In-situ vitrification of hazardous waste

In-situ vitrification of hazardous waste occurs within human-made caverns. The human-made caverns may be located at distal (terminal) ends of substantially vertical wellbores and the human-made caverns may be located within deep geological rock formations, that are located at least two thousand feet below the Earth's surface. The hazardous waste that is vitrified into glass within such human-made caverns may be radioactive. The vitrification within a given human-made cavern is accomplished by at least one heater that operates according to a predetermined heating and cooling profile. During vitrification the heater may be reciprocated up and down to introduce currents into the waste liquid for uniform temperature dispersion. The heater may be removable, reusable, single use, and/or disposable. Cold caps and/or insulating blankets may be used over a given layer of vitrified waste product within the given human-made cavern. Heater weights, mixing vanes, and/or downhole sealing packer may also be used.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to in-situ vitrification of waste materials and more specifically to the in-situ vitrification of waste materials in human-made subterranean caverns and the subsequent containment, storage, and/or subsequent disposal of the vitrified materials and products within these human-made subterranean cavities located in deep (underground) geological formations.

COPYRIGHT AND TRADEMARK NOTICE

BACKGROUND OF THE INVENTION

In the United States and other countries across the globe, the nuclear weapons production industry has left a massive and devastating legacy when the nuclear reactors were decommissioned. For example, the nuclear weapons manufacturing processes have left behind about 53 million US gallons (or about 200,000 cubic meters) of high-level radioactive waste stored within 177 storage tanks. In addition, about 25,000,000 cubic feet (or about 710,000 cubic meters) of solid radioactive waste have been produced; as well as, a resulting contamination zones covering several square miles with contaminated groundwater beneath the sites. Much of this liquid waste has been leaking into the surrounding the earth (soils, rocks, formations, and strata) creating significant health, environmental, and economical problems. There is a tremendous safety and environmental need to store and/or dispose of such radioactive materials (wastes).

Radioactive waste is often generally categorized as high level waste (HLW) or low level waste (LLW).

In the past, it has been challenging, dangerous, and/or expensive to try to store radioactive and/or nuclear materials (such as radioactive/nuclear waste materials) in underground structures, except in some limited scenarios for those cases where solid quantities of material are stored in barrels, individual capsular containers, slurry material, open pits and also within shallow mines which are very close to the surface.

Many processes have been studied and implemented in different forms to dispose of, get rid of, and/or contain these dangerous waste materials. For example, “vitrification” has been tried in several countries.

Vitrification is a process in which a substance is transformed into a glass. Glass may be defined as a non-crystalline amorphous solid. Glass may also be defined in a broader sense to include solids that are amorphous in structure at the atomic scale and that exhibit a reversible change from a hard and relatively brittle state into a viscous or rubbery state when heated above a given melting temperature. This reversible change point may be defined as the “glass transition point.”

Vitrification is usually achieved by heating materials to a liquid state, then cooling the liquid, often rapidly, so that it passes through the glass transition point to form a glassy solid, i.e., a glass.

In practice, vitrification involves melting of waste materials with glass-forming additives, usually called “frit” so that the final vitreous product incorporates the waste contaminants macroscopically and microscopically. The vitrified glass material is usually referred to as “melt” during the glass-forming process. In the macroscopic form, the waste material may be considered encapsulated; while, in the microscopic form, the waste material forms an integral structural part of the glass material.

Glass has many physical and chemical properties and attributes that make it an ideal candidate for the reliable waste immobilization, for safe long-term storage, for transportation, and for consequent disposal of nuclear, radioactive, and/or hazardous waste materials. Glass is amorphous. It has been shown to be generally insensitive to the effects of radiation and radioactive decay. The finished glass material can chemically and physically incorporate many waste elements and products over wide composition ranges. The basic glass-making process has been practiced for millennia, it is relatively simple and offers a means for waste disposal in radioactive operations in which massive volumes of HLW and/or LLW need to be safely disposed of. The HLW that has to be disposed of, generally contains insufficient amount of glass precursors, such as, but not limited to, silicon, and as such, to produce a long lived glass product silica and/or other glass-forming materials may be added chemically and/or as a glass product called frit.

The vitrification process applied to nuclear waste is attractive, at least in part because it is flexible and/or it is applicable to a variety of radioactive elements that may be incorporated in the glass. In addition, the glass product is minimally leachable, resists corrosion, it is durable and the compactness, volume reduction and ease of handling of the waste form are all positive attributes. Natural analogues of vitrified products include silicate glasses found in the geologic record from volcanic glasses, these records have displayed minimal degradation processes over several million years.

Vitrification is a mature technology and has been used for HLW immobilization in many batch or continuous processes in limited volumes for more than 50 years in France, Germany, Belgium, Russia, UK (United Kingdom), India, Japan, and in the United States (US).

The prevailing concepts in vitrification of nuclear waste, focus on the long-held view currently exhibited by the major US companies disposing of nuclear waste. These US companies are spending an enormous of money, up to $37 billion (in US dollars) projected in 2019 to: (a) vitrify the waste in massive plants employing several thousand workers; (b) store the vitrified products in stainless steel containers; (c) transport the vitrified products to disposal locations; (d) entomb the vitrified containers in shallow salt formations; and (e) to then wait for mother nature to encapsulate the glass bearing containers to be subsumed by the salt encroachment over thousands of years of geologic time before leaching or surface contamination can occur via migration of radionuclides.

This current practice has essentially spent and continues to spend billions of dollars to merely “kick the can down the road” for future generations to deal with. The waste is contained (temporarily) but it has not been disposed of.

Today, there is a well felt need for a better and more complete solution to the HLW and LLW waste problem.

It is at least one objective of this inventive application to solve the containment and disposal problem as completely as possible.

To this end this patent application may combine at least some existing prior art elements, introduce additional novel concepts, and attains a level of disposal and containment that hitherto has not been achieved by providing an in-situ vitrification process deep in geological formations (e.g., rocks) from which no (waste) material can migrate over millions of years of geologic time.

There has not been any attempt to vitrify radioactive materials in-situ in very deep geologically located caverns as illustrated in the subject patent application because: (1) such caverns do not generally naturally exist in rock formations at very great depths; (2) it had been impossible to economically fabricate or produce large diameter caverns or to implement them in deep enough geological formations which are necessary to maintain a level of safety such that there would be no migration of radionuclides from the radioactive materials to the surface over geologic time; (3) the requisite technology to vitrify the waste material though available at the surface has only been tried in shallow surface pits and has not been extended to deep underground systems; and/or (4) the electrical power systems needed to transmit, control, and deliver sufficient electric power to deep downhole heaters had not been safely nor operationally perfected.

The process of vitrification may be simple in some respects, consider for example: (a) the given waste is dried, then heated to convert nitrates to oxides; (b) glass-forming additives or frit may added, as needed or desired, to the waste material and heated again to a given and predetermined melt temperature (e.g., around 1,000 degrees Celsius to around 1,500 degrees Celsius); (c) the now molten liquid is poured into a suitable containment vessel to cool and form the solid glass; and (d) the solidified vitreous product has incorporated the waste materials in its macro- and micro-structures, and the hazardous waste constituents are thus immobilized within the glass. For example, borosilicate and phosphate glasses are the two main types of glass frit currently used to immobilize nuclear waste (both of these materials can immobilize large amounts of radioactive products).

The ability to economically provide a human-made cavern, located within a deep geological formation, of sufficient size and volume, for efficient in-situ vitrification and also for safe disposal of substantial quantities of vitrified radioactive waste is completely feasible with embodiments of the inventions disclosed herein. What is required is more than just the ability to vitrify some small amounts of nuclear waste in a series of surface batch operations, there are real needs for the economic vitrification, disposal and storage of massive quantities of waste in the millions of gallons. To date (2020), the current best available technology at the Hanford site in the US contemplates an expensive, single, stand-alone vitrification unit. If that unit fails, the vitrification industry stops until a better solution is found.

The systems and/or methods that are proposed herein in this invention are different. Some embodiments contemplated may provide for a means to significantly multiply the application of the novel systems and/or methods by running multiple systems in parallel. Just like in the oil and gas industry where literally dozens of oil wells can be drilled by individual drilling rigs simultaneously to develop a given field, a plurality of vitrification systems can be implemented to provide up to fifty or more simultaneous in-situ vitrification operations at the same or different locations across a given country. This application may provide a measurable economy of scale to resolve this seemingly intractable problem of disposing of millions of gallons of waste.

At least some of the technical drivers that have allowed the embodiments of present invention herein to be implemented may be as follows: (a) drilling rig design features have improved; (b) increased hydraulic pressure availability downhole in the wellbore at the drill bit; (c) available drilling rig horsepower up to as much as 4,000 hydraulic horsepower; (d) available pump horsepower; (e) available drilling rig capacity up to 2,000,000 pounds of dead weight lift is available; and/or (f) high downhole drilling fluid pressures can be maintained. These may provide for the ease of implementation of deep human-made caverns for in-situ vitrification and for loading or disposing of waste products into such human-made caverns.

Specific technological improvements that pertain to the drilling of under-reaming operations and under-reaming equipment have allowed successful under-reaming needed to make and manage large diameter human-made caverns. At least some of these improvements may include: (a) hydraulically actuated reamer elements expandable and retractable with pump pressure and downhole RFID (radio frequency ID) triggering with injected RFID tags; (b) cutter arms movable upward and out simultaneously in the body; (c) fail-safe cutter arm retraction; (d) reverse actuating mechanism maintains that tool is open while drill string weight prohibits tool closure; (e) unrestricted fluid flow through internal diameters of the wellbore tubular goods; (f) roller cone cutters are specifically designed for the Drill Time Under-reamers and are consistent with downhole diameters; (g) reamer bodies machined from heat-treated steel bar, giving it exceptional strength; (h) jet nozzles near the cutters allow for cutter washing and cooling; and (i) a variety of cutting structures are available to facilitate the reaming process.

Additionally, the electric power and applied industries have developed and implemented improved, surface facilities, control mechanisms and power cables which deliver electric power efficiently and controllably to the downhole heater equipment. Power cables have significant improvements and are now capable of transmitting megawatts of power over several thousand feet in a wellbore environment regularly and safely without accident. These computerized systems can minimize power losses in transmission, maximize energy deliverability downhole, allow the types of temperature control needed to optimize the melt process and the annealing and cooling of the melt in the subterranean cavern during vitrification.

