraulic fracturing dates back to the late 1940s and early 1950s. Generally, hydraulic fracturing processes pump fluids down a well into the formation where the fluids penetrate the formation and fracture the rock layers, for example, forcing the rock layers to break apart or fracture. These fractures form channels or flow paths with cross-sectional areas ranging from a few microns to a few millimeters and potentially larger in size. The fractures can also extend from the well for a few feet, several feet, and tens of feet or more in all directions. The fractures can be kept open by the use of proppants (e.g., sand or other mineral grains of various sizes) that are forced into the well with the fracturing fluid in a single process. It should be remembered that the longitudinal axis of a well within a reservoir is not vertical, but may be inclined (up-dip or down-dip) or horizontal. The section of the well that is located within the reservoir, i.e. the section of the formation that contains the natural resource, may be called the pay zone.

[0019] As used herein, the terms "hydrogen exploration and production", "carbon dioxide exploration and production", "helium exploration and production", "dihydrogen sulfide exploration and production", "exploration and production activities", "E&P", "E&P activities", and similar terms, unless otherwise specified, are to be given the broadest possible meaning and include surveying, geological analysis, well planning, reservoir planning, reservoir management, well drilling, workover and completion operations, hydrogen production, hydrogen discharge from wells, hydrogen recovery, secondary and tertiary recovery from wells, hydrogen discharge management from wells, carbon dioxide injection, carbon dioxide sequestration, carbon dioxide minerals, dihydrogen sulfide injection, dihydrogen sulfide sequestration, dihydrogen sulfide minerals, or other upstream activities.

[0020] As used herein, the terms "fluid injection" or "fluid" and "specially treated or heated steam" mean The terms "water," "hot water," "brine water," "compressed hot water," "effluent," "wastewater," "seawater," "geothermal fluid," "geothermal exhaust fluid," "other heated (e.g., waste heat) thermal fluid," "CO2," "gaseous CO2," "supercritical CO2," or other heated thermal fluid, alone or mixed with, dissolved in, or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, effluent, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, other heated (e.g., waste heat) thermal fluid, "H2S," "gaseous H2S," "supercritical H2S," or other heated thermal fluid, alone or mixed with, dissolved in, or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, effluent, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, other heated (e.g., waste heat) thermal fluid, and similar terms are to be given the broadest possible meaning unless otherwise specified.

[0021] The term "reactant" as used herein, unless otherwise specified, includes any component necessary to effect a change within a subterranean formation including "fluid," "thermal fluid," "heat," "CO2," "gaseous CO2," "supercritical CO2," or other heated thermal fluids, alone or mixed or dissolved or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, wastewater, effluent, seawater, geothermal fluids, geothermal exhaust fluids, other heated (e.g., waste heat) thermal fluids, "H2S," "gaseous H2S," "supercritical H2S," or other heated thermal fluids, alone or mixed or dissolved or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, wastewater, effluent, seawater, geothermal fluids, geothermal exhaust fluids, other heated (e.g., waste heat) thermal fluids.

[0022] As used herein, the terms "fracturing," "stimulation," "fracking," or other terms are to be given their broadest possible meaning unless otherwise specified.

[0023] The terms "sulfur mineralization," "sulfur sequestration," "sulfur mitigation," "carbon dioxide mineralization," "carbon dioxide sequestration," "carbon dioxide mitigation," "carbon mineralization," "carbon sequestration," "carbon mitigation," and similar terms as used herein, unless otherwise specified, are to be given the broadest possible meaning and include surveying, geological analysis, well planning, reservoir planning, reservoir management, well drilling, workover and completion operations, sulfur injection, dihydrogen sulfide injection, carbon injection, carbon dioxide injection, supercritical dihydrogen sulfide injection, supercritical carbon dioxide injection, managed inflow of sulfur, dihydrogen sulfide, carbon, carbon dioxide, supercritical dihydrogen sulfide, or supercritical carbon dioxide to a well, and other upstream activities.

[0024] The term "ground", as used herein, unless otherwise specified, is to be given the broadest possible meaning and includes all natural materials, such as soil, rocks, and man-made materials, such as concrete, well casing, pipes, or fill, that are or may be present in the land.

[0025] The terms "offshore" and "offshore drilling operations" and similar terms as used herein are to be given the broadest possible meaning unless otherwise specified and may include any water-based and underwater drilling operations, whether freshwater or saltwater, man-made or naturally occurring, such as rivers, lakes, canals, inland seas, oceans, seas such as the North Sea, inlets and bays such as the Gulf of Mexico. The term "offshore drilling rig" as used herein is to be given the broadest possible meaning unless otherwise specified and may include fixed towers, tenders, platforms, barges, jack-ups, floating platforms, drillships, dynamically deployed drillships, semisubmersibles, and dynamically deployed semisubmersibles. The term "seabed" as used herein is to be given the broadest possible meaning unless otherwise specified and may include the under or bottom surface of any body of water, whether freshwater or saltwater, man-made or naturally occurring.

[0026] The term "borehole" as used herein, unless otherwise specified, is given the broadest possible meaning and includes any opening formed in the earth that is substantially longer than it is wide, such as wells, well borings, well holes, microholes, slimholes, and other terms commonly used or known in the art to define these types of elongated passages. Wells may further include exploratory, discovery, production, decommissioning, re-entry, rework, recirculation, and injection wells. These may include cased and uncaseable wells, and portions of these wells. Uncased wells, or portions of wells, may also be referred to as open holes, work holes, open bore holes, or open bore portions. A borehole may further have sections or portions that have different orientations, and they may have straight and arcuate portions, and combinations thereof. Thus, as used herein, the "bottom" of a borehole, the "bottom" of a borehole, and similar terms, unless otherwise specified, refer to the end of the borehole, i.e., the portion of the borehole that is furthest along the path of the borehole from the opening of the borehole, the surface of the earth, or the start of the borehole. The terms "side" and "wall" of a borehole are given the broadest possible meaning and include the longitudinal surfaces of a borehole whether or not a casing or liner is present, and thus these terms include the sides of an open borehole or the sides of casing disposed within a drilling premises. A borehole may be composed of a single passage, multiple passages, connected passages (e.g., branched, fishbone, bilateral, trilateral, quadrilateral, pitchfork, feather, or comb configurations), and combinations and variations thereof.

[0027] Boreholes are typically created and advanced using a mechanical drilling device having a rotating drilling tool, e.g., a bit. For example, typically, when creating a borehole in the earth, a drill bit is extended into the earth and rotated to create a hole in the earth. To perform a drilling operation, the bit must be pressed against the material to be removed with sufficient force to exceed the shear strength, compressive strength, or a combination thereof, of the material. The material that is removed from the earth is commonly known as cuttings or drill waste, e.g., rock fragments, dust, rock fibers, and other types of materials and structures that may result from the bit interacting with the earth. These cuttings are typically removed from the borehole using a fluid, which may be a liquid, foam, or gas, or other material known in the art.

[0028] The term "drill pipe" as used herein is given the broadest possible meaning, unless otherwise specified, and includes all forms of pipe and collars used in drilling activities, and refers to a single section or portion of pipe or collar. The terms "stand of drill pipe", "drill pipe stand", "stand of pipe", "stand" and similar terms as used herein are given the broadest possible meaning, and include two, three or four sections of drill pipe that are connected, e.g., typically joined together by a joint having a threaded connection. The terms "drill string", "string", "string of drill pipe", "string of pipe" and similar terms as used herein are given the broadest possible definition, and include a stand or stands that are joined together for use in a wellbore. Thus, a drill string may include numerous stands and hundreds of sections of drill pipe.

[0029] The terms "subsurface formation," "rock formation," "formation," "reservoir," "pay zone," and similar terms as used herein are to be given the broadest possible meaning, unless otherwise specified, and include all places, areas, and geological features within the earth that contain, may contain, or are believed to contain iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-bearing igneous, metamorphic, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous, metamorphic, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich deposits, hydrogen, carbon dioxide, helium, or dihydrogen sulfide.

[0030] As used herein, the terms "resource field," "oil field," "gas field," and similar terms are to be given the broadest possible meaning unless otherwise specified and may include land, ocean, or water loosely or directly associated with geological formations, and in particular resource-bearing formations. Thus, a resource field may have one or more exploration and production wells associated with it, a resource field may have one or more governmental or private resource leases associated with it, and one or more resource fields may be directly associated with resource-bearing formations.

[0031] As used herein, the terms "conventional hydrogen," "conventional carbon dioxide," "conventional helium," "conventional dihydrogen sulfide," "conventional natural gas," "conventional," "conventional production," and similar terms are given the broadest possible meaning, unless otherwise specified, and include hydrogen, carbon dioxide, helium, dihydrogen sulfide, or natural gas trapped in underground structures. Generally, in such conventional formations, the hydrogen, carbon dioxide, helium, dihydrogen sulfide, or natural gas travel through permeable, semi-permeable, or fractured formations to reach the area where they are trapped or accumulated. Typically, in conventional formations, there is a non-porous, relatively non-permeable layer above or surrounding the area that accumulates the hydrogen, carbon dioxide, helium, dihydrogen sulfide, or natural gas and traps the hydrogen, carbon dioxide, helium, dihydrogen sulfide, or natural gas in the accumulation layer. Conventional reservoirs have historically been the source of most of the observed hydrogen, carbon dioxide, helium, and dihydrogen sulfide. As used herein, the terms "unconventional hydrogen," "unconventional carbon dioxide," "unconventional helium," "unconventional dihydrogen sulfide," "unconventional natural gas," "unconventional," "unconventional production," and similar terms, unless otherwise specified, are to be given the broadest possible meaning and include hydrogen, carbon dioxide, helium, dihydrogen sulfide, or natural gas contained in iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich sediments, low porosity rocks, or low permeability rocks, or non-permeable rocks, or that have not migrated to a trap or accumulation area.

[0032] The term "gold hydrogen" as used herein is to be given the broadest possible meaning, unless otherwise specified, and refers to rocks or deposits that are composed of iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, rocks or deposits that contain serpentine minerals, partially or partially composed of serpentine minerals, with or without fracture or other forms of mechanical stimulation. Refers generally to hydrogen produced underground by drilling or by drilling and stimulation of fully serpentinized rocks, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich deposits, uranium- and thorium-rich igneous or metamorphic rocks (e.g., granite and granite gneiss), or uranium- and thorium-rich deposits or sedimentary rocks, which may provide an abundant source of low or negative carbon emissions, low cost, fully deliverable energy.

