Methods and systems for in-SITU quantification of lithium brine

Abstract

A system for in-situ quantification of lithium brine constituents, the system comprising: a probe for isolating a lithium brine sample; a sample extraction means configured to displace a lithium brine sample into the probe; and a device configured to perform low field quantitative nuclear magnetic resonance analysis on the lithium brine sample; wherein the probe and the device are deployed in- situ at a location within a lithium brine extraction site.

Description

METHODS AND SYSTEMS FOR IN-SITU QUANTIFICATION OF LITHIUM BRINEFIELD

[0001] This relates to methods and systems for in-situ quantification of lithium brine.BACKGROUND

[0002] Lithium has various uses across different industries and applications. Some of the primary uses of lithium include batteries, electric vehicles, aerospace applications, and the medical industry.

[0003] Lithium brine is a concentrated solution of lithium salts typically found in underground reservoirs. There exist extraction methods which allow lithium to be extracted from lithium brine for industrial use.SUMMARY

[0004] According to a first aspect of the invention, there is provided a system for in-situ quantification of lithium brine constituents, the system comprising: a probe for isolating a lithium brine sample; a sample extraction means configured to displace a lithium brine sample into the probe; and a device configured to perform low field quantitative nuclear magnetic resonance analysis on the lithium brine sample; wherein the probe and the device are deployed in-situ at a location within a lithium brine extraction site.

[0005] In an example of the first aspect of the invention, the location is a surface location.

[0006] In a further example of the first aspect of the invention, the sample extraction means is deployed at an extraction point, a junction point, an accumulation point, or a concentration point of the brine extraction site.

[0007] In a further example of the first aspect of the invention, the system further comprises a remotely controlled vehicle configured for attachment of the probe and the device thereto.

[0008] In a further example of the first aspect of the invention, the location is a downhole location.

[0009] In a further example of the first aspect of the invention, the sample extraction means is configured to divert a lithium brine sample from a pipeline of a formation tester and displace the diverted lithium brine sample into the probe.

[0010] In a further example of the first aspect of the invention, the system further comprises a communications module, wherein the communications module is configured to interface with a multiconductor wireline cable.

[0011] In a further example of the first aspect of the invention, the location is at a submersible pump.

[0012] In a further example of the first aspect of the invention, the location is at a lithium brine producer aquifer.

[0013] In a further example of the first aspect of the invention, the system further comprises a temperature control unit for controlling the temperature of the lithium brine sample.

[0014] In a further example of the first aspect of the invention, the low field quantitative nuclear magnetic resonance analysis is characterized by a magnetic flux density of less than 1 T.

[0015] According to a second aspect of the invention, there is provided a device for performing quantitative analysis of lithium brine, the device comprising: a probe for isolating a lithium brine sample; a fluid inlet for receiving the lithium brine sample; a fluid outlet for flushing the lithium brine sample; a permanent magnet surrounding the probe, the permanent magnet being configured to apply a static magnetic field to the lithium brine sample; a radiofrequency coil configuredto apply an oscillating magnetic field to the lithium brine sample and receive a magnetic resonance signal; and a quantitative nuclear magnetic resonance instrument.

[0016] In an example of the second aspect of the invention, the permanent magnet and the radiofrequency coil form a discrete-Halbach arrangement.

[0017] In a further example of the second aspect of the invention, the permanent magnet is configured to apply a static magnetic field that has a magnetic flux density of about 0.5 to 0.7 T.

[0018] In a further example of the second aspect of the invention, the device further comprises a temperature control unit for controlling the temperature of the lithium brine sample.

[0019] In a further example of the second aspect of the invention, the probe comprises a tube that has an outer diameter of at least 10 mm.

[0020] In a further example of the second aspect of the invention, the probe is made of polyetheretherketone.

[0021] According to a third aspect of the invention, there is provided a method of quantifying constituents of lithium brine, the method comprising: tuning a quantitative nuclear magnetic resonance instrument to a Larmor frequency; displacing a lithium brine sample into a probe; applying a static magnetic field to the lithium brine sample; applying an oscillating magneticfield to the lithium brine sample; and receiving a magnetic resonance signal from nuclei spin precession.

[0022] In an example of the third aspect of the invention, the NMR instrument is tuned to the lithium Larmor frequency at ambient conditions using a saturated lithium nitrate LiNOs solution or another suitable reference.

[0023] In a further example of the third aspect of the invention, applying the static magnetic field comprises determining that at least 99% magnetization has been achieved.

[0024] In a further example of the third aspect of the invention, the method further comprises repeating and stacking quantitative nuclear magnetic resonance measurements.

[0025] In a further example of the third aspect of the invention, the method further comprises optimizing the repeating and stacking of quantitative nuclear magnetic resonance measurements for precision.

