CN117203305A

CN117203305A - In situ methane production recovery from waste

Info

Publication number: CN117203305A
Application number: CN202280028915.6A
Authority: CN
Inventors: 盖里·万津; 约瑟夫·爱德华·泽梅特拉; 罗兰·P·德布鲁恩; 约翰·多伊斯
Original assignee: Transwold Technology Co ltd
Current assignee: Transwold Technology Co ltd
Priority date: 2021-02-25
Filing date: 2022-02-25
Publication date: 2023-12-08

Abstract

An exemplary method of producing methane in a reservoir may include accessing a microbial consortium in a geological formation. The method may include delivering an aqueous solution comprising waste to the microbial consortium. The method may include increasing the production of the gaseous material by the microbial consortium. The method may include recovering a gaseous product from the reservoir. The gaseous product may be characterized by an enriched methane concentration.

Description

In situ methane production recovery from waste

Cross Reference to Related Applications

The present application claims the benefit and priority of U.S. provisional application No. 63/153,732 filed on 25 months 2 of 2021. The application also claims the benefits and priority of U.S. provisional application No. 63/229,361 filed on 8/4 of 2021. The contents of both applications are incorporated herein by reference in their entirety for all purposes.

Technical Field

The present technology relates to the recovery and production of methane. More particularly, the present technology relates to the use of biowaste in situ generation from biogenic methane to enhance methane recovery.

Background

The increasing world energy demand presents unprecedented challenges for harvesting energy resources and mitigating the environmental impact of using these resources. Some believe that global productivity of oil and domestic natural gas will peak in ten years or less. Once this peak is reached, the primary recovery of oil and domestic natural gas will begin to drop as the most readily available energy inventory begins to run out. Historically, once the easily mined material is extracted, the old oil field and carbonaceous formations are discarded.

As global energy prices continue to rise, it may be economically viable to extract more petroleum and carbonaceous materials from these formations using conventional drilling and mining techniques. However, a point is reached where the energy required to harvest the resource is greater than the energy available for harvesting. By this point, the traditional harvesting mechanism will become uneconomical regardless of the energy price.

Thus, there remains a need for improved methods of recovering petroleum and other carbonaceous materials from the formation environment. There is also a need for a method of introducing chemical modifiers into geologic formations that will promote the biological production of methane, which can be used as an alternative source of natural gas for energy production independent of the original reserve of energy material. These and other needs are met by the present technology.

Disclosure of Invention

An exemplary method of producing methane in a reservoir may include approaching (accessing) a microbial consortium in a geological formation. The method may include delivering an aqueous solution comprising waste to the microbial consortium. The method may include increasing the production of the gaseous material by the microbial consortium. The method may include recovering a gaseous product from a reservoir. The gaseous product may be characterized by an enriched methane concentration.

In some embodiments, the aqueous solution may comprise less than 50vol.% or about 50vol.% waste. The aqueous solution may comprise produced water extracted from a geological formation. The gaseous feed recovered from the reservoir may be characterized by a carbon dioxide concentration of less than 10vol.% or about 10 vol.%. The method may include characterizing an environment of the geological formation. Characterizing the environment of the geological formation may include determining one or more of sulfate concentration, salinity, temperature, or pH within the geological formation environment. The aqueous solution may comprise greater than 0.1vol.% or about 0.1vol.% glycerol. The method may include recovering the flowing out aqueous material at an outlet of the reservoir. The method may include monitoring the concentration of carbonaceous waste in the effluent aqueous material. The aqueous solution delivered may be characterized by a pH of less than 8 or about 8. The pH of the aqueous solution may be adjusted by incorporating hydrochloric acid or phosphoric acid.

The method may include measuring a calcium concentration of an aqueous material flowing out of a geological formation recovered. The method may include reducing the pH of the aqueous solution with hydrochloric acid when the calcium concentration is measured to be greater than 20mg/L or about 20 mg/L. The method may include reducing the pH of the aqueous solution with phosphoric acid when the calcium concentration is measured to be less than 80mg/L or about 80 mg/L. The method may include providing a phosphate compound to the aqueous solution when the pH of the aqueous solution is reduced with hydrochloric acid. The aqueous solution delivered into the geological formation may be characterized by a first concentration of salts and a first concentration of free fatty acids. The waste feed may be adjusted over time to increase the carbonaceous material in the aqueous solution. The aqueous solution may be adjusted over time to increase the free fatty acid to a second concentration that is greater than the first concentration of free fatty acid. The aqueous solution may comprise one or more of a yeast extract, inorganic nitrogen, carboxylate material, metalloid material or metal material.

Some embodiments of the present technology may include a method of producing methane in a reservoir. The method may include accessing a microbial consortium in the geological formation. The method may include delivering an aqueous solution incorporating a waste stream having a carbon-containing waste concentration of greater than 10wt.% or about 10wt.% to a microbial consortium. The method may include increasing the yield of gaseous material by consuming waste through the microbial consortium. The method may include recovering a gaseous product from the reservoir. The gaseous product may be characterized by a carbon dioxide concentration of less than 40vol.% or about 40 vol.%.

In some embodiments, the method may include identifying microorganisms from the genus Thermotoga (Thermotoga). The method may include incorporating xylan into an aqueous solution delivered to the microbial consortium. The method may include separating carbon dioxide from methane recovered from the reservoir. The method may include reinjecting carbon dioxide separated from the methane into the geological formation.

Some embodiments of the present technology may include a method of producing methane in a reservoir. The method may include accessing a microbial consortium in the geological formation. The method may include delivering an aqueous solution to the microbial consortium that is doped with waste having a glycerol concentration of greater than 0.1vol.% or about 0.1 vol.%. The method may include increasing the yield of gaseous material by consuming waste through the microbial consortium. The method may include recovering a gaseous product from the reservoir. The gaseous product may be characterized by a methane concentration of greater than 51vol.% or about 51 vol.%. In some embodiments, the method may include characterizing one or more aspects of the geological formation selected from the group consisting of temperature, salinity, sulfate concentration, alkalinity, pH, or permeability. The method may include modifying one or more aspects of the geological formation.

In accordance with some embodiments of the present technology, a method of increasing methanogenic activity in a reservoir may include accessing a microbial consortium in a geological formation comprising a carbonaceous material. The method may include characterizing a formation environment. The method can include delivering an aqueous material to the microbial consortium that is doped with glycerol at a concentration greater than 0.1wt.% or about 0.1 wt.%. The method may include increasing the production of the gaseous material by the microbial consortium. The method may include recovering methane from the reservoir.

In some embodiments, the method may include subsequently increasing the glycerol concentration in the aqueous feed to greater than 1.0wt.% or about 1.0wt.%. The gaseous feed may comprise methane, hydrogen or carbon dioxide. The aqueous material conveyed may be characterized by a pH of less than 8 or about 8. The pH of the aqueous material may be adjusted by the incorporation of hydrochloric acid or phosphoric acid. The method may include measuring a calcium concentration of an aqueous material flowing out of a geological formation recovered. The method may include reducing the pH of the aqueous material with hydrochloric acid when the calcium concentration is measured to be greater than 20mg/L or about 20 mg/L. The method may include reducing the pH of the aqueous material with phosphoric acid when the calcium concentration is measured to be less than 80mg/L or about 80 mg/L. The method may include providing a phosphate compound to the aqueous material when the pH of the aqueous material is reduced with hydrochloric acid.

The method may include recovering the flowing out aqueous material at the reservoir outlet. The method may include monitoring the concentration of glycerol in the effluent aqueous material. The glycerol feed initially delivered into the geological formation may be characterized by a first concentration of free glycerol and a first concentration of free fatty acids. The glycerol feed may be adjusted over time to reduce the free glycerol to a second concentration that is less than the first concentration. The glycerol feed may be adjusted over time to increase the free fatty acid to a second concentration greater than the first concentration. The aqueous material may comprise one or more of a yeast extract, a carboxylate material, or a metal material. Characterizing the formation environment may include determining one or more of sulfate concentration, salinity, temperature, or pH within the formation environment.

Some embodiments of the present technology may include methods of increasing methanogenic activity in a reservoir. The method may include accessing a microbial consortium in a geological formation comprising a carbonaceous material. The method may include delivering an aqueous material to the microbial consortium that is doped with waste glycerol at a concentration of greater than 1wt.% or about 1 wt.%. The method may include increasing the production of gaseous material by consumption of waste glycerol by the microbial consortium. The method may include recovering methane from the reservoir.

In some embodiments, the method may include identifying a microorganism from the genus Thermotoga. The method may include incorporating xylan into an aqueous material delivered to the microbial consortium. The method may include separating carbon dioxide from methane recovered from the reservoir. The method may include reinjecting carbon dioxide separated from the methane into the geological formation.

Some embodiments of the present technology include methods of increasing methanogenic activity in a reservoir. The method may include accessing a microbial consortium in a geological formation comprising a carbonaceous material. The method may include delivering an aqueous material to the microbial consortium that is doped with glycerol at a concentration of greater than 1wt.% or about 1 wt.%. The method may include increasing the production of the gaseous material by consumption of glycerol by the microbial consortium. The method may include recovering methane from the reservoir.