[0033] The term "element", as used herein, unless otherwise specified, is given the broadest possible meaning and generally refers to each of over 100 chemical substances that are not chemically interconverted or broken down into simpler substances and that are major building blocks of matter, each of which can be distinguished by its atomic number, i.e., the number of protons in the nucleus of that atom.

[0034] The term "molecule," as used herein, unless otherwise specified, is to be given the broadest possible meaning and generally refers to a group of atoms bonded together that represent the smallest fundamental unit of a chemical compound capable of participating in a chemical reaction.

[0035] The term "measurement" as used herein is given the broadest possible meaning, unless otherwise specified, and generally refers to the act of measuring something. The examples of elemental, molecular, isotope, and isotope ratio geochemical measurements described above may be performed using a variety of chemical instruments, including chromatography, mass spectrometry, spectroscopy, or other methods.

[0036] The term "measurement" as used herein, unless otherwise specified, is to be given the broadest possible meaning and generally refers to an apparatus or tool used for scientific purposes, including the study of natural, laboratory-based, and theoretical purposes.

[0037] Here, unless otherwise specified, room temperature is 25° C., and standard temperature and pressure are 25° C. and 1 atmosphere.

[0038] In general, the term "about" as used herein, unless otherwise specified, is meant to encompass a variance or range of ±10%, the experimental or instrumental error associated with obtaining the stated value, and preferably the greater of these.

[0039] Herein, unless otherwise stated, the recitation of ranges of values ​​is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, and unless otherwise stated, each separate value within a range is incorporated herein as if it were individually set forth herein.

[0040] "CO 2e The term "carbon intensity" is used to define the carbon dioxide equivalent of the more potent greenhouse gases (i.e. methane and nitrous oxide) relative to other carbon dioxide, based on a 100-year global warming potential basis, based on the IPCC AR5 methodology. The term "carbon intensity" refers to the life cycle CO2 generated per unit mass of a product. 2e means.

[0041] CO2 is widely recognized as a greenhouse gas, and the continued accumulation of CO2 and other greenhouse gases in the atmosphere is expected to cause problematic changes to the Earth's ecosystems and contribute to a myriad of other problems such as ocean acidification and sea-level rise. Two fundamental causes of global carbon emissions are the use of fossil fuels for electricity generation and transportation.

[0042] Given the risks of CO2 emissions, a great deal of effort has been expended to find alternatives to existing high-carbon energy sources or ways to decarbonize existing energy sources. However, many of these low-carbon alternatives are not economical or deliverable enough to replace current options.

[0043] The term "sulfur equivalent" or "SO x " is used to define the dihydrogen sulfide or sulfur dioxide offset equivalent of sulfur emissions. The term "sulfur intensity" refers to the amount of SO2 generated per unit mass of a product. x This refers to the life cycle of

[0044] Sulfur, in various forms including but not limited to dihydrogen sulfide, sulfur dioxide, sulfuric acid, and sulfates, is widely recognized as a toxic and harmful air and water pollutant, and its deposition in soils, waterways, and other environments is predicted to cause problematic changes in the Earth's ecosystem and contribute to a myriad of other problems, such as acid rain, soil acidification, deforestation, ocean acidification, and other toxic effects. The root causes of global dihydrogen sulfide emissions are associated with oil and natural gas extraction and refining, pulp and paper, rayon fiber manufacturing, waste disposal, landfills, water and wastewater treatment plants, and municipal solid waste disposal. In addition, natural sources such as volcanoes, hot springs, thermal eruptions, geysers, fumaroles, "sour" natural gas fields, biodegradation oil fields, and geothermal power plants also constitute major natural sources of dihydrogen sulfide and carbon dioxide.

[0045] Given the risks of dihydrogen sulfide and other forms of sulfur emissions, much effort has been expended on developing sulfur removal technologies, low sulfur fuels, or methods to desulfurize existing energy sources and processes. However, many of these low sulfur alternatives create their own cost limitations, are uneconomical, or limit the deliverability of the energy source.

[0046] Based on the risks of sulfur emissions, the U.S. Environmental Protection Agency (IRC 45H) created a cap-and-trade sulfur credit program for offsetting, sulfur reduction, and sequestration. The U.S. Internal Revenue Service 45Q tax credit program is similar to the carbon dioxide sequestration tax credit program.

[0047] In electricity generation, alternatives to reliable, low-cost but high-emission energy sources (gas and coal) are either deliverable and expensive (e.g., nuclear, hydro, green or blue hydrogen) or cheap and intermittent (e.g., solar and wind, and possibly green hydrogen). There is only one existing source of low-cost and deliverable electricity: geothermal. However, geothermal resources are limited by geography and size, many of the economically productive geothermal resources are already exploited and nearing the end of their life, and many geothermal resources are already in decline. Thus, the prospects for growth of geothermal energy resources are limited without major technological advances.

[0048] Green hydrogen (hydrogen produced from water without the use of fossil fuels) produced by electrolysis fueled by either solar, wind, hydroelectric, or geothermal energy can be a reliable low-carbon energy source when combined with storage, but high capital costs, intermittent generation from intermittent energy sources or the high cost of energy when grid-tied, and the high cost and low availability of suitable hydrogen storage resources limit its applicability. In addition, electrolysis consumes significantly more energy to produce hydrogen than is stored in the hydrogen, leading to low round-trip efficiency of the system.

[0049] Blue hydrogen faces similar problems as green hydrogen, taking low-cost, high-emission fuel sources like coal and natural gas and converting them into high-cost, low-emission energy sources by adding expensive and parasitic carbon capture equipment. Thus, even though large amounts of hydrogen are formed in a subsequent process that prevents greenhouse gas emissions into the atmosphere, newly developed hydrogen resources are not cost-competitive with other forms of energy derived from fossil fuels. Furthermore, challenges associated with finding carbon sequestration resources that can be used to permanently store the carbon captured from such processes lead to limited opportunities to deploy such technologies today.

[0050] Natural hydrogen (or "golden hydrogen") produced from underground by drilling or by mining and stimulation of iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, pyrite, iron-rich sandstone, olivine or pyroxene-containing igneous rocks, olivine or pyroxene-containing sediments or sedimentary rocks, olivine or pyroxene-containing metamorphic rocks, or iron-rich sediments, uranium- and thorium-rich igneous or metamorphic rocks (e.g., granite and granite gneiss), or uranium- and thorium-rich sediments or sedimentary rocks, with or without fracturing or other forms of mechanical stimulation, may provide an abundant source of low-emission, low-cost, fully deliverable energy.

[0051] Each of these energy sources and their inherent benefits and limitations are also relevant to transportation. When considering fuels for transportation, the primary fuel sources are diesel and gasoline, both of which are derived from crude oil production. In addition, while electric vehicles have gained market share in recent years, the cost of electric vehicles is still higher than their fossil fuel equivalents and they have limitations in terms of the cost for batteries and energy storage, charging time, and primary resources for batteries and energy storage. Electric long-haul trucking is also challenging given the weight of batteries, and most long-haul truck manufacturers are looking for affordable low or negative carbon options such as hydrogen fuel trucking.

[0052] Natural hydrogen produced by various enhanced hydrogen production reactions could be the answer to low or negative carbon, low cost, reliable transportation problems for long-haul trucking and potentially other forms of transportation. For other forms of transportation, natural hydrogen as a compressed or liquefied product, or as a feedstock for synthetic liquid fuels ("efuels"), could be a reliable low cost, low or negative carbon solution. In addition, natural hydrogen could be combined with nitrogen to produce a carbon-free ammonia product, which is being widely discussed as a potential replacement for bunker fuel in transportation and as a feedstock for synthetic fertilizer production.

[0053] Direct Emissions Reductions: There are no direct CO2 emissions from the combustion or typical use of hydrogen, so CO2 emission reductions are a function of what the hydrogen replaces. In many cases, low or negative carbon hydrogen can replace hydrogen from steam methane reforming (SMR) as a chemical feedstock for ammonia production, petroleum refining, and other chemical manufacturing. In some cases, low or negative carbon hydrogen can replace natural gas, diesel fuel, gasoline, or jet fuel as a heat source or transportation fuel.

[0054] For ammonia production and refining, natural gas is used, via steam methane reforming (SMR), to produce hydrogen, which is used as a chemical feedstock in both the refining and ammonia production processes. Today, more than 95% of hydrogen is produced in steam methane reformers (SMRs) using natural gas. The carbon intensity of hydrogen production using SMRs without carbon capture is 10.4 tonnes of CO2 emitted per tonne of hydrogen produced. Therefore, the direct substitution of natural hydrogen with hydrogen produced by the SMR process would result in a reduction of 10.4 tonnes of CO2 / 1 tonne of H2.

[0055] For electricity generation using gas turbines, hydrogen must replace an equivalent amount of energy (btu) from natural gas. Hydrogen has an energy density of 290 btu / cf or 51,682 btu / lb. In comparison, the energy density of natural gas is 983 btu / cf or 20,267 btu / lb, and the carbon intensity of natural gas is 52.91 kg CO2 / mmbtu CH4 or 54.87 kg CO2 / mcf, or 3.5 kg CO2 / kg CH4.

[0056] Hydrogen has 2.6 times higher energy density per unit mass than natural gas, so only 40% of the total tonnage of fuel is required to achieve the same power output. Therefore, burning one tonne of H2 to generate electricity reduces natural gas consumption by approximately 2.6 tonnes and reduces CO2 emissions by 9.1 tonnes.

[0057] When comparing natural hydrogen produced by enhanced hydrogen production reactions to hydrogen produced by electrolysis, the carbon reduction is a function of the carbon intensity of the electricity used in the electrolysis process. There are no direct emissions in the electrolysis process, but there can be large indirect emissions associated. However, natural hydrogen produced by enhanced hydrogen production reactions directly sequester sulfur emissions and, when combined with carbon dioxide, permanently sequester carbon dioxide in mineral form. As a result, there are direct emission reductions for sulfur or both sulfur and carbon dioxide as part of the various enhanced hydrogen production processes. With regard to H2S and carbon dioxide when CO2 is involved in the enhanced hydrogen production process, there are direct emission reductions of approximately 10 tons of CO2 emitted per tonne of hydrogen produced compared to electrolytically produced hydrogen (or other forms of hydrogen generation). The integration of this process achieves net carbon negative hydrogen production.

