DK181523B1

DK181523B1 - Water treatment method and device

Info

Publication number: DK181523B1
Application number: DKPA202200886A
Authority: DK
Inventors: Juul Paw; Mathiesen Sune
Original assignee: Lithium Harvest ApS
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2024-04-02
Also published as: DK202200886A1; WO2024067932A1

Abstract

A method for processing produced water (10) from an oil and/or well (4) is disclosed. The method comprises the step of: a) receiving permeate from pre-treated produced water (10) or b) filtering the produced water (10) in a filtration unit (24) hereby producing permeate (filtrate) and retentate. The method comprises the step of extracting lithium from the permeate.

Description

DK 181523 B1 1

The present invention relates to a method for processing produced wa- ter from an oil and/or gas well. The present invention also relates to a process unit for processing produced water from an oil and/or gas well.

Prior art

Land-based drilling rigs are used for accessing oil and gas stored in be- neath the ground. In land based drilling rigs, large quantities of high pressure, extremely hot water are pumped into the petroleum reservoir beneath the ground. The water pressure forces the oil and gas upwards.

Moreover, the heat from the forced water lowers the viscosity of the oil and gas. The fluid that returns to the surface is so-called “produced water”. The “produced water” comprises hot gas, oil and water that was trapped underground, as well as the pumped water, along with earth and debris.

When the produced water is received on ground level, oil and gas are extracted to the highest possible extent.

When the oil and gas has been extracted from the “produced water”, the remaining “wastewater” needs to be cleaned in order to eliminate all of the additional oils and other compounds before the cleaned water can be discharged into the environment or re-used through the pressure pumps for repeated cycles of petroleum extraction. Produced water typ- ically contains various toxic organic and inorganic compounds.

In many land-based drilling rigs, however, no such cleaning is possible and therefore new clean water is transported by tank trucks. Moreover, the wastewater is typically transported by a truck to either a storage or to a purification plant. These procedures are very expensive and time consuming.

DK 181523 B1 2

Land-based cleaning at the drilling rigs can be very challenging since the characteristics and physical properties of the produced water vary considerably depending on the geographic location of the field, the geo- logical formations with which the produced water has been in contact and the type of hydrocarbon product being extracted.

US 20130048562 A discloses a method for treating gas well production wastewater. The method comprises the steps of: - contacting a production wastewater with a source of sulfate ions to form one or more metal sulfates; - precipitating the one or more metal sulfates from the production wastewater; - removing the one or more precipitated metal sulfates from the production wastewater to form a wastewater brine that is sub- stantially free of precipitated metal sulfate, the wastewater brine comprising sodium, magnesium, strontium, and calcium chlo- rides; - evaporating the wastewater brine in an evaporator to form water and evaporation products, - filtering the evaporation product to form a retentate comprising crystalline sodium chloride, and a filtrate comprising the liquor; - washing the retentate with saturated sodium chloride brine; - and drying the washed retentate.

US 20130048562 A also discloses that lithium can be recovered from at least one of the liquor and the filtrate.

Thus, there is a need for a method and an apparatus which reduces or even eliminates the above mentioned disadvantages of the prior art.

As used herein “produced water” means water separated from the pro- duction stream of oil and gas wells (drilling rigs).

DK 181523 B1 3

Summary of the invention

The object of the present invention can be achieved by a method as defined in claim 1 and by a process unit as defined in claim 12. Pre- ferred embodiments are defined in the dependent subclaims, explained in the following description and illustrated in the accompanying draw- ings.

The method according to the invention is a method for processing pro- duced water from an oil and /or gas well, wherein the method compris- es the step of extracting oil and/or gas produced water and hereafter carrying out a preliminary concentration process comprising the step of filtering the produced water in a filtration unit hereby producing perme- ate (filtrate) and retentate, wherein the method comprises the step of extracting lithium from the permeate, wherein the method comprises the following steps: a) conduction an additional filtrating process after extracting lithium from the permeate and b) applying the filtrated permeate as fracturing fluid being injected into the well.

Hereby, it is possible to clean the wastewater (the produced water after oil and/or gas has been extracted) to such an extent that the cleaned water can be discharged into the environment, be used for irrigation or re-used through the pressure pumps for repeated cycles of oil and/or gas extraction. Produced water typically contains various toxic organic and inorganic compounds. At the same time, it is possible to extract lithium and thus process the wastewater in a manner that has a profita- ble outcome.

Before the preliminary concentration process is carried out, the oil and gas has been extracted from the produced water.

DK 181523 B1 4

In an embodiment, the preliminary concentration process is carried out a separate step in a first location (e.g. near the well).

In an embodiment, the preliminary concentration process is carried out by using a processing unit according to the invention. The processing unit may be located in a location distance from the well.