In some embodiments, the method may include characterizing one or more aspects of the geological formation selected from the group consisting of temperature, salinity, sulfate concentration, alkalinity, pH, or permeability. The method may include modifying one or more aspects of the geological formation. The method may include increasing the concentration of glycerol in the aqueous material delivered to the microbial consortium over time.

This technique may provide more benefits than conventional systems and techniques. For example, methane production may be increased in a formation environment by utilizing glycerol or other waste carbonaceous material as a food source for microorganisms. Furthermore, the use of waste carbonaceous material as a source of methane production may allow the waste byproducts or materials to be used in an environmentally sustainable manner. These and other embodiments, as well as many of their advantages and features, are described in more detail in conjunction with the following description and accompanying drawings.

Drawings

A further understanding of the nature and advantages of the disclosed technology may be realized by reference to the remaining portions of the specification and the attached drawings.

Fig. 1 illustrates an exemplary operational flow diagram of a method of increasing methanogenic activity from a reservoir in accordance with some embodiments of the present technique.

Figures 2A-2D illustrate graphs of glycerol consumption to produce methane in accordance with some embodiments of the present technology.

Figure 3 illustrates a graph of the synergistic effect of combining supporting waste streams in accordance with some embodiments of the present technique.

Figure 4 illustrates a graph of the synergistic effect of combining supporting waste streams in accordance with some embodiments of the present technique.

Figure 5 shows a graph of antagonistic effects of combining multiple waste streams in accordance with some embodiments of the present technology.

Detailed Description

Biogenic methane is a common source of methane from petroleum and other reservoirs containing soluble organic compounds. Since microorganisms utilize these hydrocarbon materials as a carbon source, the microorganisms tend to inhabit the areas of the reservoir directly at the interface between these materials and the water residing in the formation. In hydrocarbon-containing environments, the gas present is typically (if not exclusively) the result of microbiological treatment of soluble hydrocarbons, producing methane with specific characteristics, which may be nearly identical to the gas produced during non-geologic periods due to the promotion of methane production. Such methanogenic activity may involve accelerating the degradation of carbonaceous materials in the reservoir, or may include methane produced from alternative carbon sources. To produce more renewable forms of methane, a bioreactor may be used. However, providing enough material to support bioreactor activity can be challenging.

With the continued development of alternative fuel technology, additional carbon sources are available and can be used to produce sustainable amounts of methane. For example, biodiesel is a fuel derived from plants or animals, typically produced by chemical reaction of lipids such as animal fat, soybean oil, or some other vegetable oil with a caustic alcohol solution. The product can be used as a ready-made substitute for petroleum diesel. The popularity of biodiesel has increased significantly over the past two decades, with global biodiesel production increasing by several orders of magnitude at that time. However, as biodiesel production increases, the amount of byproducts produced also increases. While many of these byproducts are useful in other industries, the vast production of biodiesel has far exceeded the demand for byproducts.

As one example, biodiesel production produces about 10wt.% crude glycerol. While purified glycerol is used in many products, the large amount of waste crude glycerol produced by biodiesel production has created an over-demand situation in the by-product market. Waste glycerol may contain many different impurities such as salts, alcohols, fatty acids, soaps, and fatty acid methyl esters, and these impurities may be difficult to remove. However, by properly formulating glycerol as a carbon source, waste raw glycerol can be consumed by anaerobic digestion, producing biogas including methane. Various other carbonaceous waste materials can be consumed by anaerobic digestion as well. By providing consistent amounts of glycerol or other waste to the microbial consortium, the present technology can create a sustainable bioreactor for producing methane.

In addition, the production of biodiesel also includes a cleaning or scrubbing process of the biodiesel product. The scrubbing process removes a large amount of contaminants from the fuel to improve quality and meet fuel stock specifications, but such scrubbing produces wastewater characterized by significant contaminant levels and high chemical oxygen demand. Similarly, agricultural processes typically consume large amounts of water in the treatment and runoff, which may also produce wastewater characterized by increased contaminants, rendering the water unsuitable for further use. Similarly, many different other industrial or domestic processes may produce waste including carbonaceous material and other contaminant material, which may be referred to in the art as wastewater, waste, or carbonaceous waste. Although a water treatment process may be performed, the process may be expensive and may still not be sufficiently purified. These wastes, which originate mainly from industrial processes, are produced and rapidly oxidized aerobically to carbon dioxide, increasing the global carbon budget without the formation of usable energy sources. While anaerobic degradation of these wastes to form methane has been attempted, many of these waste streams are very dilute and require significant capital equipment and long digestion times if used in conventional surface anaerobic digesters.

These surface anaerobic digesters or ex situ bioreactors may be used to perform microbial digestion on some of these products. However, in addition to cost issues, these bioreactors may have limited capacity and may be environmentally unfriendly. For example, building a bioreactor can be a cost-intensive process, and continuous feeding, cleaning, and processing of byproducts from an ex-situ bioreactor can result in cost inefficiency. Furthermore, byproducts of methanogenesis may include unusable material, which may be an environmental burden. For example, methane is produced by microorganisms that consume waste carbon sources to produce approximately equal amounts of methane and carbon dioxide. The ex situ bioreactor arrangement forces the carbon dioxide to be released with the methane. While methane can be fixed and sold, carbon dioxide is often released, increasing greenhouse gas emissions and limiting the ability of ex situ reactors to operate as an environmentally friendly renewable methane production source.

The present technology overcomes the limitations and disadvantages of ex situ reactors by forming in situ bioreactors in a geological formation environment (e.g., a formation environment that may have additional hydrocarbon materials such as petroleum, coal, or other carbonaceous materials). By utilizing an in situ bioreactor, carbon fixation may be initiated, which may reduce or limit the amount of carbon dioxide produced and released. For example, carbon dioxide generated in situ may be carried by the water and form bicarbonate, which may reduce or limit carbon dioxide release from the system. Bicarbonate can be treated or removed separately, and carbon dioxide generation and release can be limited, as described below. Accordingly, the gaseous product produced and recovered by the present techniques may be characterized by an increased ratio of methane relative to methane to carbon dioxide produced by natural stoichiometry of methanogenic activity. Similarly, the gas produced may be characterized by a reduction in the mole fraction of carbon dioxide relative to stoichiometrically produced carbon dioxide as predicted by recovered methane. Thus, using the waste discussed in this application as a carbon source, an environmentally friendly and renewable methane source can be produced. Although partial digestion of hydrocarbons may occur in the formation, the methane produced may be based substantially on the consumption of the transported carbon material.

Turning to fig. 1, a method 100 of increasing methanogenic activity in a reservoir or formation environment is shown that may be or include operating as an in situ bioreactor from a transported carbon material to produce methane. The method may be designed to promote the consumption of waste components by microbial consortia in the geological formation to produce methane and other materials that may be recovered from the geological formation. The methods performed may promote and/or activate the consortium in the formation to begin producing methane, and may increase the amount of methane that may naturally form in the environment. The method may also include stopping or reducing the "flipping" effect, for example, when the concentration of methane or other metabolite begins to plateau after a monotonically increasing period. These and other promoting effects may be promoted by materials delivered to the environment according to the present method. The method may be performed in a variety of environments, including in situ formation environments as well as ex situ reactors that may be developed in which operations may be performed. However, by performing an in situ process as described, the disadvantages of ex situ carbon dioxide generation can be avoided or limited. The method 100 may include a number of optional operations that may or may not be specifically associated with some embodiments of the method in accordance with the present technique. For example, to provide a broader process operation that may be included in some embodiments of the present technology but is not critical to the technology or may be performed using alternative methods that are readily understood, a number of operations are described.

The method 100 may include an operation 105 of accessing a consortium of microorganisms in a geological formation, but as described above, it should be understood that in some embodiments, the method may be performed in an external reactor in which the microorganisms may be placed. Microorganisms may be present in petroleum, carbonaceous materials, formation water, or at the interface between materials. The geological formation may be a previously mined oilfield or hydrocarbon farm in which production may be reduced or where increased production may be sought. In other embodiments, the geological formation may be a subterranean formation of carbonaceous material, such as coal deposits, natural gas reservoirs, carbonaceous shale or other naturally occurring carbonaceous material, or a subterranean soluble organic compound. In many of these examples, accessing the formation may involve utilizing a previously produced or drilled access point to the formation. For unexplored formations, access to the formation may require digging or drilling through the surface layer to access the underlying location where the microorganisms are located.

Once access to the microorganisms in the formation is available, an optional operation 110 may be performed, analysis of the microorganisms and the overall formation environment. This may include in situ analysis of the chemical environment and/or remote analysis of gas, liquid or solid matrices extracted from the formation. Where the conditions and characteristics of the formation environment are known or acceptable, the method 100 may be initiated by delivering materials to the environment or reactor, whether in situ or ex situ.

When characterized, a number of operations can be performed to ensure that the environment can include appropriate conditions for producing methane or for receiving conversion of glycerol or other carbon waste into biogas. Exemplary characterizations may include extraction of a formation sample, which may then be analyzed using spectrophotometry, NMR, HPLC, gas chromatography, mass spectrometry, voltammetry, isotope analysis, and other chemical instrumentation. These tests can be used to determine the presence and relative concentrations of elements such as dissolved carbon, phosphorus, nitrogen, sulfur, magnesium, manganese, iron, calcium, zinc, tungsten, cobalt, and molybdenum, and other elements. The analysis can also be used to measure e.g. PO ₂ ^3- 、PO ₃ ^3- And PO (PO) ₄ ^3- 、NH ₄ ⁺ 、NO ₂ ^- 、NO ₃ ^- And SO ₄ ^2- Polyatomic ions and other ions. The amount of vitamins and other nutrients may also be determined. And the analysis of the chemical characteristics of the stratum environment such as pH, salinity, oxidation potential and the like can be performed.