[0058] Indirect Emissions Reductions: Analysis of the life cycle carbon intensity of natural hydrogen using the Oil Production Greenhouse Gas Emissions Estimator (OPGEE) indicates that the life cycle carbon intensity of natural hydrogen ranges from 0.1 to 0.4 tonnes CO2 / tonne H2, with additional emission reductions equivalent to the mass of carbon dioxide mineralized by Heat Assisted Enhanced Hydrogen Production (HAEHP), and additional carbon can be mineralized by the SCMEHP process along with sulfur. Similar studies for other methods of hydrogen production are not available. However, using an average grid intensity of 0.5 tonnes CO2 / MWh, and considering that electrolysis requires about 50 MWh / tonne H2, the indirect emissions associated with electrolysis are about 25 tonnes CO2 / tonne H2 assuming grid electricity. Of course, electrolyzer operators could synthetically reduce the carbon footprint of their electricity usage by purchasing renewable energy credits, but this cannot be persistently recognized by the market as a way to eliminate real-time carbon emissions.

[0059] The realization of abundant natural hydrogen could achieve comparable large reductions in carbon emissions.

[0060] Embodiments herein relate generally to producing hydrogen by injecting gas, liquid, or supercritical CO2, H2S, heated water, or combinations thereof into underground geological formations in one or more of specially treated steam, water, hot water, brine, compressed hot water, wastewater, wastewater, seawater, geothermal fluids, geothermal effluent, or other heated thermal (e.g., waste heat) fluids. The heated fluid is heated by various means at the surface prior to injection into subsurface formations of iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-bearing igneous rocks, metamorphic or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rocks, metamorphic or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich deposits. Fluid injection may be performed with or without fracturing or other forms of mechanical stimulation of the subsurface formations. In some embodiments, treatments may be applied to subsurface formations via fracturing, acid treatment, or stimulation to increase the porosity and permeability of iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-containing igneous rocks, metamorphic or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rocks, metamorphic or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich deposits.

[0061] In some embodiments, hydrogen may be produced by injecting at least one reactant into a subterranean formation. The reactant may include dihydrogen sulfide (H2S) for sulfur enhanced hydrogen production ("SEHP"), either as dihydrogen sulfide or a mixture of dihydrogen sulfide and carbon dioxide dissolved or combined with treated or heated steam, water, hot water, brine, compressed hot water, wastewater, wastewater, seawater, geothermal fluid, geothermal drainage, or other heated thermal (e.g., waste heat) fluid, among others, or a mixture of dihydrogen sulfide (H2S) and carbon dioxide (CO2) for sulfur-carbon mixture enhanced hydrogen production ("SCMEHP"), or a mixture of dihydrogen sulfide or a mixture of dihydrogen sulfide and carbon dioxide combined with treated or heated steam, water, hot water, brine, compressed hot water, wastewater, wastewater, seawater, geothermal fluid, geothermal drainage, or other heated thermal (e.g., waste heat) fluid, among others. Hydrogen production has been observed over a range of CO2 / H2S ratios from about 10:1 to about 50:1 (10-50 parts CO2 to 1 part H2S), with a peak in hydrogen production near 35:1, although other concentrations and ratios of CO2 / H2S are contemplated.

[0062] Further embodiments of hydrogen production may involve the injection of thermal fluids into underground rock formations. Thermal fluids may include various forms of heat, heating, or other temperature-controlled fluids (e.g., steam, water, hot water, salt water, pressurized hot water, wastewater, effluent, seawater, geothermal fluids, geothermal effluents, or other heated thermal (e.g., waste heat) fluids, among others, that have been treated or heated. Hydrogen production may be referred to as thermally assisted enhanced hydrogen production ("HAEHP"). The thermal fluids may be formed at the surface prior to injection into the formation or system, or below the surface before, during, or after injection. Heat for the heated (or otherwise temperature-controlled) fluids may be provided by various means, at the surface prior to injection into the formation or system, or below the surface before, during, or after injection. The embodiments disclosed herein may be applied to situations with naturally occurring geothermal gradients (i.e., geothermal systems). Among other advantages, embodiments provide systems and methods that significantly increase the resources that can be recovered by various types of underground hydrogen production systems or natural geothermal systems, significantly increasing the economic drivers of subsurface sulfur and carbon mineralization. In this embodiment, H2S, CO2, or mixtures thereof may be injected, alone or dissolved or in combination with specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, effluent, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid, into porous, faulted, or geologically or primarily fractured iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or deposits with or without iron-rich fractures.

[0063] In some embodiments, water or dihydrogen sulfide present as reactants in the thermal fluid may react with minerals in the rock to produce hydrogen and heat based on the exothermic nature of the reaction. In some embodiments, carbon dioxide present in the injected thermal fluid may react with minerals in the subsurface rock formation to produce carbon minerals and sequester carbon dioxide, mineralized sulfur, and mineralized carbon. In other embodiments, the temperature control fluid may be injected into porous, faulted, or geologically or initially fractured subsurface formations with or without fracturing, in combination with other forms of mechanical stimulation or other forms of enhanced hydrogen production (e.g., SEHP or SCMEHP).

[0064] In some embodiments, water or dihydrogen sulfide present in the injected fluid may react with minerals in the rock to produce hydrogen and generate heat based on the exothermic nature of the reaction, and carbon dioxide present in the injected fluid may react with minerals in the rock to produce carbon minerals and sequester carbon dioxide.

[0065] The embodiments disclosed herein may be applied to situations with naturally occurring geothermal gradients (e.g., geothermal systems), as well as systems heated by other forms of above-ground or underground integration. In some embodiments, the methods for producing hydrogen from subsurface geological formations may expand the ability to produce low or negative carbon hydrogen underground from limited areas to areas where subsurface formations exist at sufficient depths in the earth's crust but where excess geothermal heat is not present.

[0066] Additionally, the techniques and systems disclosed herein define the kinetics of subsurface hydrogen generation. SEHP and SCMEHP may include direct hydrogen production following pyritization reactions. Additionally, the reactions may increase porosity following fluid-rock interactions (e.g., pyrite mineralization following interaction of iron-rich minerals with dihydrogen sulfide, or pyrite and / or other sulfur mineral species and / or magnesite and other carbon mineral species following interaction of iron- and magnesium-rich minerals (e.g., olivine and pyroxene) with either dihydrogen sulfide or a combination of dihydrogen sulfide and carbon dioxide) that increase surface area and volume for reaction and maximize delivery of reactants to and recovery of fluids from the subsurface.

[0067] In some embodiments, SEHP and SCMEHP can increase permeability following fluid-rock interaction and also catalyze subsurface exothermic reactions (e.g., pyritization and decarbonation / serpentinization reactions) that provide additional heat to enhance the kinetic rates of hydrogen generation, sulfur and carbon mineralization, and combinations and transformations thereof.

[0068] In some embodiments, the HAEHP may manage hydrogen production following serpentinization or pyritization reactions that benefit from elevated temperatures within a targeted underground reservoir following the injection of heat, heating, or other temperature-controlled fluids.

[0069] In some embodiments, maintenance of a selected temperature or temperature range (e.g., 25° C. to 500° C.) can promote the kinetics of targeted reactions (e.g., serpentinization and decarbonation) and suppress subsequent reactions (e.g., the Sabatier reaction) that would otherwise consume newly produced hydrogen. Targeted delivery of these treatment fluids to specific lithologies, geologic structures (e.g., faults, folds), and other subsurface deformation features (e.g., pre-existing and incipient fracture networks) can further increase the amount of hydrogen production, drive chemical reactions toward thermodynamic equilibrium, and maximize the potential for controlling porosity and permeability.

[0070] Embodiments herein utilize different injection fluids external to the geological system, injection fluids heated from a source external to the geological system, or combinations thereof, and provide low carbon (in the case of either SEHP or HAEHP) and negative carbon (in the case of SCMEHP or HAEHP which contain carbon dioxide in some form) hydrogen production that relies on serpentinization (Table 1), decarbonation (Table 2), or pyritization reactions (Table 3) as described below.

[0071] SEHP utilizes dihydrogen sulfide as an injectate. FIG. 2 is a schematic diagram of sulfur-enhanced hydrogen production 200 in a subterranean formation, according to one embodiment. The pyritization reaction uses iron-rich and perovskite mineral phases in a subterranean rock formation 205 of mafic igneous rock (e.g., olivine and pyroxene) as catalysts to reduce sulfides to pyrite mineral phases and produce hydrogen (H2) gas. One embodiment of SEHP 200 includes utilizing the same process of injecting dihydrogen sulfide to react with iron-rich olivine, orthopyroxene, perovskite, or other iron-rich mineral phases and iron-rich rock phases by also injecting heat and water from a source external to the geological system at injection wells 210, either before, during (mixed fluids), or after the dihydrogen sulfide is injected into the geological system. Hydrogen gas can be collected from recovery wells 215. Within the subterranean rock formation 205, serpentinization reactions occur in region 220, and pyritization reactions are shown in region 225. Reactions can occur in natural or induced fractures 230 throughout the subterranean formation 205.

[0072] SCMEHP utilizes various mixtures of dihydrogen sulfide and carbon dioxide as injectates. FIG. 3 is a schematic diagram of sulfur-carbon mixture enhanced hydrogen production 300 in the subsurface 305 according to one embodiment. Pyritization and serpentinization / decarbonation reactions use iron-rich mineral phases (e.g., olivine and pyroxene) and poor perovskite mineral phases as catalysts to reduce sulfides to pyrite mineral phases and carbon dioxide to carbonate minerals and produce hydrogen (H2) gas. Hydrogen gas may be collected from collection wells 315. Within the subsurface rock formation 305, serpentinization reactions occur in region 320 and pyritization reactions are shown in region 325. Additionally, CO2 reduction to carbonate minerals occurs as shown in region 335. Reactions may occur in natural or induced fractures 330 throughout the subsurface formation 305. One embodiment of the SCMEHP 330 includes utilizing the same process of injecting a dihydrogen sulfide mixture with carbon dioxide to react with the iron-rich olivine, orthopyroxene, perovskite, or other iron-rich minerals and iron-rich rock phases by injecting heat into the geological system from an external source either before, during (mixed fluid), or after the dihydrogen sulfide, carbon dioxide, or dihydrogen sulfide mixture with carbon dioxide is injected into the geological system through the injection well 310.