In an embodiment, the preliminary concentration process is carried out by using a first treatment unit that is not a part of the processing unit according to the invention. In this embodiment, the processing unit is configured to receive wastewater defined as permeate from the prelimi- nary concentration process that is carried out in order to extract oil and/or gas from the produced water.

In an embodiment, the well is designed for accessing oil stored in be- neath the ground.

In an embodiment, the well is designed for accessing gas stored in be- neath the ground.

In an embodiment, the well is designed to access oil and gas stored in beneath the ground.

In an embodiment, the method processes produced water from a land- based drilling rig.

In an embodiment, the step of extracting oil and/or gas produced water comprises: a) a first step, in which electrocoagulation and dissolved air flotation are applied and b) a second step applying ultrafiltration.

Hereafter, lithium is extracted from the permeate. In an embodiment, the lithium is extracted from the permeate through several process

DK 181523 B1 steps.

In an embodiment, the first lithium extracting step comprises a Direct

Lithium Extraction process. In this process step (ion-exchange resin 5 method) a selective absorbent is used to extract lithium from the per- meate. The solution extracted from the permeate is then polished of impurities to yield high-grade Lithium Carbonate and Lithium Hydrox- ide.

When the resin is washed away and the "extracted" lithium is released, this water is sent to nanofiltration and Reverse Osmosis filtration for concentration. The permeate from these two processes can be reused for irrigation or as re-injection water. The retentate from the Reverse

Osmosis filtration unit must be further processed into Lithium Car- bonate.

In an embodiment, the method comprises the following steps: a) extracting lithium from the permeate is carried out by using an ion- exchange resin method that extracts lithium ions (Direct Lithium Ex- traction method) or a method that removes divalent metal ions in the permeate and leaves a concentrated lithium fluid and b) recovery of Li" as precipitates of Li>COs or LiOH.

In an embodiment, the method comprises the step of extracting lithium by using a precipitation method.

In an embodiment, the method comprises the step of extracting lithium by using an extraction method.

In an embodiment, the method comprises the step of extracting lithium by using a carbonization method.

DK 181523 B1 6

In an embodiment, the method comprises the step of extracting lithium by using a calcination leaching method.

In an embodiment, the method comprises the step of extracting lithium by using Xu's method (see: Extraction of lithium with functionalized lith- ium ion-sieves, September 2016, Progress in Materials Science 84).

In an embodiment, the method comprises the step of extracting lithium by using an electrodialysis method.

Lithium can be recovered in multiple ways. Fig. 5 illustrates how adsor- bents or ion exchange resins can be used. Adsorbents will absorb lithi- um ions onto the surface of the adsorbents.

A resin adsorption method is used by utilizing lithium-ion exchange ad- sorption technology. Either method will extract the lithium from the permeate and ready the solution containing lithium for lithium concen- tration. The adsorbents can be titanium dioxide, metal phosphates, composite antimonates, aluminum salt adsorbents or organic ion ex- change resins, nanometer adsorbents or reactive polymers.

The desorption is done when the absorbent is saturated with lithium. A desorption solution is fed backwards through the adsorption resin tank, and the desorbed lithium is ready for further concentration. The desorp- tion solution can be a variety of desorption solutions: aqueous electro- lyte solution, low salinity water, demineralized water, deionized water, saline solution, hydrochloric acid solution, acidic solution, sodium hy- droxide solution, alkalic solution.

Further concentration of lithium can be done by employing filtration technologies like nanofiltration and RO (reverse osmosis) filtration.

Nanofiltration can be done by utilizing polymer membranes and/or ce-

DK 181523 B1 7 ramic membranes (materials, SiC, Al20s, TiO3, ZrO3). This is done to concentrate the lithium before Ca/Mg removal and Li precipitation be- fore ending up with final product lithium carbonate (battery grade).

The permeate (filtered water) from both the nanofiltration and Reverse

Osmosis (RO) filtration will partly be used in the above process, but it can also be used for reuse purposes in the oil and gas industry as re- injection water.

In an embodiment, the method comprises the following steps: a) selectively removing unwanted contaminants from the permeate and/or b) selectively removing lithium from the permeate.

In an embodiment, the step of extracting lithium from the permeate is carried out by using a Li* selective membrane to carry out a selective membrane filtration.

In an embodiment, the recovery of Li* (as precipitates of Li>COs or Li-

OH) is done by extracting lithium from the resin and recovering Lit as precipitates of Li>CO3 or LiOH after a washing process.

In an embodiment, the recovery of Lit (as precipitates of Li>COs or Li-

OH) is done by a filtration process (e.g. nanofiltration and/or Reverse

Osmosis filtration) in which precipitates of Li>CO3 or LIOH are retained.

