EA042122B1 - METHOD FOR CONTROL OF MINERALIZATION OF LOW-MINERALIZED INJECTION WATER - Google Patents

Description

Technical field

The present invention relates to oil recovery methods using stimulation techniques such as brackish water flooding.

State of the art

One of the problems associated with brackish water flooding is that the water produced by demineralization technologies has a mineralization level that is less than optimal for continuous injection into an oil-bearing formation. Indeed, demineralized water can degrade the reservoir properties of the oil-bearing rock in the reservoir and slow down the recovery of oil, for example, causing an increase in injectivity losses from clay swelling and the migration of fine particles. Therefore, there is an optimal degree of salinity of the injected water, combining the advantage of increased oil recovery (with secondary / intensifying methods of production) and at the same time reducing the risk of deterioration of the reservoir properties of the formation, and this optimal salinity can vary within one productive formation depending on changes in the composition of the rock in space layer (both vertically and horizontally). Generally, when an oil reservoir contains a rock with a high amount of swellable clays, deterioration of the reservoir properties of the reservoir with continued oil recovery can be avoided if the injected water has a total dissolved solids content (TSDS) in the range of 200 to 10,000 parts per million (ppm). ), and the ratio of the concentration of polyvalent cations in low-mineralized injected water to the concentration of multivalent cations in the relict water of the formation is less than 1, for example, less than 0.9.

Another problem associated with brackish water flooding is the reservoir's susceptibility to acidification or scaling, whereby sulfate levels in the injected brackish water usually need to be kept low. Acidification occurs due to the multiplication of sulfate-reducing bacteria, using sulfates in their metabolism, with the formation of hydrogen sulfide. Salt precipitation occurs due to mineral precipitation when injection water containing phosphates is mixed with connate water containing precipitation precursor cations such as barium cations.

Definitions.

In the description below, the following terms are used.

Highly Mineralized/Highly Mineralized Feedwater - Feedwater for a demineralization plant, which is typically sea water (MB), estuary water, aquifer water, or mixtures thereof.

Reverse osmosis (OO) filtration module - comprises a high pressure vessel or housing containing one or more OO membrane elements, preferably 1 to 8, in particular 4 to 8 OO membrane elements.

Nanofiltration Module (NF) - contains a pressure vessel containing one or more NF membrane elements, preferably from 1 to 8, in particular from 4 to 8 NF membrane elements.

The reverse osmosis (OO) stage of a demineralization plant is a group of OO filtration modules connected in parallel to each other. Similarly, the nanofiltration (NF) stage of a demineralization plant is a group of NF filtration modules connected in parallel to each other.

Membrane block - contains stages of OO- and NF-filtration, connected to each other to provide a stepped separation of the concentrate and having, as a rule, a common system of valves (in particular, valves, gate valves and other pipeline fittings) and pipelines. One, two or more membrane units can be mounted on a frame base.

Relic water - water present in the pore space of the oil-bearing layer of the reservoir.

Aqueous displacement fluid - an aqueous fluid that can be injected into an injection well after injection of a small pore volume (PV) plug (slug) of mixed brackish injection water.

An oil zone is a term well known to those skilled in the art for a portion of a formation rock layer(s) in which oil saturation has been increased due to the application of an enhanced oil recovery process that acts on immobile oil.

Pore volume entrained (PVR) - the pore volume of the formation rock layer(s) flushed by injection fluids (low-mineralized injection water and any aqueous drive fluid) between the injection well and the production well, averaged over all flow paths. When two or more production wells are associated with an injection well, the term swept pore volume means the pore volume of the formation rock layer(s) swept by the injected fluids between the injection well and its associated production wells.

A plug (slug) is a low pore volume of a liquid injected into an oil-bearing layer of a productive formation. The pore volume values for brackish injection water plugs are based on the swept pore volume (PVR) of the formation rock layer(s).

The injection system includes an injection line and one or more injection pumps for pumping injection water through the injection well and injection of injection water into the reservoir formation.

Well injectivity refers to how easily a fluid (eg, injected water) is injected into the reservoir layer.

The mixing system contains several feed lines for transferring mixed flows leading to at least one confluence point, and a discharge line for diverting the mixed (composite) injection water flow from the confluence point(s) (places).

OS PTB or OK PTB is the total content or total concentration of dissolved solids in the water stream, usually expressed in mg/l (ppm equivalent). In the case of a water stream in the embodiments described here, the dissolved solids are ions, so the TBS or TBR is a measure of the salinity of the water stream.

The Sodium Adsorption Relative Ratio (SAR) is used to assess the state of flocculation or dispersion of clays in reservoir rock. Generally, sodium cations help to disperse the clay particles, while magnesium cations cause them to flocculate. The relative sodium adsorption rate (SAR - from the English sodium adsorption ratio) is calculated using the following formula:

^(0.5[Ca2+CMg2+]') where the concentration of sodium, calcium and magnesium cations is expressed in milliequivalents per 1 liter.

Xmas tree fittings are a set of valves, pipe assemblies and connecting devices used for water injection wells and allow you to control the flow of water into the injection well.

Dry X-mas tree (also called land-based X-mas tree) means a surface X-mas tree (on the ground or on a platform or floating oil production, storage and offloading system FPSO (from the English Floating Production, Storage & Offloading facility).

Bottom X-mas tree means an underwater X-mas tree located below the water surface, in particular on the seabed.

Disclosure of invention

The present invention relates to the control of salinity of low-salinity (low-salinity) injection water during waterflooding of an oil reservoir with low-salinity water, when the formation rock surrounding the first injection well and the second injection well has different chemical characteristics, resulting in a different risk of deterioration of reservoir properties. formation (loss of permeability), when low-mineralized injected water is injected into the reservoir through injection wells. The present invention also relates to controlling the concentration of one or more individual ions, or individual ions by ion type, in brackish injection water(s) injected into injection wells drilled into different areas of a reservoir having different rock characteristics, resulting in a different risk of deterioration of reservoir properties. formation.

According to a first aspect, the present invention relates to a method for producing a first mixed brackish injection water for injection into at least one injection well drilled into a first region of an oil reservoir and a second mixed brackish injection water for injection into at least one injection well drilled in the second area of the oil-bearing formation, and the reservoir rock of the first and second areas have, respectively, the first and second composition of the rock, which presents a different risk of deterioration of the reservoir properties of the reservoir, and the first and second mixed brackish injection waters contain variable amounts of permeate (filtrate) nanofiltration, permeate reverse osmosis and, in some cases, varying amounts of seawater and/or fines stabilization additives, and the compositions of the first and second mixed brackish injection water are maintained within the limits, respectively, of the first and second predetermined operating ranges, which allows you to combine improving or maximizing enhanced oil recovery from the first and second areas of the reservoir while reducing or minimizing the deterioration of reservoir properties when injecting the first and second mixed low-salinity injection water from the injection well(s) into the first and a second region of the oil-bearing formation.