[0073] FIG. 4 illustrates a flowchart 440 of a method for implementing sulfur enhanced hydrogen production and sulfur-carbon mixture enhanced hydrogen production, according to an embodiment. As shown, act 405 may include a target rock formation being identified. The target rock formation may be evaluated in act 410 for rock / mineral type, and thermal fluid and / or reactants (e.g., dihydrogen sulfide, water, carbon dioxide) may be formulated according to the rock / mineral type in the target rock formation. As shown in act 415, a well may be drilled or an existing well may be used to provide stimulation fluid to the target rock formation. The rocks / minerals in the rock formation may be stimulated in act 420 by injecting heated stimulation fluid into the well, as shown in act 425, or by injecting heat into the well before, during, or after injection of the stimulation fluid. Heat for the heated stimulation fluid may be provided by equipment located at the surface (e.g., above) or within the well. The heat is provided, at least in part, by a source external to the formation. In some embodiments, heat can be supplied from natural processes and reactions, as shown in act 430.

[0074] Depending on the composition of the fluid injected into the subsurface rock formation, one or more of SEHP or SCMEHP are performed in situ in the target rock formation. SEHP produces hydrogen and mineralizes sulfur in the rock formation, as shown in act 435. SCMEHP produces hydrogen and mineralizes sulfur from dihydrogen sulfide in the rock formation, as well as mineralizes carbon from carbon dioxide, as shown in act 440. Thus, hydrogen is produced and one or more of the sulfur, carbon, or other injectates are sequestered.

[0075] In embodiments of both techniques, when sulfur disulfide gas or supercritical sulfur disulfide is injected into porous, faulted, or geologically or initially fractured iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-containing igneous, metamorphic, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous, metamorphic, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstone, or other iron-rich sedimentary rocks with elevated ambient temperature regimes, i.e., geothermal systems with temperatures in the range of 25-500° C., depending on the mineralogy, pore size, intensity of fractures, pore fluid composition, and purity of the gas injectate, the pyritization reaction will independently produce hydrogen.

[0076] In some instances, pyritization can lead to the potential for hydrogen recovery and sequestration through mineralization of sulfur from natural (e.g., geothermal systems) or various anthropogenic sources (SEHP435), or sulfur and carbon dioxide from natural (e.g., geothermal systems) or various anthropogenic sources (SEHP435). [Table 1]

[0077] In some embodiments, the temperature range for the pyritization and decarbonation / serpentinization reactions is between about 25° C. and about 500° C. It is understood that the temperature can be greater than about 100° C., greater than about 120° C., greater than about 150° C., less than about 500° C., less than about 400° C., from about 90° C. to about 500° C., from about 150° C. to about 250° C., and all temperatures between these values ​​as well as higher and lower temperatures. Depending on the depth of iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene bearing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, olivine or pyroxene bearing igneous rocks, metamorphosed or hydrothermally altered igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstones, other iron-rich sedimentary rocks, or iron-rich deposits, the geothermal gradient conditions, and the pore fluid chemistry in the particular geological setting, the temperature ranges described herein may exist in areas where there is excessive geothermal heating of the ground that enhances the kinetics of pyritization and / or pyritization plus serpentinization / decarbonation reactions. [Table 2]

[0078] Tables 1 and 2 show the serpentinization and decarbonation reactions that produce hydrogen and mineralize CO2. For example, a geothermal gradient of 100°C / km (e.g., near a geothermal system) will result in a reaction temperature of 100°C at 1 km depth, and in the pyritization reaction, if there is sufficient carbon dioxide fugitive capacity in the pore fluid system, the kinetics will improve to about 300°C where the Sabatier reaction will begin to consume the hydrogen produced by reforming CO2 or dissolved inorganic carbon to produce naturally occurring methane or other species. The temperature of the target formation capable of producing hydrogen by the reactions described herein can be maintained by excess heat from the surrounding geothermal gradient and exothermic heat released by mineralization. The temperature of the formation can be maintained for a period between about one day and several decades. It is understood that the temperature can be maintained for more than about 30 days, more than about 45 days, more than about 90 days, less than about 30 days, less than about 20 days, or more than about one day to more than 30 years.

[0079] Among the many factors in determining and configuring the application of SEHP and SCMEHP technologies, such as natural geothermal conditions, are the limitations of porosity and fracture networks in many subsurface formations, similar to the redox conditions (pH and Eh) found in nature. These factors should preferably be understood and addressed when applying systems and methods to evaluate subsurface resources and recover resources, such as hydrogen, from reservoirs. [Table 3]

[0080] Embodiments include injecting dihydrogen sulfide (HS) in the form of gas, bound HS dissolved or combined with specially treated or heated steam, water, hot water, salt water, hot compressed water, waste water, effluent, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid (SEHP), or gaseous, supercritical, or HS mixtures dissolved or combined with specially treated or heated steam, water, hot water, salt water, hot compressed water, waste water, effluent, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid (SCMEHP) into a geological or initially fractured subterranean formation having sufficient ambient geothermal conditions (e.g., exhibiting temperatures in the ranges disclosed herein). The technology disclosed herein can take advantage of the coexistence of H2S in geothermal systems, which is a significant challenge for the operation of conventional geothermal energy systems or the application of other hydrogen production means to geological systems with high (greater than 20°C / km) natural geothermal gradients, and can improve the economic and environmental impact of existing and developing geothermal energy. The presence of H2S itself must often be removed, which can lead to significant economic and environmental problems for the operation of conventional geothermal systems, and similar challenges are anticipated for other hydrogen production means. Here, H2S produced along with specially treated or heated steam, natural hydrogen, or a mixture of other gases from a geothermal system can be injected directly or along with specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, effluent, seawater, geothermal fluids, geothermal exhaust fluids, or other heated thermal fluids to enhance the kinetics and yield of pyritization reactions that directly produce H2. The injected H2S increases the kinetics and yield of chemical alterations of subsurface formations that increase the surface area and rock volume for ongoing reactions during subsequent stages of SEHP.

[0081] Other embodiments include injecting gaseous HS, bound HS dissolved or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, effluent, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid, or gaseous, supercritical, or HS mixtures dissolved or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, effluent, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid, into geological or initially fractured subterranean formations having sufficient ambient geothermal conditions (e.g., exhibiting temperatures in the ranges disclosed herein). The technology disclosed herein can take advantage of the coexistence of anthropogenic sources of H2S (e.g., fossil fuel-fired power plants, industrial waste streams, refineries, gas separation systems, ethanol plants, steel mills, liming operations, cement plants, waste incinerators, landfills, metallurgical plants, coking facilities, pulp and paper, sewage treatment plants, gas processing exhaust or effluent, processed natural gas, processed H2S from natural gas, or other low BTU natural gas reservoirs) and may improve the economic and environmental impact of these industries as well. The presence of H2S itself often must be removed, which can lead to economic and environmental issues of operating these types of processes on a commercial scale, and similar challenges are anticipated for other hydrogen production means. Here, H2S produced with fossil fuel-fired power plants, industrial waste streams, refineries, gas separation systems, ethanol plants, steel mills, liming operations, cement plants, waste incinerators, landfills, metallurgical plants, coking facilities, pulp and paper, sewage treatment plants, gas processing exhaust or effluent, processed natural gas, processed H2S from natural gas, or other low BTU natural gas reservoirs, or other may be injected directly or with specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, effluent, seawater, geothermal fluids, geothermal exhaust fluids, or other heated heat (e.g., waste heat) fluids to enhance the kinetics and production of pyritization reactions that directly produce H2. The injected H2S increases the kinetics and production of chemical alterations of subsurface formations that increase the surface area and rock volume for reactions that proceed during subsequent stages of SEHP, SCMEHP, or other means of subsurface enhanced hydrogen production.

[0082] In general, further improvements to the SEHP and SCMEHP can be provided by utilizing additional H2S and CO2 waste streams from geothermal power plants, fossil fuel-fired power plants, industrial waste streams (e.g., refineries, gas separation systems, ethanol plants, steel mills, liming operations, cement plants, waste incinerators, landfills, metallurgical plants, coking plants, pulp and paper, sewage treatment plants), gas processing exhaust or effluent, processed natural gas, processed H2S from natural gas, or other low BTU natural gas reservoirs. This can also be applied to natural geothermal systems. In general, further improvements to the SCMEHP can be provided by utilizing additional H2S and CO2 waste streams from geothermal power plants, industrial waste streams (e.g., refineries, sewage treatment plants, pulp and paper), gas processing exhaust or effluent, processed natural gas, processed H2S from natural gas, or other natural gas reservoirs.

[0083] In some embodiments, during the interaction of HS fluids with iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich sediments, as described above, SEHP and SCMEHP can be beneficial in several related but independent ways. First, iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-bearing igneous rocks, metamorphic or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rocks, metamorphic or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstones, other iron-rich sedimentary rocks, or reduced iron mineral phases in iron-rich sediments, and the parallel release of zero carbon and sulfur negative hydrogen using SEHP. Second, a catalyst for the mineralization of sulfur as carbon dioxide in iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-bearing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, serpentinized rocks or deposits, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstone, or iron-rich sediments, and / or reduced iron mineral phases in perovskite, olivine or pyroxene-bearing igneous rocks, olivine or pyroxene-bearing sediments or sedimentary rocks, olivine or pyroxene-bearing metamorphic rocks, and various carbonate minerals, and the in-line release of carbon-negative hydrogen using SCMEHP. Third, as the chemical alteration of olivine, pyroxene, and other minerals is improved by the pyritization process, the subsurface formation achieves increased porosity, permeability, and thus greater capacity for additional hydrogen production, carbon and sulfur mineralization, and improved kinetics and yield of reactions.

[0084] In underground wells, SEHP may involve injecting dihydrogen sulfide (H2S) into geologically or initially fractured subsurface formations with sufficient ambient geothermal conditions. SEHP can take advantage of the common coexistence of H2S in geothermal systems, near anthropogenic waste streams, or sulfur-rich gas fields, which represents a significant challenge in the operation of conventional geothermal energy systems or the application of other means of underground hydrogen production.