[0026] In a further example of the third aspect of the invention, the method further comprises optimizing the repeating and stacking of quantitative nuclear magnetic resonance measurements for acquisition time.

[0027] In a further example of the third aspect of the invention, the method further comprises compensating for magnetic field fluctuations caused by temperature variations using a predetermined calibration curve.

[0028] In a further example of the third aspect of the invention, the method further comprises controlling the temperature of the lithium brine sample.

[0029] In a further example of the third aspect of the invention, the method does not require a calibrant or a paramagnetic particle.BRIEF DESCRIPTION

[0030] The description is framed by way of example with reference to the drawings which show certain embodiments. However, these drawings are provided for illustration only, and do not exhaustively set out all embodiments.

[0031] Figure 1 shows an example lithium brine system in a surface application.

[0032] Figure 2 shows a further example lithium brine system in a surface application.

[0033] Figure 3 shows an example lithium brine system in a downhole application.

[0034] Figure 4a shows a further example lithium brine system in a downhole application.

[0035] Figure 4b shows a further example lithium brine system in a downhole application.

[0036] Figure 5 shows an example lithium brine quantification device.

[0037] Figure 6 shows a further example lithium brine quantification device.

[0038] Figure 7 shows an example magnet configured for use in a lithium brine quantification device and system.

[0039] Figure 8 shows a method for quantifying constituents of lithium brine.DETAILED DESCRIPTION

[0040] Quantitative analysis of lithium brine involves determining the concentration of lithium and other relevant elements in the brine sample. This analysis is crucial for assessing the economic viability of lithium extraction, optimizing extraction processes, and ensuring the quality of the extracted lithium.

[0041] Quantitative analysis of lithium brine is currently typically achieved through lab analysis methods, which requires lithium brine to first be pumped to the surface from an underground reservoir and appropriately sampled. The collected brine samples are then sent to a laboratory for chemical analysis. Lab techniques that are commonly employed include atomic absorption spectroscopy (AAS), optical emission spectroscopy (OES), mass spectrometry, inductively coupled plasma (ICP) spectroscopy, ion chromatography, and high field quantitative nuclear magnetic resonance (high field qNMR). These analytical techniques and processes usually require large, heavy, and power-hungry instruments with permanent installation and strict environmental control, making them not portable and not suitable for field deployment. Furthermore, they require sample manipulation, and the accuracy of AAS and OES measurement could be affected by other ions present in the lithium brine. Brine samplemanipulation for quantitative analysis may not be suitable for in-situ applications in the lithium brine industry.

[0042] In particular, qNMR is a technique used for the quantitative analysis of chemical compounds based on nuclear magnetic resonance spectroscopy. NMR is a powerful analytical technique that exploits the magnetic properties of certain atomic nuclei to provide information about the structure and environment of molecules. While traditional NMR is often used for structural elucidation, qNMR extends its application to determine the concentration of specific compounds in a sample. Classic qNMR techniques require sample preparation such as adding paramagnetic particles to reduce relaxation times and mixing calibrants (reference compounds of known concentration) with the sample.

[0043] The main constituents of natural lithium brine are the following: Lithium Li, Calcium Ca, Sodium Na, Boron B, Potassium K, Magnesium Mg, Strontium Sr, Chlorides Cl, Sulfates SO4.

[0044] The following table presents their corresponding NMR properties:Table 1

[0045] Benchtop NMR equipment represents a less expensive alternative to lab analysis of lithium brine. Benchtop NMR equipment is portable to a certain degree: the equipment can be installed in an environmentally controlled area at the lithium production site. This has the advantage of eliminating the need to transport the samples to an offsite laboratory. However, installing the benchtop NMR at the lithium production site can still be costly, consume large amounts of power, and require a dedicated and controlled environment to be made available for housing the equipment.

[0046] There are described herein examples of methods and systems for extraction of lithium brine and quantification of lithium brine constituents. In particular, the quantification may be in-situ quantification that can be applied at surface or downhole conditions. The quantification may be achieved through the use of a quantification device comprising a probe, a magnet configured to apply a permanent magnetic field and an oscillating magnetic field, and a qNMR instrument. The quantification may allow for more precise and accurate control of variables throughout the production process, thereby optimizing the lithium extraction process.

[0047] High field NMR is typically used for molecular structure analysis mainly through chemical interaction frequency shift (chemical shift). High field NMR instruments require temperature and environmental control, are bulky and heavy, require sample manipulation, and are sensitive to molecular imperfections in a sample tube. While high field NMR systems have generally better accuracy and resolution, these limitations make high field NMR infeasible or at least non-ideal for in-situ quantification of lithium brine.