The first mixed low-salinity injection water may be injected into the injection well(s) drilled into the first region of the reservoir, and the second mixed low-salinity injection water may simultaneously (in parallel) be injected into the injection well(s) drilled into the second region of the reservoir. However, the start and end of injection of the first and second brackish waters into the injection well(s) drilled into the first and second reservoir regions, respectively, need not be simultaneous.

- 2 042122

Alternatively, injection of the first mixed brackish water into the injection well(s) drilled into the first reservoir region may be prior to injection of the second mixed brackish water into the injection well(s) drilled into the second reservoir region (or vice versa), m .e. injection of the first and second mixed brackish injection waters may be carried out sequentially.

It is also contemplated that the reservoir may have one or more additional regions (third, fourth, etc. regions) whose reservoir degradation risk(s) is different from the risk in the first and second regions. Accordingly, at least one injector well drilled in additional reservoir region(s) may be injected with additional mixed brackish injection water(s) maintained within another predetermined operating range(s), allowing for a combination of growth to maximizing enhanced oil recovery from the additional reservoir area(s) and at the same time minimizing the risk of reservoir degradation by injecting additional mixed brackish injection water from the injection well(s) into the additional reservoir area(s).

Additional mixed low-salinity injection waters (third, fourth, etc. mixed low-salinity injection waters) may be injected into additional area(s) (third, fourth, etc. areas) of the reservoir simultaneously or in parallel with the injection of the first and second mixed low-salinity injection waters. waters in the first and second areas of the productive formation. Alternatively, the first, second, and additional mixed brackish injection waters (third, fourth, etc. mixed brackish injection waters) may be injected sequentially into the first, second, and additional reservoir regions (in any order).

Preferably, if there is a risk of reservoir acidification or scaling, operating ranges for the first, second, and any additional mixed brackish injection waters may be selected to reduce or minimize the risk of acidification or scaling in the reservoir.

According to a second aspect, the present invention relates to a method for producing a single mixed low-salinity injection water of variable composition for simultaneous (parallel) injection into at least one injection well drilled into a first region of an oil-bearing formation, at least one injection well drilled into a second region of an oil-bearing formation. formation, and, in some cases, at least one injection well drilled into additional region(s) of the oil-bearing formation, where the reservoir rock of the first, second, and additional regions has a first, second, and additional rock composition, respectively, which presents different risks for deterioration of reservoir properties, and where the mixed brackish injection water may contain varying amounts of nanofiltration permeate, reverse osmosis permeate and, in some cases, varying amounts of sea water and/or at least one stabilization additive small particles. According to this additional feature of the present invention, the composition of the single mixed low-salinity injection water is maintained within the overlap operating range defined by the boundary values for the area of overlap of the specified operating ranges for the compositions of the mixed low-salinity injection waters for the first, second and optional areas of the reservoir, where the specified operating ranges allow combine improving or maximizing enhanced oil recovery from the first, second, and optional additional reservoir regions, while attenuating or minimizing reservoir degradation in the first, second region, and, in some cases, additional reservoir regions.

Preferably, if there is a risk of acidification or scaling in the reservoir, an overlapping operating interval may also be selected to minimize the risk of acidification or scaling in the reservoir.

The different regions (first, second, and any additional region(s)) of the reservoir may be different regions of the reservoir rock layer in which the rock composition varies across the layer. Alternatively, the different regions (first, second, and any other region(s)) of the reservoir may be different reservoir layers, each with a different rock composition.

The third aspect of the present invention relates to an integrated system for injecting a single mixed low-salinity injection water of variable composition simultaneously into at least one injection well drilled into a first region of an oil reservoir and at least one injection well drilled into a second region of an oil reservoir , and including a control unit, a demineralization unit, a mixing system and a pressure system, moreover:

the demineralization unit contains an OO unit for obtaining an OO permeate mixed flow and for transferring an OO permeate mixed flow into a mixing system, and an NF unit for

- 3 042122 for obtaining the NF-permeate blending stream and for transferring the NF-permeate blending stream to the mixing system;

the mixing system comprises an RO permeate feed line, an NF permeate feed line, an RO permeate discharge line, an NF permeate discharge line, a confluence point for mixing the RO permeate and NF permeate to form mixed low-salinity injection water, and a discharge line for transferring mixed low-salinity injection water into the injection system;

the injection system comprises an injection line having at least one injection pump for supplying mixed injection water to:

(a) an injection well(s) drilled into a first region of an oil reservoir, (b) an injection well(s) drilled into a second region of an oil reservoir, and, (c) in some cases, an injection well(s) drilled into one or more additional areas of the oil reservoir;

and the control unit of the demineralization plant can change the operation of the demineralization plant in real time, to control the amount of mixed streams of RO-permeate and / or NF-permeate that must be mixed at the confluence point, thereby maintaining the composition of the mixed (composite) low-salinity water stream within overlapping operating range defined by the boundary values for the overlap area of the first, second and optional additional specified operating range(s) for the composition of brackish injection water for, respectively, the first, second and optional additional area(s) of the oil-bearing formation, where the specified operating ranges allow you to combine improving or maximizing oil recovery from the first, second, and optional additional area(s) of the reservoir, while attenuating or minimizing reservoir degradation in the first, second, and optional additional area(s) of the product formation, and where the operating ranges have been entered into the control unit, and the control unit either determines the overlapping operating range, or the overlapping operating range has been entered into the control unit.

Preferably, a mixing system producing a single mixed brackish water comprises a reservoir for a concentrated aqueous solution of at least one fine particle stabilization additive (hereinafter referred to as the fine particle stabilization concentrate) and a fine particle stabilization concentrate feed line equipped with an adjustable flow valve that allows varying amounts of fines stabilization concentrate to be mixed with brackish injection water. Alternatively, the tank may be equipped with a dosing pump for precise dosing of the fines stabilization concentrate into the injection water. The metering pump may be connected to a flow meter which may be used to control the concentration of the fine particle stabilization additive to meet the concentration profile of the fine particle stabilization additive(s). The control unit of the complex system can change the operation of the mixing system in real time, to regulate the amount of concentrate for stabilizing fines fed to: the confluence point of the mixing system or the injection line, thereby maintaining the composition of the resulting single mixed brackish water within the overlapping operating interval, which is additionally determined by the boundary values of the concentration of the additive for stabilizing fine particles for the overlap area of the first, second and any additional operating ranges (for the first, second and any additional areas of the reservoir, respectively). Thus, the intended operating ranges for each of the first, second, and any additional reservoir regions include upper and lower limits for the concentration of one or more fines stabilization additives.