Bioassays of microorganisms can also be performed to identify methanogenic bacteria and any other beneficial species that may promote conversion to methane, including bacteria from the genus robe, as discussed further below. This may include quantitative analysis to determine population size by direct cell count techniques, including the use of microscopy, DNA quantification, phospholipid fatty acid analysis, quantitative PCR, protein analysis, or any other identification mechanism. The genus and/or species of one or more members of the microbial consortium may also be identified by genetic analysis. For example, the DNA of the microorganism may be analyzed, wherein the DNA is optionally cloned into a vector and a suitable host cell to amplify the amount of DNA for detection. In some embodiments, the detection is of all or part of a DNA or ribosomal gene of one or more microorganisms. Alternatively, all or part of other DNA sequences specific for the microorganism may be detected. Detection may use any suitable method known to those skilled in the art. Non-limiting examples may include 16S ribosomal DNA metagenomic sequencing; restriction fragment length polymorphism or terminal restriction fragment length polymorphism, polymerase chain reaction, DNA-DNA hybridization (e.g., hybridization with a probe, southern analysis, or use of an array, microchip, bead-based array, etc.), denaturing gradient gel electrophoresis, or DNA sequencing (including cDNA sequencing made from RNA as non-limiting examples).

In embodiments of the present technology, formation analysis may be performed to limit adverse effects on the microbial community and to ensure efficient conversion of glycerol or other waste. It should be appreciated that while the following discussion will include features of a subsurface environment, these features may be equally applicable to ex situ bioreactors where production may be sought. For example, microorganisms within the consortium may include both methanogenic bacteria and sulfate-reducing bacteria. Although methanogenic bacteria may utilize the transported waste products to produce methane, sulfate-reducing bacteria may have deleterious effects in the formation environment and may inhibit the formation of methane. Sulfate-reducing bacteria can utilize hydrogen to reduce sulfate to hydrogen sulfide, which can cause problems with acidizing and corrosion in the oilfield or formation environment. The increase in hydrogen sulfide production can affect the consortium itself and can reduce the methanogenic bacteria relative to other bacteria, potentially reducing methane production and limiting additional recovery.

When sulfate is present in the environment, a volume of the improver increases the relative abundance of sulfate-reducing bacteria in the formation water. This, in turn, can increase sulfate consumption rate, producing additional hydrogen sulfide gas, thereby limiting the production of methanogenic bacteria. These deleterious effects may be related to the amount of sulfate present in the formation environment. Thus, high concentrations of sulfate, such as greater than 200mg/L or about 200mg/L in formation water, may increase deleterious effects and limit enhanced oil recovery. Thus, in some embodiments, the method may be performed in an environment characterized by a sulfate concentration of less than 200mg/L or about 200mg/L, and may be performed in an environment characterized by a sulfate concentration of less than 150mg/L or about 150mg/L, less than 100mg/L or about 100mg/L, less than 90mg/L or about 90mg/L, less than 80mg/L or about 80mg/L, less than 70mg/L or about 70mg/L, less than 60mg/L or about 60mg/L, less than 50mg/L or about 50mg/L, less than 40mg/L or about 40mg/L, less than 30mg/L or about 30mg/L, less than 20mg/L or about 20mg/L, less than 10mg/L, or about 10 mg/L. Depending on the sulfate concentration in the formation environment, some embodiments of the present technology may employ hydrogen sulfide mitigation techniques, including adding nitrate or other materials to reduce the sulfate concentration in the formation.

Salinity levels in the formation environment may also be determined. When the salinity of the formation water may be greater than 6vol.% or about 6vol.%, certain microorganisms in the formation environment may reduce activity due to higher salt concentrations or brackish water. In addition, waste glycerol or other waste is characterized by a relatively high salt concentration, and the salt concentration may be an order of magnitude or more greater than virgin formation water. As described below, while ensuring that the formation environment has a similar salt concentration to provide compatibility of the conveyed material with the formation environment, the salinity of the injected fluid may be controlled by altering the aqueous conveyed material. Thus, in some embodiments, the salinity (e.g., sodium concentration) in the formation environment and conveyed aqueous material may be sought or maintained to less than 20,000mg/L or about 20,000mg/L via dilution, and may be maintained at less than 18,000mg/L or about 18,000mg/L, less than 15,000mg/L or about 15,000mg/L, less than 12,000mg/L or about 12,000mg/L, less than 10,000mg/L or about 10,000mg/L, less than 9,000mg/L or about 9,000mg/L, less than 8,000mg/L or about 8,000mg/L, less than 7,000mg/L or about 7,000mg/L, less than 6,000mg/L or about 6,000mg/L, less than 5,000mg/L or about 5,000mg/L, less than 4,000mg/L or about 4,000mg/L, less than 3,000mg/L or about 2 mg/L.

When using subsurface bioreactors, the permeability and/or porosity of the formation environment may affect the effectiveness of the conveyance. Glycerin may have a characteristic of viscosity that may be challenging to transport into and through the formation environment. In addition, other waste materials, including semi-solid organic waste materials, can have solids concentrations or viscosities that can be challenging to transport. The waste glycerol or other waste carbon products that may be used in embodiments of the present technology may also contain several weight percent ash that is not digested by microorganisms. As such ash or other byproducts build up in the formation, plugging and reduced moisture migration may occur. In addition, due to the injection of glycerol or other carbon source into the formation environment, if unevenly distributed, microorganisms may preferentially grow near the injection site, which may block the passage through the formation. Depending on the viscosity of the injection solution, glycerol or other waste may also cause clogging of the pores. As the process continues over time, the permeability may decrease, and thus in some embodiments, the formation environment may be sought or maintained to have a permeability sufficient to support the flow rate of commercial water, including aqueous materials having the characteristic of increased viscosity, attributable to the incorporation of glycerol, other waste, or other additives. Increasing permeability or porosity may be performed in any of a variety of ways, including by chemical treatment, transporting materials to increase fracturing in the formation, or any other method.

Once the appropriate environment is determined or developed, the method 100 may include delivering an aqueous solution to the formation environment in operation 115. In some embodiments, the aqueous solution may also contain suspended materials, which may be transported by flooding the formation environment. The water injection process may include injecting (including pressurized injection) an aqueous material into the formation environment. In addition to physically displacing petroleum and other carbonaceous materials, water injection may force aqueous materials to pass through formation water and permeable surfaces in the formation environment to gain access to the microbiological environment. The aqueous solution delivered may include a quantity of waste from many different operations, including but not limited to biodiesel wastewater or agricultural wastewater, as well as any other wastewater or waste described further below. In some embodiments, the water or waste stream may comprise a carbonaceous material, and may be a carbonaceous waste. Furthermore, the aqueous solution delivered may contain an amount of glycerol, which similarly may be referred to as glycerol, and may be part of the wastewater or waste stream itself, or may be added, such as crude or waste glycerol. In some embodiments, the glycerol may comprise different types of glycerol. For example, the biodiesel waste stream may comprise purified glycerol, crude glycerol, and glycerol residues. The present technology may use one or more of these materials in the waste stream, and in some embodiments may include any combination of these components. In operation 120, the conveyed material may be consumed by microorganisms, which may increase the yield of gaseous material, such as biogas. Biogas may contain methane and hydrogen, as well as carbon dioxide and other materials. In addition, carbon consumption by microorganisms can also produce liquid materials or carbonaceous liquids. For example, succinic acid may be produced by microorganisms along with biogas.

In operation 125, the generated gas and/or liquid may be extracted or otherwise collected from the formation environment. For example, recovery from a formation environment may include a combination of water, gas, and other formation materials (e.g., petroleum). Gases, oil and other materials may be separated from the water, which may be used for subsequent transport. The water may be stored in a storage tank or injected directly back into the formation environment with additional makeup water, wastewater or waste streams, and/or other nutrients, and the process repeated. The water used to deliver and/or disperse the consortium may come from a variety of sources. One source that may be very close to the formation is formation water. Systems and methods for transporting anaerobic formation water from a subterranean geological formation may be used to extract formation water from the reservoir, incorporate glycerol and/or other carbon-containing waste components described below, and reinject the material back into the formation. The formation water may be anaerobic and may be characterized as having little or no dissolved oxygen, for example, less than 4mg/L or about 4mg/L, and may be less than 2mg/L or about 2mg/L, less than 0.1mg/L or about 0.1mg/L, as measured at 20 ℃ and atmospheric pressure. Thus, the extraction process may include maintaining anaerobic conditions, or reducing oxygen incorporation prior to re-injection. In embodiments of the present technology, any other water source may also be used as a supplemental water source, although the use of seawater and/or surface water may affect microbial consortia and, if not properly controlled prior to injection, may contaminate the reservoir environment.