Today (2020), the understanding of vitrification processes and operational conditions have improved considerably. The compositions of the waste, the chemical and physical formulation of the frit and other physical descriptors have been studied by investigators across the globe. Additionally, the development and application of computational fluid dynamic (CFD) modelling platforms for vitrification simulation have provided insights into and preconditions necessary for an optimal vitrification process without the need for hundreds of time consuming and ineffective laboratory or small-scale experiments.

Though most physical vitrification test efforts have been on small scale experiments, it is generally accepted that larger batch operations can be more tolerant to compositional variations than small scale laboratory tests. The inventive systems taught in this application are for very large cavern-based waste systems in which several tons of waste are controllably vitrified in massive underground cylindrical cavern(s) with electrically powered heating controlled from the terrestrial surface.

Recapping at least some of the above discussion, some embodiments of the present invention may provide means, systems, mechanisms, and/or methods for the vitrification and/or disposal of nuclear/radioactive materials (waste) (and/or other hazardous waste) within human-made subterranean cavities (caverns) within deep geological formations in manners that may be safe (for humans and the environment), economically feasible, and efficient.

These and other advantages and features of the present invention are described herein with specificity so as to make the present invention understandable to one of ordinary skill in the art, both with respect to how to practice the present invention and how to make the present invention.

Turning now to a discussion of the prior art. The prior art related to this patent application has been developed in three primary technical areas of interest.

The first area is the thermal oil recovery systems that have been used in the heavy oil production industries and have been utilized to develop downhole heaters, long distance power cables to deliver electric power safely and efficiently downhole; and also the power generation and delivery systems which are implemented on the terrestrial surface.

The second area focuses on the vitrification process with emphasis on the glass form and melt systems which include chemical and mechanical design of the materials and compositions used in the glass processing systems. Specifically, in developing and optimizing the glass melt material to ensure correct melt behavior and lower energy costs. More than 30 vitrification processes have been documented by the IAEA (International Atomic Energy Agency) in the last 50 years.

The third area is related to historical environmental operations to vitrify contaminants in shallow soils and also in the surface pits or shallow wellbores, often less than 20 feet deep, and also in some applications in shallow holes used for support pilings in the building and construction industry.

Specifically, the prior art involves the thermal recovery of heavy oils in the oil industry, that have been utilized for more than 60 years. In these oil recovery processes, deep “heavy oil” reservoirs that contain viscous heavy crudes have been thermally stimulated by wellbore heaters which heat up the adjacent rock formations radially and vertically and make the viscous crude more mobile by decreasing crude viscosity. These recovery processes may range in depth from 500 feet to more than 4,000 feet deep from the terrestrial surface. In these systems, electric power cables to deliver the power, downhole in-wellbore heaters, downhole packers (seals) to control flow, and surface power delivery systems may be utilized installed. Safety systems have also been developed for the operations and installations that are capable of operating safely and that have been used for decades.

In addition to the thermal recovery methods in wellbores, another complimentary area of technology and investigation has been “rock welding.” This prior art process has been developed to facilitate the sealing of the vertical wellbores used for nuclear waste disposal. Operationally, the “rock welding” method involves the utilization of electrical downhole heaters to provide sufficient heat energy to melt several feet of the vertical wellbore zone at temperatures in excess of 800 degrees Celsius. The melted rock is allowed to cool forming a homogenous matrix within and with the native rock thus completely sealing the nuclear waste inside the bottom portions of the wellbore.

The second element is the glass melt composition, its formulation and its operating parameters. For centuries, glass making is a well-developed industry and the glassmaking operations are worldwide, massive, and provide a range of compositions of glass forming materials to meet many requirements in industry.

The compositions of glass forming additives, the temperatures of operations, the timing of the processes, and the time temperature profiles for annealing of the melt to meet required glass in products are well detailed in practice and have been used successfully for many years. Today (2020) many melt process operating parameters are developed by computational simulation models before they are implemented in the field. This minimizes costs and enhances the level of success of the projects. Furthermore, by incorporating Artificial Intelligence (AI) methodologies on the vast historical and evolving database of information on glass forming and vitrification, an AI driven “front end” approach may be employed to optimize the processing systems that may be used in the inventive means taught in this application.

The third area involves the utilization of surface and near surface vitrification processes to treat contaminated soils and hazardous chemicals to convert them to stable glass products. These operations resemble “open burning pit” processes for trash incineration, except the near surface vitrification system uses multiple high voltage electrical electrode arrays embedded in the soil material which when energized are capable of heating the soil to melting temperatures, e.g., often in excess of 2,000 degrees Celsius. As the waste material melt grows, power is maintained to offset heat losses from the surface and the surrounding soil region. The off gases produced create a problem which has been resolved usually by the use of a hood to collect and control off gas movement.

BRIEF SUMMARY OF THE INVENTION

To minimize the limitations in the prior art, and to minimize other limitations that will be apparent upon reading and understanding the present specification, the present invention may describe means, systems, mechanisms, and/or methods for the vitrification of waste materials, including nuclear and/or non-nuclear materials, into deep underground caverns, located within deep geological formations.

Briefly, the vitrification method in accordance with some embodiments of this invention may achieve at least some of the intended objectives by including the steps of: drilling a pilot wellbore which intersects a deep geologic formation; forming of a human-made cavern within that deep geological formation, using the pilot wellbore; implementing an electrically energizable heating system in the subject human-made cavern into which the waste products have been disposed, for subsequent vitrification. and while safely disposing of the off-gas products (from the vitrification) in subterranean formations, while allowing the melted waste to remain sequestered in the given human-made cavern for thousands of years, if so desired.

It is an objective of this inventive application to solve the containment and disposal problem of nuclear, radioactive, and/or hazardous wastes as completely as possible.

In light of the problems associated with the known methods of vitrifying waste (including in liquid/slurry format), it may be an objective of some embodiments of the present invention, to provide methods for the vitrification of nuclear waste and other (waste) material in human-made caverns which is safe, with very high volumetric capacity, that is cost-effective, that is easily deployable, and that may meet the regulatory requirements for safety and environmental protection.

It may be another objective of some embodiments of the present invention to provide methods of the types described herein wherein the vitrification processes may occur several thousand feet below the terrestrial surface away from potential contamination of the ecosphere.

It is an objective of the present invention to provide means, systems, mechanisms, and/or methods for the vitrification and/or disposal of nuclear/radioactive materials (waste) (and/or other hazardous waste) within human-made subterranean cavities (caverns) within deep geological formations in manners that may be safe (for humans and the environment), economically feasible, and efficient.

It is another objective of the present invention to provide systems and methods for in-situ vitrification of hazardous waste occurs within human-made caverns, wherein the human-made caverns are within deep geological rock formations, that are located at least two thousand feet below the Earth's surface.

It is another objective of the present invention to provide systems and methods for in-situ vitrification of hazardous waste occurs within human-made caverns, wherein heating to liquify the hazardous waste and its subsequent cooling to glass operates according to predetermined heating and cooling profiles.

It is another objective of the present invention to provide systems and methods for in-situ vitrification of hazardous waste occurs within human-made caverns, wherein heating to liquify the hazardous waste may occur in part by a heater that reciprocates up and down in the liquified hazardous waste to impart a uniform temperature to the liquified hazardous waste.

It is another objective of the present invention to provide systems and methods for in-situ vitrification of hazardous waste occurs within human-made caverns, wherein heating to liquify the hazardous waste may occur in part by a heater that with mixing vanes for imparting currents into the liquified hazardous waste that results a uniform temperature to the liquified hazardous waste.

It is another objective of the present invention to provide systems and methods for in-situ vitrification of hazardous waste occurs within human-made caverns, wherein the heaters may be removable, reusable, single use, and/or disposable.

It is another objective of the present invention to provide systems and methods for in-situ vitrification of hazardous waste occurs within human-made caverns, wherein cold caps and/or thermal insulating blankets may be used over a given layer of vitrified waste product within the given human-made cavern.

It is yet another objective of the present invention to provide systems and methods for in-situ vitrification of hazardous waste occurs within human-made caverns, wherein the human-made caverns are within deep geological rock formations, wherein a portion of the deep geological rock formations may be used as a reservoir for long-term storage/disposal of off-gas from the vitrified hazardous waste.

These and other advantages and features of the present invention are described herein with specificity so as to make the present invention understandable to one of ordinary skill in the art, both with respect to how to practice the present invention and how to make the present invention.

REFERENCE NUMERAL SCHEDULE

With regard to the reference numerals used, the following reference numerals are used throughout the various drawing figures.28workover oilfield rig2829well cellar2930cold cap3031avitrified soil31a31bvitrified soil and waste31b31cvitrified waste31c31dvitrified waste31d31ecooled solidified melt material31e32soil and melt interface3233soil3334off-gas3434aleading edge of off-gas migrating in formation34a34boff-gas accumulating at top of cavern34b34coff-gas volumes migrated into formation34c35electrode3536off-gas vent3637ground surface3738power cable3839wellbore3940melter4041melter support4142storage container for melt4243calciner system4343afeeder for waste material to calciner43a44melt in storage container4445melt outflow4550heater device5050aheater device centralizer50a51weight device below heater5152wellbore5252asteel casing52a53unheated underground formations5353aheated underground formations adjacent to heater53a53bboundary facies change between underground formations53b53cunheated underground formations53c(deep geological [rock] formation53)53dunheated “tight” underground formations53d54power supply5460human-made subterranean cavern6061top of human-made subterranean cavern6162melt and formation interface6263downhole sealing packer system6364heater vane/mixer6465direction of upward motion for heater6566direction of downward motion for heater6667mixing flow lines of melt67301insulation blanket material301200prior art vitrification process200201collect waste201203separate HLW and LLW products203205two stage vitrification205207calcination process207209one stage vitrification209211vitrification process211213simple POT vitrification process213215storage & disposal of vitrification process215500method of in-situ vitrification of waste in deep underground caverns500501step of preprocessing and modeling of/for the intended vitrification process501502step of forming wellbore and human-made cavern502503step of preparing the waste and frit503504step of installing downhole heater system504505step of introducing the waste mixture into human-made cavern505506step of installing cold cap above waste mixture506507step of installing the packer seal device in wellbore507508step of activating heating of the heater system508509step of melting the melt mixture509510step of venting off-gas to surrounding porous and permeable formation rock510511step of continued heating/melting per predetermined temperature-time profile511512step of reciprocating heater up and down within melt mixture512513step of removing heater from melt mixture while still liquid513514step of leaving the heater in place in melt mixture514515step of cooling melt mixture to a final temperature515516step of removing seal packer and power cable system516517step of making decision to re-run vitrification operations517518step of stopping operations518700heater systems700701heater701711heater energizer711713resistive energizer713715inductive energizer715717electromagnetic energizer717721heater architecture721723single element723725multiple elements725727stacked727729unstacked729731heater usage type731733single use heater733735reusable heater735737disposable heater737739non-disposable heater739

DETAILED DESCRIPTION OF THE INVENTION

As noted above, embodiments of the present invention may describe means, systems, mechanisms, and methods for the in-situ vitrification of nuclear, radioactive materials (waste) and/or other waste products within human-made subterranean cavities (caverns) within deep geological formations. In some embodiments, sequential operations of the vitrification process may be implemented (see e.g.,FIG. 3BthroughFIG. 3Dand seeFIG. 5).