Although the integrated system according to this feature of the present invention is adapted to supply a single mixed brackish injection water simultaneously (or in parallel) to the injection well(s) drilled in each of the areas, it can be modified to supply the first mixed injection water, the second mixed injection water and, optionally, one or more additional mixed injection waters in succession to at least one injection well drilled into the first reservoir region, at least one injection well drilled into the second reservoir region, and optionally at least in one injection well drilled into additional area(s) of the reservoir, respectively, where each area is characterized by its own risk of deterioration of reservoir properties. In such an embodiment, operating ranges for the first, second, and any additional injection waters are entered into a control unit that adjusts the compositions of the mixed low-salinity injection water to match one of the first, second, or additional operating range(s), thereby forming one of the first , second or additional mixed low-mineralized injected waters. The main injection line of the injection system may be further hydraulically (fluidly) connected to the injection well(s) drilled into the appropriate area of the reservoir. Thus, if

- 4 042122 the complex system is used to form the first mixed brackish injection water, the main injection line is hydraulically connected to the injection well(s) drilled into the first area of the reservoir. Similarly, if the integrated system is used to generate the second injection water or additional injection water(s), the main injection line is hydraulically connected to the injection well(s) drilled into the second or additional reservoir area(s), respectively. It can be seen that in such a modified system there is no requirement to introduce an overlapping operating interval into the control unit or to determine, by means of the control unit, an overlapping operating interval. In contrast, the control unit controls the composition of the mixed low-salinity injection water to match the operating range for one of the first, second, or additional reservoir regions.

It is envisioned that the integrated system or modified integrated system according to this third aspect of the present invention may be located onshore for use with onshore fields, or offshore (eg, on a platform or FPSO) for use in offshore fields. Where, however, the integrated system is intended for offshore use, it is also possible that the demineralization plant may be located onshore and the RO-permeate and NF-permeate streams may be transferred to a mixing system located offshore.

The integrated system or modified integrated system according to this third feature of the present invention is preferably used with an offshore reservoir having an injection system comprising a single (main) injection line connected to a single subsea reservoir in which branch injection lines lead from the reservoir to the injection well. (s) drilled into the first, second and any additional area(s) of the oil reservoir.

If a single mixed low-salinity injection water whose composition is within the overlapping range of operating conditions is to be injected in parallel into each area of the reservoir, the control unit opens valves in the main injection line and manifold to supply injection water from the main injection line in parallel to the injection wells drilled in each area of the productive formation. If the first, second, and optionally additional low-salinity injection waters are to be supplied sequentially to the first, second, and optional reservoir areas (in any order), the control unit opens and closes valves in the manifold to provide a hydraulic connection between the main injection line and the injection well( ami) drilled into one of the first, second or optional area(s) of the productive formation.

Alternatively, the main injection line may be divided to form a first main injection line, a second main injection line, and, in some cases, at least one additional injection line leading to a dedicated first manifold, a second manifold, and optionally additional manifold(s). ) for the first region, the second region, and optional additional reservoir region(s), respectively, wherein the dedicated reservoir for each reservoir region has branched injection line(s) leading to the injection well(s) drilled into each region. Accordingly, each of the dedicated reservoirs can simultaneously transfer injected water from the main injection line to the injection well(s) drilled into each region of the reservoir. Alternatively, brackish injection water with different compositions can be supplied sequentially to one of the first, second and any additional dedicated (special) reservoir, and from the reservoir to the injection well(s) drilled into one of the first, second and any additional area of the productive formation.

According to a fourth aspect of the present invention, an integrated system is provided for producing first, second, and, in some cases, at least one additional mixed low-salinity injection water, each of which has a variable composition, for simultaneous or parallel injection into at least one injection well drilled into the first oil-bearing formation region, at least one injection well drilled into the second oil-bearing formation region, and at least one injection well drilled into any additional oil-bearing formation region(s); wherein the reservoir rock of the first, second and additional area(s) has the first, second and additional rock composition(s), respectively, characterized by different risks of deterioration of the reservoir properties of the reservoir, and the first, second and additional mixed brackish waters may contain variable amounts of nanofiltration permeate , reverse osmosis permeate, and optionally varying amounts of sea water and/or at least one fine particle stabilization additive. According to this additional feature of the present invention, the composition of each mixed low-salinity injection water is maintained within a predetermined operating range so that it provides a combination of maximum enhanced oil recovery from each area while minimizing to

- 5 042122 minimum risk of reservoir properties deterioration in each area. The complex system contains a control unit, a demineralization unit, a mixing system and a blower system, wherein the demineralization unit comprises an OO unit for obtaining an OO permeate mixed flow and for transferring an OO permeate mixed flow to the mixing system, and an NF unit for obtaining an NF permeate mixed flow and for transferring the mixed flow of NF-permeate to the mixing system;

the mixing system contains the main feed line of the RO-permeate, the main feed line of the NF-permeate, the line of discharge of the RO-permeate, the line of discharge of the NF-permeate, the first and second confluence and the first and second outlet lines, and the lines of discharge of the OO-permeate and NF permeate hydraulically connected to the main feed line RO-permeate; the main feed line of the OO permeate is separated to form the first and second branch feed lines of the OO permeate to transfer the RO permeate to the first and second confluence points, respectively, the main feed line of the NF permeate is separated to form the first and second branch feed lines of the NF permeate to transfer the NF- permeate to the first and second confluence points, respectively, and the first and second outlet lines are hydraulically connected to the first and second confluence points and are designed to transfer the first and second mixed brackish injection water to the injection system;

the injection system contains at least the first and second dedicated (special) injection lines, each of which has at least one injection pump, the first and second injection lines being hydraulically connected to the first and second discharge lines of the mixing system, respectively, and the first dedicated the injection line is configured to supply the first mixed low-salinity injection water to the injection well(s) drilled into the first region of the oil reservoir, and the second injection line is configured to supply the second mixed low-salinity injection water to the injection well(s) drilled into the second region of the oil reservoir;

while the control unit of the demineralization unit can change the operation of the demineralization unit in real time to control the amounts of mixed streams of RO-permeate and/or NF-permeate, which are to be mixed at the first and second confluence points, thereby maintaining the composition of the first and second mixed streams brackish water within the first and second preset operating ranges previously entered into the control unit.

It should be understood that the mixing system in this additional feature of the present invention may, in some cases, have additional point(s) of confluence, additional branch line(s) OO and additional branch line(s) NF in fluid communication with additional point(s). ) confluence, and at least one additional outlet line(s) hydraulically connected to the additional point(s) of confluence, for transferring additional mixed brackish water(s) to an additional dedicated injection line(s) of the injection system (having at least one pump), wherein the additional dedicated injection line(s) is designed to transfer additional mixed low-salinity injected water(s) to additional area(s) of the oil-bearing formation, and the control unit can change the operation of the demineralization unit in real time, to control the amounts of mixed flows of OO- permeate and/or NF-permeate, which are to be mixed at the additional confluence(s), thereby maintaining the composition of the additional mixed brackish water stream(s) within the additional preset operating range(s) previously entered into the control unit for the additional reservoir area(s).