[0085] In some embodiments, SCMEHP may be utilized in a similar or identical manner to SEHP to produce subsurface hydrogen. SCMEHP also utilizes the pyritization reaction (shown in Table 3) that uses iron-rich mineral phases (e.g., olivine and pyroxene) and poor perovskite mineral phases as catalysts for sulfide reduction to pyrite mineral phases and production of H2 gas, and integrates this reaction with the serpentinization (i.e., hydrogen formation) and decarbonation (i.e., carbon mineralization) reactions (shown in Tables 1 and 2).

[0086] The advantages of SCMEHP compared to other forms of enhanced hydrogen production relate to the increased porosity and permeability that can be achieved through the pyritization reaction, and how the increased porosity and permeability can be utilized for further reactions within the rock formation, especially when utilized in various or repeated steps. For example, the pyritization reaction chemically alters grains of olivine, pyroxene, and other iron-rich minerals (e.g., ilmenite, siderite, hematite, epidote), increasing the surface area of ​​the remaining grains, thereby further improving the kinetics of the reaction and the total yield. This is improved by the decrease in pH, which further alters the chemical alteration of the surrounding mineral grains. Furthermore, the formation of pyrite leads to the formation of minerals with a dense isotropic / cubic lattice structure that increases the density, but reduces the volume of the pyrite minerals with respect to the original olivine, orthopyroxene, or other iron-rich minerals (e.g., ilmenite, siderite, hematite, epidote). The net result of this volume reduction is an increase in the porosity (i.e., the volume of pore space other than rock) of subsurface rock formations.

[0087] The increase in porosity further increases the surface area and permeability of the rock formation, catalyzing further reactions and increased interaction rates. These factors are essential in themselves for hydrogen movement and eventual production, but are also based on the ability of reactions to increase fluid transmission to unaltered rock. Fluid flow, both for fluid injection into the system and for hydrogen withdrawal from the system, benefits from the sufficient permeability and increased hydraulic conductivity demonstrated by the SEHP and SCMEHP techniques. Hydraulic conductivity, and in particular the inflow or outflow of fluids into or out of the target system, varies as a function of porosity and permeability, with the latter generally increasing in proportion to the former. Thus, as a result of the SEHP process or the pyritization plus serpentinization (hydrogen formation) and decarbonation (carbon mineralization) SCMEHP process, the target subsurface formation may accommodate the injection of more fluids (e.g., carbon dioxide, dihydrogen sulfide, water) and more efficient recovery of hydrogen (or other resources including helium, neon, krypton, and xenon). In particular, the serpentinization reaction directly produces hydrogen gas that can be recovered as a low or negative carbon resource. In this manner, the injected fluids may be exposed to a greater surface area and total volume of the target rock within the target system. The end result of this process that benefits from the addition of dihydrogen sulfide or a mixture of dihydrogen sulfide with carbon dioxide is that more sulfur and / or carbon dioxide may eventually be mineralized and more hydrogen may be produced from the system due to improved porosity and permeability of the target subterranean formations.

[0088] An additional advantage of the SCMEHP process relates to the fact that these reactions can be carried out sequentially, repeatedly, or in other combinations with other forms of enhanced hydrogen production or restimulation of the target formation to increase hydrogen production and sulfur and / or carbon mineralization, as compared to other forms of enhanced hydrogen production that do not utilize a mixture of dihydrogen sulfide and carbon dioxide. As an example, cycles of pyritization or SCMEHP are expected to increase porosity and permeability and increase injection fluid flow. This process may lead to a second stage of SCMEHP, where carbon dioxide mineralization can increase mineral volume and induce new fractures, and localized mineralization can effectively keep fracture fractures open, subsequently maintaining both the porosity and permeability of the subsurface formation. Each of these processes increases the surface area for hydrogen production and increases the pathways for hydrogen recovery.

[0089] Injection of the various fluid mixtures may be done sequentially or in cycles, including these and other types of cycles for subsurface enhanced hydrogen production. In embodiments, cycles may be utilized that first inject dihydrogen sulfide or a mixture of dihydrogen sulfide and carbon dioxide dissolved in or mixed with specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, or other heated thermal (e.g., waste heat) fluids, followed by injection of gaseous or supercritical dihydrogen sulfide or a mixture of gaseous or supercritical dihydrogen sulfide and carbon dioxide. In an embodiment, an initial cycle of injection of gaseous or supercritical dihydrogen sulfide, or a mixture of gaseous or supercritical dihydrogen sulfide and carbon dioxide, is followed by a cycle of injection of dihydrogen sulfide or a mixture of dihydrogen sulfide and carbon dioxide dissolved in or mixed with specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, effluent, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid.

[0090] In an embodiment, when a mixture of dihydrogen sulfide and carbon dioxide gas is injected into a subterranean formation, pyritization and decarbonation / serpentinization reactions are allowed in parallel to produce hydrogen. Using either the SEHP or SCMEHP process, depending on the mineralogy, pore size, fracture strength, pore fluid composition, and purity of the gas injection, this injection can occur when these fluids are injected into subterranean systems with elevated ambient temperature regimes, i.e., geothermal systems where temperatures range from about 25-500° C., or when the temperature is elevated using treated and temperature-controlled fluids. SEHP and SCMEHP, when used alone or in combination with HAEHP, also offer the opportunity to sequester (by mineralization) sulfur and carbon dioxide from natural (e.g., geothermal systems) or various anthropogenic sources.

[0091] In one embodiment, a well or a series of injection / production wells are drilled into a layer of iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich sediment, and further fractured to increase porosity and permeability, thereby improving the available reaction surface area and volume. Reactants such as dihydrogen sulfide or a mixture of dihydrogen sulfide and carbon dioxide (gaseous or supercritical) can then be injected into the natural geothermal system with sufficient temperature to catalyze pyritization or pyritization and decarbonation / serpentinization reactions. In some embodiments, fluids including one or more of specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, or other heated thermal (e.g., waste heat) fluids may then be added to the subterranean formation. H2 produced from the reaction of the reactants with the subterranean formation may be recovered and mineralized carbon and sulfur may be sequestered within the subterranean formation.

[0092] Fluids containing dihydrogen sulfide or a combination of dihydrogen sulfide and carbon dioxide may be injected into the formation (e.g., geothermal systems) via an injection device / injection well. Hydrogen gas formed in the subterranean formation is collected at the injection well or at a separate hydrogen production or recovery well. In some embodiments, hydrogen may be recovered from the recovery well. The recovery well may be specifically designed for hydrogen gas production. In some embodiments, hydrogen may be stored in large quantities for long periods of time. This is advantageous for the shipping and general transportation, industrial, and energy sectors. Additionally, hydrogen may be used in oil refining, metals processing, fertilizer production, and food processing.

[0093] The SEHP200 and SCMEHP300 methodologies may include in and out cycling of the various fluids described herein, or a set of injection / production wells operating together. In either case, continuous or periodic injection of H2S or a mixture of H2S plus CO2 may maintain the temperature of the chemical reactions in the target formation very close to the selected reaction temperature. Given that rock and pore fluid chemistry may vary from one vein to another, the selected reaction temperature may vary. The temperature may be adjusted for each vein based on experiments performed on core, rock, and pore fluid samples taken from the vein.

[0094] While the techniques disclosed herein are accomplished using H2S and / or CO2, it should be understood that other chemical species may be utilized to enhance the kinetics and yield of hydrogen production by chemical alteration of minerals in subterranean formations. For example, halogen acids (e.g., HF, HCl, HBr, or HI), sulfuric acid, or additional chemical species may be utilized to enhance the kinetics and yield of the subterranean reaction to produce hydrogen using subterranean minerals as a catalyst.

[0095] A system suitable for use with the techniques disclosed herein includes one or more wells (e.g., injection or production wells), one or more sources of dihydrogen sulfide or a combination of dihydrogen sulfide and carbon dioxide, one or more pumps for pumping the one or more sources of dihydrogen sulfide or a combination of dihydrogen sulfide and carbon dioxide to the one or more wells, a subsurface temperature sensor, a hydrogen collection device, and a controller operably coupled to one or more of the foregoing to control the injection of the solution into the subsurface formation and the collection of hydrogen from the subsurface formation.

[0096] 5 is a diagram illustrating an HAEHP 500 with an embodiment of carbon or sulfur sequestration in a subterranean formation, according to one embodiment. The HAEHP 500 is a carbon or sulfur sequestration system that uses specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid, carbon dioxide (CO2) or other fluid or gas, or a mixture of supercritical carbon dioxide (CO2), carbon dioxide (CO2), dihydrogen sulfide (H2S) or other fluid or gas, or supercritical carbon dioxide (CO2) dissolved in or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid. The method includes injecting a mixture of dihydrogen sulfide (H2S) or dihydrogen sulfide (H2S) dissolved in or combined with specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, effluent, seawater, geothermal fluid, geothermal exhaust fluid, or other heated thermal (e.g., waste heat) fluid, or a mixture thereof with carbon dioxide (CO2) and dihydrogen sulfide (H2S) or other fluid, through an injection well 510 into a porous, permeable, faulted, or geologically or initially fractured subterranean formation 505 having sufficient ambient geothermal conditions using a heat source external to the geological system.

[0097] Hydrogen gas may be recovered from recovery wells 515. Within the subterranean rock formation 505, serpentinization reactions occur in region 520 and pyritization reactions are shown in region 525. Additionally, CO2 reduction to carbonate minerals occurs as shown in region 535. Reactions may occur in natural or induced fractures 530 throughout the subterranean formation 305.

[0098] One embodiment of the HAEHP500 takes advantage of the coexistence of geothermal heat with natural sources of CO2 and H2S, which are released into the environment during conventional geothermal energy extraction. The geothermal waste products CO2 and H2S represent a significant challenge to the operation of conventional geothermal energy systems or the application of other means of hydrogen production in geothermal systems with high (>20°C / km) natural geothermal gradients. The presence of H2S in particular, which often must be removed, can lead to significant economic and environmental problems in the operation of conventional geothermal systems. Similarly, there are social and environmental drivers to mitigate the CO2 emissions associated with geothermal energy.