In some embodiments of the present technology, the waste that may be used may come from many different sources that produce wastewater, effluent streams, waste, or organic waste materials having a carbonaceous material component, and may be consumed by microorganisms in the formation environment. As noted above, the waste or carbonaceous material sources may include biodiesel wastewater or agricultural wastewater, however the present technology may use wastewater or waste streams, which are all contemplated as waste, including carbonaceous materials from various sources. The present technology may use any type of waste, including waste streams formed by mixing or dissolving waste materials in water, or effluent waste streams resulting from one or more other activities.

As non-limiting examples, the present technology may utilize one or more waste streams, including waste from agriculture, horticulture, aquaculture, forestry, hunting, or fishery; waste from the preparation and processing of meat, fish or other animal food products, such as effluent streams from slaughterhouses or commercial food production; waste from fruit, vegetable, plant, cereal, edible oil, cocoa, coffee, tea or tobacco preparation or processing; production of candied fruit, production of yeast and yeast extract, preparation of molasses and fermentation; waste from sugar processing; carbonaceous waste from refinery or other manufacturing plant processes; waste from dairy industry; waste from baking and confectionery industry; waste materials from the production or fermentation of alcoholic and non-alcoholic materials or beverages (e.g., including vinegar production); waste from wood processing and panel and furniture production; waste from pulp, paper or board production and processing; waste materials from textile industry production, which may include grease, wax or other materials; waste from the manufacture, formulation, supply or use of the base organic chemical, which may or may not include glycerol residues; waste from the aerobic treatment of waste, such as non-composted parts of municipal or similar waste; waste from anaerobic treatment of waste, such as liquids from anaerobic treatment of municipal waste or similar waste; grease or oil mixtures from oil/water separation containing edible oils or fats; garden and park waste, including cemetery waste; or any other waste, residue or effluent formed during the processing of other materials.

According to some embodiments, the waste may comprise semi-solid waste, for example, including wet solids remaining from filtration or as previously entrained solids, for example from the production of food products. As a non-limiting example, vegetarian or vegetarian alternative products may be produced from process feedstocks including nuts, soybeans, or plant material, and the remaining solid or semi-solid waste material or wet stream may be incorporated into the waste stream for delivery to the formation environment. Furthermore, the waste stream may be formed from renewable biomass products or waste materials. As non-limiting examples, renewable biomass products may include materials or waste from planted crops or crop residues, and may include all annual or perennial crops available on the agricultural land as renewable fuel feedstock, such as cereal, oilseed, or sugarcane, as well as energy crops, such as switchgrass, grassland grasses, duckweed, or other planted, pond, or cultivated species. Similarly, crop residues may include biomass remaining from harvesting or processing of planted crops from existing agricultural lands, or any biomass removed from existing agricultural lands that facilitate crop management, including biomass removed from such lands that is associated with invasive species control or fire management, whether or not the biomass includes any portion of a crop or crop plant. Renewable biomass may include planted trees or tree residues, including branches and any wood residues generated during tree processing for actively managed tree plantation planting for wood, paper, furniture, or other applications. Renewable biomass may include branches and pre-business thinnings, biomass obtained from a building or other area where people often live or near public infrastructure at risk of wildfires, algae, and such materials or waste including animal waste material and animal by-products or separated yard waste or food waste, including recycled cooking or collection grease, dairy and pig manure, landfill, waste water or waste water sludge, food waste, green waste, municipal greening waste or other organic waste. In addition, as described below, one or more waste streams may be combined to further increase methane production.

Wastewater or aqueous waste may have high levels of contaminants and variable pH characteristics based on the waste generation process. For example, from acidic wastewater having a pH of as low as 5 to alkaline wastewater having a pH of as high as 11, the waste streams used in embodiments of the present technology may be diluted and/or pH treated in some embodiments of the present technology. pH treatment will be discussed below, and dilution may help reduce any waste characteristics such as chemical oxygen demand, biochemical oxygen demand, suspended solids, oils and greases. The carbonaceous material content in the waste stream may be greater than 10wt.% or about 10wt.%, may be greater than 15wt.% or about 15wt.%, greater than 20wt.% or about 20wt.%, greater than 25wt.% or about 25wt.%, greater than 30wt.% or about 30wt.%, greater than 35wt.% or about 35wt.%, greater than 40wt.% or about 40wt.% in the aqueous stream.

In addition, the waste streams used in some embodiments of the present technology may be characterized by a chemical oxygen demand of greater than 3,000mg/L or about 3,000mg/L, and may be characterized by a chemical oxygen demand of greater than 5,000mg/L or about 5,000mg/L, greater than 10,000mg/L or about 10,000mg/L, greater than 25,000mg/L or about 25,000mg/L, greater than 50,000mg/L or about 50,000mg/L, greater than 100,000 or about 100,000mg/L, greater than 200,000mg/L or about 200,000mg/L, greater than 300,000mg/L or about 300,000mg/L, greater than 400,000mg/L or about 400,000mg/L, greater than 500,000mg/L, greater than 600,000mg/L or about 600,000mg/L or greater. In addition, the biochemical oxygen demand may be greater than 1,000mg/L or about 1,000mg/L, and may be greater than 10,000mg/L or about 10,000mg/L, greater than 25,000mg/L or about 25,000mg/L, greater than 50,000mg/L or about 50,000mg/L, greater than 100,000mg/L or about 100,000mg/L, greater than 200,000mg/L or about 200,000mg/L, greater than 300,000mg/L or about 300,000mg/L or higher. For some waste materials, suspended solids may be negligible and may be greater than 100mg/L or about 100mg/L, greater than 500mg/L or about 500mg/L, greater than 1000mg/L or about 1000mg/L, greater than 2500mg/L or about 2500mg/L, greater than 5000mg/L or about 5000mg/L, greater than 10,000mg/L or about 10,000mg/L, greater than 20,000mg/L or about 20,000mg/L, greater than 30,000mg/L or about 30,000mg/L or higher. The oil and grease incorporation may be greater than 100mg/L or about 100mg/L, and may be greater than 500mg/L or about 500mg/L, greater than 1000mg/L or about 1000mg/L, greater than 2500mg/L or about 2500mg/L, greater than 5000mg/L or about 5000mg/L, greater than 10,000mg/L or about 10,000mg/L, greater than 20,000mg/L or about 20,000mg/L, greater than 30,000mg/L or about 30,000mg/L, greater than 40,000mg/L or about 40,000mg/L or higher.

As described below, sulfate may adversely affect the formation environment, and thus in some embodiments, the utilized waste stream may be treated or otherwise characterized by a sulfate concentration of less than 500ppm or about 500ppm, and may be characterized by a sulfate concentration of less than 400ppm or about 400ppm, less than 300ppm or about 300ppm, less than 200ppm or about 200ppm, less than 100ppm or about 100ppm, less than 75ppm or about 75ppm, less than 50ppm or about 50ppm, less than 25ppm or about 25ppm, less than 20ppm or about 20ppm, less than 15ppm or about 15ppm, less than 10ppm or about 10ppm, less than 5ppm or about 5ppm, less than 2ppm or about 2ppm or less. In addition, the waste stream used may be characterized by a conductivity less than 1000 μS/cm or about 1000 μS/cm indicative of salinity, and may be characterized by a conductivity less than 800 μS/cm or about 800 μS/cm, less than 600 μS/cm or about 600 μS/cm, less than 500 μS/cm or about 500 μS/cm, less than 400 μS/cm or about 400 μS/cm, less than 300 μS/cm or about 300 μS/cm, less than 200 μS/cm or about 200 μS/cm, less than 100 μS/cm or about 100 μS/cm or less.

By diluting the waste stream in some embodiments, the concentration of these and other materials described below may be controlled, which may increase the consumption capacity in the formation environment. For example, formation water and/or one or more other supplemental water sources may be combined with the waste stream and/or glycerol to produce an aqueous solution in which the waste, wastewater, or effluent stream may be less than 50vol.% or about 50vol.% of the aqueous solution. In some embodiments, the waste may be less than 45vol.% or about 45vol.% of the aqueous solution, and may be less than 40vol.% or about 40vol.%, less than 35vol.% or about 35vol.%, less than 30vol.% or about 30vol.%, less than 25vol.% or about 25vol.%, less than 20vol.% or about 20vol.%, less than 15vol.% or about 15vol.%, less than 10vol.% or about 10vol.%, less than 5vol.% or about 5vol.%, less than 3vol.% or about 3vol.%, less than 1vol.% or about 1vol.% or less. This can increase the consumption of material by increasing the consumption capacity of the microorganisms and allow for a gradual increase over time in the carbon-containing material provided and thus the methane yield. In addition, by utilizing the diluted waste, metal or metalloid deposits, such as aluminum, boron, barium, iron, zinc, lead, silver, mercury, copper, nickel, chromium, cadmium, and tin, that are produced in formation water may be limited.