Preferably, the mixing system comprises a reservoir for a concentrated aqueous solution of at least one fine particle stabilization additive (hereinafter referred to as the fine particle stabilization concentrate) and a main feed line for the fine particle stabilization concentrate having first, second and, in some cases, additional branch feed lines. lines each equipped with a flow valve, wherein the first, second and optional branch feed lines provide various amounts of fines stabilization concentrate as an admixture stream for the first, second and additional mixed brackish injection waters. For example, the first, second, and additional branch line(s) may supply the fines stabilization concentrate to:

(a) the first, second, and additional confluence(s) of the mixing system, respectively;

(b) injection points located in the first, second and, in some cases, additional dedicated injection lines of the injection system, respectively; or (c) the injection points of the Christmas tree chemicals of the injection well(s) drilled into the first region, the second region, and optionally the additional region(s) of the oil-bearing formation, respectively.

The control unit of the complex system can change the operation of the mixing system in real time to control the amount of fines stabilization concentrate supplied as a mix stream for the first, second, and any additional mixed low-mineralized injection waters, thereby maintaining the compositions of the mixed streams low-mineralized water within the specified operating ranges, including the boundary values for at least one additive to stabilize fine particles.

An integrated system according to this aspect of the present invention may be located on land and used with an oil reservoir on land, or may be located offshore (eg, on a platform or FPSO) for use in offshore oil fields. It is also contemplated that the demineralization unit of the integrated system according to this aspect of the present invention may be located onshore and the mixing system may be located offshore, with the onshore demineralization unit providing for the transfer of RO-permeate and NF-permeate streams (through feed lines RO-permeate and NF-permeate, respectively) into an offshore mixing system.

In the event that an integrated system according to this aspect of the present invention is located onshore for use with an onshore oil reservoir, there is no difficulty in injecting first, second, or additional mixed brackish water into the injection well(s) drilled in the first, second, and optionally , additional reservoir area(s), since all injection wells have dry X-mas trees.

Alternatively, if the entire complex system or the mixing system of the complex system is located offshore, the injection wells drilled into the first, second, and optionally additional reservoir area(s) may have dry wells located on the platform or FPSO, thereby providing , injecting brackish water of various compositions into the injection well(s) drilled into the first, second and, optionally, additional area(s) of the productive formation. In this case, injection wells can generally be extended from the seabed to the platform or FPSO. Alternatively, injection wells drilled into the first, second, and optionally additional reservoir area(s) may have bottom X-mas trees with associated first, second, and optionally additional water injection lines extending from the platform or FPSO. to the seabed. Typically, dedicated first, second, and optionally additional water injection lines may be connected to the first, second, and optionally additional subsea manifolds, where each manifold has one or more branch injection lines connected to the bottom injection tree(s). well(s) drilled into each reservoir region (ie, there is a dedicated water injection line and a dedicated reservoir for the injection well(s) of each reservoir region).

The injection well(s) drilled into the first region of the reservoir may be in fluid communication with the first dedicated injection line, whereby opening a valve in the Christmas tree(s) of the injection well(s) allows the first mixed brackish injection water to flow from the dedicated first injection line. water into the injection well(s) drilled into the first region of the reservoir. Similarly, the X-mas tree(s) of the injection well(s) drilled into the second region (or any additional region) of the reservoir may be in fluid communication with the second dedicated water injection line (or any additional dedicated water injection line) whereby opening the valve in X-mas tree(s) will allow the second mixed brackish injection water to flow from the second dedicated water injection line into the injection well(s) drilled into the second area of the reservoir (or any additional injection water(s) to flow from the additional dedicated injection line(s) into injection well(s) drilled into additional reservoir area(s).

The control unit of the complex systems of the present invention may include a CPU (central processing unit), RAM (Random Access Memory), ROM (Read Only Memory), HDD (hard disk), I/O interface (input/output interface), machine readable code (for example, software and / or built-in), etc. The control unit may store in memory instructions that can be executed by the processor, providing configuration of the processor to perform any functions or operations described in relation to or regarding the control unit, according to the instructions stored in the memory. Although the above description refers to the processor and memory, according to some features, application-specific integrated circuits (ASICs) can be developed to perform these same functions.

Boundary values for the compositions of the first, second and any additional mixed brackish injection waters for each area of the oil reservoir can be entered into the control unit of the complex system. The control unit may further determine operating ranges for the mixed brackish injection water composition for each reservoir region, the operating ranges being determined by the boundary values. However, it seems that operating ranges can also be obtained by entering the limit values into a computer located at a remote location, outputting the limit values from the computer and transmitting them to the control unit of the complex system over the network. These operating ranges can be defined by cut-off values (upper and lower limits) for one or more of: TSP (mineralization), ionic strength, individual ion concentration (e.g., sulfate anions, nitrate anions, calcium cations, or magnesium cations). ), individual ion concentrations by ion type (for example, monovalent cations, monovalent anions, polyvalent anions, polyvalent cations, or divalent cations), ratios by individual ion types, or ratios of individual ions (for example, relative sodium adsorption rate), or any combination of these .

Compositions within the operating range for a certain area of the reservoir are compositions that are predicted to provide enhanced oil recovery (EOR) from each area of the reservoir, the use of which eliminates, reduces or minimizes the risk of deterioration of reservoir properties in this area of the reservoir.

Where there is a risk of reservoir acidification or scale formation, compositions within the operating range for the area (i.e. first, second, or any additional area(s)) of the reservoir are preferably those that are predicted to also reduce reservoir acidification or inhibit scale formation. Those skilled in the art are aware that not all reservoirs are at risk of acidification or scale formation. Thus, acidification can occur when a formation is colonized by sulfate reducing bacteria (SBR) that obtain energy from the oxidation of organic compounds while reducing sulfate to hydrogen sulfide. Deposits can form when connate waters containing high amounts of precipitating precursor cations, such as barium or strontium cations, mix with injection water with a relatively high content of sulfate anions, resulting in the precipitation of insoluble sulfate salts (mineral deposits).

It is envisioned that each reservoir region may have a number of different operating ranges defined by different cut-off values for each parameter, where different operating ranges balance different levels of enhanced oil recovery (EOR) and different levels of reservoir degradation risk for each reservoir region. A number of operating ranges for each area of the reservoir may also take into account the risk of reservoir acidification or scale formation. A number of different operating ranges for mixed brackish injection water compositions for each region (first, second, and any additional region(s)) of the reservoir may be entered into the control unit.

To maintain the composition of the first, second, and any additional mixed brackish waters within the predetermined (predetermined) range of operating conditions for the first, second, and any additional reservoir areas, or to maintain the composition of the single mixed brackish injection water within the overlapping operating range for these areas , the amounts of NF-permeate and RO-permeate mixed to produce a mixed brackish water stream(s) can be adjusted in real time in response to a decrease in well injectivity in one or more reservoir regions.

In the mixing system of the integrated system of the present invention, the amount of NF permeate or RO permeate stream available for mixing to form the mixed brackish injection water stream(s) can be rapidly changed (in real time) by diverting variable amounts of NF stream - permeate or RO-permeate flow from the demineralization unit, for example, to the water area (ocean), through the NF-permeate or OO-permeate discharge line, each of which is equipped with an unloading valve. The unloader valve is an adjustable valve (such as a throttle valve) that can be set to different positions (from fully closed to fully open) to control the amount of NF permeate or RO permeate withdrawn from the mixing system.