[0099] Embodiments herein disclose that CO2 and / or H2S produced from a geothermal system along with steam, natural hydrogen, or a mixture of other gases can be treated and temperature controlled prior to injection directly or along with specially treated or heated steam, water, brine, compressed hot water, wastewater, effluent, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids, or other fluids. This embodiment beneficiates low carbon and low sulfur hydrogen by elevating fluid and formation temperatures using a heat source external to the geological system.

[0100] HAEHP may promote hydrogen formation by injecting various forms of heated water to increase serpentinization reactions. In some embodiments, hydrogen formation may also be promoted by injection of heated fluids before, during, or after carbon dioxide injection to stimulate serpentinization and decarbonation reactions, and / or injection of H2S and other fluids to catalyze pyritization reactions as described above with reference to Figures 2 and 3 (i.e., SEHP and / or SCMEHP). These embodiments may directly produce low carbon H2 and sequester carbon and sulfur. In particular, HAEHP may also be applied to heat-assisted production systems in geological situations that do not benefit from naturally elevated geothermal conditions / gradients, but where the key reactants (i.e., heat, water, carbon dioxide, and dihydrogen sulfide) can be supplied by utilizing various heat sources and / or waste heat to formations that have abundant reduced iron reactants but lack the key reactants (i.e., heat, water, carbon dioxide, and dihydrogen sulfide) to produce hydrogen, carbonate minerals, and sulfide minerals as products. The HAEHP500 therefore benefits from both natural and anthropogenic sources of CO2 and H2S, the latter including those associated with other forms of fossil energy, other means of energy generation, and other means of hydrogen production.

[0101] Embodiments herein utilize heated injection fluids from a source external to the geological system and provide an important low or negative carbon and negative sulfur production route for hydrogen that relies on the serpentinization / decarbonation and pyritization reactions described in Tables 1-3 above.

[0102] In embodiments of the HAEHP, the reservoir may be formed from porous, faulted, geologically or initially fractured, iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, peridotite, especially when mixed with injection of treated or heated steam, water, hot water, brine, compressed hot water, wastewater, effluent, seawater, geothermal fluids, geothermal exhaust fluids, or other heated heat (e.g., waste heat) fluids, with the integration of various upper heat injected at depth by various means of alternative means, resistive heating, plasma, combustion, nuclear reaction, waste heat recovery, or other means after fluids containing carbon dioxide or dihydrogen sulfide are introduced to achieve reservoir temperatures ranging from about 25° C. to about 500° C., depending on the mineralogy, pore size, fracture strength, pore fluid composition, and purity of the gas injectate. The reactions that produce hydrogen and sequester carbon and sulfur may achieve high kinetics (e.g., faster) and high yields when heated carbon dioxide gas, heated dihydrogen sulfide, heated fluid mixtures of carbon dioxide, heated fluid mixtures of dihydrogen sulfide, heated fluid mixtures of carbon dioxide and dihydrogen sulfide, or supercritical forms of carbon dioxide or dihydrogen sulfide are injected into systems of olivine or pyroxene-containing igneous, metamorphic, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous, metamorphic, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich sediments.

[0103] The HAEHP500 significantly improves the geological / geographical breadth of enhanced hydrogen production applications to geological systems with suitable reactant mineralogy (e.g., rocks containing olivine, orthopyroxene, ilmenite, siderite, hematite, and epidote) and no excess thermal energy (e.g., areas without geothermal heat and no excess geothermal gradients) or other primary reactants (e.g., water, dihydrogen sulfide, and carbon dioxide). Thus, integration of this embodiment improves the potential for low carbon hydrogen capture and sequestration (through mineralization) of carbon and / or sulfur from natural (e.g., geothermal systems) or anthropogenic sources.

[0104] The preferred temperature range for the decarbonation, serpentinization, and pyritization reactions embodied in the HAEHP is between about 25° C. and about 500° C. The temperature can be greater than about 100° C., greater than about 120° C., greater than about 150° C., less than about 500° C., less than about 400° C., from about 90° C. to about 500° C., from about 150° C. to about 250° C., and all temperatures between these values ​​and higher and lower temperatures. Depending on the depth in a particular geological setting, the geothermal gradient conditions of the subsurface formation, and the chemistry of the pore fluids, the temperature ranges described may exist in areas where there is excess geothermal heating of the earth, or where sufficient geothermal gradients are introduced by the various means described herein to increase the kinetics and production of the serpentinization, pyritization, and decarbonation reactions. The selected temperatures can be achieved with the upper integration of heated fluids utilizing heat from a source external to the geological setting. The fluid is heated, cooled, or otherwise temperature controlled to a selected temperature range, or in the case of a particular reservoir, and is injected into subsurface rock formations to reach and maintain a selected reaction temperature to promote the kinetic rate and production of the targeted reactions (e.g., serpentinization, decarbonation, pyritization), while temperature control inhibits undesirable follow-on reactions (e.g., the Sabatier reaction) that would otherwise consume newly produced hydrogen and form naturally occurring methane or other species. Some heat is lost via conduction to the surrounding rocks, but over time, the rocks closest to the reaction zone will warm up toward the selected temperature or range, allowing for higher kinetic rates to occur that allow the fluid-rock reactions of decarbonation, serpentinization, and / or pyritization to occur and to more closely approach thermodynamic equilibrium. Additionally, the exothermic nature of the reactions increases or maintains the continued production of heat, thereby regulating the temperature of the targeted formation.

[0105] In underground rock formations with a geothermal gradient of 100°C / km, a reaction temperature of 100°C can be obtained at a depth of 1 km, but as the Sabatier reaction begins to consume the hydrogen produced by reforming carbon dioxide or dissolved inorganic carbon (if present), the temperature increases to about 300°C, where it can produce naturally occurring methane or other species. The temperature of the target formation capable of producing hydrogen by the reactions described herein may be maintained by one or more of injections of heated carbon dioxide gas, heated dihydrogen sulfide gas, supercritical carbon dioxide, supercritical dihydrogen sulfide, or other gases or supercritical fluids, specially treated or heated steam, water, hot water, salt water, pressurized hot water, wastewater, effluent, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids, or any other heated fluids in combination with heated carbon dioxide gas, heated dihydrogen sulfide gas, carbon dioxide gas, dihydrogen sulfide gas, supercritical carbon dioxide, supercritical dihydrogen sulfide, or other gases or supercritical fluids, via heat released by serpentinization, pyritization, or decarbonation reactions, or optionally by excess heat from the surrounding geothermal gradient. In any of these cases, the temperature of the formation may be maintained for periods ranging from one day to several decades. It is understood that the temperature can be maintained for greater than about 30 days, greater than about 45 days, greater than about 90 days, less than about 30 days, less than about 20 days, from about 1 day to greater than 30 years.

[0106] In general, embodiments disclosed herein provide for further stimulation of the HAEHP by utilizing additional CO2 and H2S waste streams from sources including geothermal power plants, fossil fuel-fired power plants, industrial waste streams (e.g., refineries, gas separation systems, ethanol plants, steel mills, liming operations, cement plants, waste incinerators, landfills, metallurgical plants, coking facilities, sewage treatment plants, pulp and paper), gas process exhaust or effluent, processed natural gas, other low BTU natural gas reservoirs, etc. The HAEHP can be applied to natural geothermal or geological systems including subsurface formations, but requires a thermal assist or other primary reactants (e.g., water, CO2, H2S). The latter can complement the geothermal heating of iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine- or pyroxene-bearing igneous, metamorphic, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine- or pyroxene-bearing igneous, metamorphic, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich deposits, greatly broadening the application of HAEHP.

[0107] FIG. 6 is a flow chart of a method 600 for performing HAEHP, according to one embodiment. As shown in act 605, a target rock formation may be identified. As shown in act 610, the target rock formation may be evaluated for rock / mineral type, and a stimulation fluid (e.g., temperature, heated water, carbon dioxide, dihydrogen sulfide) may be formulated according to the rock / mineral type in the target rock formation. In act 615, a well may be drilled or an existing well may be used to supply stimulation fluid to the target rock formation. In act 620, rocks / minerals in the subterranean formation may be stimulated by injecting heated stimulation fluid into the target formation in the well. Heat for the heated stimulation fluid may be provided by equipment located at the surface (e.g., above) or deep in the well. The heat may be provided, at least in part, by a source external to the formation, as shown in acts 625 and 630. Depending on the composition of the fluid injected into the subterranean rock formation, HAEHP may be performed in situ in the target rock formation. HAEHPs can generate hydrogen and mineralize carbon and sulfur in rock formations, thus producing hydrogen and sequestering carbon, sulfur, or other inputs.

[0108] Depending on the composition of the fluid injected into the subsurface rock formation, one or more of SEHP or SCMEHP are performed in situ in the target rock mass. SEHP generates hydrogen and mineralizes sulfur in the rock formation, as shown in act 635. SCMEHP generates hydrogen and mineralizes both sulfur from dihydrogen sulfide and carbon from carbon dioxide in the rock formation, as shown in act 640. Thus, hydrogen is produced and one or more of the sulfur, carbon, and other injected materials may be sequestered.

[0109] The benefits of HAEHP or heat-assisted forms of SEHP or SCMEHP compared to other forms of enhanced hydrogen production relate to increased kinetics, increased production of hydrogen, and increased sequestration of carbon from serpentinization and decarbonation reactions. Fluid flow, both injected fluids into the system and hydrogen pumped out of the system, operates via hydraulic conductivity. Hydraulic conductivity and especially the flow of injected fluids into and out of the target system vary as a function of porosity and permeability, the latter generally increasing in proportion to the former. Among the many factors in determining and setting up the application of HAEHP in natural geothermal settings, either heat-assisted hydrogen production systems, SEHP, or SCMEHP, are the limitations of porosity and fracture networks in many subterranean formations, similar to the redox conditions (pH and Eh) in nature. These factors should preferably be understood and addressed when applying systems and methods to evaluate subterranean resources and recover resources, e.g., hydrogen, from reservoirs.