In some embodiments, an operational method for nuclear waste disposal may be described. Such operational methods may provide more efficient methodology to allow safer, more economical, and long-lasting disposal of the nuclear waste in the deep underground human-made caverns as compared against prior art methods.

An existing consideration should be addressed for long-term nuclear waste disposal. That is the migration of radioactive material away from a given human-made cavern system, which in turn may contaminate ground water if not addressed. Some mechanisms are needed to minimize this possibility. A long-lived technology system is required to guarantee within scientific certainty that the nuclear waste can be contained adjacent to and within the human-made caverns zones. Vitrification is considered to be at least one such method to guarantee such desired containment.

In some embodiments, a means may be utilized that may provide for very long-lived protection from the migration of radioactive material away from the given human-made cavern.

In this patent application, the terms “radioactive material,” “radioactive waste,” “nuclear material,” “nuclear waste,” and “high-level nuclear waste” may be used interchangeably herein. In addition, the term “waste” generally means nuclear or radioactive waste of any kind. However, the embodiments described herein are not limited to radioactive waste, but may be applied to other forms of non-radioactive (hazardous) wastes.

In this patent application, the terms “cavern,” and “cavity” may be used interchangeably with a same meaning. Further, “cavern” or “cavity” as used herein may mean a cavern/cavity that may be human-made (e.g., via under reaming operations).

In this patent application, “formation,” “zone,” “rock,” and/or “rock medium” may be used interchangeably; and may refer to a rock structure within a deep geological formation (e.g., thousands of feet below the terrestrial surface) that may be hosting (housing) one or more human-made caverns.

In this patent application, the terms “well” and “wellbore” may be used interchangeably and may refer to cylindrical drilled out elements implemented in design and/or installation processes of some embodiments of the present invention. The term “wellbore packer,” “packer,” “wellbore seal,” and/or “HYDRIL,” may be used interchangeably to mean a sealing device or system to seal the internal bore of a given wellbore.

In this patent application, the terms “single well” or “common well” may refer to a wellbore that may be shared.

In this patent application, the term “ream” and “under-ream” may be used interchangeably to mean the enlarging of a wellbore or hole in a rock medium (wherein such continued enlargement may be used to form a given human-made cavern).

In this patent application, vitrified soil31a, vitrified soil and waste31b, vitrified waste31c, and/or vitrified waste31dmay refer to: waste products to be vitrified (e.g., immediately before vitrification), liquified products (liquified by vitrification), cooled solidified products, combinations thereof, and/or the like. The “a,” “b,” “c,” and “d” designations of reference numeral “31” may refer to that different materials may be the subject of vitrification processes. Vitrified waste31emay refer to cooled and substantially solidified vitrified waste31d. Additionally, “melt” may replace terminology of “vitrified soil,” “vitrified soil and waste,” “vitrified waste,” and/or “vitrified product.”

In this patent application, “vertical wellbores” need not be geometrically perfectly vertical (parallel) with respect to the Earth's gravitational field; but rather may be substantially (mostly) vertical (e.g., more vertical than horizontal with respect to Earth's terrestrial surface37).

FIG. 1Aillustrates a prior art technology that was developed in 1950s and is still operational today (2020) to allow the thermal recovery of heavy crude oils by heating the underground oil-bearing formations using a downhole heater system50. Shown inFIG. 1Ais a means whereby an underground formation53sometimes referred as a “pay” zone, saturated with high viscosity crude, may be heated via a downhole heater50. In these prior embodiments, massive amounts of heat energy may be delivered to a rock formation53afrom terrestrial surface37to decrease oil viscosity by several orders of magnitude providing flowability of the crude. The thermal delivery system may include a power supply54with the necessary controllers and a power cable system38. The power supply cable system38is safely and routinely disposed within a vertical wellbore52. This prior art technology provided a durable heater system50which worked for decades in severe oilfield operational conditions to mobilize viscous crude and produce this now mobile hydrocarbon from heated deep formations53avia vertical wellbores52.

This combination of elements shown inFIG. 1Amay be modified to provide some elements that are discussed in several embodiments of the current invention. Extending these embodiments to the current invention is one of the objectives of the current vitrification processes for waste disposal in deep underground human-made cavities60.

FIG. 1Billustrates a construction example in the prior art which utilized the application of vitrification processes for secure ground pilings. Shown inFIG. 1Bis a region of soil33into which a borehole39is formed. The prior art system includes a power cable38for supplying electrical power to heating electrode35. The electrode35is lowered into the borehole39until it is adjacent to the bottom of the borehole39. The electrode35is energized to vitrify adjacent soil33at or near the bottom of the borehole39forming a vitrified soil31a. The electrode35may be vertically raised within the borehole39during formation of the vitrified soil31ain order to increase and extend the vertical extent of the vitrified soil31a. After the vitrified soil31ahas been formed at or near the bottom of the borehole39, the electrode35may be removed from the borehole39. Now borehole39with its vitrified surroundings is ready to accept a piling.

However, in the subject invention, the vitrification process may be implemented not near surface37in normally unconsolidated soils33but rather in deep generally consolidated rock formations53.

It is contemplated that elements of the prior art shown in thisFIG. 1Bmay be significantly modified and improved to provide a new approach to in-situ vitrification of waste materials.

FIG. 1Cillustrates a prior art technology that was developed by the USDoE (US Department of Energy) for in-situ joule heating to convert near surface contaminated soils and wastes to a glass product or a crystalline product (vitrified soil and waste31b). InFIG. 1C, graphite electrodes35may provide electrical energy which heats up and liquefies the soil-waste mixture yielding vitrified soil and waste31b. Vitrified soil and waste31bmay be heated up to 2,000 degrees Celsius. Pyrolysis products produced in the melting process migrate vertically upwards and the off-gas may be collected by a hood then vented through off-gas vent36. A cold cap30resides above the vitrified soil and waste31band allows the off-gas and other products to migrate upwards vertically and be vented through off-gas vent36.

ContinuingFIG. 1C, the off-gas34produced may be a major problem which requires major processing subsystems for treatment of this off-gas34product. This additional requirement for off-gas34treatment is not needed in the operations of the current invention. It is contemplated that in the current inventive process that off-gas34is allowed to migrate into the upper gas zone of the subterranean cavern34c(off-gas volumes migrated into formation34c) where the off-gas34may remain captured in rock formations53. See e.g.,FIG. 3A.

In practice, the prior art technology taught inFIG. 1Cwas limited to a maximum depth of 19 feet—which is too restrictive. Further, the longest operating time period may be less than 200 hours—which is too restrictive. Under the published operating conditions and parameters, the total maximum throughput of waste is between 50 tons to 500 tons waste processed—which is too restrictive.

It is contemplated that elements of the prior art shown in thisFIG. 1Cmay be significantly modified and improved to provide a new approach to in-situ vitrification of waste material by providing methods and systems that treat significantly larger volumes of waste products for a longer period of time in a manner which allows for significant reduction in the millions of gallons of waste material that are now stored on terrestrial surface37. In addition, this inventive process may leave the vitrified waste31din a safe deep underground location53while the off-gas34produced may be disposed in the pore spaces of these porous deep underground formations forming a secondary gas cap34c(off-gas volumes migrated into formation34c).

FIG. 1Dillustrates a well-developed example in the prior art which utilized the application of vitrification processes in industry.FIG. 1Dutilizes a process called Joule Heated Ceramic Melter (“JHCM”) system, developed in the US, Germany, and several other countries. In this JHCM process, the waste material is melted in a ceramic lined container40, on the terrestrial surface37location, yielding vitrified waste31c. The untreated (pre-vitrified) waste product is added to the ceramic lined container40via a feeder for waste material to calciner43athat leads into calciner43, which leads into the main body/portion of the ceramic lined container40. InFIG. 1Dvitrified waste31cis initially produced within the ceramic lined container40, wherein this ceramic lined container40is only of a few feet in size. And ceramic lined container40is located on terrestrial surface37.

However, in the subject invention, the vitrification process may be implemented, not in a limited container that is a few feet in size, but in a massive system, in a much larger underground human-made cavity60, of industrial size proportions of hundreds of feet in length and up to 84 inches or so in diameter (in some embodiments). See e.g.,FIG. 3AandFIG. 8.

It is contemplated that elements of the prior art shown in thisFIG. 1Dmay be significantly modified and improved to provide a new approach to in-situ vitrification of waste material. In the current application, a heater system50may be implemented using variations of design such that the inherent convective behavior of the heated liquid melt material provides for convective mixing of the vitrified waste31dand thus heat transfer within the cavity system60more efficient.

FIG. 2is a flow chart depicting methods and steps generally used in the prior art techniques. It is an objective of the proposed invention to improve upon these prior art techniques.FIG. 2may depict steps in prior art method200. Method200may teach methods that have been utilized to implement the vitrification processes for nuclear waste products. The following steps characterize method200: step201, step203, step205, step207, step209, step211, step213, and step215.

Continuing discussingFIG. 2, step201is a step of collecting radioactive waste from multiple locations. Step201flows into step203. Step203is a step of separating HLW (high level waste) products from LLW (low level waste) products. In practice step203may involve multiple processes to accomplish this separation. Step203is a very expensive, time consuming, and dangerous; in which radioactive elements can create additional safety concern for workers and the environment.

Continuing discussingFIG. 2, a decision has to be made after step203to proceed in a direct single step process or a sequential two-step process. Step203flows into step205or into step209. Step205is a two-stage process for vitrification. Step205flows into step207. Step207is a calcination process in which the waste is calcined or dried prior to vitrification. Step207flows into step211. Step211implements vitrification of a calcined product from step207. Step211flow into step215.

Continuing discussingFIG. 2, step209is a single stage process for vitrification. Step209flows into step213. Step213implements the original nuclear waste material directly in a single step in what is generally termed “pot” verification. Step213flows into step215.

Continuing discussingFIG. 2, step215involves storing the vitrified products in steel canisters or other means for ultimate disposal at a later date, usually in a deep underground system. Yucca Mountain is a typical indication of where this final disposal waste may occur. Other waste disposal operations such a deep lateral wellbores have been provided in prior art as well as deep underground cavern systems.

