Improved compositions and systems to form a thermally conductive sheath

Abstract

A high thermal conductivity suspension is provided, comprising a high apparent viscosity carrier liquid and a plurality of high thermal conductivity particles. A system for forming a compacted high thermal conductivity sheath using this high thermal conductivity suspension is also proposed. This system includes the steps of settling the plurality of high thermal conductivity particles previously suspended in the high viscosity carrier liquid through viscosity reduction, and consolidating the settled plurality of particles through hydraulic or chemical consolidation. The resulting high thermal conductivity compacted sheath enhances heat transfer of the working fluid from a target location in the formation to the closed-loop collector casing within the geothermal wellbore for the generation of electrical or thermal energy.

Description

Technical Field

[0001] This application claims priority to co-pending U.S. Provisional Patent Application No. 63 / 550,959 (filed February 7, 2024) and U.S. Provisional Patent Application No. 63 / 550,937 (filed February 7, 2024), both of which are incorporated herein by reference.

[0002] The field of the present invention is an improved composition and system for supplying a pumpable suspension, settling a high thermal conductivity (k) material from the pumpable suspension, and consolidating the high thermal conductivity material from the pumpable suspension to form a compacted high thermal conductivity sheath, particularly relating to filling the annular space between a wellbore and a closed-loop heat harvesting system. Prior Technology

[0003] The background description includes information that may help in understanding the invention. It is not acknowledged here that any information provided is prior art or related to the currently claimed invention, or that any publication explicitly or implicitly referenced is prior art.

[0004] All publications and patent applications herein are incorporated by reference to the same extent that each individual publication or patent application is explicitly and individually indicated to be incorporated by reference. If a definition or use of a term in the incorporated references is inconsistent with or contrary to the definition of that term provided herein, the definition provided herein shall apply, and the definition in the references shall not apply.

[0005] Geothermal wells have been used to provide heating and cooling systems that transfer heat to and from the surface. In a typical vertical closed-loop well system, two pipes connected by a U-shaped connector at the bottom to form a continuous casing are vertically placed in a drilled wellbore (see U.S. Patent Application Publication No. 2012 / 0247766). This type of system is commonly used for heating and cooling in residential and commercial buildings. In such systems, a conventional grouting mixture is typically clay-based and is pumped into the wellbore to fill the annular space between the casing and the formation. The resulting grout forms a seal to prevent underground contamination from the surface and to prevent groundwater contamination. The grouting mixture may also include a thermally conductive material to help transfer heat between the working fluid in the casing and the target location, and the working fluid can circulate through the well loop to transfer heat to or from a surface heat exchanger.

[0006] In many cases, traditional geothermal wells contain a significant amount of curable materials (e.g., binders) used to harden the grout mixture. Unfortunately, these curable materials do not exhibit high thermal conductivity, which means that even if the grout composition contains some thermally conductive materials, a large portion of the grout composition will lack thermal conductivity at best and will only function as an insulator at worst.

[0007] Therefore, although various compositions and methods for geothermal heat transfer are known in the art, all or almost all of them have certain drawbacks, especially when the materials lack high thermal conductivity. Thus, there is still a need for an improved material that is pumpable, thermally coupled to the formation and casing within the wellbore, and exhibits a higher thermal conductivity than cement. Summary of the Invention

[0008] The subject matter of this invention relates to various compositions and systems for settling and consolidating high thermal conductivity materials in pumpable suspensions to form a compacted high thermal conductivity sheath within an annular space between a wellbore and a closed-loop heat collection system.

[0009] In one aspect of the subject matter of this invention, the inventors have conceived of a mixture comprising a suspended heat arrival enhancement (TRE) solid and a high apparent viscosity carrier liquid. The TRE solid exists in the form of a plurality of TRE particles suspended throughout the high apparent viscosity carrier liquid. The high apparent viscosity carrier liquid of the pumpable suspension has a composition that allows additives or triggering events to in situ alter the physical and / or chemical properties of the mixture, thereby reducing viscosity and allowing the particles to settle by gravity at a target location to form a settled particle sheath within the annular space of the wellbore. Furthermore, the TRE particles have a composition that allows the settled particle sheath to consolidate to form a highly thermally conductive compacted sheath within the annular space of the wellbore.

[0010] In some embodiments, consolidation includes hydraulic and / or chemical consolidation of the TRE particles.

[0011] Most typically, these TRE particles comprise materials selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloys, alumina, rhodium, cobalt, copper alloys, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy. Optionally, these TRE particles comprise at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloys, alumina, rhodium, cobalt, copper alloys, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy.

[0012] A more broad conception is that the shapes of these TRE particles are selected from the group consisting of flakes, plates, spheres, irregular shapes, cubes, rods, discs, prisms, needles, tubes, fibers, angular shapes, subangular shapes, circles, subrounded shapes, dumbbell shapes, and stars. In other options, the first and second portions of these TRE particles will have shapes selected from this group, wherein the shapes of the first and second portions are different.

[0013] In some embodiments, a first portion of the TRE particles has a composition and shape that causes the mass of the first particle to elastically and plastically deform under compressive load, and wherein a second portion of the TRE particles has a composition and shape that causes the mass of the second particle to elastically deform only under compressive load.

[0014] Preferably, but not necessarily, the D50 particle size of these TRE particles is between 0.05 micrometers (μm) and 5.0 millimeters (mm), and accounts for between 30% and 70% of the total suspension by volume.

[0015] Typically, high apparent viscosity carrier liquids include a certain amount of water. However, when necessary, high apparent viscosity carrier liquids may also include water-soluble biopolymers, water-soluble derived biopolymers, water-soluble gums, water-soluble cellulose, water-soluble synthetic polymers, or surfactants. Optionally, the gum, cellulose, polymer, biopolymer, or surfactant in the carrier liquid may form a network, crosslink, or form a supramolecular structure. Furthermore, the gum, cellulose, polymer, biopolymer, or surfactant may bind to the TRE particles and form suspended particles, particle-filled networks, crosslinked particle-filled polymer networks, and / or particle-filled supramolecular structures.

[0016] In another embodiment, the high apparent viscosity carrier liquid also includes a viscosity modifier. Among other options, preferred viscosity modifiers include guar gum, polysaccharides (starch, guar, cellulose, cellulose derivatives, alginate, carrageenan, or locust gum), saffron gum, hydroxylethyl cellulose (HEC), carboxymethyl guar (CMG), carboxymethyl hydroxylethyl cellulose (CMHEC), hyperbranched polyglycerol (HPG), carboxymethyl hydroxypropyl guar (CMHPG), carboxymethyl cellulose (CMC), high strength molding compound (HMC), acrylamide, poly(acrylamide / acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid) (AMPS-AA-AM), and viscoelastic surfactant (VES). As understood, the amount of the viscosity-enhancing agent present is from 0.01 wt.% to 20 wt.% of the pumpable suspension.

[0017] Preferably, the high apparent viscosity carrier liquid has a composition that allows for a reduction in apparent viscosity in response to a triggering event, such as a chemical or enzymatic reaction (which reduces molecular weight / polymer chain length), an increase in temperature, a change in reactivity or pH, or a change in time. Therefore, the high apparent viscosity carrier liquid may have a composition that allows for a reduction in viscosity using additives selected from oxidants, bio-based enzymes, bacteria, and pH adjusters, or a composition that allows for a reduction in viscosity using shear force or temperature changes. Thus, the additive may comprise 0.001 wt.% to 10 wt.% of the total suspension weight percentage (wt.%). Furthermore, the additive may also alter the temperature stability of the pumpable suspension.

[0018] Suitable additives include crosslinking agents, dispersants, fragmentation agents, and stabilizers. For example, crosslinking agents may be based on antimony, aluminum, chromium, boron, titanium, or zirconium; dispersants may be surfactants, polymers, salts, or pH modifiers; fragmentation agents may be pH adjusters, oxidants, enzymes, or bacteria; and stabilizers may be oxidants. Furthermore, the composition may include at least two different additives.

[0019] In some embodiments, the crosslinking agent additive may be aluminum, chromium, antimony, boron, titanium, or zirconium-based. The dispersant additive is envisioned as a surfactant, polymer, salt, or pH adjuster. In other embodiments, the de-airing additive may be polydimethylsiloxane, alcohol, stearate, ethylene glycol, surfactant, alkylphenol ethoxylate, silicone defoamer, mineral oil defoamer, vegetable oil defoamer, wax-based defoamer, polymer defoamer, or silicone-free defoamer. Furthermore, the fracturing agent additive may be a pH adjuster, oxidant, enzyme, or bacteria. Finally, the stabilizer additive may be an oxidant or a gelling agent. Preferably, the composition may include at least two different additives.

[0020] Broadly envisioned, the pumpable suspension may optionally further include a second additive that promotes the binding of the TRE particles to the viscosity-enhancing agent, thereby improving the mixing and dispersion of the TRE particles in a high apparent viscosity carrier liquid. Alternatively, or additionally, the pumpable suspension may optionally further include a second additive that optionally disrupts the polymer backbone or polymer-polymer crosslinking in response to a triggering event. In some embodiments, the pumpable suspension may optionally further include a second additive that absorbs thermal energy to extend the usable temperature range of a particular polymer by 5°C to 50°C.

[0021] Preferably, but not necessarily, the TRE particles are suspended in a high apparent viscosity carrier liquid until the viscosity of the carrier liquid decreases due to an in-situ triggering event. In some embodiments, the high apparent viscosity carrier liquid has a dynamic viscosity of at least 5,000 centipoise (cP) before the triggering event and a dynamic viscosity of no more than 1,000 cP after the triggering event. Most typically, the TRE particles are of a size such that they settle at least 1 meter within 24 hours after the viscosity decreases. Therefore, the settled particle sheath has an final porosity equal to or less than 80% and a thermal conductivity between about 1.5 W / mK and 400 W / mK. Subsequently, the settled particle sheath can be consolidated to have a permeability equal to or less than 0.01 Darcy. In various embodiments, the resulting compacted sheath has a thermal conductivity greater than 1.5 W / mK.