[0048] In contrast, the low field qNMR device and system described herein overcome the deficiencies of a high field NMR counterpart. In particular, being able to operate low-field means a smaller and a more light-weight system is possible. It has been found that while low field NMR may not provide the same level of accuracy as high field NMR, the accuracy is sufficient for the control and optimization of parameters involved in the lithium production process.System

[0049] Quantification and analysis of lithium brine may occur in a surface application or a downhole application. There are described below examples of systems for quantification of lithium brine in a surface application or a downhole application.Surface Application

[0050] Figure 1 shows an example system which may be used for lithium extraction from lithium brine and quantification of lithium brine in a surface application.

[0051] The example system 100 of Figure 1 is configured for an evaporitic enrichment process based on the continuous cycling of brine through a series of ponds that increase in saturation.

[0052] The example system 100 comprises one or more wells 101, a feed pond 102, successive evaporation ponds 103, a salt collection point 104, a first impurity removal point 105, a second impurity removal point 106, a third impurity removal point 107, a heater 108, a lithium precipitation point 109, a belt 110, a rinsing point 111, a centrifuge 112, a dissolution point 113, a dryer 114, and one or more quantification devices 199.

[0053] Each well 101 comprises a wellhead and a pump 120.

[0054] Brine is pumped from wells 101 to a feed pond 102. Calcium hydroxide (lime) is added at wells 101 to remove magnesium by forming magnesium hydroxide and calcium sulphate (gypsum).

[0055] Successive evaporation ponds 103 are used to increase the brine concentration while precipitating salts, which are then collected from the ponds at a salt collection point 104. Between 9 and 24 months may be required to enrich the brine for lithium recovery.

[0056] Magnesium and calcium may be removed by way of clarification at a first impurity removal point 105. Calcium and boron may be removed by way of ion exchange at a second impurity removal point 106. Boron may be removed by way of solvent extraction at a third impurity removal point 107.

[0057] The brine is heated to about 80 to 90 degrees Celsius at a heater 108. At a lithium precipitation point 109, sodium carbonate (soda ash) is added to precipitate lithium carbonate crystals, which are filtered through a belt 110, washed using ultra-pure water at a rinsing point 111, and centrifuged at a centrifuge 112.

[0058] The resulting lithium carbonate product may be dissolved using CO2 at a dissolution point 113 and further re-precipitated, filtered, washed, and centrifuged. This cycle may be repeated until a predetermined lithium purity is reached. In one example, the predetermined lithium purity is the battery-grade purity at 99.5 wt.%.

[0059] At a dryer 114, the purified lithium carbonate product meeting the predetermined lithium purity is dried to obtain the final lithium carbonate product.

[0060] In another example, the resulting lithium product may be lithium chloride, and the production process may be modified accordingly.

[0061] Mother liquor exiting the lithium precipitation point 109 is fed back into the evaporation ponds 103. This is a recycling step as the mother liquor can still contain residual lithium.

[0062] The example system 100 comprises one or more quantification devices 199 provided at one or more points in the system. The quantification devices 199 are configured to perform quantitative analysis on lithium brine and can be mobilized when needed. Multiple quantification devices 199 may be deployed at multiple points of interest in the system 100 to form a production monitoring network for the brine field.

[0063] Points at which a quantification device 199 may be deployed non- limitingly include a point of extraction (e.g. a pump or wellhead at wells 101), a point of accumulation or concentration (e.g. a feed pond 102 or an evaporation pond 103), and generally any point along the flow stream within a lithium carbonate processing plant (e.g. interconnecting pipelines, processing plants, tanks, recirculation lines, or effluent lines).

[0064] Examples of quantification device 199 are described in more detail below.

[0065] The output of the one or more quantification devices may be collated and processed to form a part of the feedback loop in a closed-loop control system. The quantitative data obtained may be used to optimize lithium production by adjusting one or more of the following:• Operational control of evaporation ponds (control lithium and impurities concentration, control input and output flows)• Control of reagents addition in evaporation ponds (e.g., lime addition to remove magnesium)• Control of brine production wells for aquifer monitoring over time• Control of impurities removal (boron, calcium, magnesium, and others) with ion exchange resins• Control of impurities removal with solvent extraction• Control of impurities removal with precipitation• Control of soda ash (sodium carbonate) to remove impurities• Control of crystallization sequence for competing metal complexes removal• Control of flow stream compositions within lithium processing plants (e.g. direct lithium extraction plant, carbonation plant, lithium hydroxide production plant, and other lithium derivates production plants)• Control of spent lithium brine recycling• Control of effluents composition (e.g., mother liquor)• Control of recirculation streams composition (e.g., reverse osmosis permeate)• Control of direct lithium extraction process performance (control of lithium and impurities concentration in the different direct lithium extraction stages)• Control of lithium concentration equipment performance (reverse osmosis, evaporators, others)

[0066] Figure 2 shows a further example system 200 which may be used for lithium extraction from lithium brine and quantification of lithium brine in a surface application.

[0067] The example system 200 is configured for direct lithium extraction (DLE), which can extract lithium from brine within weeks. Direct lithium extraction typically makes use of a combination of technologies within a processing plant of a much smaller footprint compared to evaporation ponds.