The step of filtering the produced water in a filtration unit hereby pro- ducing permeate (filtrate) and retentate is a pre-treatment that is car- ried out before the step of extracting lithium from the permeate.

In an embodiment, the filtration unit is an ultrafiltration unit that com- prises:

DK 181523 B1 8 a) flat sheet membranes and/or b) tubular membranes, wherein the membranes are made of: - a ceramic material preferable SiC, Al203, TiO3 or ZrOs or - a polymer material.

In an embodiment, the ultrafiltration unit comprises ceramic flat sheet membranes arranged in a membrane reactor, wherein granular activat- ed carbon is present in the membrane reactor.

In an embodiment, magnetic water treatment is applied to initiate pre- cipitation of particles.

Magnetic water treatment may be applied to initiate precipitation of par- ticles such as salts (carbonate, chloride and sulphate salts of Cax*,

Mg>*, Fe>+ and Fes* cations).

In an embodiment, a first post-processing step is carried out, wherein said first post-processing step concentrates, or purifies an output from a previous method step.

In an embodiment, a second post-processing step is carried out after the first post-processing step, wherein said second post-processing step concentrates or dries an output from the first post-processing step.

The process unit according to the invention is a process unit comprises a separator that is configured to receive and process permeate (filtrate) from the produced water, wherein the separator is arranged and config- ured to extract lithium from the permeate, wherein the process unit comprises a filtration unit arranged and configured to extract oil and/or gas from the produced water and hereafter filter the produced water hereby produce permeate (filtrate) and retentate.

DK 181523 B1 9

Hereby, it is possible to clean the wastewater (the produced water after oil and/or gas has been extracted) to such an extent that the cleaned water can be discharged into the environment, used for irrigation or re- used through the pressure pumps for repeated cycles of oil and/or gas extraction. Produced water typically contains various toxic organic and inorganic compounds. At the same time, it is possible to extract lithium and thus process the wastewater in a manner that has a profitable out- come.

The separator is a treatment unit that comprises one or more devices arranged and configured to process the permeate.

It is an advantage that the process unit comprises a filtration unit ar- ranged and configured to extract oil and/or gas from the produced wa- ter and hereafter filter the produced water hereby produce permeate (filtrate) and retentate. Hereby, it is possible to process the produced water that comprises oil and/or gas and hereby extract the oil and/or the gas from the produced water.

In an embodiment, the separator is arranged and configured for a) extracting lithium from the permeate is carried out by using an ion- exchange resin method that extracts lithium ions via a direct extrac- tion method or a method that removes divalent metal ions in the permeate and b) recovering Li* as precipitates of Li>CO3 or LiOH.

In an embodiment, the separator is arranged and configured to a) selectively removing unwanted contaminants from the permeate and/or

DK 181523 B1 10 b) selectively removing lithium from the permeate.

In an embodiment, the separator comprises one or more Li* selective membranes that are arranged and configured to extracting lithium from the permeate by carrying out a selective membrane filtration.

In an embodiment, the separator comprises: - a washing unit that is arranged and configured to wash the resin and - an extracting unit that is arranged and configured to extract lithium from the resin and recovering Lit as precipitates of Li>COz or LiOH when the resin has been treated in the washing unit.

In an embodiment, the separator is configured to recover Li" (as precip- itates of Li2CO3 or LIOH) by extracting lithium from the resin and recov- ering Li* as precipitates of Li>COs or LiOH after a washing process.

In an embodiment, the separator comprises a filter assembly that is arranged and configured to recover Li" (as precipitates of Li>CO3 or Li-

OH) by filtration and hereby retaining precipitates of Li>COs: or LiOH.

In an embodiment, the filtration unit is an ultrafiltration unit that com- prises: a) flat sheet membranes and/or b) tubular membranes, wherein the membranes are made of: - a ceramic material preferable SiC, Al203, TiO3 or ZrOs or - a polymer material.

In an embodiment, the ultrafiltration unit comprises a number of ce- ramic flat sheet membranes arranged in a membrane reactor, wherein activated carbon is present in the membrane reactor. In an embodi- ment, the activated carbon is granular activated carbon.

DK 181523 B1 11

In an embodiment, the process unit comprises a magnetic water treat- ment unit that is arranged and configured to initiate precipitation of particles.

In an embodiment, the process unit comprises a first post-processing unit arranged and configured to concentrate or purify an output from a processing unit of the process unit.

In an embodiment, the process unit comprises a second post-processing unit is arranged and configured to concentrate or dry an output from the first post-processing unit.