When used or included, the glycerol provided to the formation environment may be any type of glycerol, including refined glycerol or unrefined glycerol, such as byproducts from other processes, and may be glycerol that remains in the wastewater. Furthermore, in some embodiments, additional polyols or hydroxyl-containing materials may be used, including other low molecular weight polyols or polymeric polyols. The polyol may include sugar alcohols including maltitol, sorbitol, xylitol, erythritol or isomalt, as well as any other polyol materials. As previously described, while waste glycerol from any source may be used in accordance with some embodiments of the present technology, some embodiments of the present technology may use waste glycerol generated from biodiesel production. Further, in some embodiments, the material incorporated into the aqueous transport may be any source of carbon, which may be waste or a byproduct of a biofuel production or any other production process that generates waste carbon material. The waste glycerol may include a quantity of free glycerol, as well as methanol, water, and various other chemicals and byproducts. Other chemicals may include many different materials, but in some embodiments may include salts, alcohols, soaps, fatty acid methyl esters, glycerides, free fatty acids, and ash. The incorporation of these materials can affect the consumption of microorganisms and, depending on concentration, can inhibit or prevent the production of methane.

The process of producing methane from waste and/or glycerol may include allowing microorganisms to grow and adapt to the lift-off period of the carbonaceous feedstock. Methanogenic bacteria tend to digest free glycerol, methanol and other carbon materials, while handling soaps, fatty acids and ash presents difficulties. Thus, the initiation period of the process 100 may include utilizing first glycerin and/or waste featuring increased free glycerin and/or methanol or increased carbonaceous waste in the waste stream, as well as other beneficial component materials. Less refined glycerol or waste may be reduced or exchanged over time as the consortium grows and becomes adapted to digest the glycerol or treated waste stream carbonaceous material as well as the constituent materials in the waste glycerol or waste stream. Furthermore, the concentration of glycerol and/or waste in the stream may increase over time, which may also increase methane production.

Thus, in some embodiments, the glycerol added to the aqueous solution may begin with greater than 0.1wt.% or about 0.1wt.% of spent glycerol, and may begin with greater than 0.2wt.% or about 0.2wt.% of spent glycerol, greater than 0.5wt.% or about 0.5wt.% of spent glycerol, greater than 1.0wt.% or about 1.0wt.% of spent glycerol, greater than 1.5wt.% or about 1.5wt.% of spent glycerol, greater than 2.0wt.% or about 2.0wt.% of spent glycerol, or higher, although the initial amount of glycerol may remain below a threshold value to ensure consumption of microorganisms and to ensure that plugging of the equipment or formation environment is limited. Similarly, as described above, the concentration of waste in the aqueous solution may begin at a lower concentration and may increase in a similar percentage over time as previously described.

In an optional operation 130, a threshold for initial delivery or even delivery over time may be readily determined by monitoring the outflow of aqueous material from the formation environment. As the consortium may grow, glycerol-reducing bacteria and/or carbon-consuming bacteria may multiply and the delivery of glycerol or carbonaceous material may not remain unchanged. For example, monitoring the amount of glycerol or carbonaceous waste in the effluent stream may help determine the consumption or rate of consumption of glycerol or carbonaceous material by microorganisms. Thus, a first concentration of glycerol and/or carbonaceous waste may be provided in the aqueous transport, and then the concentration of glycerol, carbonaceous material, or free fatty acid in the aqueous material may be increased over time, which may occur at any ramp rate based on various aspects of the environment. As the bioreactor continues to produce and increase the capacity to consume glycerol or carbonaceous material, the concentration of any of these materials may increase to greater than 2wt.% or about 2wt.%, and may increase to greater than 5wt.% or about 5wt.%, greater than 7wt.% or about 7wt.%, greater than 10wt.% or about 10wt.%, greater than 12wt.% or about 12wt.%, greater than 14wt.% or about 14wt.%, greater than 16wt.% or about 16wt.%, greater than 18wt.% or about 18wt.%, greater than 20wt.% or about 20wt.%, greater than 22wt.% or about 22wt.%, greater than 24wt.% or about 24wt.%, greater than 26wt.% or about 26wt.%, greater than 28wt.% or about 28wt.%, greater than 30wt.% or about 30wt.%, greater than 32wt.%, or about 32wt.%, greater than 34wt.%, or about 34wt.%, greater than 36wt.%, or about 36wt.%, greater than 38wt.%, or about 40wt.%, the amount of glycerin or any other viscous or semi-solid material may be maintained below a threshold that may cause formation plugging, such as a concentration of less than 80wt.% or about 80wt.%, less than 60wt.% or about 60wt.% or less.

It should be appreciated that the conveyance concentration may be adjusted based on the volume of dilute material residing in the formation environment. For example, in a formation environment, the concentration of glycerol or waste carbonaceous material may be diluted after injection, and may be diluted two or more times any of the values noted above, and may be diluted to any of the levels noted previously. As one non-limiting example, if glycerol is delivered at a 2wt.% incorporation percentage, a two-fold dilution may result in 1wt.% incorporation in the formation environment. In some embodiments, the dilution of any of the foregoing concentrations may be a dilution of greater than 2-fold or about 2-fold, greater than 3-fold or about 3-fold, greater than 5-fold or about 5-fold, greater than 10-fold or about 10-fold, greater than 15-fold or about 15-fold, greater than 20-fold or about 20-fold, greater than 25-fold or about 25-fold, greater than 30-fold or about 30-fold, greater than 35-fold or about 35-fold, greater than 40-fold or about 40-fold, greater than 45-fold or about 45-fold, greater than 50-fold or about 50-fold or more. In some embodiments, measuring the concentration in the formation environment may be performed by entering the formation at one or more locations and withdrawing formation water, and then determining the concentration of glycerol or waste carbonaceous material in the withdrawn portion.

Determining the rate of increase for the transport of glycerin or waste streams may be based on the concentration of material at the outlet of the formation environment, optionally monitored during method 100. For example, the concentration of glycerol or carbonaceous material in the conveyed material may be increased due to the reduction of glycerol or carbonaceous waste to less than 5.0wt.% or about 5.0wt.%, less than 4.0wt.% or about 4.0wt.%, less than 3.0wt.% or about 3.0wt.%, less than 2.0wt.% or about 2.0wt.%, less than 1.0wt.% or about 1.0wt.%, less than 0.50wt.% or about 0.50wt.%, less than 0.10wt.% or about 0.10wt.%, less than 0.050wt.%, less than 0.010wt.% or about 0.010wt.% or less at the time of production. Although the recovered aqueous material may be reused in subsequent injections, limiting the concentration of glycerol or carbonaceous waste at the outlet may improve overall conversion and material application.

Similar to increasing concentration over time, the purity of the material may decrease over time, which may allow for the use of more cost effective waste glycerol or waste streams. For example, the initial glycerol feed may be characterized by a free glycerol concentration of greater than 20% or about 20% in the waste glycerol, and may be characterized by a free glycerol concentration of greater than 22% or about 22%, greater than 24% or about 24%, greater than 26% or about 26%, greater than 28% or about 28%, greater than 30% or about 30%, greater than 32% or about 32%, greater than 34% or about 34%, greater than 36% or about 36%, greater than 38% or about 38%, greater than 40% or about 40%, greater than 42% or about 42%, greater than 44% or about 44%, greater than 46% or about 46%, greater than 48% or about 48%, greater than 50% or about 50% or more. Similarly, the initial glycerol feed that is incorporated into the aqueous feed may be characterized by a methanol concentration of greater than 5% or about 5% and may be characterized by a methanol concentration of greater than 6% or about 6%, greater than 7% or about 7%, greater than 8% or about 8%, greater than 9% or about 9%, greater than 10% or about 10%, greater than 11% or about 11%, greater than 12% or about 12%, greater than 13% or about 13%, greater than 14% or about 14%, greater than 15% or about 15% or more. Furthermore, due to microbial community adaptation, the waste stream may be characterized by an initial carbonaceous material concentration of greater than 20% or about 20% or more prior to utilizing the waste stream characterized by a decreasing or increasing concentration over time. These concentrations can be achieved by treating or refining waste glycerol or waste. Over time, these concentrations may be reduced to any of the values shown, which may reduce the cost of the materials.

As described above, waste glycerol or other materials in the waste can inhibit the formation of methane at higher concentrations. However, these same materials may be beneficial for conversion as the microbial community grows and is better able to accommodate these materials. For example, while soaps, fatty acid methyl esters, and free fatty acids may initially inhibit methanogenic activity, these same materials may provide better stoichiometric conversion of carbon material to methane when the consortium has been adapted to these materials. Thus, while these materials remain below the inhibition threshold, these materials may help to increase methane production over free glycerin alone or single waste. The concentration of these inhibitory materials may be diluted based on the concentration of waste glycerol or waste in the aqueous solution, although maintaining these materials below the threshold in the waste glycerol or waste stream may initially be beneficial to the microorganism in increasing the consumption capacity over time. Thus, the initial concentration of these materials in glycerol or waste may be initially reduced or limited while allowing or resulting in increased concentrations over time.

The soap contained in the material may directly dissolve or destroy microorganisms, thus the soap concentration in the waste glycerol or waste stream at initial delivery may remain below 30wt.% or about 30wt.% and may remain below 28wt.% or about 28wt.%, below 26wt.% or about 26wt.%, below 24wt.% or about 24wt.%, below 22wt.% or about 22wt.%, below 20wt.% or about 20wt.%, below 18wt.% or about 18wt.% or less. Over time, as the microbial population increases and the effects of soaps can be overcome, the amount can be allowed to increase close to the amount of received waste glycerol or waste stream without further refinement, and can be allowed to increase to greater than or about any of the values described above.