The problems that may occur with the aforementioned steps of vitrification are several fold, some of these problems may be enumerated below.

First, a costly system of above ground infrastructure is needed to be constructed with a multiplicity of melters to achieve the vitrification process of method200.

Second, these surface operations are costly and intensively manpower demanding. For example, at Hanford, Wash., in the US today (2020) there are more than 8,368 people working on the disposal problems. Current estimates on the vitrification and other associated costs for the Hanford, Wash., disposal are estimated at $37 Billion.

Third, published sources indicate that the techniques of method200have not all been tested and as such there is no guarantee that the complex “first of a kind” technology contemplated would even function as designed given the large differences of composition of the waste material.

Fourth, the feed compositions of the nuclear waste varies considerably. These variations create problems in design simulation of the process using Computational Fluid Dynamics (CFD) means. The net result is that on a daily basis, the input feed may vary. This means that there is a constant change in the operating compositions and there are ongoing requirements to “fine tune” the complex physical-chemical operating conditions in near real time. In contrast to this type operation, the in-situ vitrification taught in the present application in deep underground caverns is less demanding and more fault tolerant of variations in input waste feeds.

Fifth, the operating melting temperatures for vitrification may be in the range of 1,150 degrees Celsius or more. Controlling such massive amounts of heat in and at surface37operations is often problematic and dangerous. Such high temperatures may not create a problem in a human-made cavern60of the deep underground vitrification system process because the human-made cavern60is surrounded by significant and substantial walls of consolidated rock matrix on all sides, i.e., the earth itself, functioning as a massive heat sink, which allows the excess heat energy to be conducted safely away in all directions by the solid rock matrix material in the formation53from the human-made cavern60are located. In the embodiments taught in this invention, it is noted that these human-made cavern(s)60may be implemented between 2,000 to 20,000 feet below the surface37of the earth. The human-made cavern(s)60are essentially in fully surrounded and buried in solid consolidated rock53. The typical melter in the prior art does not have such a massive physical mass of surrounding heat sink material, capable of “absorbing” a very high heat load generated during the vitrification process.

Sixth, another serious limiting factor in the prior art technology during operation may be the destructive corrosive effects of certain waste constituents on the physical structure of the melter itself. Under the operating conditions in the melter, the destructive problems are encountered because the corrosive nature of the vitrified waste31cmay degrade the physical structure of the melter significantly requiring the need for expensive, elaborate, replaceable, noncorrosive melter systems to remedy this potential problem.

The embodiments taught in the subject inventive means do not require these special features. The present invention using deep underground human-made caverns60in rock formations53, is able to withstand the corrosive activities since the human-made cavern60has wall thicknesses that extend radially (horizontally) in the formations53up to several miles. Any corrosion or physical erosion of the walls of the human-made cavern60may be minimally deleterious to the surrounding formation rock53. Rock formations53are by definition very expansive. The formation53are vertically and horizontally thick and extend more than necessary in three dimensions.

Seventh, insoluble materials are usually present in waste melt materials of vitrified waste31cduring the vitrification process. In the prior art methods, in practice, the quantity of insoluble materials present may limit the waste loading of the vitrified waste31cand thus degrade the overall efficiency of the vitrification process. Also, these insoluble materials may settle out of the vitrified waste31cthus affecting the melter efficiency and operation and in some cases curtail the melter operation. The embodiments taught in this invention may allow insoluble materials to segregate toward the bottom of the given human-made cavity60and accumulate in a location where upon, continued vitrification can occur above these insoluble precipitates. The embodiments taught in this invention may be more tolerant of problems that may occur in the prior art approaches to the vitrification process and may therefore allow vitrification to occur over a wide range of hitherto before, limiting conditions.

Eighth, the off-gas34that is produced in these prior art approaches has to be safely treated and disposed of at the site of vitrification (e.g., on surface37) and this may be problematic. It is well known that certain off-gases34may be produced under operating conditions in the vitrification process. The embodiments taught in this inventive system may define a means whereby the off-gases34migrate or bubble upwards from the vitrified product31dand into a zone above the vitrified product31dto form an off-gas zone34b(off-gas accumulating at top of cavern34b) inside the human-made cavern60. This off-gas34is prevented from migrating up the vertical wellbore52by the packer system63(downhole sealing packer system63) inside the wellbore52and also in addition by the fact that the wellbore52may have casing which is firmly cemented annularly to the rock formations53that extend from the human-made cavern60location all the way to the terrestrial surface37. There is no escape route for off-gas34to the terrestrial surface37in some embodiments of the present invention. The off-gas34may further migrate out of the human-made cavern60into the formation rock53forming what is called in the industry a gas cap region34c(off-gas volumes migrated into formation34c). This gas cap34c(off-gas volumes migrated into formation34c) may extend for large distances laterally (horizontally) and with proper design and selection of the stratigraphic location of the given human-made cavern60, within the given deep geological formation53, these off-gases34may be trapped in the given deep geological formation53for time periods measured in geologic time scales (e.g., on the order of for thousands of years or more); similar to natural gas reservoirs in rock formation that have trapped hydrocarbon gases, essentially methane, for millions of years.

Ninth, in the prior art, because of the tremendous costs associated with prior art vitrification processes, typically only one vitrification “project” proceeds at a given time—which is grossly below the demand. Whereas, in the proposed invention, a plurality of deep human-made cavern60systems, undergoing in-situ vitrification as described herein, may literally “dot” the landscape operating simultaneously with a minimal level of staffing. This mode of operation may be analogous to the development operations in a new oilfield where dozens of drilling operations with separate ongoing drill rigs occur simultaneously. In these embodiments, it is contemplated that less than 10 people (workers) for each in-situ vitrification site is required to “man” and operate a disposal project of this type.

There is a long-felt need to limit or eliminate the effects of these above noted problems and their shortcomings.

It is contemplated that elements and steps of the prior art shown in thisFIG. 2may be significantly modified and improved to provide a new approach to in-situ vitrification of vitrified waste31dby: (a) providing more robust methods and systems that treat significantly larger volumes of vitrified waste31d; (b) providing for a longer period of vitrification operating time; (c) vitrifying waste products of less stringent compositions, i.e., wider compositional variations of waste and glass formers; (d) allowing more heterogeneity in the physical mixture of vitrified waste31d; and (e) in manners which allow for significant reduction in the millions of gallons of waste material that are now stored on the surface37.

In addition, under the embodiments taught in this inventive process at the end of the proposed vitrification process the embodiments of this inventive process may leave the vitrified waste31din a safe deep underground location, i.e., deep geological formation53, while the off-gases34produced may be disposed in the pore spaces of these deep underground formations53forming a secondary gas cap34cand the solid vitreous mass of radioactive waste (vitrified waste31d) is encased in deep geological formation53, which is the essential definition of a deep geological repository as advocated and anticipated by all governing agencies worldwide as the ideal means for the ultimate disposal of this radioactive waste product.

The novel features which are considered characteristic for various embodiments of the invention are set forth in the appended claims. Embodiments of the invention itself, however, both as to its construction and its methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of the specific embodiments when read and understood in connection with the accompanying drawings. Attention is called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims. In addition, certain elements may be omitted from certain drawings to enhance clarity without detracting from the meaning or the idea taught in the drawing.

These and other advantages and features of the present invention are described herein with specificity so as to make the present invention understandable to one of ordinary skill in the art, both with respect to how to practice the present invention and how to make the present invention.

In the following discussion that addresses a number of embodiments and applications of the present invention, reference is made to the accompanying drawings that form a part thereof, where depictions are made, by way of illustration, of specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and changes may be made without departing from the scope of the invention.

FIG. 3Amay illustrate a general overview of a vitrification system contemplated herein.FIG. 3Amay illustrate a general overview of a deep geologic nuclear waste disposal system and/or process implemented in deep human-made cavern(s)60and using vitrification.FIG. 3Amay be a schematic (cross-sectional side view) showing an overview of contemplated inventive means, systems, mechanisms, and/or methods for the in-situ vitrification of radioactive materials within a human-made subterranean cavern(s)60within a deep geological formation53; showing a vertical wellbore52system which is drilled from the terrestrial surface37and cased (lined) with steel casing52a, and at least one human-made cavern60disposed of in a deep rock formation53with melt materials31d(vitrified product31d) placed in or disposed of inside of the at least one human-made cavern60. In some embodiments, at least one human-cavern60may be located entirely within deep geological formation53. See e.g.,FIG. 3A(andFIG. 3G).

In some embodiments, the selected deep geologic formation53(or host rock) may be igneous, metamorphic, sedimentary type formations or structural combinations of two or more of these three rock types. The selected host rock53may have desirable and required properties to contain vitrified radioactive waste material31d(vitrified product31d) over (geologically) long time intervals and may be able to minimize migration away from the human-made caverns60. In some embodiments, some of required properties of rock formation53may be demonstrated by petrophysical analysis.

Continuing discussingFIG. 3A, in some embodiments, at least one wellbore52may run at least from terrestrial surface37of the Earth to the at least one human-made cavern60. In some embodiments, the at least one wellbore52may terminate in the at least one human-made cavern60. In some embodiments, the at least one wellbore52may be at least two thousand (2,000) feet long before the at least one wellbore52runs into the at least one human-made cavern60. In some embodiments, a diameter of the at least one wellbore52is less than a diameter of the at least one human-made cavern60. In some embodiments, a majority of an interior of at least one wellbore52may be lined with a substantially cylindrical casing52a. In some embodiments, the substantially cylindrical casing may be steel casing52a. See e.g.,FIG. 3A(andFIG. 3G).

Continuing discussingFIG. 3A, in some embodiments, below the vertical wellbore52, a human-made caverns60, is reamed out below the vertical wellbore section52using under-reaming equipment readily available today (2020) in the oil-well and drilling services industries.

In some embodiments, the deep geological formation53may be located at least two thousand feet (2,000) below a terrestrial surface37of the Earth. In some embodiments, deep geological formation53(also known as the host rock53) may be located substantially from about 2,000 feet to about 30,000 feet below earth's surface37, plus or minus 1,000 feet. In some embodiments, human-made cavern60may have a diameter from 30 inches to 120 inches, plus or minus 6 inches. In some embodiments, human-made cavern60may have a height or vertical length of 100 feet to 10,000 feet plus or minus 50 feet.