[0022] From another perspective, the inventors envision a system configured to transfer heat from the formation to a collector casing. The envisioned system includes a collector casing disposed within a wellbore, the wellbore descending substantially vertically from a top position to a target location in the formation; a heat arrival enhancement (TRE) structure located at the target location, the TRE structure comprising a first high thermal conductivity material; wherein the TRE structure extends distally from the wellbore into the formation at the target location, and wherein the TRE structure has an opening at the wellbore; a high thermal conductivity compacted sheath comprising a plurality of sheath segments along a vertical length of the high thermal conductivity compacted sheath, the high thermal conductivity compacted sheath being thermally coupled to (a) the outer surface of the casing and extending substantially vertically along some length of the target location in the annular space of the wellbore, and (b) the opening of the TRE structure, thereby forming a continuous heat transfer path from the target location through the TRE structure and the compacted sheath to the casing.

[0023] Most typically, the target location is at a depth between 150 meters and 20,000 meters, where the strata at the target location have a geostatic temperature between 120°C and 600°C.

[0024] Furthermore, it is broadly envisioned that the TRE structure comprises a plurality of particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy. Optionally, the TRE structure comprises at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy. Preferably, but not necessarily, the TRE structure has a width that gradually decreases from the proximal end to the distal end. In some embodiments, the TRE structure extends longitudinally along the wellbore, wherein the TRE structure has a width between 1 mm and 100 mm and extends longitudinally into the formation by a distance of 1 meter to 200 meters. Furthermore, the TRE structure may also have a winged configuration.

[0025] Furthermore, the envisioned TRE structure has a thermal conductivity between 1.5 W / mK and 150 W / mK, and the first high thermal conductivity material at the proximal end of the orifice is flush with the annular space of the wellbore. Additionally, the envisioned system may include a second TRE structure, which is vertically offset from the first TRE structure by 10 meters to 100 meters and radially offset from the first TRE structure by 15 degrees to 90 degrees. Typically, the first high thermal conductivity material at the proximal end of the TRE structure is flush with the annular space of the wellbore.

[0026] In some embodiments, the second TRE structure comprises at least two chemically distinct particles, including materials selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloys, alumina, rhodium, cobalt, copper alloys, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hersted alloys.

[0027] Regarding the compacted sheath, it is broadly envisioned that the compacted sheath has a thermal conductivity between approximately 1.5 W / mK and 50 W / mK, or between approximately 30 W / mK and 400 W / mK. In some embodiments, the compacted sheath comprises two different types of thermally conductive particles. Most typically, each segment of the compacted sheath has a height between 3 meters and 500 meters. Preferably, the compacted sheath extends substantially vertically between 10% and 70% of the target location.

[0028] In another embodiment, the thermal conductivity of the compacted sheath is equal to or differs from no more than 50% of the thermal conductivity of the TRE structure. In other embodiments, the thermal conductivity of the compacted sheath is equal to or differs from no more than 30% of the thermal conductivity of the TRE structure. However, in some embodiments, the thermal conductivity of the compacted sheath is equal to or differs from no more than 10% of the thermal conductivity of the TRE structure, or both have the same thermal conductivity.

[0029] From another perspective, the inventors envision a system configured to transfer heat from the formation to a collector casing, comprising a collector casing disposed within a wellbore that descends substantially vertically from a top position to a target location in the formation. The system is also envisioned to include a high thermal conductivity compacted sheath comprising a plurality of sheath segments along a vertical length of the high thermal conductivity compacted sheath, thermally coupled to (a) the outer surface of the casing and extending substantially vertically along a length of the target location within the annular space of the wellbore, and (b) the target location in the formation, thereby forming a continuous heat transfer path from the target location through the high thermal conductivity compacted sheath to the casing.

[0030] Typically, the target location is at a depth between 150 meters and 20,000 meters, and the strata at the target location have a geostatic temperature between 120°C and 600°C.

[0031] Broadly envisioned, the compacted sheath has a thermal conductivity between approximately 1.5 W / mK and 50 W / mK, or between approximately 30 W / mK and 400 W / mK. In some embodiments, each segment of the compacted sheath has a height between 5 meters and 500 meters. Preferably, the compacted sheath extends substantially vertically along 10% to 70% of the target location.

[0032] When needed, the compacted sheath can include two different types of thermally conductive particles.

[0033] Various objects, features, aspects and advantages of the subject matter of the invention will become more apparent from the following detailed description of preferred embodiments and the accompanying drawings, in which the same reference numerals denote the same parts. Simple Explanation of the Diagram

[0034] Figure 1 depicts a photograph showing the porosity changes that occur depending on the consolidation method used.

[0035] Figure 2 is an exemplary schematic diagram showing the two steps (i.e., settlement and consolidation) required to achieve compaction.

[0036] Figure 3 is a graph depicting the heat generated per kilometer of wellbore depending on the change in thermal conductivity of the settling particle sheath placed in the formation without a TRE structure. Implementation

[0037] Inventors have discovered various compositions and systems for providing high thermal conductivity (K) sheaths derived from a pumpable suspension comprising a high apparent viscosity carrier liquid and a plurality of high thermal conductivity particles. Most typically, the high apparent viscosity carrier liquid is diluted or broken up to reduce viscosity and allow previously suspended TRE particles to settle. In some embodiments, these particles settle in an annular space, thereby forming clumps and, upon consolidation, forming a compacted sheath that thermally couples the collector casing to the geological resource. Preferably, but not necessarily, the compacted sheath has a thermal conductivity of at least 1.5 W / mK, or at least 5 W / mK, or at least 10 W / mK, or at least 25 W / mK, or at least 50 W / mK, or at least 100 W / mK, or at least 200 W / mK, or at least 300 W / mK, or at least 400 W / mK.

[0038] Conventionally, geothermal wells contain a significant amount of curable material (e.g., binder) for hardening the grout mixture. However, curable materials do not exhibit ideally high thermal conductivity. Alternatively, particulate mixtures without curable materials have been used in certain underground applications, such as clogging underground pipes (see, for example, U.S. Patent Publications 6,715,543 and 7,258,174). While these particulate mixtures do not contain curable materials, they lack high thermal conductivity and are generally unsuitable for installation at extreme temperatures (e.g., 300°C) near the target location (e.g., geothermal energy source).

[0039] On the other hand, certain mixtures of highly thermally conductive fluids have also been disclosed. For example, World Patent Publication No. WO 2014 / 092940 discloses a method and composition for introducing shear-thinning, pumpable, and solidifiable fluids into a well through a drill string assembly or bottom hole assembly. While interesting, this reference primarily focuses on treating oil or gas production wells (i.e., altering the condition of a portion of the wellbore or the subsurface formation adjacent to the wellbore) and reducing the amount of drilling fluid lost into the formation, rather than increasing thermal conductivity.

[0040] Similarly, U.S. Patent Application Publication No. 2011 / 0232858 teaches a system and method for extracting thermal energy for power generation from geology with high temperatures (e.g., 500°C), wherein one or more boreholes contain thermally conductive compacted filler, and a conduit system that conducts the thermal energy to a target location. Here, the compacted filler is powdered or rod-shaped graphite. To reduce the occurrence of void spaces that can act as insulators, U.S. Patent Application Publication No. 2011 / 0232858 relies on high-pressure compaction. Therefore, although multiple and / or large-scale carbon-filled conduits can be formed in the formation, heat transfer of the working fluid in the tube-in-tube system is typically limited to the end portion of the tube-in-tube system (otherwise the compaction pressure would overwhelm the tube-in-tube system), thus significantly reducing overall heat collection. While multiple graphite-filled channels converging in the tube-in-tube system can increase heat collection, they also increase operational complexity and cost.

[0041] Furthermore, in World Patent Publication No. WO 2023 / 150450, the slurry mixture comprises a plurality of high thermal conductivity (k) materials in the form of particles with a wide size distribution. These particles are capable of being compacted under hydrostatic pressure within cracks at the target location to form a TRE structure with high thermal conductivity, which remains movable even under tremendous forces (e.g., earthquakes). While mechanically interesting, the envisioned compaction depends on the presence of hydrostatic pressure, which significantly limits the compaction of particles within the slurry in the event of reduced or absent hydrostatic pressure.

[0042] Therefore, although various compositions and methods for geothermal heat transfer are known in the art, they all or almost all have certain drawbacks. Thus, there remains a need for compositions and systems with high thermal conductivity that are pumpable and can thermally couple formation heat to high thermal conductivity casing within the wellbore to improve the generation of electrical or thermal energy.

[0043] In light of the foregoing, it should be understood that the compositions and systems proposed herein represent a significant advancement in the field of heat transfer in geothermal power plants. The energy generated by the geothermal systems envisioned herein can be used for heating or cooling (direct use) or can be converted into electrical energy through a surface power plant that converts thermal energy into electrical energy. Furthermore, geothermal systems can be integrated with energy-consuming equipment, such as geothermal plants for producing hydrogen or other renewable fuels, carbon capture, or seawater desalination. Geothermal wells can circulate working fluids and thereby continuously generate energy at a constant rate, or the flow rate of the working fluid can be controlled to allow the geothermal well to generate energy that varies over time.

[0044] Most importantly, the compositions and systems presented in this paper are designed to deliver thermally conductive materials to target areas in the form of a pumpable suspension. This significantly simplifies the deployment of thermally conductive materials without the problems encountered with curable (typically cementing) compositions. In fact, even during deployment, the placement of the suspension and even the composition can be modified / adjusted without unintentionally or prematurely curing to a hardened state. Furthermore, the pumpable suspension (through viscosity disruption and subsequent settling of the thermally conductive particles) can be readily converted into a composition with easily controllable settling rates and velocities, achieving operational control that is impossible with other compositions. Further, additional thermal conductivity can be added through the consolidation of the settling particles, enabling the formation of highly thermally conductive compacted structures (typically sheaths surrounding the collector casing). Finally, due to viscosity control, pumping operations can even be stopped and reversed in the event of unforeseen placement difficulties or poor well conditions.

[0045] As will be readily understood, the envisioned pumpable suspension may comprise a mixture of suspended heat-reinforced (TRE) solids and a high apparent viscosity carrier liquid. In some embodiments, the TRE solids are typically present in the form of a plurality of TRE particles, with the high surface viscosity carrier liquid suspending the particles throughout the fluid. As briefly discussed above, the high apparent viscosity carrier liquid may have properties that allow for operational control over the settling of the plurality of TRE particles. Preferably, the high apparent viscosity carrier liquid has a composition that allows additives or triggering events to alter the physical and / or chemical properties of the mixture in situ, thereby reducing viscosity and thus allowing the particles to settle by gravity at a target location, thereby forming a settling particle sheath within the annular space of the geothermal wellbore at the target location. Therefore, it is envisioned that the TRE particles have a composition that can cause the settling particle sheath to solidify to form a highly thermally conductive compacted sheath within the annular space of the wellbore.