The free fatty acids contained in the material may directly inhibit microbial activity, although at a lower concentration, but may be an additional food source. Thus, at initial delivery, the free fatty acid concentration in the waste glycerol or waste stream may be maintained at less than 5wt.% or about 5wt.%, and may be maintained at less than 4wt.% or about 4wt.%, less than 3wt.% or about 3wt.%, less than 2wt.% or about 2wt.%, less than 1.5wt.% or about 1.5wt.%, less than 1.0wt.% or about 1.0wt.%, less than 0.5wt.% or about 0.5wt.% or less. The fatty acid methyl esters may be one of the major components of biodiesel and may be maintained at a level of less than 30wt.% or about 30wt.% in the waste glycerol and may be maintained at less than 28wt.% or about 28wt.%, less than 26wt.% or about 26wt.%, less than 24wt.% or about 24wt.%, less than 22wt.% or about 22wt.%, less than 20wt.% or about 20wt.%, less than 18wt.% or about 18wt.%, less than 16wt.% or about 16wt.% or less. Over time, again due to the increase in microbial population and the ability to consume these materials, this amount may be allowed to increase to near the amount of received waste glycerol or waste stream without further refinement, and may be allowed to increase to greater than or about any of the values described above.

Formation water or fluids in which microorganisms may be found may be characterized by a relatively neutral pH. Delivering an aqueous material at a pH similar to the formation environment ensures that microorganisms remain viable. Glycerol and waste streams may be characterized by a relatively high pH and may be provided at a pH of greater than 11 or about 11, although as noted above, wastewater may also be characterized by an acidic pH. If provided unabated, particularly if the concentration delivered increases over time, the pH may affect the formation environment, resulting in reduced methane production. Thus, in some embodiments, the waste glycerol or waste stream may be modified to reduce or adjust the pH and ensure that the pH of the aqueous material being conveyed is less than pH 8 or about pH 8. Slightly higher pH of the injected material also contributes to a slight increase in pH in the formation environment. In a slightly acidic environment, this increase may increase the activity of the microorganism and further increase the methanogenesis yield. When the pH reduction is performed, the pH may be reduced by modifying the glycerol or waste with an acid such as hydrochloric acid or phosphoric acid, and a weak organic acid such as citric acid or acetic acid. If the pH of the material is to be raised, any amount of caustic can be added to provide the desired pH range.

As described below, the addition of nutrients (e.g., phosphorus) can further increase methane production. Thus, lowering the pH with phosphoric acid can additionally provide phosphorus to the aqueous solution. However, the addition of nutrients (e.g., phosphate compounds or nitrogen compounds) to the subsurface may cause precipitation reactions. For example, phosphate compounds may be formed, including compounds such as hydroxyapatite or magnesium ammonium phosphate, which, along with glycerol or other material distribution, may impede water flow within the reservoir. Many factors can affect these reactions, including temperature, pH, reduction/oxidation potential, and natural concentrations of minerals and metals in the environment such as calcium, magnesium, manganese, phosphorus, sodium, bicarbonate, carbon dioxide, iron, and the like.

Models can be developed to analyze geochemical data and environmental characteristics to produce saturation indices and to facilitate determining the likelihood of precipitation. In some embodiments, the variables used in the model may include temperature in the formation and calcium concentration. As one example, these and other variables may affect the amount of phosphate that may be incorporated into the injected aqueous material. When the likelihood of precipitation of phosphate compounds increases, phosphoric acid may not be used to reduce the pH of the glycerol or waste stream, but instead an acid such as hydrochloric acid may be used. At higher temperatures and higher calcium concentrations, the likelihood of precipitation increases. Thus, when the formation temperature is less than 80 ℃ or about 80 ℃, phosphoric acid may be used with or in place of other acids, and when the formation temperature is less than 75 ℃ or about 75 ℃, less than 70 ℃ or about 70 ℃, less than 65 ℃ or about 65 ℃, less than 60 ℃ or about 60 ℃, less than 55 ℃ or about 55 ℃, less than 50 ℃ or about 50 ℃, less than 45 ℃ or about 45 ℃, less than 40 ℃ or about 40 ℃ or less, phosphoric acid may be used. Further, phosphoric acid may be used when the calcium concentration in the formation environment is less than 100mg/L or about 100mg/L, and phosphoric acid may be used when the calcium concentration is less than 90mg/L or about 90mg/L, less than 80mg/L or about 80mg/L, less than 70mg/L or about 70mg/L, less than 60mg/L or about 60mg/L, less than 50mg/L or about 50mg/L, less than 40mg/L or about 40mg/L, less than 30mg/L or about 30mg/L, less than 20mg/L or about 20mg/L or less.

Within any or all of the above ranges, the likelihood of precipitation of phosphate material increases and in some embodiments phosphoric acid cannot be used to lower glycerol pH. Instead, hydrochloric acid or other acids may be used to neutralize the glycerol or waste streams. Incorporation of phosphate is still beneficial for methanogenesis and phosphate can still be added to the aqueous material in a subsequent hydrochloric acid treatment. For example, potassium phosphate may be added, which is less likely to form a precipitate in the aqueous material, and may be added at a lower concentration to further limit precipitation. Furthermore, in some embodiments, one or more organophosphate compounds may be used, rather than any inorganic phosphate compound that is more likely to produce mineral precipitation. As an example, glycerophosphate esters do not react with water and thus no precipitation occurs, although it should be understood that any other phosphate compound may be used, including organic or inorganic phosphates, in any embodiment encompassed by the present technology.

The temperature in the formation environment and the material to be injected may be controlled to promote conversion to methane and microbial viability. In some embodiments, aqueous materials within a specific temperature and pressure range may be conveyed. The aqueous materials may be delivered at relatively increased temperatures and pressures, such as above the formation environment, which may increase the delivery capacity and material incorporation, and may also reduce the viscosity of the provided materials. For example, the aqueous solution may be delivered to the formation environment at a temperature greater than 25 ℃ or about 25 ℃, and in some embodiments, the aqueous material may be delivered at a temperature greater than 30 ℃ or about 30 ℃, greater than 40 ℃, or about 40 ℃, greater than 50 ℃, or about 50 ℃, greater than 60 ℃, or about 60 ℃, greater than 70 ℃, or about 70 ℃, greater than 80 ℃, or about 80 ℃, greater than 90 ℃, or about 90 ℃ or more. In some embodiments, the temperature may be maintained at less than 100 ℃ or about 100 ℃ to limit temperature effects in the formation environment, such as temperature effects that may affect microorganisms. In some embodiments, the temperature may be equal to a bottom hole temperature in the formation measured prior to aqueous material delivery.

The aqueous material may be delivered to the formation environment at a pressure that facilitates distribution in the formation environment and may ensure uniform distribution of glycerin and/or waste into the formation through the pores and equipment. For example, the aqueous material may be conveyed at a pressure of greater than 0.7MPa or about 0.7MPa, and in some embodiments, the conveying pressure of the aqueous material may be greater than 1MPa or about 1MPa, greater than 2MPa or about 2MPa, greater than 3MPa or about 3MPa, greater than 5MPa or about 5MPa, greater than 7MPa or about 7MPa, greater than 9MPa or about 9MPa, greater than 10MPa or about 10MPa, greater than 12MPa or about 12MPa, greater than 14MPa or about 14MPa, greater than 15MPa or about 15MPa, greater than 16MPa or about 16MPa, greater than 17MPa or about 17MPa, greater than 18MPa or about 18MPa, greater than 20MPa or about 20MPa or higher.

In some embodiments of the present technology, additional nutrients and materials may be provided in the aqueous solution. Examples of mineral improvement may include the addition of chloride, ammonium, phosphorus, sodium, magnesium, potassium, and/or calcium, as well as other types of minerals, in any concentration or combination. The metal improvements may include the addition of manganese, iron, cobalt, zinc, copper, nickel, selenates, tungstates and/or molybdates, and other types of metals to the separator. Vitamin modification may include addition of picolide, thiamine, riboflavin, calcium pantothenate, lipoic acid, para-aminobenzoic acid, niacin, vitamin B12, 2-mercaptoethane sulfonic acid, biotin and/or folic acid, and other vitamins. Yeast extract may be included to provide further nutrients to the microorganism, and digests and extracts of commercially available brewers and baker's yeasts may be included. A non-exhaustive list of other minerals and materials that may be included in any amount or ratio includes ammonium chloride, cobalt chloride, copper chloride, manganese sulfate, nickel chloride, trisodium nitrotriacetate, potassium monophosphate, potassium diphosphate, sodium molybdate dihydrate, sodium tripolyphosphate, sodium tungstate, zinc sulfate, or other phosphorus-containing compounds, sodium-containing compounds, sulfur-containing compounds, or carboxylate-containing compounds (e.g., acetates and formates).

Methanogenic bacteria in the formation environment may promote methane formation. Identification of other species in the formation environment may also improve digestion of waste glycerol or waste and constituent materials. For example, microorganisms from the genus robe may also consume glycerol or carbonaceous material in the waste stream and may be advantageous to incorporate the bacteria or identify the presence of the bacteria in the formation. By providing additional materials or nutrients that may be selectively consumed by the robe, the viability of the robe may be increased. For example, in some embodiments, one or more carbohydrate polymers, such as xylans, may be provided in the conveyed aqueous material. This may further increase the population of the thermotoga bacteria, which may increase glycerol consumption.