If the withdrawal of excess NF permeate or excess RO permeate continues for a long time, such as hours or days, then the control unit can make adjustments to the demineralization plant, decommissioning one or more NF modules from the NF node or one or more OO modules from the NF node. OO modules, thereby reducing the productivity of the production of NF-permeate or OOpermeate, respectively. If the withdrawal of excess NF-permeate or RO-permeate continues for weeks or months, the NF elements of one or more of the NF modules of the demineralization plant, in some cases, may be replaced by OO elements, or the OO elements of one or more of the OO modules may be replaced by NF elements , to increase the amount of RO-permeate or NF-permeate produced by the demineralization plant.

It is known that divalent cations can help stabilize reservoir rock that tends to shed fines and thus can act as additives to stabilize fines. In general, fine particles may include clay particles and silica particles. In some cases, the demineralization plant may have a bypass line for the highly saline water used to feed the OO and NF units of the plant, since this highly saline feed water, such as sea water (MB), is usually characterized by a high concentration of divalent cations. This bypass line is used to transfer the mixed flow of highly mineralized water (for example, the mixed flow MB) to the mixing system. Accordingly, the mixing system, in some cases, contains a feed line of highly mineralized water (for example, MB).

In the event that the mixing system is producing mixed low saline injection water with variable composition, the high saline feed water bypass can be equipped with an adjustable valve (e.g. throttle valve) that can be set to various positions between fully closed and fully open. , thereby allowing varying amounts of highly mineralized water (e.g., MB) to be mixed with the RO permeate blend stream and the NF permeate blend stream (or combined RO/NF permeate blend stream) to form a single mixed low salinity injection water(s). If desired, however, any excess brackish water may also be discharged from the mixing system into the water area via a brackish water discharge line fitted with an adjustable valve (eg, throttle valve). The use of a variable valve on the optional MB bypass line (or MB discharge line equipped with a variable valve) also provides a fast adaptation (in real time) of the TCO, the concentration of one or more individual ions to the composition(s) of the mixed brackish injection water stream(s).

If the mixing system produces first, second, and optionally one or more additional mixed brackish injection waters, the brackish water bypass line may be equipped with a first and second branch lines and, in some cases, one or more additional branch lines, each of which is equipped with an adjustable valve (eg, a throttle valve) for conveying varying amounts of brackish water to the confluence points to form the first, second, and any additional brackish injection waters.

The control unit can thus vary the amount of any highly mineralized water (e.g., MB) included in the mixed low salinity injection water stream(s) in response to changes in well injectivity in one or more of the first, second, or any additional reservoir regions. , to shift the composition(s) of the mixed brackish water stream(s) within the preferred predetermined (preselected) operating range(s) (or preferred overlapping range), where there is less risk of deterioration of the reservoir properties of the formation. The specialist should be aware that MB has a high content of sulfate anions. Accordingly, when mixing an RO permeate blend stream and an NF permeate blend stream with an MB blend stream, the risk of acidification (and scale formation) must be strictly controlled for the formation. The risk of reservoir acidification and the risk of formation of deposits in it can be controlled by entering into the control unit an upper limit (boundary value) for the concentration of sulfate in the mixed brackish injection water, typically 100 mg/l; preferably 50 mg/l and in particular 40 mg/l.

The mixing system of a complex system may, in some cases, include a reservoir (for storing a concentrate containing an aqueous solution or suspension of one or more fines stabilizing additives) and a main feed line for transferring the concentrate. In the event that a single brackish injection water is produced in the mixing system, the concentrate feed line may have a throttling valve for transferring varying amounts of an admixture concentrate stream containing an aqueous solution or suspension of one or more fines stabilization additives to a confluence point for the brackish injection stream. water. In this case, the adjustable valve can be set to different positions between the fully closed position and the fully open position, thereby allowing the transfer of different amounts of concentrate to the confluence point. Alternatively, the main concentrate feed line may be split to form first, second and optionally additional branch concentrate feed lines, each equipped with an adjustable valve (e.g., throttle valve), to convey varying amounts of the concentrate admixture stream to the confluence point. for the formation of the first, second and, optionally, additional brackish waters. In this case, the controller can maintain the compositions of the first, second and any additional mixed brackish injection waters within the specified operating ranges (or the composition of the single mixed brackish water within the overlapping operating range), further defined by the boundary values (upper and lower limits) for the concentration(s) additive(s) to stabilize fine particles. The control unit can continuously monitor (monitor) the concentrate flow rate in the main concentrate feed line or concentrate flow rates in the branch concentrate feed lines in real time, and can make quick adjustments to the concentrate flow rate using the adjustable valve(s), thereby changing the concentration one or more fine particle stabilizing additives in the composite injection water stream.

The fine particle stabilizing additive(s) may be an inorganic salt such as a divalent cation salt or a potassium salt. Preferably, the salt of the divalent cation may be

- 9 042122 calcium salt, for example calcium chloride, calcium bromide or calcium nitrate, preferably calcium chloride or calcium nitrate. Calcium nitrate may also be preferred to prevent acidification, as the nitrate anion can promote the development of nitrate-reducing bacteria, which can outcompete sulfate-reducing bacteria (SRBs) for nutrients and utilizable organic carbon. Preferably the potassium salt is selected from potassium chloride, potassium bromide and potassium nitrate. The advantage of potassium nitrate is that it can also inhibit acidification.

The control unit can automatically regulate the operation of the mixing system and thereby the amount of RO permeate stream, NF permeate stream (and any optional high mineral water stream, such as MB, or in some cases fine particle stabilizer concentrate stream) that are included in the mixed stream(s) of brackish injection water, in response to changes in injectivity of wells in one or more of the reservoir regions.

In the event that the mixing system is producing a single brackish injection water stream, the flow rate and composition of the mixed brackish injection water can be monitored in real time to determine the effectiveness of control unit-initiated changes to the mixing system to maintain the composition of the single mixed brackish injection water within overlapping operating range. If the mixing system produces a first, second, and in some cases one or more additional brackish injection waters, real-time monitoring of the mixed brackish injection water flow rates and compositions can be performed to determine the effectiveness of changes introduced by the control unit in the operation of the mixing system, aimed at maintaining the composition of the first, second and any additional brackish waters within the first, second and any additional specified operating ranges, respectively. In case of insufficient efficiency, the control unit can make additional changes in the operation of the mixing system. Accordingly, the control unit has a feedback loop for controlling the mixing of the mixed brackish water stream(s).