[0046] As used herein, the term "sedimentation" refers to the downward movement of TRE particles under the influence of gravity. This typically refers to the settling mass state of TRE particles, which move from a previously suspended state in a high apparent viscosity carrier liquid to the bottom of the annular space in the wellbore. Also as used herein, the term "consolidation" refers to the compaction of a porous material as its pore pressure decreases. Preferably, the porous material comprises a plurality of TRE particles. In some embodiments, consolidation can be hydraulic consolidation (due to Darcy's law, pore pressure decreases due to fluid flow) or chemical consolidation (due to fluid consumption resulting from a chemical reaction, leading to a decrease in pore pressure). The consolidation process typically begins after the plurality of TRE particles are no longer suspended in the high apparent viscosity carrier liquid and after sufficient settling time. Finally, as additionally used herein, the term "compaction" describes the target final state of a high thermal conductivity compacted sheath. This stage is achieved after the plurality of TRE particles have undergone the settling and consolidation processes, reaching the final desired porosity and thermal conductivity conditions.

[0047] Therefore, this paper envisions a system configured to transfer heat from the formation to a collector casing. Most typically, the collector casing can be disposed within a wellbore that descends substantially vertically from a top position to a target location in the formation. In some embodiments, a heat arrival enhancement (TRE) structure at the target location comprises a first high thermal conductivity material, wherein the TRE structure extends distally from the wellbore into the formation at the target location, and wherein the TRE structure has an opening at the wellbore. Preferably, a high thermal conductivity compacted sheath comprises a plurality of sheath segments along a vertical length of the high thermal conductivity compacted sheath thermally coupled to (a) the outer surface of the casing and extending substantially vertically along some length of the target location in the annular space of the wellbore, and (b) the opening of the TRE structure, thereby forming a continuous heat transfer path from the target location through the TRE structure and the compacted sheath to the casing.

[0048] Alternatively, another system is envisioned, configured to transfer heat from the formation to the collector casing without employing a TRE structure. In such an embodiment, the collector casing is again positioned within the wellbore, which descends substantially vertically from a top position to a target location within the formation. The high thermal conductivity compacted sheath comprises a plurality of sheath segments along a vertical length of the high thermal conductivity compacted sheath, thermally coupled to (a) the outer surface of the casing and extending substantially vertically along a length of the target location within the annular space of the wellbore, and (b) the target location within the formation, thereby forming a continuous heat transfer path from the target location through the high thermal conductivity compacted sheath to the casing.

[0049] Regardless of the system used, the target temperature at the target location is typically at least 120°C, at least 180°C, at least 250°C, at least 300°C, at least 350°C, at least 400°C, at least 450°C, or at least 500°C, or at least 600°C, and / or the target location may be located at a depth of at least 150 meters (m), at least 300m, at least 500m, at least 600m, at least 700m, at least 800m, at least 900m, at least 1,000m, at least 1,250m, at least 1,500m, at least 1,750m, at least 2,000m, at least 2,500m, at least 3,000m, at least 4,000m, at least 5,000m, at least 10,000m, or at least 20,000m.

[0050] In some embodiments, the target location extends substantially vertically. As used herein, the term "substantially" means that the target location extends toward the Earth's center, but may deviate from the center by no more than 15 degrees, 10 degrees, 5 degrees, or 1 degree. It should be understood that a geothermal wellbore may have multiple target locations, and therefore may have target locations in a substantially vertical direction and target locations extending along a direction of at least 30 degrees.

[0051] The target location is typically hot, dry rock (e.g., intrusive igneous or metamorphic rock, granite, basalt, sedimentary rock), and may or may not include multiple fractures extending longitudinally from the wellbore into the formation. In other embodiments, the target location may also include permeable or impermeable rock. Additionally, geothermal systems are envisioned to be located in hot, wet rock, "greenfields," "brownfields," subsea, and / or oil / gas wells. Regarding the use of oil / gas wells, geothermal energy can be utilized through the conversion of dormant or non-producing oil / gas wells and the co-production of active wells. For example, an old well can be cleaned up and then the system envisioned herein can be installed. In another example, an old well can be cleaned up and then deepened before installing the system envisioned herein. Alternatively, an old well can be cleaned up, sidetracked, drilled, and then the envisioned system can be installed. In the case of subsea drilling, it is envisioned to place the geothermal system at or near a submarine rift valley. Submarine drilling can also be carried out anywhere geothermal energy can be extracted, such as major plate boundaries or rift zones.

[0052] Regardless of the target location, in various embodiments, the wellbore may include artificial and / or naturally occurring cracks, and such cracks may extend longitudinally from the wellbore by a distance of at least 3m, at least 4m, at least 5m, at least 6m, at least 7m, at least 8m, at least 9m, or at least 10m, or even longer. The cracks may be at least partially filled with compacted high thermal conductivity material or heat-reinforced (TRE) particles to form a TRE structure. In some embodiments, at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%, or even more, of the volume of each crack contains compacted high thermal conductivity material.

[0053] Imagine a fracture adjacent to the wellbore and at least partially filled with a highly thermally conductive material, forming a plurality of Heat Reach Enhancement (TRE) structures. When implementing the TRE structures, it is envisioned that the highly thermally conductive material in the TRE structures is thermally coupled to the settled or compacted sheath in the wellbore. Most typically, the first highly thermally conductive material at the proximal end of the first and / or second TRE structure is flush with the annular space of the wellbore and / or the resulting compacted sheath within the annular space of the wellbore, thereby allowing heat to be continuously transferred from the formation through the highly thermally conductive compacted sheath and the collector casing to the wellbore and the working fluid.

[0054] In a further envisioned aspect, the TRE structure may have a width between 1 mm and 10 mm, between 5 mm and 30 mm, between 10 mm and 50 mm, between 25 mm and 80 mm, or between 1 mm and 100 mm. In some embodiments, the TRE structure may extend into the formation at a longitudinal distance of at least 1 m, at least 50 m, at least 100 m, at least 150 m, or at least 200 m. Furthermore, and regardless of the specific configuration, the fractures at the target location and the subsequent TRE structure placed within them are envisioned not only as single linear breaks in the rock formation but also as complex structures (e.g., mesh-like or dendritic structures). Advantageously, such complex structures will provide a heat exchange surface with the remaining unfractured rock at the target location, or even a larger surface area. For example, the TRE structure may be formed with a longitudinally complex multi-fracture geometry, with a width between 10 mm and 50 mm and a length of at least 10 m (measured from the wellbore). However, although the width and length of the fractures are given, the effective length is the amount of fractures available for the TRE structure. For example, the total length of the fracture can be 200m, but the effective length of the TRE structure is only 10m. Nevertheless, regardless of the specific dimensions, it is generally preferred that the TRE structure have a width that decreases from the near end to the far end, wherein the TRE structure extends longitudinally along the wellbore.

[0055] As previously mentioned, it should be noted in this document that the compacted high thermal conductivity material of the TRE structure typically terminates near the target location in the wellbore, allowing for uninterrupted (continuous) heat exchange between the compacted high thermal conductivity material and the high thermal conductivity sheath within the wellbore. Therefore, the high thermal conductivity material near the end of the TRE structure is typically (but not necessarily) flush with the wellbore and / or any annular space within the wellbore. This creates a continuous heat transfer path from the target location in the formation via the TRE structure and the high thermal conductivity sheath to the casing, and then to the working fluid within the casing. Furthermore, in at least some embodiments, the TRE structure will have a wedge configuration. Therefore, it should be understood that the compacted high thermal conductivity material in the fracture provides additional thermally conductive surface area to improve heat extraction from the target region within the formation, not just the formation surface immediately adjacent to the wellbore. From another perspective, the compacted high thermal conductivity material in the fracture will act as a heat sink or fin, serving as a heat exchange surface to significantly improve heat transfer per unit length of the wellbore, thereby increasing the revenue of the power generation well. High thermal conductivity materials with TRE structures will have a thermal conductivity of at least 1.5 W / mK, at least 5 W / mK, or at least 10 W / mK, or at least 25 W / mK, or at least 50 W / mK, or at least 100 W / mK, or at least 250 W / mK, or at least 500 W / mK.

[0056] In some embodiments, the crack will result in a TRE structure with a two-wing configuration, comprising a first TRE structure and / or an opposing second TRE structure. It is also contemplated that the TRE structure may be a three-wing or four-wing configuration. Additionally, the secondary, tertiary, or quaternary TRE structure will have a vertical offset of at least 5 m, or at least 10 m, or at least 20 m, or at least 40 m, or at least 60 m, or at least 100 m relative to the first TRE structure. The secondary, tertiary, or quaternary TRE structure may also have a radial offset of at least 10 degrees, or at least 20 degrees, or at least 40 degrees, or at least 90 degrees relative to the first TRE structure.

[0057] Typically, a TRE structure is envisioned to comprise a plurality of particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloys, alumina, rhodium, zinc, cobalt, copper alloys, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy alloys. When desired, a TRE structure may include at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloys, alumina, rhodium, zinc, cobalt, copper alloys, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy alloys. Similarly, the second TRE structure may also contain at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloys, alumina, rhodium, zinc, cobalt, copper alloys, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hersted alloys.

[0058] Regardless of the system used to transfer heat from the formation to the collector casing in the wellbore, i.e., whether or not a TRE structure is implemented, the aforementioned high thermal conductivity compacted sheath can be formed from the pumpable suspension envisioned herein. As briefly discussed above, a pumpable suspension comprising a mixture of multiple suspended TRE particles and a high apparent viscosity carrier liquid can settle and solidify in the annular space of the wellbore to subsequently form a high thermal conductivity compacted sheath.

[0059] Most typically, the high apparent viscosity carrier liquid of the pumpable suspension has a composition that allows additives or triggering events to alter the physical and / or chemical properties of the mixture in situ (i.e., changes in chemical reactivity, pH, temperature, or time), thereby reducing the apparent viscosity and thus allowing TRE particles to settle to the target location by gravity, thereby forming a settling particle sheath having a thermal conductivity of at least 1.5 W / mK, or at least 3 W / mK, or at least 5 W / mK, or at least 10 W / mK, or at least 20 W / mK, or at least 50 W / mK, or at least 100 W / mK, or at least 200 W / mK, or at least 400 W / mK.