As previously mentioned, the production of methane in the formation environment may also produce other materials, such as hydrogen and carbon dioxide. The carbon dioxide that may be produced may be at least partially immobilized in the environment, for example partially in an aqueous solution or dissolved in water in the form of bicarbonate, and partially immobilized in the non-mobile petroleum. However, carbon dioxide that can be released can be recovered at the exit location with the methane produced. In some embodiments, the present technology may include separating carbon dioxide from the recovered methane. Although the carbon dioxide may be depleted, in some embodiments, the carbon dioxide may be reinjected with subsequent aqueous feeds. This may help to maintain pressure in the formation and may increase movement and production in the environment. The recovered water may be recycled in a number of different ways before reinjection in subsequent treatments. If desired, the hazardous materials may be neutralized or removed, and then additional glycerin and/or nutrients may be incorporated prior to reinjection into the environment. The re-injection process may be continuous or may be performed in stages, where the environment may be sealed for a period of time after injection to allow the biogas to be generated.

In addition, carbon dioxide remaining in the formation water or hydrocarbon material may be converted to bicarbonate. Although by dispersion, bicarbonate may be distributed throughout the formation environment, in some embodiments, circulation of the aqueous material through the formation may result in an increase in bicarbonate concentration in water as well as hydrocarbon materials (e.g., petroleum) over time, which may result in a change in environmental pH and/or microbial activity. Thus, in accordance with some embodiments of the present technology, the method may include reducing the bicarbonate concentration in the aqueous material. As one non-limiting example, bicarbonate concentration may be reduced as aqueous material is recovered from the formation environment and prior to reinjection. For example, calcium carbonate may be produced and recovered as a solid from aqueous materials as well as other bicarbonate removal processes, which may result in a decrease in bicarbonate concentration as the process continues. This ensures that the build-up in the formation is controlled, thereby limiting the impact on the microbial environment.

Thus, in embodiments of the present technology, the gaseous products produced from the in situ environment, as well as the recovered gaseous products, may be characterized by an enriched methane concentration. Unlike ex situ bioreactors that produce and recover relatively equal amounts of methane and carbon dioxide as methanogenesis proceeds, the gaseous products produced by the present technology may be characterized by an increased percentage of methane relative to other materials. For example, a recovered gaseous product produced from a well in an in situ environment, without additional recovery processing, may be characterized by a methane concentration of the gaseous product of greater than 50vol.% or about 50vol.%, and may be characterized by a methane concentration of greater than 55vol.% or about 55vol.%, greater than 60vol.% or about 60vol.%, greater than 65vol.% or about 65vol.%, greater than 70vol.% or about 70vol.%, greater than 75vol.% or about 75vol.%, greater than 80vol.% or about 80vol.%, greater than 85vol.% or about 85vol.%, greater than 90vol.% or about 90vol.%, greater than 95vol.% or about 95vol.% or more, with the remainder being nitrogen, hydrogen, and/or carbon dioxide.

Similarly, a recovered gas product produced from a well in an in situ environment, without additional recovery processing, may be characterized by a carbon dioxide concentration of the gas product of less than 45vol.% or about 45vol.%, and may be characterized by a carbon dioxide concentration of less than 40vol.% or about 40vol.%, less than 35vol.% or about 35vol.%, less than 30vol.% or about 30vol.%, less than 25vol.% or about 25vol.%, less than 20vol.% or about 20vol.%, less than 15vol.% or about 15vol.%, less than 10vol.% or about 10vol.%, less than 5vol.% or about 5vol.%, less than 2vol.% or about 2vol.%, less than 1vol.% or about 1vol.% or less, and in some embodiments, the carbon dioxide is substantially or essentially absent. This may provide a renewable bioreactor that may utilize waste carbon source material to produce methane and may control or limit greenhouse gas production.

Figures 2A-2D show the effect of incorporating a first concentration of glycerol and/or additional nutrients and materials on methane production by a microbial community. Methane production is shown along the Y-axis in each figure and is shown in micromoles. Fig. 2A shows the yield based on the incorporation of glycerol alone. Figure 2B shows further incorporation of a material comprising phosphate and ammonium chloride with glycerol. Figure 2C shows the incorporation of glycerol and a material comprising phosphate and yeast extract. Figure 2D shows the incorporation of glycerol and materials comprising phosphate, acetate and yeast extract. As shown, the incorporation of other nutrients increases methane production. In addition, samples were tested in each case with or without the addition of hydrocarbon material. As shown in fig. 2A, lines 202 and 204 show the results of the test for the additional incorporation of carbonaceous material, while lines 206 and 208 show the results of the test for the non-additional incorporation of carbonaceous material. In all four examples shown in fig. 2A-2D, the production increases in the presence of additional hydrocarbonaceous material, as shown by the top two lines in each figure. Thus, by performing the treatment in an in situ bioreactor, for example in a formation environment that includes additional hydrocarbon material, the methane produced by glycerol consumption may be increased beyond that which may be produced in an ex situ environment. Thus, the present technology can provide a method for efficiently and economically consuming waste glycerol to produce biogas.

As previously described, the present technology may utilize multiple waste and/or carbonaceous streams that further increase methane production over a single waste stream, in accordance with some embodiments of the present technology. While multiple individual waste streams, either conditioned or unconditioned by any of the configuration materials or operations described above, in some embodiments, supplemental waste streams may be combined and delivered to the formation in one or more ways. The supplemental stream may include many different features that may provide a more beneficial combination of materials for the consortium, which may synergistically increase methane production, and in some embodiments, may increase methane production over any single stream used alone. Any combination of two or more of the waste streams discussed above may be used, and any of the streams may be modified, adapted, or otherwise configured by any of the steps or materials previously discussed. The inventors have identified a variety of supplemental sources of waste that, when combined, can increase methane production beyond that of any single stream, and the following examples are not intended to limit the technology or claims in any way.

Fig. 3 is a graph illustrating the synergistic effect of combining supportive waste streams in accordance with some embodiments of the present technique. The figure shows the results of a microenvironment study conducted to evaluate the synergistic effect of combining multiple types of configurable supportive materials (e.g., waste or carbonaceous materials) in the in situ generation of methane in an oilfield. Anaerobic collection is carried out on domestic oilfield produced fluid and the anaerobic collection is used for experiments. 8 125mL (164.4 mL volume) serum bottles were anaerobically filled to zero headspace from the produced fluid. 20mL UHP nitrogen was added to each bottle while venting to bring N at ambient temperature ₂ The headspace was set at 0psi. All serum bottles were inoculated with microorganisms originating from the same field, which were previously enriched in waste carbonaceous material originating from biodiesel production processes.

Additional waste carbonaceous material was added to 6 of the 8 serum bottles. 2 serum bottles were improved with configurable supportive materials derived from biodiesel production processes, 2 serum bottles were improved with configurable supportive materials derived from dairy waste, and 2 serum bottles were improved with a combination of configurable supportive materials derived from biodiesel production processes and dairy waste. The 2 serum bottles remained free of additional configurable supportive material as a control. In the experiments performed, the main organic matter from the biodiesel waste stream was a polyol compound and the main organic matter from the dairy waste stream was a protein rich compound. The total amount of configurable support material added under each test condition was the same based on Chemical Oxygen Demand (COD). With the addition of a single configurable support material, the final concentration was 100mg/L COD. In the case of the addition of a combination of two configurable supportive materials, each material was added at 50mg/L COD, for a total of 100mg/L COD. The vials were then stored at 55 ℃ to simulate in situ temperature.

After one week of incubation, the headspace gas was analyzed for methane generated from the configurable support material by gas chromatography. Figure 3 shows the average methanogenesis of the repeated measurement of the microenvironment 7 days after the experimental setup. The data of fig. 3 shows that adding multiple configurable supportive materials together provides a synergistic effect in enhancing methane production. The simultaneous provision of two configurable support materials may increase methane production by 49% or 37%, respectively, relative to the addition of only a single material derived from biodiesel production processes or dairy waste.

Fig. 4 is a graph illustrating the synergistic effect of combining supportive waste streams in accordance with some embodiments of the present technique, and may illustrate other exemplary combinations of waste stream materials that may produce a consortium supplementation effect. The figure shows an example of the synergistic effect of combining supportive waste streams in accordance with some embodiments of the present technology (where no inoculum may be added). The figure shows the results of additional microenvironment studies conducted to evaluate the effect of combining multiple types of configurable supportive materials (e.g., waste or carbonaceous materials) to generate methane in situ in an oilfield. Anaerobic collection is carried out on domestic oilfield produced fluid and the anaerobic collection is used for experiments. 8 30mL (37 mL volume) serum bottles were anaerobically filled to zero headspace from the produced fluid. 10mL UHP nitrogen was added to each bottle while venting to bring N at ambient temperature ₂ The headspace was set at 0psi.