Description of the Drawings

The invention will become more fully understood from the detailed de- scription given herein below. The accompanying drawings are given by way of illustration only, and thus, they are not limitative of the present invention. In the accompanying drawings:

Fig. 1 shows a schematic view of a prior art land-based oil well;

Fig. 2A shows a schematic view of a process unit for processing pro- duced water according to the invention;

Fig. 2B shows a schematic view of the process unit shown in Fig. 2A;

Fig. 3 shows a separator according to the invention;

Fig. 4 shows a separator according to the invention and

Fig. 5 shows how adsorbents or ion exchange resins can be used.

Detailed description of the invention

Referring now in detail to the drawings for the purpose of illustrating preferred embodiments of the present invention, a process unit 2 of the present invention is illustrated in Fig. 2.

Fig. 1 is a schematic side view of a prior art land-based well (drilling

DK 181523 B1 12 rig) 4 for accessing oil and/or gas. The well 4 comprises a first pipe for pumping pressurised water into the petroleum reservoir beneath the ground. The water pressure forces the oil and gas upwards through a second pipe 16. The first pipe 18 and the second pipe 16 extend inside a casing 14. The first pipe 18 is connected to a fracturing fluid tank 10 via a tube 8. The second pipe 16 is connected to an oil and gas tank 12 via a tube 6.

Fig. 2A illustrates a schematic view of a process unit 2 for processing produced water according to the invention. The process unit 2 is con- nected to a land-based well (drilling rig) 4 corresponding to the one shown in and explained with reference to Fig. 1.

Like the land-based well shown in Fig. 1, the well 4 comprises a tube 8 that is connected to a fracturing fluid tank (not shown). The tube 8 is in fluid communication with a pipe for injecting pressurised water into the petroleum reservoir beneath the ground.

The process unit 2 comprises a filtration unit 24 arranged and config- ured to extract oil and/or gas from the produced water and hereafter filter the produced water hereby produce permeate (filtrate) and reten- tate. Accordingly, the permeate can be processed in order to extract lithium and hereafter be filtered and used as fracturing fluid to be in- jected into the petroleum reservoir beneath the ground via the tube 8.

The well 4 comprises a tube 6 that is connected to the pipe through which the oil and/or gas containing produced water reached ground lev- el. The tube 6 is connected to the filtration unit 24. In an embodiment, the filtration unit 24 comprises several filtration modules. In an embod- iment, the filtration unit 24 comprises a first model (not shown) de- signed to extract gas and/or oil from the produced water.

DK 181523 B1 13

When gas and/or oil from the produced water has been extracted from the produced water, the wastewater is cleaned in the filtration unit 24.

A first fraction of the cleaned wastewater is guided to a fracturing fluid tank (corresponding to the one shown in Fig. 1) via line 26 and line 28.

The process unit 2 comprises a separator 20 arranged and configured to extract lithium from the permeate. The concentrated fraction (reten- tate) of the wastewater, however, may be processed by using various processing steps. Lithium may be extracted from the permeate by using various techniques.

As indicated, the process unit 2 can optionally comprise an additional treatment unit 22 arranged after the separator 20. The additional treatment unit 22 may be arranged and configured to carry out a filtra- tion process. The additional treatment unit 22 may be arranged and configured to carry out a drying process. It can be seen that clean wa- ter is leaving the additional treatment unit 22 through line 26. In an embodiment, clean water may be provided from the separator 20.

Fig. 2B illustrates a schematic view of the process unit 2 shown in Fig. 2A. The process unit 2 is, however, not connected to a well like the one shown in Fig. 2A. The process unit 2 comprises a separator 20 and op- tionally an additional treatment unit 22 like shown in and explained with reference to Fig. 2A. The process unit 2 may be placed in any suitable and desirable location.

Fig. 3 illustrates a separator 20 according to the invention. The separa- tor 20 comprises several tanks 30, 30’, 30”, 30'”. The tanks 30, 30, 30”, 30" are connected to a forward flow feed line 36 and a reverse flow feed line 38. The tanks 30, 30’, 30”, 30" are connected to a for- ward flow discharge line 34 and a reverse flow discharge line 34.

It is possible to regulate the flow through tanks 30, 30’, 30”, 30’ can

DK 181523 B1 14 be performed by valves 32, 32’ coupled to the tanks 30, 30’, 30”, 30" as shown in Fig. 3. Each tank 30, 30’, 30”, 30'” may contain a sorbent material as described herein.

The first tank 30 is the first tank to receive fluid flow through forward flow feed line 36. The second 30’ is the second tank to receive fluid flow through the forward flow feed line 36. The third 30” is the third tank to receive fluid flow through forward flow feed line 36 and the fourth tank 30" is the fourth tank to receive fluid flow through forward flow feed line 36.