[0060] High apparent viscosity carrier liquids typically comprise a certain amount of water (e.g., water-only or aqueous solvent systems). However, in some embodiments, high apparent viscosity carrier liquids most commonly comprise water-soluble biopolymers, water-soluble derived biopolymers, water-soluble gums, water-soluble cellulose, water-soluble synthetic polymers, or surfactants, and optionally, the gums, cellulose, polymers, or biopolymers and surfactants in the carrier liquid form networks, crosslink, or form supramolecular structures. Preferably, the gums, cellulose, polymers, or biopolymers are combined with TRE particles to form suspended particles, particle-filled networks, crosslinked particle-filled polymer networks, or particle-filled supramolecular structures.

[0061] In this paper, high apparent viscosity is assumed to have a dynamic viscosity between 500 cP and 10,000 cP (e.g., between 500 cP and 1,500 cP, or between 1,500 cP and 3,000 cP, or between 3,000 cP and 6,000 cP, or between 6,000 cP and 10,000 cP) at a temperature of 20°C before viscosity failure or a triggering event, and in some cases even higher (e.g., between 10,000 cP and 25,000 cP). It is generally assumed that dynamic viscosity can be measured using a Stabinger viscometer according to the standard test method provided by the American Society for Testing and Materials (ASTM) D7042. Alternatively, viscosity can also be determined according to standards established by the International Organization for Standardization (ISO). However, it is also envisioned that conventional standards and methods, such as rotational viscometers, capillary viscometers, falling ball viscometers, flow cups, or other tools commonly used in the art, can be employed. In any case, it is in this state that the high apparent viscosity carrier liquid is combined with thermally conductive particles to form a pumpable mixture for deployment to a target area in a geothermal well. As will be readily understood, the magnitude of the apparent viscosity reduction due to the chemical reaction or triggering event (viscosity reduction cracking) will depend at least in part on the specific materials and conditions used. However, it is generally envisioned that the dynamic viscosity of the carrier liquid will be at least one order of magnitude lower, or at least two orders of magnitude lower. Therefore, the appropriate dynamic viscosity after the chemical reaction or triggering event will typically be between 5 cP and 1,000 cP (e.g., between 5 cP and 15 cP, or between 15 cP and 100 cP, or between 100 cP and 500 cP, or between 500 cP and 1,000 cP), and in some cases even higher.

[0062] As used in this article, "disruption" refers to the process of reducing the viscosity of a high-viscosity fluid so that thermally conductive materials suspended in the high-apparent-viscosity fluid settle more quickly. As mentioned above and throughout the text, viscosity may decrease, and high-viscosity fluids may be disrupted by triggering events such as changes in chemical composition, pH value, temperature, and / or the passage of time.

[0063] Nevertheless, suitable additives for high apparent viscosity carrier liquids include oxidants, bio-based enzymes, bacteria, or pH adjusters that allow viscosity to be reduced through shear or temperature changes. Most typically, the additive constitutes at least 0.001 wt.%, or at least 0.001 wt.%, or at least 0.01 wt.%, or at least 0.1 wt.%, or at least 1 wt.%, or at least 5 wt.%, or at least 10 wt.% of the total suspension weight percentage (wt.%). In some embodiments, the additive alters the temperature stability of the pumpable suspension. In other embodiments, heat-absorbing additives may be used. Nevertheless, the pumpable suspension may optionally further include a second additive that promotes the binding of a plurality of TRE particles to a viscosity-enhancing agent, thereby improving the mixing and dispersion of the plurality of TRE particles within the high apparent viscosity carrier liquid. It is also contemplated that the high apparent viscosity carrier liquid may include a second additive that selectively disrupts the polymer backbone or polymer-polymer crosslinks in response to a triggering event. When needed, the pumpable suspension may optionally further include a second additive that absorbs heat to extend the usable temperature range of the particular polymer by at least 1°C, or at least 5°C, or at least 10°C, or at least 20°C, or at least 35°C, or at least 50°C.

[0064] Furthermore, additives are most commonly selected from crosslinking additives, dispersant additives, breaker additives, de-airing additives, or stabilizer additives. For example, crosslinking additives can be aluminum, chromium, antimony, boron, titanium, or zirconium-based. Dispersant additives can be surfactants, polymers, salts, or pH modifiers. The presence of de-airing additives prevents, breaks down, or releases trapped bubbles, thereby optimizing the sedimentation and consolidation process. Suitable de-airing additives include polydimethylsiloxanes, alcohols, stearates, ethylene glycol, surfactants, alkylphenol ethoxylates, silicone defoamers, mineral oil defoamers, vegetable oil defoamers, wax-based defoamers, polymer defoamers, or silicone-free defoamers. breaker additives can be pH adjusters, oxidants, enzymes, or bacteria. Preferably, stabilizer additives are oxidants or gelling agents. Nevertheless, high apparent viscosity carrier liquids typically include at least two different additives.

[0065] As will be readily understood, high apparent viscosity carrier liquids typically also include viscosity modifiers, which are used to alter the rheological properties of the high apparent viscosity carrier liquid in response to various stimuli (e.g., temperature, pressure, contact with another material, or combinations thereof), or to improve the miscibility of the pumpable suspension. Suitable viscosity modifiers include guar gum, polysaccharides (starch, guar, cellulose, cellulose derivatives, alginate, carrageenan or locust gum), saffron gum, hydroxylethyl cellulose (HEC), carboxymethyl guar (CMG), carboxymethyl hydroxylethyl cellulose (CMHEC), hyperbranched polyglycerol (HPG), carboxymethyl hydroxypropyl guar (CMHPG), carboxymethyl cellulose (CMC), high strength molding compound (HMC), acrylamide, poly(acrylamide / acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid) (AMPS-AA-AM) and / or viscoelastic surfactant (VES). Viscosity agents may also be selected from the group consisting of plasticizers, surfactants, organic polymers, silica fillers, sodium chloride (NaCl), potassium chloride (KCl) or other inorganic salts, clay, modified coal and / or combinations thereof.

[0066] Plasticizers can be present in suspensions to improve processability and facilitate placement. In various embodiments, the term "plasticizer" refers to a material that increases flowability. Suitable plasticizers may include, but are not limited to, polycarboxylic ether plasticizers, phthalate plasticizers, terephthalate plasticizers, sulfonamide plasticizers, benzoate plasticizers, phosphate plasticizers, or combinations thereof.

[0067] In some embodiments, the content of plasticizer in the pumpable suspension should be sufficient to provide the required processability to the pumpable suspension. Based on the total weight of the pumpable suspension, the plasticizer may be present in the pumpable suspension in an amount of at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, the plasticizer may be present in the pumpable suspension in an amount not exceeding 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, the plasticizer may be present in the pumpable suspension in an amount of about 1 wt.% to about 20 wt.%, about 5 wt.% to about 15 wt.%, or about 7 wt.% to about 13 wt.%.

[0068] Surfactants can be present in pumpable suspensions to improve their surface properties. Suitable surfactants may include, but are not limited to, nonionic surfactants, anionic surfactants, cationic surfactants, zwitterionic surfactants, or combinations thereof.

[0069] Suitable nonionic surfactants may include, but are not limited to, alkoxylates (for example, alkoxylated nonylphenol condensate, such as poly(oxy-1,2-ethylenedimethyl)).2-ethanediyl), α-(4-nonylphenyl)-ω-hydroxy-branched, alkylphenol, ethoxylated alkyl amine, ethoxylated oleate, tall oil, ethoxylated fatty acid, alkyl polyglycoside, sorbitan ester, methyl glucoside ester, amine ethoxylate, diamine ethoxylate, polyglycerol ester, alkyl ethoxylate, polypropoxylated and / or polyethoxylated alcohol, linear alcohol alkoxylate, dodecylbenzene sulfonic acid salt derivative, linear nonylphenol nonyl-phenol), dioxane, ethylene oxide, polyethylene glycol, ethoxylated castor oil, polyoxyethylene nonyl phenyl ether, tetraethylene glycol dodecyl ether, ethylene oxide, decylamine oxide, dodecylamine oxide, alkylamine oxide, ethoxylated amide, alkoxylated fatty acid, alkoxylated alcohol (for example,Lauryl alcohol ethoxylate, ethoxylated nonyl phenol, ethoxylated fatty amine, ethoxylated alkyl amine (for example, cocoalkylamine ethoxylate), and any derivatives thereof, and any combination thereof. As used herein, the term "derivative" means any compound made from an identified compound, for example, by replacing one atom or group of atoms in a listed compound with another atom or group of atoms, or by rearranging two or more atoms in a listed compound.

[0070] Suitable anionic surfactants may include, but are not limited to, methyl ester sulfonate, hydrolyzed keratin, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, alkyl ether sulfate, sodium 4-(1'-heptylnonyl)benzenesulfonate, sodium dioctyl sulphosuccinate, sodium octyl benzenesulfonate, sodium hexadecyl sulfate, sodium laureth sulfate, and quaternary ammonium compounds (for example,Trimethylcocoammonium chloride, trimethyltallowammonium chloride, dimethyldicocoammonium chloride, etc.; cetylpyridinium chloride; alkyl ester sulfonate; alkyl ether sulfonate; alkyl ether sulfate; alkali metal alkyl sulfate; alkyl sulfonate; alkylaryl sulfonate; sulfosuccinate; alkyl disulfonate; alkylaryl disulfonate; alkyl disulfate; alcohol polypropoxylated sulfate; alcohol polyethoxylated sulfate; any derivative of the above, or any combination thereof.

[0071] Suitable zwitterionic surfactants may include, but are not limited to, alkyl amine oxide, alkyl betaine, alkyl arnidopropyl betaine, alkyl sulfobetaine, alkyl sultaine, dihydroxyl alkyl glycinate, alkyl ampho acetate, phospholipids, alkyl aminopropionic acid, alkyl imino monopropionic acid, alkyl imino dipropionic acid, dipalmitoyl-phosphatidylcholine, amine oxide, betaine, modified betaine, and alkylamidobetaine (e.g., cocoamidopropyl betaine). betaine), and any combination thereof.

[0072] In further examples, surfactants exhibiting viscoelasticity may include, but are not limited to, sulfosuccinate, taurate, amine oxide (for example, amidoamine oxide), ethoxylated amide, alkoxylated fatty acid, alkoxylated alcohol, ethoxylated fatty amine, ethoxylated alkyl amine, betaine, modified betaine, alkylamidobetaine, quaternary ammonium compound, alkyl sulfate, alkyl ether sulfate, alkyl sulfonate, ethoxylated ester, ethoxylated glycoside ester, alcohol ether, and any derivatives thereof, and any combination thereof.