[0068] The example system 200 comprises one or more wells 201, a collection pond 202, a DLE point 203, a first tank 204, a heat exchanger 205, a reverse osmosis point 206, an ion exchanger 207, a second tank 208, a heater 209, a precipitation point 210, a belt 211, a rinsing point 212, a centrifuge 213, a dryer 214, filters 215, nanofiltration 216, a reverse osmosis point 217, a water tank 218, and one or more quantification devices 299.

[0069] Each well 201 comprises a wellhead and a pump 220.

[0070] One or more pumps 201 are provided and configured to extract lithium brine from an underground deposit and transport the lithium brine into a collection pond 202.

[0071] Fresh brine enters a DLE point 203 to obtain a dilute lithium chloride solution that contains impurities such as magnesium, calcium, potassium, and sodium.

[0072] The DLE process requires a large amount of water, which is a scarce resource. Water may be stored in a water tank 218.

[0073] The dilute lithium chloride solution is accumulated and filtered in an accumulation tank 204 from where a pretreatment stage follows to purify and concentrate the lithium chloride solution. This can comprise heating the lithium chloride solution by a heat exchanger 205, purifying the solution at a reverse osmosis point 206, and removing impurities at an ion exchanger 207. The pretreatment can remove impurities such as magnesium, calcium, and boron.

[0074] The purified and concentrated lithium chloride solution is accumulated in a tank 208 before the lithium carbonate treatment, which can comprise preheating at a heater 209 to about 80 to 90 degrees Celsius, adding sodium carbonate (soda ash) at a precipitation point 210 to precipitate lithium carbonate, and filtering at a belt 211.

[0075] The lithium carbonate may then undergo washing with ultra-pure water at a rinsing point 212, centrifuging at a centrifuge 213, and drying at a dryer 214.

[0076] The resulting lithium carbonate product may be dissolved using CO2 at a dissolution point (not shown) and further re-precipitated, filtered, washed, and centrifuged. This cycle may be repeated until a predetermined lithium purity is reached. In one example, the predetermined lithium purity is the battery-grade purity at 99.5 wt.%.

[0077] In another example, the resulting lithium product may be lithium chloride, and the production process may be modified accordingly.

[0078] Water, being a scarce resource, may be recycled and treated by processing used water via filters 215, nanofiltration 216, and reverse osmosis 217 and repositing the processed water back in the DLE water tank 218.

[0079] The resulting brine from the DLE may be sent back to the collection pond 202. The recycled brine may be reinjected in the lithium brine reservoir after hydrogeologic studies to prevent eventual dilution.

[0080] The example system 200 comprises one or more quantification devices 299 provided at one or more points in the system. The quantification devices 299 are configured to perform quantitative analysis on lithium brine and can be mobilized when needed. Multiple quantification devices 299 may be deployed at multiple points in the system 200 to form a production monitoring network for the brine field.

[0081] Points at which a quantification device 299 may be deployed non- limiti ngly include a point of extraction (e.g. a pump 201 or a wellhead), a point of accumulation or concentration (e.g. a collection pond 202 or tanks 204 and 208), and generally any point along the flow stream within a lithium carbonate processing plant (e.g. interconnecting pipelines, processing plants, tanks, recirculation lines, or effluent lines).

[0082] Examples of quantification device 299 are described in more detail below.

[0083] The output of the one or more quantification devices may be collated and processed to form a part of the feedback loop in a closed-loop control system. The quantitative data obtained may be used to optimize lithium production by adjusting one or more of the following:• Operational control of evaporation ponds (control lithium and impurities concentration, control input and output flows)• Control of reagents addition in evaporation ponds (e.g., lime addition to remove magnesium)• Control of brine production wells for aquifer monitoring over time• Control of impurities removal (boron, calcium, magnesium, and others) with ion exchange resins• Control of impurities removal with solvent extraction• Control of impurities removal with precipitation• Control of soda ash (sodium carbonate) to remove impurities• Control of crystallization sequence for competing metal complexes removal• Control of flow stream compositions within lithium processing plants (e.g. direct lithium extraction plant, carbonation plant, lithium hydroxide production plant, and other lithium derivates production plants)• Control of spent lithium brine recycling• Control of effluents composition (e.g., mother liquor)• Control of recirculation streams composition (e.g., reverse osmosis permeate)• Control of direct lithium extraction process performance (control of lithium and impurities concentration in the different direct lithium extraction stages)• Control of lithium concentration equipment performance (reverse osmosis, evaporators, others)Downhole Application

[0084] A downhole application or a downhole condition refers to quantification of lithium brine that takes place within a lithium brine production well. Figure 3 and Figures 4a and 4b show examples of quantification of lithium brine in a downhole condition.