The separator 20 may be operated in several different modes. When the fluid containing the desired constituent (brine) has been introduced to tank 30 by opening the valves 32 and 32’, the sorbent material in tank 30 begins to absorb constituents in the brine.

When the brine is a lithium-containing brine, the lithium ions are at- tracted to water molecules in the fluid by the lone pairs of electrons in water molecules. When the lithium ions of the fluid pass near the sorbent absorbing sites, the lithium loses energy by shedding the water molecules and enters the absorbing site. In an embodiment, an ion- exchange resin can be used where the lithium (or another constituent) ion is exchanged with an ion that is currently attached to the resin, where the exchange also results in a lower energy state for the constit- uent ion and/or energy state of the resin. It is important to underline that it is possible to apply other absorption techniques.

When a fluid containing the desired constituent (brine) flows from the forward flow feed line 36 to the tank 30, the valves 32, 32' are opened for letting the brine to flow through the tank 30. The brine fluid from the forward flow feed line 36 is allowed to flow through the tank 30 until sorbent material in the tank 30 has started absorbing the desired con-

DK 181523 B1 15 stituent, and may near saturation, with a desired constituent in the brine fluid from the forward flow feed line 36.

When the desired concentration of constituent has been absorbed by the sorbent, a second fluid (e.g. water) flow flows into the tank 30. As the second fluid flow begins to move through the tank 30, the interface between the brine and the second fluid (the brine-water interface) moves along the length of the tank 30. As the interface passes a certain level in the tank 30, the ions that have been captured in the sorbent may also lose energy by leaving the absorption site and entering the fluid stream in the second fluid.

In the case of lithium, the lithium ion is attracted to a plurality of water molecules in the second fluid. Hereby, these water molecules will place the lithium ion at a lower energy state in the second fluid than if the lithium ion were to remain absorbed (attached) to the sorbent particle.

The lithium is flushed or removed from the sorbent and is absorbed by the second fluid.

In an embodiment, once the sorbent material in tank 30 has been com- pletely saturated, a second dilute flow flows into tank 30. This dilute flow may come from the forward flow feed line 36 or from the reverse flow feed line 38. The dilute flow may comprise a dilute solution of the desired constituent dissolved in water and forces the remaining brine (and all of the impurities still present in the brine) from the tank 30 while at least partially filling the tank 30. By keeping a basically con- stant pressure within tank 30, the structural integrity of the sorbent material in the tank 30 is relatively maintained. The removal of the brine fluid may reduce the impurities that are present when the desired constituent is removed from the tank 30. While filling the tank 30 with the dilute flow, the second tank 30’ may be being filled with brine flow from the forward flow feed line 36. Accordingly, the tank 30 will lead

DK 181523 B1 16 the flow ahead of the second tank 30’. Other valves in the separator 20 may control the flow of brine and/or dilute flow into the tanks 30, 30, 30”, 30".

When the first tank 30 has been filled with the dilute flow, a stripping solution is placed into the tank 30 to remove the desired constituent from the sorbent material in the tank 30. This flow may also come from forward flow feed line 36 or from the reverse flow feed line 38 and re- generates the ability of tank 30 to absorb the desired constituent from a brine fluid flow.

While the first tank 30 is absorbing the desired constituent from the brine flow, the second tank 30' may be undergoing a dilute flow and third tank 30” and the fourth 30'” may be receiving the stripping solu- tion to remove the desired constituent from the sorbent material. Ac- cordingly, the separator 20 may be operated as a continuous sequential flow system, such that the brine flow from the forward flow feed line 36 is continuously flowing into one of the tanks 30, 30’, 30”, 30'” and the desired constituent is continuously being removed from another of tanks 30, 30’, 30”, 30”” once an initial cycle through the number of tanks 30, 30', 30”, 30” has been completed.

Fig. 4 illustrates a separator 20 according to the invention. The separa- tor 20 comprises a tank assembly 48. In an embodiment, the output of the tank 48 may be purified, e.g., have contaminants removed from the output stream from the tank 48, and may also be concentrated in the system with a concentration membrane.

A purification unit being either of the following: a cross-flow membrane, an ion-exchange resin, solvent extraction system, and/or other purifica- tion devices configured to allow the targeted constituent and solvent to pass, or permeate, while retaining or preventing undesired impurities

DK 181523 B1 17 from passing through the purification membrane and/or ion-exchange resin.

The one or more purification membranes may be a nanofiltration mem- brane, or other type of filtration membrane, having a porosity and/or separation affinity for specific constituents in the output of tank 48 and hereby reduce the levels of impurities to the parts per million levels.

The one or more purification membranes may be operated at any suita- ble pressure. In an embodiment, an ion-exchange resins may be em- ployed to remove polyvalent metal ions, sulphates, borates, and/or oth- er impurities as desired.