Real-time control of the amounts of RO-permeate and NF-permeate used for blending by changing the amounts of RO-permeate and NF-permeate discharged from the mixing system through an RO-permeate or NF-permeate discharge line, for example, to the water area (for example, ocean) provides reliable control of the TWTS and/or concentrations of one or more individual ions within the operating range(s) for the mixed brackish injection water stream(s). Thus, a faster response is provided than when trying to change the flow rates of feedwater supplied to the OO and NF nodes of the demineralization plant (due to dead volumes in the feed lines leading from the OO and NF nodes to the point(s) of confluence of the mixed stream(s) ) low-mineralized injected water).

Further, if highly mineralized water (e.g., MB) or fines stabilizer concentrate is used as the admixture stream, controlling the opening degree of a variable (variable) valve (e.g., throttle valve) in the high-salinity water bypass line or in the main fines stabilizer concentrate line can be adjust the composition of the single mixed brackish injection water so that it is maintained within the preferred overlying operating range in response to changes in injectivity of the injection well(s) drilled into the first, second, or any additional area of the reservoir.

In the same way, by controlling the opening degree of adjustable (variable) valves (e.g., butterfly valves) on the MB branch feed lines (and/or controlling the opening degree of variable valves (e.g., butterfly valves) on the concentrate feed branch lines), it is possible to control the compositions of the first, the second and any additional mixed brackish injection waters so that they are maintained within the preferred predetermined operating ranges, in response to changes in injectivity of the injection well(s) drilled in the first, second, or any additional areas of the reservoir.

Thus, it can be seen that the control unit can change the operation of the demineralization plant in real time by adjusting one or more parameters of the system, namely the degree of valve opening in the RO permeate discharge line, the degree of valve opening in the NF permeate discharge line, the degree of valve opening on the optional brackish water bypass line (or valve opening degree on one or more of the brackish water branch feed lines), and valve opening degree on the optional fines stabilization main concentrate feed line (or valve opening degree on one or more of the concentrate branch lines to stabilize fine particles).

In the complex system proposed in the present invention, in particular in the mixing system, various probes (sensors) can be included. These probes can be used to determine the TWTS and/or the ionic composition of the mixed brackish injection water stream(s). For example, the TWR of the mixed brackish injection water stream(s) can be

- 10 042122 determined by its conductivity, while the concentration of individual ions or individual ions by ion type can be determined using glass probes with membranes permeable to specific individual ions or individual ions by ion type. Similarly, probes (sensors) can be installed on OO-permeate and NF-permeate lines, any combined OO/NF-permeate line (where the combined OO-/NF-permeate stream, in some cases, is mixed with MB or concentrate to stabilize fines, to form a mixed brackish injection water), and an optional brackish water bypass, to provide data related to TWTS and ionic composition of the RO permeate stream, NF permeate stream, optional brine water stream (and any combined RO/NF permeate stream) . Flow sensors can also be installed in the flow lines to detect the flow rates of various mixed streams (RO-permeate stream(s), NF-permeate stream(s), optional high-salinity feedwater stream(s), and any combined RO/NF-permeate stream, and optional concentrate flow to stabilize fines), and to determine the RO permeate flow rates in the RO permeate discharge line and NF permeate in the NF permeate discharge line.

Accordingly, the mixing system may include: a) ion concentration sensors to measure salinity or total dissolved solids (Ct), concentration of individual ions (Ci) or individual ions by different types of ions in the admixture stream(s) OO permeate, admixture stream(s ) NF permeate, any combined RO/NF permeate blend stream(s), and optional MB blend stream(s), optional fines stabilization concentrate blend stream(s), and brackish injection water composite stream(s). In particular, the mixing system may have ion concentration sensors to measure at least one of:

a) TSPTS, chloride anions, bromide anions, calcium cations, magnesium cations, potassium cations, nitrate anions and sulfate anions, for RO permeate blend stream(s), NF permeate blend stream(s), any combined blend stream(s) ) RO/NF permeate, and optionally mixed stream(s) of highly mineralized water;

b) flow sensors to measure one or more of the flow rates: OO permeate blend stream(s), RO permeate waste stream, NF permeate blend stream(s), NF permeate waste stream, any combined RO/NF blend stream(s) -permeate, optional high saline water bypass stream(s), optional fines stabilizer concentrate stream(s), and mixed brackish injection water stream(s).

Ion concentration sensors, flow sensors and any other sensors described here can communicate with the control unit using any communication technique, such as direct electrical connection or wireless electrical connection (eg Wi-Fi, Bluetooth).

Due to the risk of deterioration of reservoir properties during waterflooding with brackish water, the value of the maximum allowable pressure increase in the injection well(s) drilled into the first, second and any additional areas of the productive formation can be entered into the control unit. If dedicated injection line(s) are used to transfer the first, second, and additional injection waters to the injection well(s) drilled into the first, second, and any additional reservoir area, the maximum allowable flow rate reduction for each stream can be entered into the control unit. injection water at the outlet of the injection pump(s) on each dedicated line of passage (the excess of which leads to an unacceptable decrease in well injectivity). Both an increase in downhole pressure in an injection well drilled into one of the reservoir regions and a decrease in flow after the injection pump(s) in dedicated flow lines are indicators of the loss of injectivity that occurs due to the deterioration of the reservoir properties of the formation in one of the reservoir regions. .

The pressure in the injection well(s) near the oil-bearing layer in each region of the reservoir (or the flow rate of mixed low-salinity injection water after the injection pump(s) in the dedicated injection lines of the injection system) can be observed in real time. Pressure monitoring in the injection well(s) may be carried out using a downhole measuring device, such as a pressure sensor, connected to a control unit, such as a fiber optic telemetry data link or any other suitable communication channel.

If the control unit detects a drop in injectivity of the injection well(s) drilled in one or more areas of the reservoir, it may select a different operating range (or other overlapping operating range) for the composition of the mixed injection water stream(s) predicted to have less risk of deterioration of reservoir properties (while maintaining an acceptable level of enhanced oil recovery (EOR) for the area (s) of the productive reservoir), and can further adjust the ratio of the mixture of different mixed streams so that the composition of the mixed low-salinity water injected into the injection well (s) drilled into the reservoir area(s) fell within this other operating range(s) (or other overlapping operating range). The control unit continues to execute in real time

- 11 042122 control of pressure in the injection well(s) drilled into the area(s) of the reservoir (or flow after the injection pump(s) for dedicated injection lines leading to the injection well(s) drilled into the area(s) of the reservoir , where injectivity drop is detected) in real time to determine how pressure (or flow) stabilizes in response to injection of mixed brackish injection water whose composition is in the preferred operating range (or preferred overflow operating range). If this is not the case, the control unit may make further changes to the operation of the mixing system to adapt the composition of the mixed brackish injection water stream(s) to another preferred operating range (or preferred overlay operating range) that is predicted to be at risk of reservoir degradation. lower. This is an iterative process that can be repeated many times. In some cases, the control unit may decide to reduce the rate of brackish injection water or stop injection of brackish water into the injection well(s) of one or more areas of the reservoir if the pressure continues to build up. The control unit may then decide to inject a fines stabilizing composition (e.g., an undiluted fines stabilizer concentrate) into the oil bearing layer(s) of the reservoir region(s) where injectivity has declined for a period of several days before resuming waterflooding of the low salinity water.