[0085] In a downhole application, a quantification device may be installed in-situ in or near a borehole, which is a narrow shaft drilled into the ground to explore orextract lithium resources e.g. borehole 399 in the examples shown in Figure 3, Figure 4a, or Figure 4b.

[0086] Figure 3 shows a quantification device 301 comprising a stop-flow cell 306 (or a probe) and an NMR instrument 307. The quantification device 301 is configured for attachment to a flowline 302, which may be the flowline of a formation tester tool 303. The quantification device 301 is configured to obtain a lithium brine sample into a stop-flow 306 cell via an inlet 304.

[0087] The quantification device 301 is provided as an appendix in parallel to the formation tester tool 303. In use, a small lithium brine sample is diverted into the stop-flow cell 306, which may be surrounded by a magnet.

[0088] The quantification device 301 is configured to operate independently of the normal operation of the formation tester.

[0089] The stop-flow cell 306 is configured to be flushed such that the quantification device 301 may be reused.

[0090] In use, the formation tester 303 anchors against a borehole wall and sets a rubber pad or dual packer against the formation 305. An inlet port in the middle of the pad or packers enables a connection between the formation fluids and the tool flowline 302. A pump within the formation tester tool 303 draws high pressure and high temperature formation fluid into the flowline 302. A small volume of the flowline fluid is then displaced into the high-pressure and high-temperature stopflow cell 306 and thereby isolated from the flowline 302.

[0091] The stop-flow cell 306 comprises a magnet configured to magnetize a lithium brine sample for qNMR with a static magnetic field and an oscillating magnetic field. The magnet may be the magnet 907 (described in more detail below).

[0092] The stop-flow cell 306 may also comprise a temperature control unit for regulating the temperature within the stop-flow cell. Further, the temperaturecontrol unit may also be used to stabilize the magnetic field and improve the sensitivity and accuracy.

[0093] Temperature can affect the quality of the results of qNMR in various ways. The noise level increases with increasing temperature as at least a part of the total noise will be electronic (thermal) noise. The static magnetic field strength will also vary with varying temperature. A temperature control unit can mitigate the adverse effects of varying temperature on the output of the qNMR analysis e.g. by controlling the temperature directly and / or sensing and recording the temperature variations so as to allow compensations to be made.

[0094] The quantification device 301 may comprise a power supply or a battery comprising one or more energy storage units. Alternatively or additionally, the quantification device 301 may share a power supply with the formation tester tool 303.

[0095] The quantification device 301 may comprise a communications module for wireline cable telemetry. Alternatively or additionally, the quantification device 301 may share a communications system with the formation tester.

[0096] The NMR instrument 307 is configured to perform quantitative analysis on the lithium brine solution. In use, the NMR instrument 307 derives quantitative data including the lithium-ion concentration and quantification of other constituents in relation to a lithium brine sample. The NMR instrument may comprise one or more processors, memory, and sufficient storage for storing the obtained data, which may then be periodically transmitted to a remote (surface) location via a multiconductor wireline cable 308.

[0097] In particular, the NMR instrument 307 may be configured to perform low field qNMR analysis. Low field in this context may refer to a static magnetic field (applied by a permanent magnet) having a magnetic flux density of less than 1 T. In some examples, the magnetic flux density is below 0.5 T for low field qNMR.

[0098] The temperature control units may independently or collectively mitigate the adverse effects of varying temperature on the output of the qNMR analysis e.g. by controlling the temperature directly and / or sensing and recording the temperature variations so as to allow compensations to be made.

[0099] Figure 4a shows a further example of downhole quantification of lithium brine where a quantification device 301 is provided at a downhole submersible pump for a more permanent monitoring arrangement.

[0100] Figure 4b shows a further example of downhole quantification of lithium brine where a plurality of quantification devices 301 are distributed in front of lithium brine producer aquifers.

[0101] The examples of downhole quantification of Figure 3, Figure 4a and Figure 4b may exist independently of or in addition to one another at a lithium production site.Quantification Device

[0102] An example quantification device 900 is shown in Figure 5. The quantification device is configured to perform quantitative analysis on a lithium brine sample by way of qNMR.

[0103] The device 900 comprises an antenna 901, an integrated power, communication and control unit 902, a fluid outlet 903, a fluid inlet 904, an internal pump 905 when necessary, a probe 906, a magnet 907, an NMR instrument 908, a humidity and temperature control unit 909, and a housing 910.

[0104] The antenna 901, the integrated power, communication and control unit 902, the pump 905, the probe 906, the magnet 907, the NMR instrument 908, and the humidity and temperature control unit 909 are at least partially enclosed within the housing 910. The housing 910 may be configured to withstand environmental conditions e.g. pressure, wind, humidity, and temperature variations.