In some embodiments, deep geological formation53may have geologic properties that make storing nuclear waste materials within deep geological formation53relatively safe and desirable. For example, and without limiting the scope of the present invention, in some embodiments, deep geological formation53may have one or more of the following geologic properties: structural closure, stratigraphically varied, low porosity, low permeability, low water saturation, and reasonable clay content. Shown inFIG. 3A, are the geological discontinuities53b(boundaries53b) between formation (zones) facies53. In some embodiments, it may be desirable to locate, create, form, and/or build one or more human-made cavern(s)60within deep geological formation53. In some embodiments, nuclear waste31d(vitrified product31d) may include HLW, LLW, depleted uranium products, UF6, uranium products, combinations thereof, and/or the like.

Continuing discussingFIG. 3A, in some embodiments, associated usually, but sometimes at remote locations, may be an electric power supply system54. In some embodiments, the electric power may be supplied by gas or diesel generators, solar power, geothermal, wind, battery, regional power grid distribution system, combinations thereof, and/or the like. In some embodiments, the power supply54may be connected to a regional power grid distribution system. In some embodiments, at least one power supply54may be configured for supplying the at least one heater50with electrical power.

Continuing discussingFIG. 3A, in some embodiments, the power supply54may be connected to a downhole heater system50via power supply cable system38(i.e., at least one cable38) which is implemented inside the casing52aof the vertical wellbore52. Attached below the heater device50may be one or more weight(s)51which provides continuous tension loading to the power supply cable38and heater system50. In some embodiments, this weight device51maintains the power cable system38always in tension to ensure proper operations in much the same way as “sinker rods” used in pumping operations in sucker rod oil well pumping field operations keep sucker rods in tension. In some embodiments, at least one heater50may be disposed within the at least one human-cavern60. In some embodiments, the at least one heater50may be configured to melt the hazardous waste31dreceived into the at least one human-cavern60into substantially a liquid31d; wherein upon the liquid cooling below a predetermined temperature the liquid forms a vitrified glass (waste product)31d.

Continuing discussingFIG. 3A, in some embodiments, at least one weighted device51may be attached to the at least one heater50. In some embodiments, the at least one weighted device51may be configured to maintain the at least one heater50in a substantially vertically oriented position with an overall length of the at least one heater50substantially parallel with respect to an imaginary longitudinal axis running substantially vertically of the at least one human-made cavern60. In some embodiments, the at least one weighted device51may be of a predetermined weight. See e.g.,FIG. 3A(andFIG. 3G).

Continuing discussingFIG. 3A, in some embodiments, at least one power supply54may be located proximate (e.g., above ground37and/or below ground37, but not far [deep] below ground37) to terrestrial surface37of the Earth. In some embodiments, the at least one cable38may run from the at least one power supply54to the at least one heater50. In some embodiments, the at least one cable38may connect the at least one power supply54to the at least one heater50. In some embodiments, the at least one cable38may be attached to the at least one power supply54and to the at least one heater50. In some embodiments, the at least one cable38may be configured to provide the electrical power from the at least one power supply54to the at least one heater50. In some embodiments, the at least one cable38may be configured to allow remote control of the at least one heater50from at or proximate to surface37. In some embodiments, the at least one cable38may be configured to support a weight of the at least one heater50. In some embodiments, the at least one cable38may be configured to support the weights of one or more of: at least one heater50, centralizers50a, weighted device51, mixing vanes64, combinations thereof, and/or the like. See e.g.,FIG. 3A(andFIG. 3G).

Continuing discussingFIG. 3A, in some embodiments, a wellbore packer or sealing device63is implemented inside the casing52aof the vertical wellbore52. In some embodiments, this packer or sealing device63may be located at or near the bottom of the vertical wellbore52, or at any desired or suitable position along the vertical length of the wellbore52. In some embodiments, this packer or sealing device63may be implemented with a “HYDRIL” type packing system, well known to those in the oil-filed industry, which can seal around the power cable38and any irregular object and thus prevent off-gases34or liquids from travelling vertically up the wellbore52and reaching terrestrial surface37. In some embodiments, this packer or sealing device63may be designed with an internal sliding mechanism which allows the power cable38to be reciprocated through the packer or sealing device63and provide vertical travel of up to three (3) feet or more while still sealing the wellbore52from off-gases34or liquids flowing vertically upwards.

Continuing discussingFIG. 3A, in some embodiments, at least one sealing packer system63may be disposed within the at least one wellbore52and located closer to the at least one human-made cavern60than to the terrestrial surface37of the Earth. In some embodiments, the at least one downhole sealing packer system63may be configured to seal off the at least one wellbore52from the at least one human-made cavern60(e.g., sealing off with respect to off-gas34and/or liquids/waste products31dwithin the at least one human-made cavern60). See e.g.,FIG. 3A(andFIG. 3G). In some embodiments, the at least one downhole sealing packer system63may be removed from the at least one wellbore52.

FIG. 3A(andFIG. 3G) may show a workover rig28. In some embodiments, a given workover rig28may be a truck-mounted and modified oilfield rig system which is generally used to carryout smaller operations in the field. In some embodiments, these field operations may not need the massive capacity of a full-blown drilling rig and the workover rig28may perform these routine operations like packer63setting, coiled tubing operations, winch operations, downhole tool insertions (and removals), well logging, combinations thereof, and/or the like. In such scenarios use of a workover rig28may be quicker and cheaper than use of the full-blown drilling rig. In some embodiments, workover rig28may be used to install and/or remove: heater50devices, packers63, weighted devices51, mixing vanes64, cold caps30, thermal insulating blankets301, hazardous waste31dto be vitrified, other downhole tools/sensors, other downhole operations as needed, combinations thereof, and/or the like. Also shown inFIG. 3A(and inFIG. 3G) is a well cellar29which may be a dug-out area, lined with cement and/or very large diameter thin-wall pipe, located below the given rig (e.g., workover rig28). In some embodiments, a given well cellar29may serve as a working cavity below the earth surface37level.

Continuing discussingFIG. 3A, the melt31d(vitrified product31d) is the principal material which contains the nuclear waste product which is to be vitrified according to this inventive method. In some embodiments, the composition of the melt31d(vitrified product31d) may be defined and determined in advance, by exhaustive chemical and physical analysis to meet and to satisfy the final requirements of the vitrified glass product (vitrified product31d). In addition, in some embodiments, certain predetermined glass forming agents, precursor chemicals and modifying additives may be added to the melt mixture31d(vitrified product31d) before vitrification to enhance vitrification. To those skilled in the art these analyses are available and customary in the glass making industry. In some embodiments, the calculated quantity of melt material31d(vitrified product31dbefore vitrification) may be poured, pumped, and/or delivered into the given human-made cavern60from the surface37through the wellbore52. The melt material31d(vitrified product31d), prior to vitrification, which may be in aggregate, slurry, powder, granular form, combinations thereof, and/or the like, is generally free-flowing in nature, and may accumulate inside of the given human-made cavern60and around the heater device50therein, surrounding and covering the heater device50and its centralizers50aand reaching a calculated and/or predetermined height within that given human-made cavern60.

Continuing discussingFIG. 3A, in some embodiments, at least one centralizer50amay be located within at least one human-made cavern60and disposed around at least a portion of the at least one heater50. In some embodiments, the at least one centralizer50amay be configured to maintain the at least one heater50in a center of the at least one human-made cavern60. In some embodiments, the center of the at least one human-made cavern60lies on an imaginary longitudinal axis of the at least one human-made cavern60. See e.g.,FIG. 3A(andFIG. 3G.)

Prior art vitrification processes have “batch processed” relatively small volumes of melt31c. In one example, a Direct Liquid Fed Ceramic Melt system with melter dimensions of 1.22 meter×0.86 meter×0.71 meter produced about 25 kg (kilograms) of melt31cper hour. The volumetric capacity of this melter was estimated at 744 liters of melt31c. Whereas, the embodiments contemplated in this invention, based on the projected deep underground human-made cavern60dimensions, may provide for melt31dvolumes significantly greater, by orders of magnitude, than prior art levels. Based on the projected dimensions of a given underground human-made cavern60, the systems taught herein by this invention may process between 20,000 liters to 500,000 liters of melt31dper underground human-made cavern60.

This melt processing may occur over a matter of days depending on the heater50capacity and electric energy deliverability from the surface37. By comparison, a Russian process discussed in the prior art, produced 160 tons melt31cover an 18-month period. There is a great need for a system which can process the very large volumes of high level waste (HLW) that is present worldwide today (2020).

Continuing discussingFIG. 3A, in some embodiments a cold cap system30(at least one cold cap30) may be placed above the melt material31dthat is disposed within the given human-made cavern60. In some embodiments, the at least one cold cap30may be located on top of the at least one human-made cavern60. In some embodiments, the at least one cold cap30may be located immediately above a given layer of hazardous waste31dwithin the at least one human-made cavern60. In some embodiments, the at least one cold cap30and insulation blanket material301may be used interchangeably herein. In some embodiments, the at least one cold cap30may be configured to function as a heat sink, such that when the at least one heater50is generating heat, temperatures below the at least one cold cap30are higher than temperatures above and proximate to the at least one cold cap30. In some embodiments this cold cap30which resides above the melt material31d, behaves as a blanket through which gas and vapors can move vertically from the liquid melt material31din the given human-made cavern60during the vitrification process. In some embodiments, the at least one cold cap30may be permeable to off-gas34. It has been demonstrated in the prior art, that there is significant decrease in the temperature profile from the melt material31dand its products residing at the bottom region of the melt31dto the gas cap region34bthat may exist above a top of the given human-made cavern60(or above cold cap30). In one particular prior art dataset, a temperature range is reported from a high of 1,100 degrees Celsius within the melt31c, to about 100 degrees Celsius at the top of a cold cap layer. This range of temperature may be expected in a similar manner in the vitrification process occurring within the given human-made cavern60of the present invention. It may be necessary in some processes, to heat the melt31das high as 1,600 degrees Celsius to complete the vitrification process.

In some embodiments, the composition and properties of the cold cap30may be determined by analysis and preplanning before the cold cap30is disposed of in the wellbore52, and into a top region of the given human-made cavern60above the melt material31d. In some embodiments, a given cold cap30may be a desired element for the proper operation of the vitrification process in the given human-made cavern60.

Continuing discussingFIG. 3A, in some embodiments an off-gas zone34bmay occur during the vitrification process above the cold cap30. This void space or zone34bis normally free of solid material. In some embodiments, this zone34bmay be filled with at least some of off-gas34because the off-gas34that is produced during vitrification process and is being vented from the melt31das its constituents are heated and vitrified in the given human-made cavern60directly below this zone34b. In some embodiments, this off-gas34may accumulate at the top of and/or above the given human-made cavern60forming the off-gas chamber or zone34bbecause of the density differences between the off-gas34and the liquid melt31d. As the off-gas34may accumulate at the top of and/or above the given human-made cavern60this off-gas34may migrate out of the top of that given human-made cavern60and into the pore spaces of the rock formations53around and immediately above that given human-made cavern60.