In an embodiment, the concentration membrane is configured to sepa- rate and/or remove the solvent, typically water, from the stream con- taining the desired constituent. The concentration membranes may be susceptible to impurity materials affecting the performance of the sepa- ration. In an aspect of the present disclosure, a purification membrane, such as a cross-flow membrane may be used prior to the concentration membrane to reduce the effects of impurities on the separator 20.

In an embodiment, a concentration membrane is configured to receive a certain product stream to pass through the purification membrane.

The solvent passes through the concentration membrane and the target constituent is rejected and/or retained by the concentration membrane.

In an embodiment, a Reverse Osmosis (RO) unit may be employed as a concentrating membrane. Concentration membranes operated as re- verse osmosis systems may concentrate the targeted constituent to weight percentage levels. Concentration membranes operated as re- verse osmosis systems may be limited by the osmotic pressure of the solution and the practical limits of the pressure ratings of the single el- ement components.

DK 181523 B1 18

In an embodiment, the concentration membrane is part of a heating system that boils off some of the liquid in the product stream, as well as an evaporative system that may or may not recover some of the evapo- rated liquid. In an embodiment, the concentration membrane is an evaporation pond, a boiler system, an evaporative cooler, and/or other systems that concentrate the amount of desired constituent in the product stream.

The purification membrane units and the concentration membrane units may be made up of single elements arranged in arrays. The purification and concentration membrane units can be arranged in arrays and fitted to mobile systems.

In an embodiment, the separator 20 is configured to isolate other tar- geted constituents such as CO: from a feed gas stream. The CO> may be applied to produce the final Li>COz product by reacting the lithium rich brine stream with the separated CO». In the case of LiOH produc- tion, the raw purification and separator 20 may allow the direct feed to a lithium hydroxide electrolysis system. Accordingly, the purified prod- uct will meet the raw purification standards and the system may only employ the secondary purification system to prepare the brine for elec- trolysis to LIOH. In both these product cases, lithium is the targeted constituent, but other elements may behave in a similar fashion and be targeted in accordance with the present disclosure.

The separator 20 comprises a plurality of tanks 50, 50’, 50”, 50", col- lectively referred to as a tank assembly 48. The tank assembly 48 com- prises a filtering unit 52 that may be a purification membrane and/or ion-exchange resin. The tank assembly 48 comprises a first additional treatment 54 that may be a concentration membrane.

DK 181523 B1 19

The separator 20 comprises valves 40, 40’, 40” that are arranged and configured to couple one or more of the inlets (brine) 42, the inlet (di- lute) 44 and inlet (clean water) 46 to the tanks 50 50’, 50”, 507”. The valves 40, 40’, 40” may also regulate the flow and/or flow rate of the inputs 42, 44, 46.

The valve 40”” is configured to control the flow out from the tank as- sembly 48 to direct the flow toward the filtering unit 52 or as an output via the line 68. Brine from the line 68 may be recycled to one or more of the inlets 42, 44, 46 and/or to one or more of the tanks 50 50', 50”, 50”.

The line 62 from the filtering unit 52 is passed to the first additional treatment unit 54. Another line 60 from the filtering unit 52 may exit the separator 20. Alternative, the line 60 may be recycled back to one or more inlets 42, 44, 46.

The first additional treatment unit 54 is connected to an output line 70 (for exiting the separator 20) or being recycled back to one or more inlets 42, 44, 46. A second output line 64 is connected to a second ad- ditional treatment unit 56.

In one embodiment, the separator 20 may be operated as follows. Ini- tially, the valve 40 is opened while the valves 40', 40” are closed. Ac- cordingly, the brine inlet 42 can flow through the tank assembly 48.

The brine input 42 may be analysed to determine the concentration of the desired constituent of lithium to determine how long to flow brine input 42 through tank assembly 48. The brine input 42 may be flowed through the tank assembly 48 until one of the tanks (e.g., the first tank 50) is approximately saturated with the desired constituent. The brine input 42 may then be directed toward another tank in the tank assem- bly 48 (e.g. the second tank 507). The output 68 may be recycled to the brine input 42 if desired.

DK 181523 B1 20

When a portion of the tank assembly 48 (e.g. the first tank 50) is satu- rated with the desired constituent, the flow of brine input 40 is stopped to that portion of the tank assembly 48. Now the valve second 40' is opened to allow a second flow - the "dilute flow,” "dilute input” or "di- lute stream” - to flow into the saturated portion of the tank assembly 48 in such a manner that the dilute flow displaces the remaining brine in the saturated portion of the tank assembly 48. This displacement re- duces the particulates and/or other impurities that may be captured by the filtering unit 52, while minimizing the removal of the desired con- stituent from the tank assembly 48.