[0073] In some embodiments, the surfactant may be present in a sufficient amount in the pumpable suspension to provide the desired surface properties to the pumpable suspension. Based on the total weight of the pumpable suspension, the surfactant may be present in the pumpable suspension in an amount of at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, the surfactant may be present in an amount not exceeding 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, the surfactant may be present in the pumpable suspension in an amount of about 1 wt.% to about 20 wt.%, about 5 wt.% to about 15 wt.%, or about 7 wt.% to about 13 wt.%.

[0074] Organic polymers can be present in pumpable suspensions to improve their properties. Suitable organic polymers may include, but are not limited to, natural compounds, synthetic compounds, or combinations thereof. Non-limiting examples of suitable natural compounds include polysaccharides, such as water-soluble polysaccharides and polysaccharide ethers, such as cellulose ethers, starch ethers (amylose and / or amylopectin and / or their derivatives), guar ethers dextrins, or combinations thereof. Non-limiting examples of suitable synthetic compounds include protective colloids, for example, one or more polyvinylpyrrolidones and / or polyvinylacetals, polyvinyl alcohols, melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, block copolymers of propylene oxide and ethylene oxide, styrene-maleic acid and / or vinyl ether-maleic acid.

[0075] In some embodiments, the organic polymer may be present in the pumpable suspension in an amount sufficient to provide the desired properties to the pumpable suspension. Based on the total weight of the pumpable suspension, the organic polymer may be present in the pumpable suspension in an amount of at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%. Alternatively, based on the total weight of the organic polymer, the organic polymer may be present in the pumpable suspension in an amount not exceeding 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, the organic polymer may be present in the pumpable suspension in an amount of about 1 wt.% to about 20 wt.%, about 5 wt.% to about 15 wt.%, or about 7 wt.% to about 13 wt.%.

[0076] When needed, silica fillers can be present in pumpable suspensions to improve their properties. Suitable silica fillers can be pyrogenic or precipitated finely-divided silica. Silica fillers can have particle sizes of about 50 Å to 10,000 Å, about 50 Å to about 400 Å, or about 100 Å to about 300 Å. Based on the total weight of the pumpable suspension, silica fillers can be present in the pumpable suspension at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%. Alternatively, based on the total weight of the silica filler, the silica filler may be present in the pumpable suspension in an amount not exceeding 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, or 10 wt.%. Alternatively, based on the total weight of the silica filler, the silica filler may be present in the pumpable suspension in an amount from about 1 wt.% to about 20 wt.%, from about 5 wt.% to about 15 wt.%, or from about 7 wt.% to about 13 wt.%.

[0077] Inorganic salts may be present in pumpable suspensions to improve their miscibility. Suitable inorganic salts include, but are not limited to, NaCl and KCl. Based on the total weight of the pumpable suspension, the inorganic salt may be present in the pumpable suspension at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, the inorganic salt may be present in the pumpable suspension at no more than 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, inorganic salts may be present in the pumpable suspension in amounts of about 1 wt.% to about 20 wt.%, about 5 wt.% to about 15 wt.%, or about 7 wt.% to about 13 wt.%.

[0078] Clay can be present in pumpable suspensions to alter their flowability. Suitable clays may include members of the smectite family, members of the palygorskite-sepiolite phyllosilicate family, members of the kaolinite-serpentine family, nontronite, bentonite, hectorite, attachpulgite, fluoromica, montmorillonite, beidellite, saponite, sepiolite, kaolinite, illite, and any of the above cation-exchange versions, or combinations thereof.

[0079] Among suitable bentonite families including nontronite, montmorillonite, saponite, hectorite, and beidellite, other suitable bentonite families used in the hydrous expandable clay of this application may include, but are not limited to, aliettite, ferrosaponite, sauconite, stevensite, swinefordite, volkonskoite, yakhontovite, and any combination thereof. Suitable palygorskite-sepiolite silicate groups may include, but are not limited to, attapulgite, tuperssautsiaite, windhoekite, yofortierite, falcondoite, ferrisepiolite, loughlinite, and any combination thereof. Suitable kaolinite-serpentine groups of hydrous expansive clays include, but are not limited to, kaolinite, greenalite, frapontite, halloysite, dickite, lizardite, manandonite, nacrite, cronstedtite, clinochrysotile, and clinochrysotile. hrysotile, nepouite, odinite, webskyite, pecoraite, orthochrysotile, parachrysotile, caryopilite, brindleyite, berthierine, amesite, antigorite, baumite, and any combination thereof.

[0080] In some embodiments, clay may be present in a sufficient amount to provide the desired properties to the pumpable suspension. Based on the total weight of the pumpable suspension, clay may be present in the pumpable suspension in an amount of at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, clay may be present in the pumpable suspension in an amount not exceeding 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, or 10 wt.%. Alternatively, based on the total weight of the pumpable suspension, clay may be present in the pumpable suspension in an amount of about 1 wt.% to about 20 wt.%, about 5 wt.% to about 15 wt.%, or about 7 wt.% to about 13 wt.%.

[0081] When the material comprises coal or other carbonaceous particles, it is conceivable to perform surface modification treatments on the particles, introducing one or more polar groups into the carbon structure / scaffold. As will be appreciated, such modification can be achieved by combining the coal particles with a polymer containing polar groups (e.g., using polyacrylic acid or polyvinyl alcohol in a polymer wrapping process), and more preferably by directly introducing polar groups into the coal particles. Most typically, this direct introduction will include an oxidation process that can be thermally driven, or an oxidation process that can use one or more strong oxidizing acids and / or other oxidants. In other embodiments, the direct introduction of polar groups can also be achieved using electrochemical processes or plasma gas exposure. Such polar groups can facilitate bonding with the polar groups of the casing and the polymer.

[0082] Therefore, more generally speaking, when using a viscosity modifier, based on the total weight percentage (wt.%) of the pumpable suspension, it can be assumed that the amount of viscosity modifier present in the pumpable suspension is typically at least 0.01 wt.%, at least 1 wt.%, at least 5 wt.%, at least 10 wt.%, at least 20 wt.%, at least 30 wt.%, at least 40 wt.%, at least 50 wt.%, or even higher. Thus, the viscosity modifier content range can be between 0.01 wt.% and 0.1 wt.%, or between 0.1 wt.% and 1 wt.%, or between 1 wt.% and 5 wt.%, or between 5 wt.% and 10 wt.%, or between 10 wt.% and 20 wt.%, or between 20 wt.% and 30 wt.%, or between 30 wt.% and 40 wt.%, or between 20 wt.% and 40 wt.%, or even higher.

[0083] In short, a high apparent viscosity carrier fluid is envisioned to have a composition comprising additives and / or viscosity modifiers that effectively suspend multiple TRE particles until the viscosity of the carrier fluid decreases due to an in-situ triggered event (e.g., changes in chemical reactivity, pH, temperature, or time). In response to the decrease in viscosity, the TRE particles can begin to settle and form a settled particle sheath within the annular space of the wellbore. For specific TRE particles that can be used to form a high thermal conductivity (k) settled particle sheath and thus a compacted particle sheath, TRE particles are generally envisioned to include a variety of, but not limited to, graphite, sand, diamond, silver, gold, rhodium, palladium, titanium, carbon fiber, carbon black, Hastelloy, quartz silica, carbon nanotubes, graphene, boron nitride, brass, brass alloys, chromium-nickel steel, carbon steel, stainless steel, and transition metals (e.g., copper, cadmium, cobalt, gold, silver, iridium, iron, molybdenum). The high thermal conductivity material can be selected from the group consisting of graphite powder, flake graphite, sheet graphite, pyrolytic graphite, desulfurized petroleum coke, graphene, fly ash, copper powder, aluminum nitride, aluminum oxide, alumina, silicon dioxide, silicon carbide, and combinations thereof. Furthermore, the particles can also include carbon-based inorganic materials, metals, metal oxides, metal nitrides, alloys and / or mixtures thereof, and in some embodiments, oxides and nitrides of transition metals and later transition metals (e.g., lead, tin), late transition metal alloys (e.g., lead alloys, tin alloys), alkaline earth metal alloys (e.g., beryllium alloys, magnesium alloys), oxides and nitrides of transition metals and late transition metals, ceramic composites containing silicon and / or aluminum, or combinations thereof. In some embodiments, the high thermal conductivity material can be selected from the group consisting of graphite powder, flake graphite, sheet graphite, pyrolytic graphite, desulfurized petroleum coke, graphene, fly ash, copper powder, aluminum nitride, alumina, silicon dioxide, silicon carbide, and combinations thereof. Additionally, the particles can also include carbon-based inorganic materials, metals, metal oxides, metal nitrides, alloys and / or mixtures thereof, and in some embodiments, the TRE particles include at least two chemically different materials selected from the group listed above. However, it is preferred that any thermally conductive filler or active material known in the art can be used for the envisioned pumpable suspension. Similarly, the TRE particles envisioned for use herein may have a thermal conductivity of at least 1.5 W / mK, at least 5 W / mK, at least 10 W / mK, at least 30 W / mK, at least 50 W / mK, at least 100 W / mK, at least 250 W / mK, at least 300 W / mK, or at least 400 W / mK.

[0084] Typically, the shape of TRE particles can include, but is not limited to, flakes, spheres, irregular shapes, cubes, rods, discs, prisms, needles, tubes, fibers, angular shapes, subangular shapes, circles, subrounded shapes, dumbbell shapes, and star shapes. When needed, the first and second portions of a plurality of particles may have shapes selected from the groups listed above. Additionally, the shapes of the first and second portions may differ. In some embodiments, to improve compaction, the first portions of a plurality of TRE particles have a composition and shape that allows the mass of the first particle to elastically and plastically deform under compressive load, and wherein the second portions of a plurality of particles have a composition and shape that allows the mass of the second particle to elastically deform only under compressive load.