[0105] An antenna 901 is provided for communication with other nodes within a communication network. Other nodes in the communication network may comprise other quantification devices 900 deployed at the same lithium production site and one or more controllers (servers), which may be at remote locations. The network may utilize a combination of centralized communication and decentralized communication. In the case of centralized communication, one controller will function as a central server, though other nodes may also be configured to fulfill this function.

[0106] The network may utilize a combination of wired (e.g. ethernet) and wireless connections (e.g. via antennas and a satellite). For simplicity, not all communications hardware is shown.

[0107] While not separately shown, the integrated power, communication and control unit 902 comprises a power module, a communication module, and a control module. In an alternative embodiment, the power module, communication module, and the control module may not form an integrated unit and may instead be provided as independent units.

[0108] The power module comprises a battery. The battery may be configured to power the quantification device 900. While the singular form is used in the description, the battery may comprise a plurality of batteries or energy storage units. The battery may be replaceable and / or rechargeable. The battery may be provided with one or more energy harvesting technologies e.g. solar recharging.

[0109] The fluid outlet 903, the fluid inlet 904, and the pump 905 are configured to obtain a lithium brine sample and displace it into the probe 906. The timing of the sample collection and circulation may be administered by the control module. This may follow a preprogrammed routine and / or it may be adjusted in real-time.

[0110] The probe 906 is configured to isolate the lithium brine sample and may also equivalently be a stop-flow cell. Isolation valves may be used to maintain the brine in place during the measurement period.

[0111] The probe 306 is configured to be flushed and dried such that the quantification device 301 may be reused.

[0112] A standard, commercially available NMR probe is made of borosilicateglass (Pyrex) and typically has an outer diameter of 3 to 10 mm, 5 mm being the most common. This has two key disadvantages in the context of in-situ quantification of lithium brine. First, using borosilicate glass would impair measurement of boron, which is one of the key contaminants in lithium brine. Second, the volume of the lithium brine sample contained and exposed to the magnetic field would be limited: the lithium concentration in brine is orders of magnitude smaller than the other ions such as sodium ions and potassium ions. Having a smaller sample volume means the resultant resonance signal will also have smaller amplitudes, which can contribute to a worse signal-to-noise ratio (SNR) and longer measurement time because more measurements from longer and additional measurement cycles will need to be stacked (added and averaged) to achieve the same level of precision as can be achieved in the same amount of time with a greater sample volume.

[0113] The probe 306 and any other probe or stop-flow cell disclosed herein may be made of Polyetheretherketone (PEEK), which does not impair the measurement of an isotope of interest in the lithium brine. Further, PEEK may also be particularly suitable for an in-situ, downhole application since it would be able to function in a higher-pressure environment.

[0114] The probe 306 and any other probe or stop-flow cell disclosed herein may be or comprise a tube having an outer diameter of at least 10 mm.

[0115] The magnet 907 is configured to apply one or more magnetic fields to the lithium brine sample. Figure 7 shows an example magnet 907 comprising a permanent magnet 907.1 and an RF coil 907.2.

[0116] The coil 907.2 is configured to serve as a transmitter as well as a receiver. The coil 907.2 is configured to apply an oscillating magnetic field to the lithiumbrine sample (transmitting function) and to receive a magnetic resonance signal. In this way, the RF coils 907.2 can apply RF signals and measure the response of the nuclei magnetic resonance during a CPMG echo cycle.

[0117] The magnet 907 is configured to apply a magnetic field that has a magnetic flux density of about 0.5 to 0.7 T.

[0118] The physical construction and spatial arrangement of the magnet are configured to optimize for homogeneity of the magnetic field on all the fluid inside the probe 906.

[0119] The magnet 907 may be of a discrete-Halbach arrangement configured to surround the probe 906.

[0120] The NMR instrument 908 is configured to perform quantitative analysis on the lithium brine solution. In use, the NMR instrument 908 derives quantitative data including the lithium-ion concentration and the quantification of other constituents in relation to a lithium brine sample. The NMR instrument may comprise one or more processors, memory, and sufficient storage for storing the obtained data, which may then be periodically transmitted to a remote location via the antenna 901 and the communication module. The one or more processors may be configured to perform signal processing methods on the raw data.

[0121] The humidity and temperature control unit 909 is configured to prevent condensation that might adversely affect the operation of the quantification device 900.

[0122] The one or more quantification devices 199 of example system 100 may comprise one or more quantification devices 900.

[0123] The one or more quantification devices 299 of example system 200 may comprise one or more quantification devices 900.

[0124] More generally, the quantification devices 900 are configured to be installed at various points of interest including but not limited to extraction points,junction points in a brine pipeline system, brine concentration ponds or tanks, and more generally different flow streams within a lithium brine or a lithium chemicals processing facility.

[0125] Figure 6 shows a further example quantification device 950.