Typically, correlations are entered into the control unit between the blend ratios of the various blend streams and the compositions of the first, second, and any additional brackish injection water mixed streams or single injection water stream composition (e.g., correlations between the blend ratios of the various blend streams and one or more of the parameters: TSPTV, osmotic potential, concentration of individual ions, concentration of individual ions by ion type, ratio of individual ions and ratio of individual ions by ion type in a composite flow of brackish injected water). These correlations can be based on the assumption that the compositions of the NF-permeate, RO-permeate, and optional high-salinity water (eg, MB) admixture stream remain substantially constant (within specified tolerances) during operation of the demineralization plant. The mixing ratios of the various admix streams depend on the flow rates of the various admix streams delivered to the confluence point(s) of the mixing system to form first, second, and additional mixed brackish injection water streams or a single brackish water stream.

Correlations between the opening degree of the NF unloader valve, the opening degree of the OO unloader valve, the opening degree of the adjustable valve(s) on the optional main brackish water feed line or branch lines of brackish water, and the opening degree of the regulated valve(s) on the optional the main fine particle stabilizer concentrate feed line or the fine particle stabilizer concentrate branch feed lines on the one hand, and the flow rates of the admixture streams of NF permeate, RO permeate, optional brackish water and optional fine particle stabilizer concentrate. In this case, the control unit can control the mixture ratios and thus the composition of the single mixed brackish injection water or the first, second or additional composite streams of brackish injection water, by changing the degree of opening of one or more of the above-mentioned adjustable valves, to obtain compositions of a single mixed brackish injection water. injection water or first, second and additional mixed low-salinity injection waters corresponding to a given (selected or predetermined) operating range, overlapping operating ranges for the first, second and any additional areas of the reservoir. As a result, the flow rates of the various mixing streams to be conveyed to the mixing point(s) can be controlled in real time, thereby ensuring that the composition of the single mixed brackish injection water is within an overlapping operating range, or that the compositions of the first, second and any additional brackish water within the specified operating ranges for the first, second and any additional areas of the reservoir.

As a rule, the limit values for the TWTS of the mixed brackish injection water stream(s) can be in the range from 200 to 10,000 mg/l, preferably from 500 to 10,000 mg/l. Typically, lower TWRT intervals provide higher EOR, while higher TRT intervals reduce the risk of deterioration in reservoir properties, especially in oil-bearing formations containing rock with a high content of swellable clays and/or migrating fines, e.g. clay or silica. Alternative cut-off values for TPTS may be, for example, in the range of 500 to 5000 mg/l, 500 to 3000 mg/l, 1000 to 2000 mg/l, 2000 to 5000 mg/l or 3000 to 7000 mg/l l (depending on the risk of deterioration of the reservoir properties of the formation). The control unit may control the compositions of the first, second, and any additional mixed brackish injection waters for the first, second, and

- 12 042122 any additional areas of the productive formation so as to maintain it in the selected range of boundary values for the ORTW.

If there is a risk of acidification or a risk of scaling in the reservoir, the control unit adjusts the sulfate anion content of the first, second, and any additional mixed brackish injection waters for the first, second, and additional reservoir areas (or the concentration of sulfate anions in the single mixed brackish injection water) at a level less than 100 mg/l; preferably less than 50 mg/l and most preferably less than 40 mg/l.

Typically, the control unit maintains the total concentration of multivalent cations in the first, second, and any additional mixed injection waters for the first, second, and any additional area of the reservoir (or the concentration of multivalent cations in a single mixed brackish injection water) within the range from 1 to 250 mg/l , preferably from 3 to 150 mg/l and in particular from 50 to 150 mg/l, provided that the ratio of the content of multivalent cations in the mixed brackish injection water(s) and the content of multivalent cations in the relict water located in the pore space reservoir rock in each reservoir area is less than 1. Typically, the control unit maintains the calcium cation concentration of the first, second, and any additional mixed injection waters for the first, second, and any additional reservoir area (or the calcium cation concentration of a single mixed low-salinity injection water) within the range of 1 to 200 mg/l, preferably 5 to 150 mg/l and in particular 50 to 150 mg/l, provided that the ratio of calcium cations in the mixed brackish injection water(s ) and the content of calcium cations in the relict water located in the pore space of the reservoir rock in each area of the productive formation is less than 1.

Typically, the control unit maintains the concentration of magnesium cations in the first, second, and any additional mixed brackish injection water for the first, second, and any additional reservoir area (or the concentration of multivalent cations in a single mixed brackish injection water) within the range from 2 to 400 mg/l , preferably from 10 to 300 mg/l and in particular from 100 to 300 mg/l, provided that the ratio of the magnesium cation content in the mixed brackish injection water(s) and the magnesium cation content in the relict water located in the pore space each area of the productive formation is less than 1.

Typically, the control unit maintains the concentration of potassium cations in the first, second, and any additional mixed brackish injection water for the first, second, and any additional area of the reservoir (or the concentration of multivalent cations in a single mixed brackish injection water) within the range from 10 to 2000 mg/l and in particular from 250 to 1000 mg/l, provided that the TWP in the mixed brackish injection water(s) remains within the limit values for the established operating range.

Alternatively, the control unit may maintain the composition of the single mixed low-salinity injection water within a selected range given by the Boundary Values for the TSP (and within selected intervals given by the Boundary Values for the Multivalent Cation Content, Calcium Cation Content, Magnesium Cation Content, and Potassium Cation Content) for the area of overlap of the boundary values for TSPTV (and for the area of overlap of the boundary values for the content of multivalent cations, the content of calcium cations, the content of magnesium cations and the content of potassium cations) for the first, second and any additional reservoir regions.

Boundary values for TSP and individual ion concentrations and concentrations of any fines stabilizing additives for the first, second and any additional mixed brackish injection water may vary depending on the enhanced oil recovery (ERR) response to low salinity for each reservoir area and reservoir rock composition (e) each region of the reservoir and, in particular, the content of swellable and migrating clays and minerals relevant to reservoir degradation.