[0085] Advantageously, the TRE particle network from the settled particle sheath and the optional TRE structure can have a thermal conductivity of at least 2, 3, 5, 10, or 20 times that of the rock stratum in which the Heat Reach Enhancement (TRE) system is located. For example, in the most typical example, the thermal conductivity of the rock stratum can be between 0.5 W / mK and 5 W / mK. Therefore, the envisioned TRE structure and the settled particle sheath network can have a thermal conductivity of at least 4 W / mK, or at least 6 W / mK, at least 8 W / mK, at least 10 W / mK, at least 15 W / mK, at least 20 W / mK, at least 30 W / mK, at least 40 W / mK, at least 50 W / mK, at least 60 W / mK, at least 70 W / mK, or even higher. For example, the envisioned network of high thermal conductivity particles with a TRE structure and / or a settled particle sheath could have thermal conductivity between 5 W / mK and 20 W / mK, or between 10 W / mK and 30 W / mK, 25 W / mK and 50 W / mK, or 40 W / mK and 75 W / mK. In other words, to improve heat transfer from the hot formation to the working fluid in the casing, the settled and / or compacted sheath should not act as a thermal insulator, but rather provide an effective conduit for heat energy from the formation and / or the TRE structure. The importance of thermal conductivity in the sheath can be further seen from the results in Figure 3.

[0086] In various embodiments, the number of particles required to achieve the desired thermal conductivity within the settling and / or compaction of the particle sheath may vary depending on the type and / or size of the particles. As will be readily understood, the particles may have an average D50 particle size of 0.05 μm to 5.0 mm. Furthermore, the particles may be in the form of a plurality of particles having a wide or narrow particle size distribution. Suitable sizes for high thermal conductivity particles include a maximum size between about 10 nanometers (nm) and 50 nm, or between 50 mm and 250 nm, or between 250 mm and 1,000 nm, or between 1 μm and 20 μm, or between 20 μm and 200 μm, or between 200 μm and 750 μm, or between 750 μm and 2,000 μm, or even larger. Furthermore, the first high thermal conductivity particle preferably has a relatively wide particle size distribution. Therefore, it is envisioned that high thermal conductivity particles may have a particle size distribution spanning at least 2.0 log units, or at least 2.5 log units, or even wider. Nevertheless, multiple TRE particles may have dimensions that allow the TRE particles to settle at least 1 m within 24 hours after reducing the viscosity of the high apparent viscosity carrier liquid. The time required for the formation of the TRE settling particle sheath may vary depending on the resulting porosity. For example, a sufficient settling time may be at least 12 hours, at least 24 hours, at least 36 hours, at least 48 hours, at least 72 hours, or at least 120 hours. Regardless of the required time, it is preferred that the settling particle sheath has a final porosity equal to or less than 80%.

[0087] As shown in Figure 1, after the settling particle sheath 100 is formed, it can be consolidated in various ways to improve heat transfer, forming a compacted TRE sheath. The settling particle sheath 110 can be consolidated using suction consolidation, the settling particle sheath 120 using effective stress consolidation, the settling particle sheath 130 using hydraulic consolidation, or the settling particle sheath 140 using pressure-driven hydraulic consolidation. Hydraulic consolidation can be used by draining and / or pumping the high apparent viscosity carrier liquid of the suspension from the settling particle sheath. In some embodiments, chemical consolidation is performed by applying an effective stress of at least 10 psi, at least 15 psi, or at least 20 psi to the settling particle sheath. This effective stress is applied by the solid above a given depth in the same way as when a formation is buried underground or pressure is applied above a solid column, provided that an impermeable or semi-impermeable layer exists above the solid column to convert pressure into effective stress.

[0088] The consolidation effect is further shown in Figure 2. After the pumpable suspension is placed into the annular space between casing 201 and formation 205, the particles remain suspended at the end of placement 200. Then, the suspension is broken up 210, allowing sufficient time for the particles to settle 215 in the annular space between casing 211 and formation 220. Finally, there is a consolidation step 230 through hydraulic and / or chemical consolidation, wherein an increase in effective stress is applied, thereby forming a final compacted TRE particle sheath 235 between casing 231 and formation 240 at the end of consolidation.

[0089] Therefore, after some form of consolidation of the settled particle sheath, the resulting compacted TRE sheath will have a permeability equal to or less than 0.01 Darcy. However, the permeability of the compacted TRE sheath can be equal to or less than 2 Darcy, or equal to or less than 5 Darcy, or equal to or less than 10 Darcy. From another perspective, after enhanced consolidation, the final porosity of the resulting compacted TRE sheath can be between 45% and 55%, or between 50% and 60%, or between 60% and 70%, or between 65% and 75%, or between 70% and 80%.

[0090] Regarding thermal conductivity, it is preferable to solidify the settled particle sheath to form a compacted sheath, the thermal conductivity of which is at least 1.5 W / mK, at least 3 W / mK, or at least 5 W / mK, or at least 10 W / mK, or at least 20 W / mK, or at least 50 W / mK, or at least 100 W / mK, or at least 200 W / mK, or at least 400 W / mK. Alternatively, the resulting high thermal conductivity compacted sheath may have a thermal conductivity between 1.5 W / mK and 25 W / mK, or between 20 W / mK and 50 W / mK, or between 40 W / mK and 100 W / mK, or between 50 W / mK and 200 W / mK and 100 W / mK, or between 150 W / mK and 300 W / mK. In some embodiments, the compacted sheath comprises two different types of thermally conductive particles. However, regardless of the thermal conductivity of the obtained compacted sleeve, it is assumed that high thermal conductivity sleeves generally have higher thermal conductivity than settled particle sleeves.

[0091] To control the thermal conductivity of the resulting compacted particle sheath, the amount of TRE particles present in the pumpable suspension can be adjusted to provide the desired thermal conductivity. For example, based on the total volume of the pumpable suspension, a plurality of particles may be present in the pumpable suspension in amounts of at least 1 vol%, at least 10 vol%, at least 20 vol%, at least 30 vol%, at least 40 vol%, at least 50 vol%, at least 60 vol%, at least 70 vol%, at least 75 vol%, at least 89 vol%, at least 90 vol%, at least 91 vol%, at least 92 vol%, at least 93 vol%, at least 94 vol%, at least 95 vol%, at least 96 vol%, at least 97 vol%, at least 98 vol%, or at least 99 vol%, or even higher. Alternatively, based on the total volume of the pumpable suspension, a plurality of TRE particles may be present in the pumpable suspension in amounts between about 1 vol% and about 99 vol%, between about 5 vol% and about 99 vol%, between about 40 vol% and about 99 vol%, or between about 80 vol% and about 99 vol%.

[0092] When implementing a TRE structure, the compacted TRE sheath may include a high thermal conductivity material, which can be distinguished from the high thermal conductivity material of the proximal end of the TRE structure flush with the annular space of the wellbore. On one hand, the compacted TRE sheath can be thermally coupled to the collector casing. On the other hand, the compacted TRE sheath is preferably thermally coupled to the high thermal conductivity material of the TRE structure and, optionally, the high thermal conductivity material of a second TRE structure. In many embodiments, the high thermal conductivity compacted sheath extends substantially vertically along a vertical length of at least 5%, at least 10%, at least 20%, at least 40%, at least 70%, or at least 85% of the target location in multiple segments. In such embodiments, each segment of the compacted sheath may have a height of at least 3m, at least 5m, at least 10m, at least 25m, at least 50m, at least 100m, at least 200m, at least 300m, at least 400m, or at least 500m. Therefore, the compacted multi-segment sheath can have a total length of at least 50m, or at least 100m, or at least 200m, or at least 500m, or at least 750m, or at least 1,000m, or at least 2,000m, or at least 3,000m, or at least 4,000m, and each compacted sheath includes 2 to 5 sheath segments, or 5 to 10 sheath segments, or 10 to 50 sheath segments, or even more.

[0093] Advantageously, the thermal conductivity of the TRE particle network formed by the compacted particle sheath and the previously discussed TRE structure can be at least 2, 3, 5, 10, or 20 times that of the thermal conductivity of the rock stratum containing the reinforcing structure. For example, the thermal conductivity of the rock stratum can be between 0.5 W / mK and 5 W / mK in the most typical example, between 5 W / mK and 7 W / mK in some examples, and between 7 W / mK and 10 W / mK in others. Therefore, the envisioned TRE structure and the compacted TRE sheath network can have a thermal conductivity of at least 4 W / mK, or at least 6 W / mK, at least 8 W / mK, at least 10 W / mK, at least 15 W / mK, at least 20 W / mK, at least 30 W / mK, at least 40 W / mK, at least 50 W / mK, at least 60 W / mK, at least 70 W / mK, or even higher. For example, a proposed network of high thermal conductivity particles with a TRE structure and / or a compacted particle sheath may have thermal conductivity ranging from 5 W / mK to 20 W / mK, or 10 W / mK to 30 W / mK, 25 W / mK to 50 W / mK, 40 W / mK to 75 W / mK, etc. In this document, it is generally preferred that the thermal conductivity of the TRE structure and the compacted particle sheath in the formation be relatively closely matched to obtain long-term power generation. For example, the thermal conductivity of the TRE structure and the compacted TRE particle sheath may differ by no more than 50%, or no more than 30%, or no more than 20%, or no more than 10%, or no more than 5%, or be the same. Furthermore, it is generally preferred that, in the event of a thermal conductivity deviation, the thermal conductivity of the compacted TRE particle sheath is greater than that of the TRE structure. From different perspectives, the compacted sheath typically has a thermal conductivity that is the same as or differs from that of the TRE structure to which it is thermally coupled by no more than 10%, 20%, 30%, 40%, or 50%.

[0094] The term "compaction" as used herein means that the settling and consolidation steps have been completed. For example, a compacted granular sheath has (a) a moisture content reduction of at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, or 99 wt.%, compared to a settling granular sheath before consolidation; (b) a density increase of at least 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, wt.%, 100 wt.%, or more, compared to a settling granular sheath before consolidation; or (c) (a) a decrease in moisture content and (b) an increase in density.

[0095] Various configurations, systems, methods, and ideas for installing a thermally conductive sheath are applicable hereof, and particularly envisioned configurations, systems, methods, and ideas are disclosed in the concurrently filed international patent application, "Systems and Methods to Place a Thermally Conductive Sheath in a Geothermal Well," the entire contents of which are incorporated herein by reference.

[0096] [All aspects] []

[0097] This application will be better understood by reading the following numbered aspects, which should not be confused with the claims. In some cases, each aspect described below may be combined with other aspects, including those described elsewhere in this application or those from the examples below, without departing from the spirit of this application.