The flow rate of dilute input 44 may be measured such that a bed vol- ume, multiple bed volumes, and/or some other desired amount, of di- lute input 44 is flowed through the desired portion of the tank assembly 48. Dilute input 44 may be passed through filtration unit 52 or be di- rected to output line 68 as desired by changing the position of valve 40'”. The position of the valve 40”” may be changed during the dilute input 44 flow to reduce any losses of desired constituent that may be dislodged from the tank assembly 48 during the dilute input 44 flow.

When a portion of the tank assembly 48 is saturated with the desired constituent, and the dilute input 44 has displaced the brine input 42 in that portion of the tank assembly 48, the valve 40” is opened and the valve 40”” is positioned to pass flow from the tank assembly 48 to the filtration unit 52. This flow (the clean flow or clean input 46) removes the desired constituent from the tank assembly 48 and passes the de- sired constituent in solution to filtration unit 52 and subsequently to the first additional treatment unit 54 and optionally to the second additional treatment unit 56.

The clean input 46 removes the desired constituent from the tank as- sembly 48 in solution. This solution is then flowed through the filtration

DK 181523 B1 21 unit 52 to remove impurities from the solution prior to the output line 62. Hereafter, the output line 62 is flowed through the first additional treatment unit 54 in order to remove the desired constituent from the flow in the line 62 as a concentrated output through the line 64, while the solvent is removed through output line 70.

Fig. 5 illustrates how adsorbents or ion exchange resins can be used.

Adsorbents will absorb lithium ions onto the surface of the adsorbents.

A resin adsorption method is used by utilizing lithium-ion exchange ad- sorption technology. Either method will extract the lithium from the permeate and ready the solution containing lithium for lithium concen- tration. The adsorbents can be titanium dioxide, metal phosphates, composite antimonates, aluminum salt adsorbents, organic ion ex- change resins, nanometer adsorbent or reactive polymers.

Desorption is done when the absorbent is saturated with lithium. A de- sorption solution is fed backwards through the adsorption resin tank, and the desorbed lithium is ready for further concentration. The desorp- tion solution can be a variety of desorption solutions: aqueous electro- lyte solution, low salinity water, demineralized water, deionized water, saline solution, hydrochloric acid solution, acidic solution, sodium hy- droxide solution, alkalic solution.

Nanofiltration can be done by utilizing polymer membranes and/or ce- ramic membranes (materials, SiC, Al20s, TiO3, ZrO3). This is done to concentrate the lithium before Ca/Mg removal and Li precipitation be- fore ending up with final product lithium carbonate (battery grade).

DK 181523 B1 22

The permeate (filtered water) from both the nanofiltration and Reverse osmosis (RO) filtration will partly be used in the above process, but it can also be used for reuse purposes in the oil and gas industry as re- injection water.

DK 181523 B1 23

List of reference numerals 2 Process unit 4 Well 6,6", 8 Tube

Fracturing fluid tank 12 Oil and gas tank 14 Casing 16 Pipe 10 18 Pipe 20 Separator 22 Additional treatment unit 24 Filtration unit 26, 28, 29 Line 30, 30’, 30”, 30" Tank 32, 32’ Valve 34 Discharge line 36 Feed line 38 Valve 40, 40’, 40”, 40" Valve 42 Inlet (brine) 44 Inlet (dilute) 46 Inlet (clean water) 48 Tank assembly 50, 50’, 50”, 50" Tank 52 Filtering unit 54 First additional treatment unit 56 Second additional treatment unit 58, 60, 62 Line 64, 66, 68, 70 Line

Claims

DK 181523 B1 24 Patent claim

1. Method for treating formed water (10) from an oil and/or gas source (4), where the method comprises the step of extracting oil and/or gas formed water and then carrying out an initial concentration process comprising the steps with filtering the formed water (10) in a filtration unit (24), whereby permeate (filtrate) and retentate are produced, where the method comprises the step of extracting lithium from the permeate, characterized in that the method comprises the following steps: a) carrying out of a supplementary filtration process after extracting lithium from the permeate and b) using the filtered permeate as a fracturing fluid that is injected into the bread (4).

2. Method according to claim 1, where the method comprises the following steps: a) extraction of lithium from the permeate is carried out by means of an ion exchange resin method, whereby lithium ions are extracted, or a method whereby divalent metal ions in the permeate are removed, leaving a concentrated lithium fluid, and b) recovery of Lit as precipitates of Li>2COs3 or LiOH.

3. Method according to one of the preceding claims, where the method comprises the following steps: a) selective recovery of unwanted contaminants from the permeate

DK 181523 B1 25 and/or b) selective removal of lithium from the permeate.