It is well known in the art that sedimentary rocks53have varying porosities and permeabilities, even igneous rocks have fracture porosity and permeability, and as such the off-gas34may migrate into these zones (e.g., immediately above the given human-made cavern60) some distance to form a gas cap region34a. Such gas caps may accommodate large volumes of gas (e.g., off-gas34). For example, and by comparison in oil fields, natural gas caps normally contain many millions of cubic feet of natural gas, thus the gas zone delineated by the leading edge34aof the off-gas34migrating into the formations53may accommodate a significant amount of off-gas34produced during the melt31dvitrification process within that given human-made cavern60. The deep underground formation53may thus provide a secure disposal for the off-gases34, some of which may later condense and remain trapped as condensate in the pore spaces of the rock formations53. This storage of the off-gas34within portions of the deep geological formation53is a major accomplishment of the new invention.

FIG. 3B,FIG. 3C, andFIG. 3Dmay illustrate a sequence of operations in which the vitrification of multiple discrete quantities or batches of melt31dare completed in sequential succession in the same deep geological human-made cavern60via the same wellbore52. In this embodiment, as shown inFIG. 3B, the heater50and cable system38are disposed at or near the bottom of the given human-made cavern60, a calculated and/or predetermined volume or batch of melt31d(before being melted) is introduced into that given human-made cavern60from the surface37using wellhead equipment and wellbore52, to at least partially cover over heater device50. The cold cap30is put in place above the melt mixture31dand the wellbore packer system63is then installed above that that given human-made cavern60. The heat system50is energized and the vitrification of the then present melt31dis completed by an initial heating cycle, followed by cooling cycle i.e., decreased heat input, according to the temperature/time profiles type as shown inFIG. 4and which profile is selected for the specific melt mixture31din that human-made cavern60. After cooling to a pre-determined temperature, of this initial batch of melt31d, the heater50, may be removed from that batch of cooling melt31d, if the heater50is non-disposable; whereas, if the heater50is disposable, then the heater50is left in the melt31dpermanently as that melt31dcools and solidifies.

The cable system38and packer system63are removed and a layer of protective material301is disposed above the cooled vitreous glass melt31efrom the surface37via the wellbore52. Melt31e(or vitrified waste31e) may denote waste product that has been vitrified and has cooled sufficiently to at least substantially solidify. In some embodiments, at least one insulation blanket material301may be disposed between two layers of the hazardous waste31d/31ewithin the at least one human-made cavern60. In some embodiments, the at least one insulation blanket material301may be configured to substantially thermally isolate the two layers of the hazardous waste31d/31efrom each other. Continuing withFIG. 3C, a heater50and cable system38may be re-installed into that given human-made cavern60. This could be a new disposable heater50, or a re-installation of the original and reusable heater50. Above the protective layer301, a calculated and/or predetermined volume or batch of new/additional melt mixture31d(before melting) is introduced into that given human-made cavern60from the surface37via wellbore52. Another cold cap30is emplaced above that newly added melt mixture31dand a packer seal system63is re-installed (installed) in the wellbore52above that given human-made cavern60. Then the heater system50is energized and the vitrification process is initiated again, i.e., that newly added melt31dis liquified by heater50. The cable system38and packer system63are removed and a new layer of protective material301is disposed above the most recent cooled vitreous glass melt31eby using the wellbore52from surface37.

InFIG. 3Da similar process is repeated; i.e., a heater50and cable system38may be re-installed into that given human-made cavern60; then additional/new melt31d(before melting) is added to that given human-made cavern60; another cold cap30is emplaced above the last added melt mixture31dand a packer seal system63is re-installed (installed) in the wellbore52above that given human-made cavern60; then the heater system50is energized and the vitrification process is initiated again; heating is stopped; some cooling occurs; a new protective layer301is installed over the last vitrified waste31d; and so on, until that given human-made cavern60is filled to a desired and/or predetermined level with vitrified waste31d. Multiple sequences of this process can be cycled through until that given human-made cavern60is filled to a prescribed height (volume) with vitrified waste31d. Thus, whileFIG. 3B,FIG. 3C, andFIG. 3Dshow portions of three sequential vitrification rounds, additional sequences may occur.

FIG. 3EandFIG. 3Fmay illustrate heater50system types and are discussed more fully later in the section dealing withFIG. 7wherein varieties of heaters are illustrated.FIG. 3Emay show at least one main heater50being used in the vitrification process; whereas,FIG. 3Emay show at least two main heaters50, arranged in parallel, being used in the vitrification process.

FIG. 3Gmay illustrate an embodiment of the invention which shows development and subsequent utilization of a gas cap region34cto contain the off-gas34produced in the vitrification process in the given human-made cavern60. In the vitrification process, the off-gas34is heated and thus pressurized above the melt31d(vitrification products31d) since the off-gas34is prevented from escaping via the wellbore52by the wellbore seal63. In some embodiments, this off-gas34a path available which is to migrate into and remain inside the porous zones of rock53d(“tight” underground formations53d) above and proximate to the given human-made cavern60.

Continuing discussingFIG. 3G, in this embodiment of the invention, it is contemplated that the underground human-made cavern60may be implemented in a specified (and predetermined) deep geologic formation53(or region53) such that a gas cap region34cmay be structurally available above the formation53in which the human-made cavern60is reamed out from.

Today (2020) current geophysical exploration techniques allow for very precise definition and location of such prospective underground zones53(deep geologic formation53) with potential gas cap formation zone(s)53d(“tight” underground formations53d) to accommodate gas cap regions34c. This technology is routinely done in oilfield work both onshore and offshore. It is contemplated in this embodiment that this gas cap formation zone53d(“tight” underground formations53d) may be permeable, porous, structurally closed and may be comprised of sandstones, conglomerates or combinations thereof, with the necessary overburden of a tight mostly impermeable zone53csuch as a shale or clay acting as an impermeable cap. This impermeable zone53cwould prevent the vertical (upwards) migration of the off-gas34from exiting gas cap formation zone53d; i.e., gas cap region34cwould exist in gas cap formation zone53d. An analogy operation to the gas cap migration into the zone53c, is the re-injection of natural gas into deep closed porous sandstone reservoirs by the gas utilities to store their gas for later production and consumer use in the heating season.

Continuing discussingFIG. 3G, in such a geologic environment with a gas cap formation53dstructurally closed by a cap layer or formation53c, the off-gas34may remain in place (in gas cap formation53das gas cap region34c) for as long as several million years of geologic time just like a natural gas reservoir may have retained natural gas for millions of years in such underground formations.

FIG. 4may be an illustration depicting the temperature of the melt mixture and time of heating relationship in a vitrification process. This graphic may be considered to be a heating and cooling curve. The curve shown in thisFIG. 4is shown as a curve with dimensionless variables. Those skilled in the art know that a dimensionless variable is unitless and is useful in modeling relationships among physical variables. The dimensionless variable value is independent of the dimensional system in which it is expressed.

Continuing discussingFIG. 4, it has been recognized that in the vitrification process it can be important for that glass melt to cool at controlled rates such that proper annealing occurs and that the glass end product of the vitrification does not undergo fracturing within the solid glass product which would severely degrade the long term performance of the formed glass because of the massive increase in surface areas because of internal fractures and the subsequent effect on leaching and other reactions over time period.

In some embodiments taught in this invention, a temperature/time profile for heating and cooling of the subject waste may be established as shown inFIG. 4by computational analysis of the melt mixture31dbefore undergoing the actual vitrification process. The temperature/time profile values may be displayed as dimensionless variables TDfor temperature as shown in the vertical axis and tDfor time as shown in the horizontal axis ofFIG. 4.

As shown in theFIG. 4, the initial heating curve of A-B indicates the heat up of the melt31dsystem. The levelized section B-C may indicate the time period of constant heating of the melt31dinside the subject human-made cavern60. The vitrification process may require a cool down process to enable annealing and this is illustrated by the cool-down section C-D. In some embodiments of the inventive process, the heat input into the melt31dby the heater50may be controlled precisely by monitoring the electric power, current, and/or voltage, that is inputted to the downhole heater system50. At the end of the heating cycle the electric power is shut off (or brought below a minimum threshold) (and the heater50may be removed while the melt is still liquid, in some embodiments). To relieve stresses (and mitigate undesired fractures), which can lead to breakage at room temperature, cooling of the resulting glass product (vitrified waste31d) may occur in a controlled manner through a predetermined temperature gradient. This allows the surface and interior of vitrified waste31dto cool substantially uniformly. This controlled process for cooling the glass (vitrified waste31d) to relieve interior stresses is called annealing in this vitrification context.

FIG. 5may depict a flowchart of at least some steps in a method500. In some embodiments, method500may be a method of in-situ vitrification of waste31din deep underground human-made caverns60located within deep geological formations53. In some embodiments, sequential operations of the vitrification process may be implemented.

In some embodiments, method500operations may be a method of in-situ vitrification as opposed to batch melter vitrification in which the prior art and current vitrification occurs in a physical vessel or crucible-like system at or near the surface37.

Continuing discussingFIG. 5, in some embodiments, step501may be a step of preprocessing and modeling of/for the intended vitrification process. In some embodiments, analysis and/or preprocessing of the waste melt material31dmay yield at least some operating parameters for the intended vitrification process. This analysis step501may be a comprehensive modelling operation in which CFD (computational fluid dynamic) and/or other means of analysis are utilized to provide parametric data such as time, temperature, energy input, compositions and/or other variables for optimizing the intended vitrification process. In some embodiments, step501may yield/produce a “roadmap” for the intended vitrification process in the deep human-made cavern60. In some embodiments, step501may transition into step502. In some embodiments, step501may be optional to method500.