[0110] For example, more carbon dioxide or dihydrogen sulfide in the injectate fluid may be available in certain rock formations depending on the rock type, porosity, and permeability than in other rock formations with different rock types, porosity, or permeability. Additionally, iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, metamorphosed or hydrothermally altered olivine or pyroxene-containing igneous rocks, metamorphic rocks, or sedimentary rocks or deposits, rocks or deposits containing serpentinite minerals, partially or fully serpentinized rocks, serpentinite, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich sediments may be further fractured, acidified, or stimulated to increase the rock's porosity and permeability and thus the available reactive surface area and volume.

[0111] In one embodiment, a well or a series of injection / production wells may be drilled into the underground formations of the thermally assisted underground system and optionally the natural geothermal underground system. Injection of heated fluids, including CO2 or H2S, into the wells (and rock formations) may be performed using any of the fluids disclosed herein. When these fluids are injected into underground systems with elevated ambient temperature conditions, i.e., geothermal systems with temperatures ranging from about 25°C to about 500°C, serpentinization, decarbonation, and pyritization reactions may be performed at higher kinetic rates and yields compared to techniques using unheated fluids, depending on the mineralogy, pore size, fracture strength, pore fluid composition, and purity of the gas injectate. HAEHP offers the potential for hydrogen recovery and sequestration (mineralization) of carbon dioxide and dihydrogen sulfide from natural sources (e.g., geothermal systems) or various other anthropogenic sources.

[0112] In particular, fluids including one or more of treated or heated steam, water, hot water, salt water, compressed hot water, wastewater, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, or other heated thermal (e.g., waste heat) fluids can be heated under pressure into the form of high pressure steam or high pressure high temperature fluids, held at a temperature between about 25° C. and about 500° C., mixed with a supply of CO2 and / or H2S, and injected into a subsurface formation to perform a HAEHP.

[0113] 7 is a schematic diagram of a HAEHP 700 in a subterranean formation 705, according to one embodiment. Gaseous, dissolved, or supercritical carbon dioxide or dihydrogen sulfide may be injected directly into the formation via an injector / injection well 710. The well extends into the subterranean formation 705. Hydrogen gas formed in the subterranean formation may be collected in the injection well or in a separate hydrogen production or recovery well 715. After collection, the hydrogen gas may be stored or mixed with other gases (e.g., methane) for stable transportation and / or use.

[0114] In some embodiments, the HAEHP may include injecting specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids, gaseous CO2, supercritical CO2, gaseous H2S, supercritical H2S, or other heated thermal fluids into a subterranean formation. CO2, gaseous H2S, and / or supercritical H2S may be dissolved in or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids and injected into a subterranean formation to increase hydrogen production.

[0115] In some embodiments, heat may be provided to underground formations via injection of hot supercritical CO2 or H2S, as well as or instead of hydrothermal water. In other embodiments, other means of heat may be applied downhole to rock formations, including, but not limited to, heat released by laser heating, combustion, electrical resistance heating, plasma heating, nuclear heating, exothermicity of reactions, or other means. Heating by these mechanisms may achieve suitable temperatures of about 25°C to about 500°C in deep reservoirs or rock formations, depending on the physicochemical conditions of the water, pores, and chemical species present in the pores, and the mineralogy and chemistry of the rock matrix of any deposits.

[0116] In some examples, the subsurface rock formations may be fractured, acidified, or stimulated to increase porosity and permeability and further increase the surface area available for reactions (e.g., serpentinization and pyritization reactions). Specially treated or heated steam, water, hot water, brine, compressed hot water, waste water, effluent, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids, CO2 or H2S, gaseous CO2 or H2S, supercritical CO2 or H2S, or other thermal fluids dissolved in or combined with specially treated or heated steam, water, hot water, brine, compressed hot water, waste water, effluent, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids may then be heated under pressure to form a high-pressure fluid having a temperature in the range of 25° C. to 500° C. or thereabouts depending on the physicochemical conditions of the water, pores, and chemical species present in the pores. The heated fluid may then be injected into the fractured subsurface rock formations.

[0117] The HAEHP may include circulating various heated fluids described herein in and out of injection wells 710 (e.g., a "huff and puff" operation), or injecting into and out of a set of cooperating injection wells 710 and production wells 715. In some embodiments, a cycle of initially injecting specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids may be followed by a cycle of injecting CO2 or H2S, gaseous CO2 or H2S, or supercritical CO2 or H2S dissolved in or combined with specially treated or heated steam, water, hot water, brine, compressed hot water, wastewater, wastewater, seawater, geothermal fluids, geothermal exhaust fluids, other heated thermal (e.g., waste heat) fluids. In some embodiments, a cycle of injecting specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, effluent, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, other heated thermal (e.g., waste heat) fluid may be followed by a cycle of first injecting CO2 or H2S, gaseous CO2 or H2S, or supercritical CO2 or H2S dissolved in or combined with specially treated or heated steam, water, hot water, salt water, compressed hot water, waste water, effluent, wastewater, seawater, geothermal fluid, geothermal exhaust fluid, other heated thermal (e.g., waste heat) fluid.

[0118] Regardless of the embodiment, continuous or periodic injection of specially treated or heated thermal fluids and / or reactants can maintain the temperature of the target rock formation very closely to a selected reaction temperature (e.g., 25° C. to 500° C.) that allows hydrogen production and prevents hydrogen consumption by subsequent reactions (e.g., the Sabatier reaction). Considering that rock mineralogy, rock chemistry, and pore fluid chemistry may differ for each vein, the selected reaction temperature may be different in different situations. For example, as shown in FIG. 7, the subterranean formation may be located near a steam chamber 720 that contributes to a higher temperature. The steam chamber 720 may be separated from the subterranean formation 705 by unreacted rock 725. The selected temperature may be adjusted for each vein based on experiments performed on core and rock samples or pore fluid samples taken from a given vein.

[0119] A system suitable for use with the techniques disclosed herein includes one or more wells (e.g., injection or production wells) extending through the surface 730 and cap rock 735, one or more sources of carbon dioxide, dihydrogen sulfide, or water, one or more heat sources (e.g., heat exchangers) for heating the carbon dioxide, dihydrogen sulfide, or water, one or more pumps for pumping the carbon dioxide, dihydrogen sulfide, or water to the one or more wells, a subsurface temperature sensor, a hydrogen collection device, and a controller operably coupled to one or more of the foregoing to control the injection of fluids (e.g., heated water, dihydrogen sulfide, and carbon dioxide) into the subsurface formation and the collection of hydrogen from the subsurface formation.

[0120] It should be noted that it is not necessary to provide or address the theory underlying the new and innovative production rates, performance, or other beneficial features and characteristics that are the subject of or related to embodiments of the present invention. Nevertheless, various theories are provided herein to further advance the art in this important field, particularly the important fields of exploration, production, and downstream conversion or utilization of hydrogen, carbon dioxide, dihydrogen sulfide, and helium. These theories described herein are not intended to limit, restrict, or narrow the scope of protection afforded to the claimed invention unless otherwise stated. These theories are not required or implemented to utilize the present invention. Moreover, the present invention may lead to new and previously unknown theories for explaining the electrical conductivity, cracking, drainage, resource production, chemical properties, and functional characteristics of embodiments of the methods, articles, materials, apparatus, and systems according to the present invention, and such subsequently developed theories do not limit the scope of protection afforded to the present invention.

[0121] Various embodiments of the apparatus, systems, activities, methods, and operations described herein may be used with, in, or by various processes, industries, and operations in addition to the illustrated embodiments and those disclosed herein. Various embodiments of the apparatus, systems, activities, and operations described herein may be used with other processes, industries, and operations that may be developed in the future, with existing processes, industries, and operations that may be modified based on the teachings herein, and with other types of gas recovery and valorization systems and methods. Additionally, various embodiments of the apparatus, systems, activities, methods, and operations described herein may be used with each other in a variety of different combinations. Thus, for example, configurations provided in various embodiments herein may be used with each other. For example, components of an embodiment having A, A', and B, and components of an embodiment having A", C, and D may be used with each other in various combinations, such as A, C, D, and A, A", C, and D, in accordance with the teachings herein. Thus, the scope of protection given to the present invention should not be limited to the specific embodiments, configurations, or arrangements described in the specific embodiments, examples, or embodiments of the specific figures.

[0122] The described embodiments are to be considered in all respects only as illustrative and not restrictive. For example, features from any of the disclosed embodiments may be used in combination with each other without limitation. Additionally, other features and advantages of the present disclosure will become apparent to those skilled in the art upon consideration of the detailed description.

[0123] (Additional Note) (Appendix 1) injecting a reactant into the subterranean formation; reacting the reactant with the subterranean formation to form at least one of hydrogen gas or a mineralization product within the subterranean formation; collecting hydrogen produced from the reaction of the reactants with the subterranean formation or sequestering one or more components of the reactants to form mineralized sulfur or mineralized carbon; 1. A method for producing hydrogen from a subterranean formation comprising:

[0124] (Appendix 2) 2. The method of claim 1, wherein the reactants include at least one of dihydrogen sulfide, carbon dioxide, water, steam, salt water, geothermal fluid, or waste heat fluid.

[0125] (Appendix 3) 2. The method of claim 1, wherein the subsurface formation comprises at least one of iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich deposit.

[0126] (Appendix 4) 2. The method of claim 1, wherein the subterranean formation comprises a porous, faulted, or geologically or initially fractured rock formation.

[0127] (Appendix 5) 2. The method of claim 1, further comprising heating the reactants prior to injecting the reactants into the subterranean formation, the reactants being heated from a source external to the subterranean formation.

[0128] (Appendix 6) 2. The method of claim 1, further comprising fracturing or stimulating the subterranean formation.

[0129] (Appendix 7) 2. The method of claim 1, wherein the reaction comprises one or more of a serpentinization reaction, a pyritization reaction, or a decarboxylation reaction.

[0130] (Appendix 8) 2. The method of claim 1, wherein the subsurface formation comprises a natural geothermal system.

[0131] (Appendix 9) injecting a fluid comprising at least one of carbon dioxide and dihydrogen sulfide into a subsurface rock formation; reacting the fluid with elements of the subsurface rock formation to form at least one of hydrogen gas, mineralized carbon, or mineralized sulfur; 1. A method for sequestrating carbon dioxide or dihydrogen sulfide in subterranean rock formations, comprising:

[0132] (Appendix 10) 10. The method of claim 9, wherein the subsurface rock formation comprises one or more of: iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich deposit in the subsurface rock formation to form hydrogen gas and mineralize carbon from carbon dioxide.