4. Method according to claim 1, wherein the step of extracting lithium from the permeate is carried out by means of a selective Li' membrane to carry out a selective membrane filtration.

5. Method according to one of claims 2-4, where the recovery of Li" (as precipitates of Li>CO3 or LIOH) takes place by: a) extraction of lithium from the resin and recovery of Li" as precipitates of LizCO3 or LIOH after a washing process .

6. Method according to one of claims 2-4, where the recovery of Lit (as precipitates of LizCO3 or LiOH) takes place by a filtration process in which precipitates of LizCO3 or LiOH are retained.

7. Method according to one of the preceding claims, wherein the filtration unit (24) is an ultrafiltration unit (24) comprising: a) flat plate membranes and/or b) tube membranes, where the membranes are made of: - a ceramic material, preferably SiC, Al 2 O 3 , TiO 3 or ZrO 3 , or - a polymer material.

8. Method according to claim 7, wherein the ultrafiltration unit (24) comprises ceramic, flat plate membranes arranged in a membrane reactor, where granular activated carbon is present in the membrane reactor.

DK 181523 B1 26

9. Method according to one of the preceding claims, where magnetic water treatment is used to initiate particle precipitation.

10. Method according to one of the preceding claims, where a first post-processing step is carried out, where in the first post-processing step, an output from a previous process step is concentrated or purified.

11. Method according to claim 10, where a second finishing step is carried out after the first finishing step, where an output from the first finishing step is concentrated or dried in the second finishing step.

12. Treatment unit (2) for treating produced water (10) from an oil and/or gas well (4), wherein the treatment unit (2) comprises a separator (20) configured to receive and treat permeate (filtrate) from the water formed (10), where the separator (20) is arranged and configured to extract lithium from the permeate, characterized in that the treatment unit (2) comprises a filtering unit (24) which is arranged and configured to extract oil and/or gas from the formed water (10) and then filter the formed water (10), thereby producing permeate (filtrate) and retentate.

13. Treatment unit (2) according to claim 12, where the separator (20) is arranged and configured for: a) extraction of lithium from the permeate is carried out by means of an ion exchange resin method, whereby lithium ions are extracted, or a method whereby divalent metal ions in the permeate is removed, and a concentrated one is left behind

DK 181523 B1 27 lithium fluid, and b) recovery of Li' as precipitates of Li2CO3 or LiOH.

14. Treatment unit (2) according to claim 12 or 13, where the separator (20) is arranged and configured to: a) selectively remove unwanted contaminants from the permeate and/or b) selectively remove lithium from the permeate.

15. Treatment unit (2) according to claim 12 or 13, where the separator (20) comprises one or more selective Li* membranes that are arranged and configured to extract lithium from the permeate by performing a selective membrane filtration.

16. Treatment unit (2) according to one of claims 12-15, wherein the separator (20) comprises: - a washing unit which is arranged and configured to wash the resin, and - an extraction unit which is arranged and configured to extract lithium from the resin and recover Lit as precipitates of Li2COs or LiOH after the resin has been treated in the washing unit.

17. Treatment unit (2) according to one of claims 12-16, wherein the separator (20) is configured to recover Li" (as precipitates of Li2CO3 or LIOH) by extracting lithium from the resin and recovering Lit as precipitates of Liz2COz or LiOH after a washing process.

18. Treatment unit (2) according to one of claims 12-16, where separate

DK 181523 B1 28 the reactor (20) comprises a filter device which is arranged and configured to recover Li" (as precipitates of Li2CO3 or LiOH) by filtration, and whereby pre-precipitates of Li2CO3 or LiOH are retained.

19. Treatment unit (2) according to one of claims 12-16, where the filtration unit (24) is an ultrafiltration unit (24) comprising: a) flat plate membranes and/or b) tubular membranes, where the membranes are made of: - a ceramic material, preferably SiC, Al 2 O 3 , TiO 3 or ZrO 3 , or - a polymer material.

20. Treatment unit (2) according to one of claims 12-19, wherein the ultrafiltration unit (24) comprises a number of ceramic, flat plate membranes which are arranged in a membrane reactor, where granular activated carbon is present in the membrane reactor .

21. Treatment unit (2) according to one of claims 12-20, wherein the treatment unit (2) comprises a magnetic water treatment unit that is arranged and configured to initiate particle precipitation.

22. Treatment unit (2) according to one of claims 12-20, wherein the treatment unit (2) comprises a first post-treatment unit (52) which is arranged and configured to concentrate or purify an output from a treatment unit of the treatment unit (2 ).

DK 181523 B1 29

23. Processing unit (2) according to claim 22, wherein the processing unit (2) comprises a second post-processing unit (54) which is arranged and configured to concentrate or dry an output from the first post-processing unit (52).