Continuing discussingFIG. 5, in some embodiments, step502may be a step of forming the substantially vertical wellbore52and then forming at least one human-made cavern60from a portion of that wellbore52. In some embodiments, wellbore52may be drilled into a deep underground geological formation53. In some embodiments, wellbore52may terminate in a deep underground geological formation53. In some embodiments, at least one human-made cavern60may be located in the deep underground geological formation53. In some embodiments, the substantially vertical wellbore52may be drilled from the terrestrial surface37and into the deep underground geological formation53with substantially conventional oil-well drilling equipment. At the completion of the substantially vertical wellbore52drilling operation, at least one human-made cavern60may be reamed out from/below the substantially vertical wellbore52using special “under-reaming” tools which are available in the oil and gas industry today. In some embodiments, wellbore52may be fitted with casing(s)52a(e.g., steel casing(s)52a, such as, steel piping). Some embodiments in this invention may include the cementing in the annular ring between casing52aand the substantially vertical wellbore52. This cement which is set by pumped circulation of cement slurries in the annular region between the steel casing52aand the wellbore52/earth interface. The cement completely and externally seals the wellbore52and prevents any fluid communication from the human-made cavern60upwards and laterally into the rock53surrounding the wellbore52. This procedure is commonly referred to as cementing in the oil industry and is done successfully in several hundred thousand wells annually. In some embodiments, method500may begin with step502. In some embodiments, step502may transition into step503.

Continuing discussingFIG. 5, in some embodiments, step503may be a step of preparing the waste for vitrification treatment. This step503may be a broad and/or variable operation in which many different types of wastes may be routinely processed by a series of well accepted methods which have been tested over more than 50 years. At the end of this step503the waste may include glass formers and/or frit to form a mixture31dwhich is ready for transferring down into the wellbore52and into the given human-made cavern60. In some embodiments, the melt mixture31dmay be modified to provide a free flowing granular, slurry, powder, aggregate mixture, combinations thereof, and/or the like. In some embodiments, step503may transition into step504. (In some embodiments, step503may be omitted, e.g., if the waste has already been prepared or is in a state ready for vitrification; in which case, step502may progress to step504.)

Continuing discussingFIG. 5, in some embodiments, step504may be a step of installing at least one heater50system into the given human-made cavern60, via wellbore52, and from surface37. In some embodiments, step504may also comprise installing/inserting the weighted device51downhole below and attached to at least one heater50system. In some embodiments, step504may also comprise installing/inserting downhole, the power cable38system that has a distal end that is attached to and powers the at least one heater50system. A proximal end of power cable38may be attached to one or more power supplies54located at or near surface37. In some embodiments, step504may also comprise installing/inserting one or more centralizers50ainto the given human-made cavern60and around the at least one heater50. In some embodiments, the one or more centralizers50amay keep the at least one heater50substantially centrally located (e.g., with respect to a longitudinal axis) within the given human-made cavern60. In some embodiments, centralizers50amay be installed on the at least one heater50to allow the heater50to “standoff” from the human-made cavern60walls and be centralized in the melt31dvolume. Being centralized in the volume of the melt31dmay allow the heating process to be more uniformly effective in melting the waste material31d. In some embodiments, the at least one heater50and the weighted device51, one or more centralizers50a, and at least portions of power cable38may be inserted into the given human-made cavern60, via wellbore52, from surface37; wherein the given human-made cavern60is located in the deep geological formation53. In some embodiments, step504may be accomplished using downhole service operations which are very well established in the oil-well servicing industries. These operations have been used in oil thermal recovery projects and in installing submersible high capacity downhole pumps that require high rates of electric power, with specialized cable systems and other known well servicing operations and equipment. In some embodiments, step504may transition into step505.

Continuing discussingFIG. 5, in some embodiments, step505may be a step of introducing the product of step503(e.g., the prepared waste mixture) into the given human-made cavern60, via wellbore52, from surface37; wherein the given human-made cavern60is located in the deep geological formation53. In some embodiments, a predetermined amount (e.g., volume and/or mass) of the product of step503(e.g., the prepared waste mixture) may be introduced into the given human-made cavern60in step505(or each iteration of step505). In some embodiments, step505may result in the filling the given human-made cavern60to a predetermined level/height. In some embodiments, the melt mixture31dmay now completely cover the at least one heater50. In some embodiments, step505may transition into step506.

Continuing discussingFIG. 5, in some embodiments, step506may be a step of installing the cold cap30above the melt mixture31d. The cold cap30which is well known in the industry is a complex mixture of predetermined solid materials which maintains a blanket above the melt31dduring the vitrification process. In some embodiments, step506may transition into step507.

Continuing discussingFIG. 5, in some embodiments, step507may be a step of installing the packer seal device63in the wellbore52by well-known oilfield practices which convey the packer seal device63to the wellbore52at pre-set (predetermined) levels within the wellbore52. In some embodiments, a type of packer seal device63used may be a HYDRIL type (or the like) which is able to seal around regular or irregular shapes. Packers are designed for multiple types of uses in oil and gas work. Hundreds of types of packers are available in the industry today. In some embodiments, step507may transition into step508.

Continuing discussingFIG. 5, in some embodiments, step508may be a step of activating (energizing) the at least one heater50that may be submerged within the melt mixture31d, within the given human-made cavern60. In some embodiments, step508may be accomplished in part by use of power cable38and power supply54. In some embodiments, operation of the at least one heater50may be controlled from surface37via power cable38. In some embodiments, step508may result in the at least one heater50emitting heat into the surrounding melt mixture51d. In some embodiments, step508may transition into step509.

Continuing discussingFIG. 5, in some embodiments, step509may be a step of melting the melt mixture31dby the energized and heat emitting at least one heater50. In some embodiments, in step509the heating/melting aspects of the vitrification process may be undertaken. In some embodiments, the downhole heater50system is energized and may be maintained, controllably, according to the pre-determined temperature-time profile illustrated inFIG. 4. In some embodiments, this operational profile may be followed in practice to control and/or maintain melt31dtemperatures such that optimal heating/cooling may occur to facilitate proper and complete glass formation and to then prevent subsequent fracturing of the cooling/cooled glass31d. In some embodiments, step509may transition into step510.

Continuing discussingFIG. 5, in some embodiments, step510may be a step of venting off-gas34into surrounding porous and permeable formation rock53dforming off-gas cap34c. In some embodiments, in step510the off-gas34(produced in step509and in step511from the melting of the melt mixture31d) may be vented upwards through the given human-made cavern60, through cold cap30, and into surrounding porous and permeable formation rock53dfor long-term storage therein. In some embodiments, step510may transition into step511.

Continuing discussingFIG. 5, in some embodiments, step511may be a step of continued heating/melting according to the predetermined temperature-time profile that is illustrated inFIG. 4. Off-gas34produced in step511may be vented according to step510noted above. In some embodiments, in step511, the downhole heater50system may be energized and maintained controllably according to the predetermined temperature-time profile (predetermined heating and cooling profile) that is illustrated inFIG. 4. This predetermined temperature-time profile may be followed in practice to control, maintain melt31dtemperatures such that optimal heating/cooling may occur to prevent fracturing of the melt glass31don cooling suddenly. In some embodiments, during step511power to the at least one heater50may be modulated. In some embodiments, step511may extend for a relatively long time. For example, and without limiting the scope of the present invention, this relatively long time may be from ten (10) days to ninety (90) days per cycle/iteration of method500and/or step511; whereas, in other embodiments, other (predetermined) time periods may be applicable for step511. In some embodiments, step511may extend for a relatively long time depending on the results of the CFD models of the vitrification process (and/or the like) which predict the operating parameters and operations time for the at least one heater50to be in activated and operating. In some embodiments, step511may transition into step512.

Continuing discussingFIG. 5, in some embodiments, step512may be a step of reciprocating the at least one heater50up and down within the melt mixture31d. In some embodiments, reciprocating the at least one heater50up and down within the melt mixture31dmay introduce currents to the melt mixture31dboth by the movement of the at least one heater50and by convection from the heat emanating from the at least one heater50. In some embodiments, these currents may aid in the mixing and/or melting process of the melt31d, by facilitating uniform temperatures within the melt mixture31d. In some embodiments, this up and down reciprocation may occur over a predetermined distance and over a predetermined pathway. For example, and without limiting the scope of the present invention, this predetermined distance may be three feet, plus or minus 6 inches; i.e., the at least one heater50may travel upwards three feet and then downwards three feet. In some embodiments, this up and down reciprocation may occur over a predetermined timeframe. For example, and without limiting the scope of the present invention, this predetermined timeframe may be for several minutes. In some embodiments, step512may transition into step513; or step512may transition into step514. In some embodiments, step512may be optional or omitted. In embodiments where step512may be omitted, step511may transition into step513or step511may transition into step514.

Continuing discussingFIG. 5, in some embodiments, step513may be a step of removing the at least one heater50from the melted melt mixture31d, while the melt mixture31dis still in a substantially liquid phase. In some embodiments, the at least one heater50may be reusable. In some embodiments, the at least one heater50may pulled out (retrieved) from the given human-made cavern60, from wellbore52, and back to surface37. In some embodiments, step513may operationally depend on a type of heater50used in the vitrification process. If the heater50is a non-disposable type, the downhole heater system50may be removed from the liquid melt31dand returned to the surface37to be reused in later cycles of operations. The removal process is realized by the operations shown in step516of this method later in this discussion. If the heater50is disposable or sacrificial, step514is implemented after the cable38is retrieved. In some embodiments, step513may transition into step515.

Continuing discussingFIG. 5, in some embodiments, step514may be a step of leaving the at least one heater50in the melt mixture31d, and the melt mixture31dwill solidify around that the at least one heater50. In step514, the heater50may be left in the melt31das it solidifies and the heater50is embedded inside the cooled glass melt31d. In some embodiments, the at least one heater50may be disposable and/or not reusable. In some embodiments, step514may transition into step515.

Continuing discussingFIG. 5, in some embodiments, step515may be a step of cooling the melt mixture31dwithin the given human-made cavern60a predetermined temperature. In some embodiments, step515may be a step of cooling the melt mixture31dto a final target temperature according to the predetermined temperature time profile (seeFIG. 4) to provide annealing of the glass melt31dwithout fracturing the glass material. In some embodiments, step515may transition into step516.

Continuing discussingFIG. 5, in some embodiments, step516may be a step of removing (withdrawing) the downhole seal and packer system63and the power cable38from the given human-made cavern60and/or from wellbore52, and back to the surface37. In some embodiments, step516may transition into step517.

Continuing discussingFIG. 5, in some embodiments, step517may be a decision check point. In some embodiments, at step517method500may be ascertaining if that given human-made cavern60is sufficiently filled with waste product31d, in which case method500may process from step517to step519; or if that given human-made cavern60may accommodate more waste product31d, then step517may progress back to step503. In this manner, sequential iterations of method500may occur within a single given human-made cavern60; see alsoFIG. 3BtoFIG. 3Dwhich also illustrates this sequential iteration of method500. In some embodiments, step501may determine how many iterations of method500may be appropriate for a given human-made cavern60and a given amount of waste31dto be vitrified. In some embodiments, step517may progress into step519; or step517may transition back to step503.