[0133] (Appendix 11) 10. The method of claim 9, further comprising heating the fluid prior to injecting the fluid into the subsurface rock formation.

[0134] (Appendix 12) 12. The method of claim 11, wherein the fluid is heated by a heat source external to the subsurface rock formation.

[0135] (Appendix 13) 10. The method of claim 9, wherein reacting the fluid with elements of the subsurface rock formation comprises one or more of a serpentinization reaction, a pyritization reaction, or a decarbonation reaction.

[0136] (Appendix 14) 10. The method of claim 9, further comprising collecting the hydrogen gas formed by reacting the fluid with elements of the subsurface rock formation.

[0137] (Appendix 15) 10. The method of claim 9, wherein the subsurface rock formation comprises a porous, faulted, or geologically or originally fractured rock formation, or a natural geothermal system.

[0138] (Appendix 16) injecting a thermal fluid into a subterranean rock formation, the thermal fluid including reactants and being heated by a heat source external to the subterranean rock formation, the reactants including one or more of dihydrogen sulfide or carbon dioxide; reacting the reactant with components in the subterranean formation to form at least one of hydrogen gas, mineralized sulfur, or carbon; collecting hydrogen produced from the reaction of said reactants with said subterranean formation or sequestering mineralized sulfur and carbon within said subterranean formation; 1. A method for producing hydrogen from subterranean rock formations, comprising:

[0139] (Appendix 17) 17. The method of claim 16, wherein the subsurface rock formation comprises one or more of iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich deposit.

[0140] (Appendix 18) 17. The method of claim 16, wherein the thermal fluid comprises at least one of water, steam, salt water, geothermal fluid, or waste heat fluid.

[0141] (Appendix 19) 17. The method of claim 16, wherein the thermal fluid comprises a supercritical fluid.

[0142] (Appendix 20) 17. The method of claim 16, wherein the subsurface rock formation comprises a porous, faulted, or geologically or originally fractured rock formation, or a natural geothermal system.

[0143] (Appendix 21) injecting a fluid into a subsurface rock formation; injecting one or more fluids, including dihydrogen sulfide or a combination of dihydrogen sulfide and carbon dioxide, into the subsurface rock formation; collecting hydrogen produced from the reaction of the fluid with the subsurface rock formation; and 1. A method for producing hydrogen from a subterranean formation comprising:

[0144] (Appendix 22) heating one or more fluids, such as water, carbon dioxide, dihydrogen sulfide, or combinations thereof; injecting the fluid into a subterranean rock formation; injecting one or more fluids, including dihydrogen sulfide or a combination of dihydrogen sulfide and carbon dioxide, into the subsurface rock formation; collecting hydrogen produced from the reaction of the fluid with the subsurface rock formation; and 1. A method for producing hydrogen from a subterranean formation comprising:

[0145] (Appendix 23) heating the fluid with heat from a source external to the subsurface rock formation; injecting the fluid into a subterranean rock formation; injecting one or more fluids, including dihydrogen sulfide or a combination of dihydrogen sulfide and carbon dioxide, into the subsurface rock formation; collecting hydrogen produced from the reaction of the fluid with the subsurface rock formation; and 1. A method for producing hydrogen from a subterranean formation comprising:

[0146] (Appendix 24) heating the carbon dioxide containing fluid with heat from a source external to the underground rock formation; injecting the fluid into the subterranean rock formation; 1. A method for producing hydrogen from underground rock formations comprising:

[0147] (Appendix 25) heating the carbon dioxide containing fluid with heat from a source external to the underground rock formation; injecting the fluid into the subterranean rock formation; collecting hydrogen produced from the reaction of the fluid with the subsurface rock formation; and 1. A method for producing hydrogen from a subterranean formation comprising:

[0148] (Appendix 26) injecting a heated fluid into a subterranean rock formation, the heated fluid being heated by a heat source external to the subterranean rock formation; A method for producing hydrogen from underground rock formations.

[0149] (Appendix 27) injecting a heated fluid comprising carbon dioxide into a subterranean rock formation, the fluid being heated by a heat source external to the subterranean rock formation; reacting the heated fluid with the subsurface rock formation to effect one or more of the formation of hydrogen gas or the mineralization of carbon; reacting the fluid with one or more of the following in the subsurface rock formation: iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich sediment to form hydrogen gas and mineralize carbon from carbon dioxide; 1. A method for sequestrating carbon dioxide in underground rock formations comprising:

[0150] (Appendix 28) The amount of sequestered carbon dioxide is expressed as carbon dioxide or CO 2e 28. The method according to claim 27, wherein the fossil fuel equivalent is

[0151] (Appendix 29) injecting a heated fluid containing dihydrogen sulfide or other sulfur compounds into a subterranean rock formation, the heated fluid being heated by a heat source external to the subterranean rock formation; reacting the heated fluid with the subsurface rock formation to effect one or more of the formation of hydrogen gas or the mineralization of sulfur; reacting the heated fluid with one or more of the following in the subsurface rock formation: iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich sediment to form hydrogen gas and mineralize sulfur from dihydrogen sulfide; 16. A method for sequestrating sulfur in underground rock formations comprising:

[0152] (Appendix 30) injecting a heated fluid comprising a mixture of dihydrogen sulfide and carbon dioxide into a subterranean rock formation, the fluid being heated by a heat source external to the subterranean rock formation; reacting the heated fluid with the subsurface rock formation to effect one or more of the formation of hydrogen gas or the mineralization of sulfur and carbon; reacting the fluid with one or more of the following in the subsurface rock formation: iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich sediment to form hydrogen gas and mineralize sulfur from dihydrogen sulfide and carbon from carbon dioxide; 1. A method for sequestrating a mixture of dihydrogen sulfide and carbon dioxide in a subterranean rock formation comprising:

[0153] (Appendix 31) 31. The method of any one of claims 21 to 30, wherein the heated fluid comprises heated water.

[0154] (Appendix 32) 31. The method of any one of claims 21 to 30, wherein the heated fluid comprises steam.

[0155] (Appendix 33) 31. The method of any one of claims 21 to 30, wherein the heated fluid is a supercritical fluid.

[0156] (Appendix 34) 31. The method of any one of claims 21 to 30, wherein the heated fluid comprises carbon dioxide.

[0157] (Appendix 35) 31. The method of any one of claims 21 to 30, wherein the heated fluid comprises supercritical carbon dioxide.

[0158] (Appendix 36) 31. The method of any one of claims 21 to 30, wherein the heated fluid comprises dihydrogen sulfide.

[0159] (Appendix 37) 31. The method of any one of claims 21 to 30, wherein the heated fluid comprises supercritical dihydrogen sulfide.

[0160] (Appendix 38) 31. The method of any one of clauses 21 to 30, wherein the subsurface rock formation comprises one or more of iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, metamorphosed or hydrothermally altered olivine or pyroxene-bearing igneous rock, metamorphic rock, or sedimentary rock or deposit, rock or deposit containing serpentinite minerals, partially or fully serpentinized rock, serpentine, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich deposit.

[0161] (Appendix 39) 31. The method of any one of claims 21 to 30, wherein the subsurface rock formation comprises a natural geothermal system.

Claims

1. Injecting the reactant into the underground layer, The method involves reacting the reactants with the underground layer to form hydrogen gas and at least one of the mineralization products inside the underground layer, wherein the mineralization product includes mineralized sulfur. Collecting hydrogen produced from the reaction between the reactants and the subsurface layer, and isolating one or more components of the reactants to form mineralized sulfur via a pyrite formation reaction, A method for producing hydrogen from underground layers containing [unspecified].

2. The method according to claim 1, wherein the reactant comprises dihydrogen sulfide and at least one of carbon dioxide, water, steam, brine, geothermal fluid, or waste heat fluid.

3. The method according to claim 1, wherein the underground layer comprises at least one of the following: iron-rich rock, mafic igneous rock, metamorphosed or hydrothermally altered mafic igneous rock, igneous or metamorphic rock containing olivine or pyroxene, metamorphosed or hydrothermally altered igneous or metamorphic rock containing olivine or pyroxene, rock containing serpentinite minerals, partially or completely serpentinized rock, serpentinite, pyrite, iron-rich sandstone, other iron-rich sedimentary rock, or iron-rich sediment.

4. The method according to claim 1, wherein the subsurface layer includes a porous, faulted, or geologically or initially fractured rock layer.

5. The method according to claim 1, further comprising heating the reactant before injecting it into the underground layer, wherein the reactant is heated from a source outside the underground layer.

6. The method according to claim 1, further comprising crushing or stimulating the underground layer.

7. The method according to claim 1, wherein the reaction comprises one or more serpentinization reactions or decarboxylation reactions.

8. The method according to claim 1, wherein the underground layer includes a natural geothermal system.

9. The method involves injecting a thermal fluid into an underground rock layer, wherein the thermal fluid contains reactants, is heated by a heat source outside the underground rock layer, and the reactants contain one or more dihydrogen sulfide and carbon dioxide. The reactants are reacted with components in the underground rock layer to form hydrogen gas and mineralized sulfur via a pyrite mineralization reaction, Collecting the hydrogen gas produced from the reaction between the reactants and the underground rock layer, and isolating the mineralized sulfur within the underground rock layer, A method for producing hydrogen from underground rock layers, which includes [a specific feature / technology].

10. The method according to claim 9, wherein the underground rock layer comprises one or more of the following: iron-rich rocks, mafic igneous rocks, metamorphosed or hydrothermally altered mafic igneous rocks, igneous or metamorphic rocks containing olivine or pyroxene, metamorphosed or hydrothermally altered igneous or metamorphic rocks containing olivine or pyroxene, rocks or sediments containing serpentinite minerals, partially or completely serpentinized rocks, serpentinite, pyrite, iron-rich sandstone, other iron-rich sedimentary rocks, or iron-rich sediments.

11. The method according to claim 9, wherein the thermal fluid includes at least one of water, steam, brine, geothermal fluid, or waste heat fluid.

12. The method according to claim 9, wherein the thermal fluid includes a supercritical fluid.

13. The method according to claim 9, wherein the underground rock layer includes a porous, faulted, geologically or early-fractured rock layer, or a natural geothermal system.

Images