[0098] 1. A pumpable suspension comprising: a mixture including a suspended thermal reach enhancement (TRE) solid and a high apparent viscosity carrier liquid; wherein the TRE solid exists in the form of a plurality of TRE particles, and the high apparent viscosity carrier liquid suspends the particles throughout the liquid; wherein the high apparent viscosity carrier liquid has a composition that allows an additive or a triggering event to in situ alter the physical and / or chemical properties of the mixture, thereby reducing viscosity and allowing the particles to settle by gravity at a target location to form a settling particle sheath; and wherein the TRE particles have a composition that allows the settling particle sheath to consolidate to form a highly thermally conductive compacted sheath within the annular space of the wellbore.

[0099] 2. The suspension as described in aspect 1, wherein the consolidation includes hydraulic consolidation and / or chemical consolidation.

[0100] 3. The suspension as described in any of the foregoing aspects, wherein the TRE particles comprise materials selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy, and optionally, wherein the TRE particles comprise at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy.

[0101] 4. The suspension as described in any of the foregoing aspects, wherein the compacted sheath has a thermal conductivity greater than 1.5 W / mK.

[0102] 5. The suspension as described in any of the foregoing aspects, wherein the shape of the TRE particles is selected from the group consisting of flakes, sheets, spheres, irregular shapes, cubes, rods, discs, prisms, needles, tubes, fibers, angular shapes, subangular shapes, circles, subrounded shapes, dumbbell shapes, and stars.

[0103] 6. The suspension as described in any of the foregoing aspects, wherein a first portion and a second portion of the TRE particles have a shape selected from the group consisting of flakes, plates, spheres, irregular shapes, cubes, rods, discs, prisms, needles, tubes, fibers, polygonal shapes, semi-angular shapes, circles, sub-circular shapes, dumbbell shapes, and stars, and wherein the first portion and the second portion have different shapes.

[0104] 7. The suspension as described in any of the foregoing aspects, wherein a first portion of the TRE particles has a composition and shape that allows the mass of the first particle to elastically and plastically deform under compressive load, and wherein a second portion of the TRE particles has a composition and shape that allows the mass of the second particle to elastically deform only under compressive load.

[0105] 8. The suspension as described in any of the foregoing aspects, wherein the D50 particle size of the TRE particles is between 0.05 micrometers (μm) and 5.0 millimeters (mm).

[0106] 9. The suspension as described in any of the foregoing aspects, wherein the TRE particles constitute between 30% and 70% of the total suspension by volume.

[0107] 10. The suspension as described in any of the foregoing aspects, wherein the high apparent viscosity carrier liquid comprises a certain amount of water.

[0108] 11. The suspension as described in aspect 10, wherein the high apparent viscosity carrier liquid comprises a water-soluble biopolymer, a water-soluble derived biopolymer, a water-soluble gel, a water-soluble cellulose, a water-soluble synthetic polymer, or a surfactant, and optionally, wherein the gel, the cellulose, the polymer, or the biopolymer in the carrier liquid forms a network, crosslinks, or forms a supramolecular structure.

[0109] 12. The suspension as described in aspect 11, wherein the gel, the cellulose, the polymer or the biopolymer is combined with the TRE particles to form a suspended particle, a particle-filled network, a cross-linked particle-filled polymer network or a particle-filled supramolecular structure.

[0110] 13. The suspension as described in aspect 10, wherein the high apparent viscosity carrier liquid comprises a viscosity agent selected from guar gum, polysaccharides (starch, guar, cellulose, cellulose derivatives, alginate, carrageenan or locust gum), saffron gum, hydroxylethyl cellulose (HEC), carboxymethyl guar (CMG), carboxymethyl hydroxylethyl cellulose (CMHEC), hyperbranched polyglycerol (HPG), carboxymethyl hydroxypropyl guar (CMHPG), carboxymethyl cellulose (CMC), high strength molding compound (HMC), acrylamide, poly(acrylamide / acrylic acid / ... The group consisting of 2-acrylamide-2-methylpropanesulfonic acid (AMPS-AA-AM) and viscoelastic surfactant (VES).

[0111] 14. The suspension as described in aspect 13, wherein the amount of the viscosity-enhancing agent is from 0.01 wt.% to 20 wt.% of the pumpable suspension.

[0112] 15. The suspension as described in any of the foregoing aspects, wherein the high apparent viscosity carrier liquid has a composition that allows for viscosity reduction by additives selected from oxidants, bio-based enzymes, bacteria, and pH modifiers, or a composition that allows for apparent viscosity reduction by shear force or temperature changes.

[0113] 16. The suspension as described in any of the foregoing aspects, wherein the triggering event is a change in pH, temperature, or time.

[0114] 17. The suspension as described in any of the foregoing aspects, wherein the additive accounts for 0.001 wt.% to 10 wt.% of the total suspension by weight percentage (wt.%).

[0115] 18. The suspension as described in any of the foregoing aspects, wherein the additive alters the temperature stability of the pumpable suspension.

[0116] 19. The suspension as described in any of the foregoing aspects, wherein the pumpable suspension optionally further includes a second additive that promotes the binding of the TRE particles with the viscosity-enhancing agent, thereby improving the mixing and dispersion of the TRE particles in the high apparent viscosity carrier liquid.

[0117] 20. The suspension as described in any of the foregoing aspects, wherein the pumpable suspension optionally further includes a second additive that optionally disrupts the polymer backbone or polymer-polymer crosslinks in response to the triggering event.

[0118] 21. The suspension as described in any of the foregoing aspects, wherein the pumpable suspension optionally further comprises a second additive that absorbs thermal energy to extend the usable temperature range of the particular polymer by 5°C to 50°C.

[0119] 22. The suspension as described in any of the foregoing aspects, wherein the additive is selected from the group consisting of a crosslinking agent additive, a dispersant additive, a fragmentation agent additive and a stabilizer additive.

[0120] 23. The suspension as described in aspect 22, wherein the crosslinking agent additive is aluminum, chromium, antimony, boron, titanium, or zirconium-based.

[0121] 24. The suspension as described in aspect 22, wherein the dispersant additive is a surfactant, polymer, salt, or pH modifier.

[0122] 25. The suspension as described in aspect 22, wherein the de-airing additive is polydimethylsiloxane, alcohol, stearate, ethylene glycol, surfactant, alkylphenol ethoxylate, silicone defoamer, mineral oil defoamer, vegetable oil defoamer, wax-based defoamer, polymer defoamer, or silicone-free defoamer.

[0123] 26. The suspension as described in aspect 22, wherein the fracturing agent additive is a pH adjuster, an oxidant, an enzyme, or bacteria.

[0124] 27. The suspension as described in aspect 22, wherein the stabilizer additive is an oxidant or a gel.

[0125] 28. The suspension as described in aspect 22, wherein the composition comprises at least two different additives.

[0126] 29. The suspension as described in any of the foregoing aspects, wherein the high apparent viscosity carrier liquid suspends the TRE particles until the apparent viscosity of the carrier liquid decreases due to an in-situ triggered event.

[0127] 30. The suspension as described in any of the foregoing aspects, wherein the high apparent viscosity carrier liquid has a dynamic viscosity of at least 5,000 centipoise (cP) before the triggering event and a dynamic viscosity of no more than 1,000 cP after the triggering event.

[0128] 31. The suspension as described in any of the foregoing aspects, wherein the TRE particles have a size such that the TRE particles settle a distance of at least 1 meter within 24 hours after the viscosity is reduced.

[0129] 32. The suspension as described in any of the foregoing aspects, wherein the thermal conductivity of the settling particle sheath is between about 1.5 W / mK and 400 W / mK.

[0130] 33. The suspension as described in any of the foregoing aspects, wherein the settling particle sheath has an ultimate porosity of 80% or less.

[0131] 34. The suspension as described in any of the foregoing aspects, wherein the sheath of the settled particles is solidified to have a permeability equal to or less than 0.01 Darcy.

[0132] 35. A system configured to transfer heat from a formation to a collector casing, the system comprising a collector casing disposed in a wellbore descending substantially vertically from a top position to a target position in a formation; a heat arrival enhancement (TRE) structure located at the target position, the TRE structure comprising a first high thermal conductivity material; wherein the TRE structure extends distally from the wellbore into the formation at the target position, and wherein the TRE structure has an opening at the wellbore; a high thermal conductivity compacted sheath comprising a plurality of sheath segments along a vertical length of the high thermal conductivity compacted sheath thermally coupled to (a) an outer surface of the casing and extending substantially vertically along a portion of the length of the target position in the annular space of the wellbore, and (b) the opening of the TRE structure, thereby forming a continuous heat transfer path from the target position through the TRE structure and the compacted sheath to the casing.

[0133] 36. The system as described in aspect 35, wherein the target location is at a depth between 150 meters and 20,000 meters.

[0134] 37. The system as described in any one of aspects 35 to 36, wherein the formation at the target location has a geostatic temperature between 120°C and 600°C.

[0135] 38. The system as described in any one of aspects 35 to 37, wherein the TRE structure comprises a plurality of particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy, and optionally, wherein the TRE structure comprises at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, zinc, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy.

[0136] 39. The system as described in any of aspects 35 to 38, wherein the TRE structure has a width that gradually decreases from the proximal end of the opening to the distal end.

[0137] 40. The system as described in any one of aspects 35 to 39, wherein the TRE structure extends longitudinally along the wellbore.

[0138] 41. The system as described in any one of aspects 35 to 40, wherein the TRE structure has a width between 1 millimeter (mm) and 100 mm.

[0139] 42. The system as described in any one of aspects 35 to 41, wherein the TRE structure extends longitudinally into the stratum at a distance of 1 meter to 200 meters.

[0140] 43. The system as described in any one of aspects 35 to 42, wherein the TRE structure has a bi-wing configuration.

[0141] 44. The system as described in any one of aspects 35 to 43, wherein the TRE structure has a thermal conductivity between 1.5 W / mK and 150 W / mK.

[0142] 45. The system as described in any one of aspects 35 to 44, wherein a first high thermal conductivity material at the proximal end of the TRE structure is flush with the annular space of the wellbore.

[0143] 46. ​​The system as described in any one of aspects 35 to 45 further includes a second TRE structure having a vertical offset between 10 meters and 100 meters from the TRE structure.

[0144] 47. The system as described in any one of aspects 35 to 46 further includes a second TRE structure having a radial offset between 15 degrees and 90 degrees from the TRE structure.

[0145] 48. The system as described in aspect 46 or 47, wherein the second TRE structure comprises at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hersted alloy.