[0126] The quantification device 950 comprises the example quantification device 900 (or its core functional components) and a remotely operated vehicle (ROV) 940. The quantification device 900 may be removably attached to the ROV 940 via a fastening arrangement that is suitable for aquatic conditions. However, the scope of the invention is not limited by the fastening arrangement.

[0127] The ROV 940 makes the quantification device 950 mobile. In this way, the example quantification device 950 is a remotely controllable and mobile quantification device.

[0128] The shape and configuration of the ROV 940 shown in Figure 6 is only exemplary in nature. The scope of the invention is not limited by the type of ROV a quantification device can attach to.

[0129] The ROV 940 comprises an ROV antenna 941, which is configured to enable remote communication with another communication node. For example, the ROV 940 may transmit its positional data to a remote controller.

[0130] The ROV 940 comprises a power module, a communication module, and a control module collectively designated part 942. The power module may comprise batteries and / or an interface for receiving power from the power grid and / or a generator.

[0131] The one or more quantification devices 199 of example system 100 may comprise one or more quantification devices 950.

[0132] The one or more quantification devices 299 of example system 200 may comprise one or more quantification devices 950.

[0133] More generally, the quantification device 950 may be particularly suitable for deployment at various ponds and tanks in a lithium brine system e.g. a concentration pond or an evaporation pond.Method

[0134] Figure 8 shows an example method 800 for performing quantification of lithium brine. The method 800 may be implemented with any of the quantification devices or systems described herein.

[0135] At step 801, an NMR instrument is tuned to a Larmor frequency of an isotope or element of interest using a reference sample. In one example, the NMR instrument is tuned to the lithium Larmor frequency at ambient conditions using a saturated lithium nitrate LiNOs solution. Small frequency shifts originated by varying ionic concentration of the brine, more particularly sodium and potassium, may be corrected by first tuning the instrument to hydrogen to measure the chemical shifts.

[0136] At step 802, a lithium brine sample is displaced into a probe. This can occur at various points of interest in a lithium brine system in surface application or a downhole application using a suitable quantification device herein.

[0137] Notably, the method 800 does not require preparation or manipulation of the sample. For example, no addition of calibrants or paramagnetic particles is required.

[0138] At step 803, the lithium brine sample in the probe is isolated for qNMR analysis.

[0139] At step 804, a static magnetic field is applied to the sample to achieve sufficient magnetization (spin polarization). This may comprise continuous or periodic monitoring to determine whether at least 99% magnetization has been achieved.

[0140] Step 804 may be performed with a magnet of a discrete-Halbach arrangement comprising a permanent magnet and an RF coil.

[0141] The static magnetic field may have a magnetic flux density of about 0.5 to 0.7 T.

[0142] At step 805, an oscillating magnetic field is applied to the sample. This may be performed with an RF coil of the magnet of step 804.

[0143] At step 806, magnetic resonance signal is received from nuclei spin precession. This may be performed with an RF coil of the magnet of step 804.

[0144] At step 807, some or all the above steps are repeated so as to obtain a plurality of measurements, which are then stacked (added and averaged). This can improve the signal to noise ratio of the measurements. The repetition of measurements may be performed periodically. In one example, each sample may take about 10 minutes to complete a single measurement cycle.

[0145] Generally, stacking more measurements will yield a better SNR and more accurate results. The process of obtaining and stacking the multitude of measurements, however, requires time. This represents a tradeoff between precision and acquisition time. It may be preferable to optimize for acquisition time (while ensuring a base level of precision) for certain tasks e.g. regular monitoring. It may be preferable to optimize for precision (while ensuring a base level of acquisition time) for other tasks e.g. daily process control. Regular monitoring may occur on a timescale of tens of minutes while daily process control may occur on a timescale of hours.

[0146] At step 808, magnetic field fluctuations (e.g. frequency shifts) caused by temperature variations are compensated for using a calibration curve, which is obtained from measurements of calibrants beforehand. This avoids the need for a calibrant, which would not be suitable for in-situ quantification of lithium brine.

[0147] At step 809, the temperature of the sample may be controlled. The T2 relaxation time, also known as the transverse relaxation time or spin-spin relaxation time, is a key parameter in qNMR and is a function of the temperature of the fluid being analyzed. NMR sensitivity increases with decreasing sample temperature. Thus, it may be preferable to accurately and steadily control the temperature of the sample, especially for a downhole application.

[0148] While steps 808 and 809 are depicted as belonging to a sequence of steps, these steps may occur throughout the quantification process not necessarily in the depicted order.

[0149] At step 810, quantification of an isotope of interest is determined. Calibration curves in relation to different concentrations are used for this purpose. The quantitative data may undergo further analysis. For example, the data may be compressed and / or encrypted in preparation for transmission.Interpretation

[0150] A number of methods have been described above. Any of these methods may be embodied in a series of instructions, which may form a computer program. These instructions, or this computer program, may be stored on a computer readable medium, which may be non-transitory. When executed, these instructions or this program cause a processor to perform the described methods.