Continuing discussingFIG. 5, in some embodiments, step519may be a step of stopping method500. In some embodiments, method500may be initiated for a new human-made cavern60.

In some embodiments, method500may be described as a method for in-situ vitrification of hazardous waste within at least one human-made cavern60. In some embodiments, method500may comprise steps of: (a) drilling at least one substantially vertical wellbore and then under-reaming a portion of that at least one substantially vertical wellbore to form at least one human-made cavern; wherein the at least one human-made cavern is formed within a deep geological formation; wherein the deep geological formation is located at least two thousand feet below a terrestrial surface of the Earth—see e.g., step502discussion above; (b) preparing the hazardous waste for vitrification by making sure the hazardous waste is capable of liquefying with a predetermined amount of heat and then cooling to form a glass—see e.g., step503discussion above; (c) installing at least one heater into the at least one human-made cavern by lowering the at least one heater through the at least one substantially vertical wellbore on at least one cable—see e.g., step504discussion above; (d) introducing a predetermined amount of product from step (b) around the at least one heater that is located within the at least one human-made cavern—see e.g., step505discussion above; (e) installing a cold cap above the hazardous waste that is located within the least one human-made cavern; wherein the cold cap is an insulation blanket material—see e.g., step506discussion above; (f) installing a packer seal device into the at least one substantially vertical wellbore above the at least one human-made cavern to seal-off the at least one substantially vertical wellbore from the at least one human-made cavern—see e.g., step507discussion above; (g) melting the hazardous waste within the at least one human-made cavern into a liquid using the at least one heater—see e.g., steps508,509, and511discussion above; and (h) cooling the liquid into the glass—see e.g., step515discussion above.

In some embodiments, during the step (g), the at least one heater50may be reciprocated up and down within the liquid31d. In some embodiments, during the step (g), the at least one heater50may not be reciprocated up and down within the liquid31d. See e.g.,FIG. 5.

In some embodiments, after the step (g), the at least one heater50may be removed from the liquid31d. In some embodiments, after the step (g), the at least one heater50(may be disposable) may be remain within the liquid31d. See e.g.,FIG. 5.

In some embodiments, the step (d) through the step (e) are repeated until the least one human-made cavern60may be substantially filled to a predetermined capacity or there is no more of the predetermined amount of product from step (b). See e.g.,FIG. 5. During iterations of method500, step503and/or step504are only re-used (re-done) as needed.

In some embodiments, the step (g) and the step (h) proceed according to a predetermined heating and cooling profile (see e.g.,FIG. 4and its discussion).

In some embodiments, during the step (g) and the step (h), off-gas34produced from the melting of the hazardous waste31dmay be routed upwards through the at least one human-made cavern60, to and through the (gas permeable) cold cap30, and into a permeable rock portion53dof the deep geological formation53at a top of the human-made cavern60, wherein the off-gas34cis contained within a region of the permeable rock portion53d. See e.g.,FIG. 3G.

FIG. 6Amay depict at least one heater50described in the subject application for the deep underground vitrification of waste31dwithin a given human-made cavern60. In some embodiments, a given heater50may comprise one or more mixing vanes64. In some embodiments, one or more mixing vanes64are implemented on an outside of a given heater50. In some embodiments, at least one mixing vane64may be located on an exterior portion of the at least one heater50. In some embodiments, the at least one mixing vane64may be configured to provide currents into the liquid31d. In some embodiments, such mixing vanes64may be of different (and predetermined) geometric/structural types/shapes to facilitate mixing of the melt31das shown by flow lines67when the heater50may be reciprocated up and down. In some embodiments, mixing vanes64when moved in an upward direction65and then in downward direction66(or vice-versa) may impart currents to melt31dindicated by flow lines67. In some embodiments, such currents (flow lines67) in melt31dmay facilitate more uniform mixing of melt31d; which in turn may minimize differences in densities; which in turn may yield a more uniform glass that is less likely to fracture. In some embodiments, such currents (flow lines67) in melt31dmay facilitate more uniform temperatures in melt31d; which in turn may yield a more uniform glass that is less likely to fracture. In some embodiments, such currents (flow lines67) in melt31dmay bubbles and/or off-gas34to move upwards for desired venting and long-term storage in the surrounding porous and permeable formation rock53d. In some embodiments, flow lines67may be convective currents as heater50may be emitting heat into melt31d. In some embodiments, disposed below and attached to the heater50system is at least one weighted mass or device51which maintains tension in the heater/cable38system.

In some embodiments, at least one heater50may be removably located within the liquid31d. In some embodiments, the at least one heater50may be removably located within the liquid (waste31d), the at least one human-made cavern60, the at least one wellbore52, combinations thereof, and/or the like.

FIG. 6Bmay illustrate a top view of a heater50described in the subject application for the deep underground vitrification of waste31din which mixing vanes64are implemented on the outside of the heater50. In some embodiments, these mixing vanes64may be of different (and predetermined) geometric/structural shapes and types. In some embodiments,64may be configured to yield currents (flow lines67) in melt31d(while still substantially liquid) during step509and/or step511of method500.

FIG. 7may illustrate an overview of the heater701systems700and technologies which are available in the engineering disciplines today and that may be utilized for the at least one heater50in method500. In the power industry, in the heavy oil recovery industry and in mechanical and electrical engineering applications there are many different types and varieties of heater701systems700which can be modified to meet the robust demands of the in-situ vitrification systems taught in this patent application.

Continuing discussingFIG. 7, in various embodiments of the application, the downhole heater50may be energized by a multiple types of different heater energizers711, energizers711which may heat: by resistive heating713, by inductive heating715, by electromagnetic heating717, combinations thereof, and/or the like. The proper selection of heater energizer711may depend on a variety of variables, such as, but not limited to: depth of the deep geological formation53; type/characteristics of the deep geological formation53; depth, length, and/or diameter of the given human-made cavern60; electric costs; operating conditions necessary for vitrification; type/characteristics of the melt31dto be vitrified; the volume/amount of specific melt31dto be vitrified; melt31dtemperatures; cooling temperatures; combinations thereof, and/or the like. Existing heater elements including electrode construction material and components have been designed to reach temperature as high as 2,830 degrees Celsius. The expected temperature ranges in this new application are significantly less and generally in the range of 1,000 degrees Celsius to 1,500 degrees Celsius, i.e., well within the range of existing heating element/electrode systems today.

Continuing discussingFIG. 7, a further consideration in some embodiments of the present invention is the heater50design architecture721. The selection process may include the choice of a single element723or multiple element725heaters50as shown inFIG. 3E, andFIG. 3F. An additional consideration in some embodiments of the present invention is whether to stack727or unstack729heater50elements. In some embodiments, stacking727may refer to vertically adding discrete heaters or heater elements above one another (e.g., in a serial fashion) inside the given deep human-made cavern60. In some embodiments, stacking727may be configured in a parallel fashion (see e.g.,FIG. 3F); and/or in serial (vertical end to end) fashion. In practice, stacking727may allow better heat distribution within the melt31dunder certain conditions of cavern60size. In some embodiments, a given heater50may have an architecture of a single continuous integral heater system50.

Continuing discussingFIG. 7, a further consideration in some embodiments of the present invention is the heater50usage types731. In some embodiments, a given heater50may be single use733(sacrificial) and/or disposable737. In some embodiments, a given heater50may be intended for multiple uses735(reusable735) and/or non-disposable739. In some embodiments, single use733(sacrificial) and/or disposable737heaters50can be cheaper to manufacture and by design may be left inside the cooled vitreous glass material31d. In some embodiments, multiple uses735(reusable735) and/or non-disposable739heater(s)50may be returned to the surface37after a given vitrification use, refurbished and re-used.

In some embodiments, multiple uses735(reusable735) and/or non-disposable739heater(s)50after being withdrawn (removed) from a treated amount/volume of melt31d, but wherein that50may still be within that given human-made cavern60, may be heated to boil and/or melt off any melt31dresidue on that given heater50(i.e., a heater50cleansing operation), prior to removal of that heater50from that given human-made cavern60(and/or prior to removal from the given wellbore52). That is, the heater50cleaning operation may occur in the safety of the deep geological formation53.

In some embodiments, a given heater50(and/or other downhole tools, components, and the like to removed) while being removed upwards towards surface37from a given human-made cavern60and/or from wellbore52, may be heated, scrubbed, washed, and/or cleaned in well cellar29which may be located below and proximate to workover rig28(and below surface37), such that the (heater50) washings fall down into wellbore52and never reach surface37to create contamination problems.

In some embodiments, a given heater50may use resistive heating713, inductive heating715, electromagnetic heating717, combinations thereof, and/or the like. In some embodiments, a given heater50may be single heating element723or multiple heating elements725. In some embodiments, a given heater50may be stacked727(e.g., serially and/or in parallel). In some embodiments, a given heater50may be unstacked729. In some embodiments, a given heater50may be single use733and/or disposable737. In some embodiments, a given heater50may be reusable735and/or non-disposable739. See e.g.,FIG. 7.

Specific additional heater50features, for some heaters50contemplated herein, are illustrated inFIG. 6AandFIG. 6B, such as mixing vanes64and/or weighted device51.

FIG. 8may illustrate the capacity (volumetric capacity) of an underground human-made caverns60, in liters, at various sizes from 36 inches to 84 inches in diameter of the given human-made cavern60and with respect to various lengths the given human-made cavern60.

Table 1 (shown below) may show volumetric capacities, in liters, of different human-made cavities60(e.g., human-made cavern60) implemented in the host rock53as a function of the given human-made cavern60diameter and length.

FIG. 8and Table 1 illustrate that such human-made caverns60may be used to dispose of and/or long-term store enormous amounts waste on par with the demand for that disposal and/or long-term storage.

Some embodiments of the present invention may be characterized as a system (or systems) system for in-situ vitrification of hazardous waste within at least one human-made cavern60. In some embodiments, such a system may comprise one or more of: the at least one or more human-made cavern60, at least one heater50, at least one power supply54, at least one cable38, at least one cold cap30, at least one insulation blanket material301, at least one weighted device51, at least one downhole sealing packer system63, at least one mixing vane64, at least one wellbore52, at least one casing52a, unheated “tight” underground formations53d(permeable rock portion53d), off-gas volumes migrated into formation34c, liquified and/or vitrified glass (waste)31d, at least one workover rig28(and/or at least one full-blown drilling rig), at least one well cellar29, combinations thereof, and/or the like.

Systems and methods for in-situ vitrification of predetermined waste products within human-made caverns, located within deep geological formations have been described. The foregoing description of the various exemplary embodiments of the invention has been presented for the purposes of illustration and disclosure. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching without departing from the spirit of the invention.