[0146] 49. The system as described in any one of aspects 35 to 48, wherein the compacted sheath has a thermal conductivity between about 1.5 W / mK and 50 W / mK, or between about 30 W / mK and 400 W / mK.

[0147] 50. The system as described in any one of aspects 35 to 49, wherein each segment of the compacted sheath has a height between 3 meters and 500 meters.

[0148] 51. The system as described in any one of aspects 35 to 50, wherein the compacted sheath comprises two different types of thermally conductive particles.

[0149] 52. The system as described in any one of aspects 35 to 51, wherein the compaction sheath extends substantially vertically between 10% and 70% of the target location.

[0150] 53. The system as described in any one of aspects 35 to 52, wherein the thermal conductivity of the compacted sheath is equal to or differs from no more than 50% of the thermal conductivity of the TRE structure.

[0151] 54. The system as described in any one of aspects 35 to 53, wherein the thermal conductivity of the compacted sheath is equal to or differs from the thermal conductivity of the TRE structure by no more than 30%.

[0152] 55. The system as described in any one of aspects 35 to 54, wherein the thermal conductivity of the compacted sheath is equal to or differs from the thermal conductivity of the TRE structure by no more than 10%, or both have the same thermal conductivity.

[0153] 56. A system configured to transfer heat from a formation to a collector casing, the system comprising a collector casing disposed in a wellbore descending substantially vertically from a top position to a target position in a formation; a high thermal conductivity compacted sheath comprising a plurality of sheath segments along a vertical length of the high thermal conductivity compacted sheath thermally coupled to (a) an outer surface of the casing and extending substantially vertically along a portion of the length of the target position in the annular space of the wellbore, and (b) the target position in the formation, thereby forming a continuous heat transfer path from the target position through the high thermal conductivity compacted sheath to the casing.

[0154] 57. The system as described in aspect 56, wherein the target location is at a depth between 150 meters and 20,000 meters.

[0155] 58. The system as described in any of aspects 56 to 57, wherein the formation at the target location has a geostatic temperature between 120°C and 600°C.

[0156] 59. The system as described in any one of aspects 56 to 58, wherein the compacted sheath has a thermal conductivity between about 1.5 W / mK and 50 W / mK, or between about 30 W / mK and 400 W / mK.

[0157] 60. The system as described in any one of aspects 56 to 59, wherein each segment of the compacted sheath has a height between 3 meters and 500 meters.

[0158] 61. The system as described in any one of aspects 56 to 60, wherein the compacted sheath comprises two different types of thermally conductive particles.

[0159] 62. The system as described in any one of aspects 56 to 61, wherein the compaction sheath extends substantially vertically between 10% and 70% of the target location.

[0160] In some embodiments, the figures used to describe and claim certain embodiments of the present application representing the amount or properties of the composition (e.g., concentration, reaction conditions, etc.) should be understood to be modified in some cases by the term "about". As used herein, the terms "about" and "approximately" when referring to specific, measurable values ​​(e.g., parameters, amounts, durations, etc.) are intended to cover specific values ​​and variations, such as variations of + / -10% or less, or + / -5% or less, or + / -1% or less, or + / -0.1% or less, provided that such variations are suitable for performance in the disclosed embodiments. Thus, the values ​​referred to by the modifiers "about" or "approximately" are also specifically disclosed themselves. The description of multiple numerical ranges herein is intended only as a shorthand method for individually referring to each individual value falling within that range. Unless otherwise stated herein, each individual value is included in the specification as if individually referenced herein.

[0161] All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise obviously contradicted by the context. The use of any and all examples or exemplary language (e.g., "such as") provided with respect to certain embodiments herein is intended only to better illustrate the application and does not constitute a limitation on the scope of the claims. No language in the specification should be construed as indicating any unclaimed element necessary for the practice of the invention.

[0162] As used herein and in the claims of the appended patent applications, the terms "a," "an," and "the" include plural references unless the context clearly indicates otherwise. Furthermore, as used herein, "in" includes both "in" and "on," unless the context clearly indicates otherwise. As used herein, unless the context specifies otherwise, the term "coupled to" is intended to include both direct coupling (where two mutually coupled elements are in contact with each other) and indirect coupling (where at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with" are used synonymously.

[0163] It will be apparent to those skilled in the art that further modifications may be made beyond those already described without departing from the inventive concept of this document. Therefore, the subject matter of this invention is not limited to the scope of the claims. Furthermore, in interpreting the specification and claims, all terms should be interpreted in the broadest manner consistent with the context. Specifically, the terms "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced element, component, or step may be present, utilized, or combined with other elements, components, or steps not explicitly referenced. When the specification or claims refer to at least one selection from a combination of A, B, C… and N, the text should be interpreted as requiring only one element from that combination, rather than A plus N or B plus N, etc.

[0164] 100: Forms a protective sheath for settled particles 110: Use suction consolidation to consolidate the sheath of settled particles. 120: Use effective stress consolidation to consolidate the sheath of settled particles. 130: Use hydraulic consolidation to consolidate the sheath of settled particles 140: Using pressure-driven hydraulic consolidation to consolidate settled particle sheaths 200: Particles remain in suspension 201,211,231: Sleeve 205, 220, 240: Strata 210: The suspension was disrupted. 215: Allow sufficient time for the particles to settle. 230: Consolidation Steps 235: Compacted TRE Particle Sheath

Claims

1. A pumpable suspension comprising: A mixture comprising a suspended thermal reach enhancement (TRE) solid and a high apparent viscosity carrier liquid; wherein the TRE solid exists in the form of a plurality of TRE particles, and the high apparent viscosity carrier liquid suspends the particles in the entire liquid; wherein the high apparent viscosity carrier liquid has a composition that allows an additive or a triggering event to in situ alter the physical and / or chemical properties of the mixture, thereby reducing viscosity and allowing the particles to settle by gravity at a target location to form a settling particle sheath within an annular space of a wellbore; wherein the high apparent viscosity carrier liquid has a dynamic viscosity of 500 centipoise (cP) to 10,000 centipoise before the triggering event and a dynamic viscosity of 5 centipoise to 1,000 centipoise after the triggering event; The TRE particles have a composition that allows the settled particle sheath to solidify to form a highly thermally conductive compacted sheath within the annular space of the wellbore; and the highly thermally conductive compacted sheath has a thermal conductivity greater than 1.5 W / mK.

2. The suspension as described in claim 1, wherein, Consolidation includes the hydraulic and / or chemical consolidation of these TRE particles.

3. The suspension as described in claim 1, wherein, These TRE particles include materials selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, zinc, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy. Optionally, these TRE particles include at least two chemically distinct particles selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, zinc, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy.

4. The suspension as claimed in claim 1, wherein, The D50 particle size of these TRE particles is between 0.05 micrometers (μm) and 5.0 millimeters (mm) and / or between 10% and 75% of the total suspension volume.

5. The suspension as claimed in claim 1, wherein, The high apparent viscosity carrier liquid includes a certain amount of water and / or further includes a water-soluble biopolymer, a water-soluble derived biopolymer, a water-soluble gel, a water-soluble cellulose, a water-soluble synthetic polymer, or a surfactant. Optionally, the gel, the cellulose, the polymer, or the biopolymer in the carrier liquid forms a network, crosslinks, or forms a supramolecular structure.

6. The suspension as described in claim 1, wherein, The triggering event is a change in pH, temperature, or time, and / or the additive is selected from the group consisting of a crosslinking additive, a dispersant additive, a breaker additive, a de-airing additive, and a stabilizer additive.

7. The suspension as described in claim 1, wherein, The settled particle sheath has an ultimate porosity of 80% or less, and / or the settled particle sheath is consolidated to have a permeability of 0.01 Darcy or less.

8. A system configured to transfer heat from the ground to a collector jacket, comprising: A collector casing disposed in a wellbore that descends substantially vertically from a top position to a target location in a formation; a heat-reach enhancement (TRE) structure located at the target location, the TRE structure comprising a first high thermal conductivity material; wherein the first high thermal conductivity material has a thermal conductivity greater than 1.5 W / mK; wherein the TRE structure extends distally from the wellbore into the formation at the target location, and wherein the TRE structure has an opening at the wellbore; a non-bonded, high thermal conductivity compacted sheath comprising a plurality of sheath segments along a vertical length of the high thermal conductivity compacted sheath thermally coupled to (a) an outer surface of the casing and extending substantially vertically along a length of the target location in the annular space of the wellbore, and (b) the opening of the TRE structure, thereby forming a continuous heat transfer path from the target location through the TRE structure and the compacted sheath to the casing; Each of these sheath segments comprises a plurality of settled and consolidated TRE particles; and the non-cemented, highly thermally conductive compacted sheath has a thermal conductivity greater than 1.5 W / mK.

9. The system as described in claim 8, wherein, A first high thermal conductivity material at the proximal end of the TRE structure is flush with the annular space of the wellbore.

10. The system as described in claim 8, wherein, The thermal conductivity of the compacted sheath is equal to or differs from the thermal conductivity of the TRE structure by no more than 50%.

11. A system configured to transfer heat from a formation to a collector jacket, comprising: A collector casing is disposed in a wellbore that descends substantially vertically from a top position to a target location in a formation; a non-cemented, highly thermally conductive compacted sheath comprising a plurality of sheath segments along a vertical length of the sheath, the sheath being thermally coupled to (a) an outer surface of the casing and extending substantially vertically along a length of the target location in the annular space of the wellbore, and (b) the target location in the formation, thereby forming a continuous heat transfer path from the target location through the highly thermally conductive compacted sheath to the casing; wherein each of the sheath segments comprises a plurality of settled and consolidated heat arrival enhancement (TRE) particles; and wherein the non-cemented, highly thermally conductive compacted sheath has a thermal conductivity greater than 1.5 W / mK.

12. The system as described in claim 11, wherein, The compacted sheath has a thermal conductivity between approximately 1.5 W / mK and 50 W / mK.

13. The system as described in claim 11, wherein, These TRE particles are selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, zinc, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy. Optionally, these TRE particles include at least two types of particles with different chemical properties, selected from the group consisting of zinc, graphite, graphene, tungsten, aluminum, silicon carbide, aluminum nitride, silicon nitride, boron nitride, gold, copper, silver, diamond, aluminum alloy, alumina, rhodium, zinc, cobalt, copper alloy, nickel, iron, platinum, palladium, tin, steel, zirconium, titanium, carbon fiber, carbon black, and Hastelloy.

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