Additional waste carbonaceous material was added to 6 of the 8 serum bottles. 2 serum bottles were improved with configurable supportive materials derived from biodiesel production processes, 2 serum bottles were improved with configurable supportive materials derived from fermentation product industry, and 2 serum bottles were improved with a combination of two configurable supportive materials derived from biodiesel production processes and fermentation product industry waste. The 2 serum bottles remained free of additional configurable supportive material as a control. Unlike the above experiments, in these experiments conducted, the primary organic matter from the biodiesel waste stream was a fatty acid/fatty acid ester compound and the primary organic matter from the fermentation product waste stream was a protein-rich compound. The total amount of configurable support material added under each test condition was the same based on Chemical Oxygen Demand (COD). With the addition of a single configurable support material, the final concentration was 500mg/L COD. In the case of the addition of two configurable supportive material combinations, each material was added at 250mg/L COD, for a total of 500mg/L COD. The vials were then stored at 55 ℃ to simulate in situ temperature.

After two weeks of incubation, the headspace gas was analyzed for methane generated from the configurable supportive material by gas chromatography. Figure 4 shows the average methanogenesis of the repeated measurement of the microenvironment 14 days after the experimental setup. The data of fig. 4 shows that adding multiple configurable supportive materials together provides a synergistic effect in enhancing methanogenesis. The simultaneous provision of two configurable support materials may increase methane production by 299% or more relative to the addition of only a single material from a biodiesel production process or from fermentation waste. As described above, the results of FIG. 3 are based on an inoculated formation water source, while the results of FIG. 4 are based on an unvaccinated formation water source. This can explain the graphical differences in methane production. The results shown in fig. 4, relative to the results discussed in fig. 3, show that even for slower responding or lower responding wells, proportional increases in methane production due to the delivery of certain mixed waste streams may occur.

Figures 3 and 4 show the synergistic effect of adding different types or categories of waste together to create a supplemental complete nutritional environment for microorganisms. Conversely, in some cases, the addition of multiple types of waste materials containing related classes of compounds may cause antagonistic effects. Figure 5 is a graph illustrating antagonism effects of combining multiple waste streams in accordance with some embodiments of the present technique. The setup and analysis of the experiments shown are the same as in fig. 4. 8 serum bottles were used in the experiment. Additional waste carbonaceous material was added to 6 of the 8 serum bottles. 2 serum bottles were improved with configurable supportive materials from the fermentation product industry, 2 serum bottles were improved with configurable supportive materials from the dairy product industry, and 2 serum bottles were improved with a combination of two configurable supportive materials from the fermentation product industry and the dairy product industry. The 2 serum bottles remained free of additional configurable supportive material as a control. The total amount of configurable support material added under each test condition was the same based on Chemical Oxygen Demand (COD). With the addition of a single configurable support material, the final concentration was 500mg/L COD. In the case of the addition of two configurable supportive material combinations, each material was added at 250mg/L COD, for a total of 500mg/L COD. The vials were then stored at 55 ℃ to simulate in situ temperature.

After two weeks of incubation, the headspace gas was analyzed for methane generated from the configurable support material by gas chromatography. Figure 5 shows the average methanogenesis of the repeated measurement of the microenvironment 14 days after the experimental setup. The data of fig. 5 shows that the addition of multiple configurable support materials of the same type may have antagonistic effects on methanogenesis. Unlike the experiments described above, in which the main organics from the fermentation waste stream were protein-rich compounds, the main organics from the dairy waste stream were also protein-rich compounds. Providing two configurable supportive materials simultaneously in one case can reduce methane production by 66%, similar to the result of adding only a single configurable supportive material in the other case. Without being bound by any particular theory, excessive incorporation of protein-rich waste streams may at least partially overwhelm microorganisms, creating toxicity in the environment. This may reduce the effect, resulting in an unfavorable production of methane. Thus, in accordance with some embodiments of the present technique, by balancing the nutrient sources of the waste streams delivered to the formation environment, the microbial consortium may be enhanced to further increase the methane production delivered relative to a single waste stream.

In the above description, for purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. However, it will be apparent to one skilled in the art that certain embodiments may be practiced without some of these details or with additional details.

Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of practicing the embodiments. Moreover, many well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Accordingly, the above description should not be taken as limiting the scope of the present technology.

Where a range of values is provided, it is understood that each intervening value, to the minimum score of a unit of lower limit, between the upper and lower limit of that range is also specifically disclosed unless the context clearly dictates otherwise. Any narrower range between any given value or any other given value or intervening value in a given range is encompassed. The upper and lower limits of these smaller ranges may independently be included in the range or excluded from the range, and each, neither or both limits included in the smaller ranges is also encompassed within the technology, subject to any specifically excluded limit in the stated range. When the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a material" includes a plurality of such materials, and reference to "a nutrient" includes one or more nutrients known to those skilled in the art and equivalents thereof, and so forth.

Furthermore, the terms "comprise," "include," "contain," "include" and "incorporating" when used in this specification and in the following claims are intended to specify the presence of stated features, integers, components or operations, but they do not preclude the presence or addition of one or more other features, integers, components, operations, acts or groups thereof.

Claims

1. A method of producing methane in a reservoir, the method comprising:

a microbial consortium in the near geological formation;

delivering an aqueous solution comprising waste to the microbial consortium;

increasing the yield of gaseous material by means of said microbial consortium; and

recovering a gaseous product from the reservoir, wherein the gaseous product comprises an enriched methane concentration.

2. The method of producing methane in a reservoir of claim 1, wherein the aqueous solution comprises less than 50vol.% or about 50vol.% waste, and wherein the aqueous solution comprises produced water extracted from the geological formation.

3. The method of producing methane in a reservoir of claim 1, wherein the gas product recovered from the reservoir is characterized by a carbon dioxide concentration of less than 10vol.% or about 10 vol.%.

4. The method of producing methane in a reservoir of claim 1, further comprising:

characterizing the environment of the geological formation, wherein characterizing the environment of the geological formation includes determining one or more of sulfate concentration, salinity, temperature, or pH within the geological formation environment.

5. The method of producing methane in a reservoir of claim 1, wherein the aqueous solution comprises greater than 0.1vol.% or about 0.1vol.% glycerol.

6. The method of producing methane in a reservoir of claim 1, further comprising:

harvesting the effluent aqueous material at an outlet of the reservoir; and

monitoring the concentration of carbonaceous waste in the effluent aqueous material.

7. The method of producing methane in a reservoir of claim 1, wherein the aqueous solution delivered is characterized by a pH of less than 8 or about 8.

8. The method for producing methane in a reservoir according to claim 7, wherein the pH of the aqueous solution is adjusted by incorporating hydrochloric acid or phosphoric acid.

9. The method of producing methane in a reservoir of claim 8, further comprising:

measuring the calcium concentration of the aqueous material flowing out of the geological formation recovered; and

reducing the pH of the aqueous solution with hydrochloric acid when the calcium concentration is measured to be greater than 20mg/L or about 20mg/L, or

The pH of the aqueous solution is reduced with phosphoric acid when the calcium concentration is measured to be less than 80mg/L or about 80 mg/L.

10. The method of producing methane in a reservoir of claim 9, further comprising:

when the pH of the aqueous solution is lowered with hydrochloric acid, a phosphate compound is provided to the aqueous solution.

11. The method of producing methane in a reservoir of claim 1, wherein the aqueous solution delivered into the geological formation is characterized by a first concentration of salts and a first concentration of free fatty acids.

12. The method of producing methane in a reservoir of claim 11, wherein the waste feed is adjusted over time to increase carbonaceous material in the aqueous solution, and wherein the aqueous solution is adjusted over time to increase free fatty acids to a second concentration that is greater than the first concentration of free fatty acids.

13. The method of producing methane in a reservoir of claim 1, wherein the aqueous solution further comprises one or more of a yeast extract, inorganic nitrogen, carboxylate material, metalloid, vitamin, mineral, or metal material.

14. A method of producing methane in a reservoir, the method comprising:

a microbial consortium in the near geological formation;

delivering an aqueous solution incorporating a waste stream having a carbon-containing waste concentration of greater than 10wt.% or about 10wt.% to the microbial consortium;

increasing the yield of gaseous material by consuming waste by the microbial consortium; and

recovering a gaseous product from the reservoir, wherein the gaseous product is characterized by a carbon dioxide concentration of less than 40vol.% or about 40 vol.%.

15. The method of producing methane in a reservoir of claim 14, further comprising:

identifying microorganisms from the genus Thermotoga.

16. The method of producing methane in a reservoir of claim 15, further comprising:

and incorporating xylan into said aqueous solution delivered to said microbial consortium.

17. The method of producing methane in a reservoir of claim 14, further comprising:

separating carbon dioxide from methane recovered from the reservoir.

18. The method of producing methane in a reservoir of claim 17, further comprising:

reinjecting carbon dioxide separated from the methane into the geological formation.

19. A method of producing methane in a reservoir, the method comprising:

A microbial consortium in the near geological formation;

delivering an aqueous solution incorporating waste having a glycerol concentration of greater than 0.1vol.% or about 0.1vol.% to the microbial consortium;

increasing the yield of gaseous material by consuming the waste by the microbial consortium; and

recovering a gaseous product from the reservoir, wherein the gaseous product is characterized by a methane concentration of greater than 51vol.% or about 51 vol.%.

20. The method of producing methane in a reservoir of claim 19, further comprising:

characterizing one or more aspects of the geological formation selected from the group consisting of temperature, salinity, sulfate concentration, alkalinity, pH, or permeability; and

improving the one or more aspects of the geological formation.