[0151] Where an approach has been described as being implemented by a processor, this may comprise a plurality of processors. That is, at least in the case of processors, the singular should be interpreted as including the plural. Where methods comprise multiple steps, different steps or different parts of a step may be performed by different processors.

[0152] The steps of the methods have been described in a particular order for ease of understanding. However, the steps can be performed in a different order from that specified, or with steps being performed in parallel. This is the case in all methods except where one step is dependent on another having been performed.

[0153] The term "comprises" and other grammatical forms is intended to have an inclusive meaning unless otherwise noted. That is, they should be taken to mean an inclusion of the listed components, and possibly of other non-specified components or elements.

[0154] While the present invention has been explained by the description of certain embodiments, the invention is not restricted to these embodiments. It is possible to modify these embodiments without departing from the spirit or scope of the invention.

Claims

CLAIMS1. A system for in-situ quantification of lithium brine constituents, the system comprising: a probe for isolating a lithium brine sample; a sample extraction means configured to displace a lithium brine sample into the probe; and a device configured to perform low field quantitative nuclear magnetic resonance analysis on the lithium brine sample; wherein the probe and the device are deployed in-situ at a location within a lithium brine extraction site.

2. The system of claim 1, wherein the location is a surface location.

3. The system of claim 2, wherein the sample extraction means is deployed at an extraction point, a junction point, an accumulation point, or a concentration point of the brine extraction site.

4. The system of claim 2 or claim 3, further comprising a remotely controlled vehicle configured for attachment of the probe and the device thereto.

5. The system of claim 1, wherein the location is a downhole location.

6. The system of claim 5, wherein the sample extraction means is configured to divert a lithium brine sample from a pipeline of a formation tester and displace the diverted lithium brine sample into the probe.

7. The system of claim 5 or claim 6, further comprising a communications module, wherein the communications module is configured to interface with a multiconductor wireline cable.

8. The system of claim 5, wherein the location is at a submersible pump.

9. The system of claim 5, wherein the location is at a lithium brine producer aquifer.

10. The system of any one of claims 1 to 9, further comprising a temperature control unit for controlling the temperature of the lithium brine sample.

11. The system of any one of claims 1 to 10, wherein the low field quantitative nuclear magnetic resonance analysis is characterized by a magnetic flux density of less than 1 T.

12. A device for performing quantitative analysis of lithium brine, the device comprising: a probe for isolating a lithium brine sample; a fluid inlet for receiving the lithium brine sample; a fluid outlet for flushing the lithium brine sample; a permanent magnet surrounding the probe, the permanent magnet being configured to apply a static magnetic field to the lithium brine sample; a radiofrequency coil configured to apply an oscillating magnetic field to the lithium brine sample and receive a magnetic resonance signal; and a quantitative nuclear magnetic resonance instrument.

13. The device of claim 12, wherein the permanent magnet and the radiofrequency coil form a discrete-Halbach arrangement.

14. The device of claim 12 or claim 13, wherein the permanent magnet is configured to apply a static magnetic field that has a magnetic flux density of about 0.5 to 0.7 T.

15. The device of any one of claims 12 to 14, further comprising a temperature control unit for controlling the temperature of the lithium brine sample.

16. The device of any one of claims 12 to 15, wherein the probe comprises a tube that has an outer diameter of at least 10 mm.

17. The device of any one of claims 12 to 16, wherein the probe is made of polyetheretherketone.

18. A method of quantifying constituents of lithium brine, the method comprising: tuning a quantitative nuclear magnetic resonance instrument to a Larmor frequency; displacing a lithium brine sample into a probe; applying a static magnetic field to the lithium brine sample; applying an oscillating magnetic field to the lithium brine sample; and receiving a magnetic resonance signal from nuclei spin precession.

19. The method of claim 18, wherein the NMR instrument is tuned to the lithium Larmor frequency at ambient conditions using a saturated lithium nitrate LiNOs solution.

20. The method of claim 18 or claim 19, wherein applying the static magnetic field comprises determining that at least 99% magnetization has been achieved.

21. The method of any one of claims 18 to 20, further comprising repeating and stacking quantitative nuclear magnetic resonance measurements.

22. The method of claim 21, further comprising optimizing the repeating and stacking of quantitative nuclear magnetic resonance measurements for precision.

23. The method of claim 21, further comprising optimizing the repeating and stacking of quantitative nuclear magnetic resonance measurements for acquisition time.

24. The method of any one of claims 18 to 23, further comprising compensating for magnetic field fluctuations caused by temperature variations using a predetermined calibration curve.

25. The method of any one of claims 18 to 24, further comprising controlling the temperature of the lithium brine sample.

26. The method of any one of claims 18 to 25, wherein the method does not require a calibrant or a paramagnetic particle.

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