These boundary values could be determined by analysis of reservoir rock samples taken from each area of the oil-bearing layer of the reservoir. Reservoir rock samples can be, for example, rock fragments or core taken from the borehole wall. Alternatively, analysis of the reservoir rock surrounding the injection well may be performed by geophysical logging using downhole logging equipment. Rock analysis for each region of the reservoir reservoir may include, among other things, determining the total mudstone content in the reservoir rock surrounding the wellbore(s) in the first, second, and any other reservoir regions. The total content of mudstone in the reservoir rock for the first, second and any additional area of the reservoir can be determined by geophysical logging, X-ray diffraction (XRD), scanning electron microscopy (SEM), scintillation counter

- 13 042122 in the IR range or by sieve analysis. The total content of mudstone in the reservoir rock may be in the range from about 2 to 20 wt.%. The analysis of the rock for each area of the oil-bearing layer of the reservoir may also include the determination of the mineral content of the clay fraction of the rock, in particular smectite clays (for example, montmorillonite), pyrophyllite clays, kaolinite clays, illite clays, chlorite clays and glauconite clays, and can be performed by the method X-ray diffraction (RD) or scanning electron microscopy (SEM). Optimal salinity (and compositions) for mixed low-salinity injection waters for each area of the reservoir can be determined by relating the deterioration of reservoir properties of the reservoir that occurs at different boundary salinity values (and various concentrations of individual ions and individual ions by ion type) of the injected water for a number of different rock samples with different shale grades and different clay compositions, and selection of cut-off values for salinity (or composition) of mixed low-salinity injected water for the rock sample that most closely matches the composition of the rock (i.e. using historical data) of each reservoir area , which must be subjected to brackish water flooding. Alternatively, experiments can be performed on rock samples taken from reservoir regions where injection wells have been drilled, using different cut-off values for salinity and composition (single ion concentrations or single ion concentrations by ion type) for mixed low-salinity injection water, for determining the optimal range for the salinity and composition of the injection water to be injected into each area of the productive formation during a low-salinity water flood.

Typically, well injectivity for the first, second, and any additional mixed brackish injection waters (or single mixed brackish injection water) is limited by the capacity of the demineralization unit. Accordingly, brackish water flooding may involve injecting a low pore volume (PV) plug of mixed brackish injection water into the injection well(s) drilled into the oil-bearing layer of each reservoir region in an amount equal to at least 0.3 pore volume and preferably less than 0.4 pore volume, since plugs with such minimum pore volumes tend to maintain their integrity within the formation. To limit the amount of water injected into each region of the reservoir through the injection well(s), it is desirable that the pore volume of the mixed brackish injection water be less than 1, more preferably less than or equal to 0.9 PO, most preferably less than or equal to 0.7 PO, in particular less than or equal to 0.6 PO, for example less than or equal to 0.5 PO.

After injecting a low pore volume of the mixed brackish injection water into the first injection well(s) drilled into the reservoir region, drive water may be injected from the injection well(s) into the oil bearing layer of the reservoir to promote the advance of the mixed brackish injection water plug (and hence , and the disconnected oil zone being moved by the displacement agent) through the oil-bearing layer of the formation to the production well drilled into the oil-bearing layer of the productive formation. In addition, drive water injection may be required to maintain pressure in this area of the reservoir. Generally, the displacing water has a PL greater than the plug of the aqueous displacing fluid.

Preferably, the drive water is produced water or a mixture of sea water and produced water, depending on the amount of produced water separated at the production facility from the produced fluids. The use of bottom water as displacement water is preferable due to restrictions on the disposal of bottom water into the marine area. Accordingly, after pumping a brackish injection water plug into the injection well(s) drilled into the reservoir region, the injection well(s) can be used as a production water disposal well.

DETAILED DESCRIPTION OF THE INVENTION The invention will now be discussed with reference to FIG. 1 and 2 In FIG. 1 shows an integrated system for producing mixed brackish injection water for a reservoir having an oil bearing layer with a first region 56 and a second region 56' having different rock properties. The first region 56 and the second region 56' are drilled through at least one injection well 20 and 20', respectively, and at least one production well 21 and 21', respectively. The complex system includes: a demineralization unit containing a membrane unit 1 for treating feed water 2 (usually sea water); a mixing system comprising various flow lines for forming a mixed flow of low-salinity injection water of various composition, in some cases, a reservoir 50 for concentrate and a pump 25 for stabilizing fine particles of the concentrate; and a control unit 52 for controlling the operation of the demineralization plant and for controlling the mixing of the low-salinity injection water flow in the mixing system. The complex system also includes an injection system containing one or more injection pumps 24 and injection lines 58 and 58' for the injection wells 20 and 20', and field equipment 54 connected to the pipeline

- 14 042122 pipelines with flow lines 28 and 28' of production wells 21 and 21'.

The membrane block 1 has a feed pump 3, a node 4 OO and a node 5 NF (each node can be either a single-stage node or a multi-stage one). Both the TOE node and the NF node can have the same feed water (eg, sea water), as shown in FIG. 1. However, it is also contemplated that the RO concentrate (also referred to in the art as retentate) from the first RO stage can be separated to form a feed stream for the second RO stage and for the NF assembly.

The TOE node 4 contains several TOE modules. Node 5 NF contains several modules NF. Typically, the number of RO assembly modules and the number of NF assembly modules are selected to match the required RO permeate and NF permeate production for a mixed brackish injection water stream in a brackish water flood. The demineralization plant can also be equipped with a bypass line 6 for feed water 2 (eg sea water).

The complex system contains valves V1-V8 and various flow lines (pipes) that form the flow paths described below. Valves V1-V8 may be throttle valves, and the degree of opening of the throttle valves may be set by the control unit (ie fully open position, fully closed position, or various intermediate positions). Accordingly, the control unit 52 can control the flows and pressures through the membrane unit by controlling the supply pump 3, valves V1-V5, or any combination thereof (for ease of presentation, Fig. 1 does not show the electrical connections between the control unit 52, the supply pump 3, and valves V1-V5 In some embodiments, communication between the control unit 52 and the supply pump 3 and valves V1-V5 may be carried out by wireless means, such as Wi-Fi or Bluetooth).

The flow sensors Q1-Q10 are used to detect the flow in the various paths of the complex system. The flow data can be sent from the flow sensors Q1-Q10 to the control unit 52 via electrical signal lines (dotted lines in Fig. 1) or via wireless communication channels such as Wi-Fi or Bluetooth. In some cases, sensors Q1 and Q2 on lines 8 and 7 for OO concentrate and NF concentrate, respectively, may not be used.

In addition, sensors S1-S7 are used to determine the total dissolved ion content (TODS) and/or the concentration of individual ions or individual ions by ion type (eg, polyvalent cations or divalent cations) in various paths. The ion concentration data is also sent from the ion concentration sensors S1-S7 to the control unit 52 via electrical signal lines (dashed lines shown in FIG. 1) or wireless communication channels such as Wi-Fi or Bluetooth. In some cases, sensors S4 and S6 on lines 7 and 8 for NF concentrate and OO concentrate, respectively, may not be used. The sensor S6 on the optional line 26 of the fine particles stabilizer concentrate can also be excluded if the concentration of this additive in the concentrate tank has been previously measured and remains unchanged over time (in this case, the measured concentration of the additive in the concentrate can be entered into the control unit 52) . It is also contemplated that sensors S1, S2, and S3 on the optional seawater bypass line 6, on the RO permeate feed line 9, and on the NF permeate feed line 13, respectively, may not be used when it can be predicted that the compositions MB, RO -permeate and NFpermeate will remain largely constant during the process.

In the shown in FIG. 1, feed pump 3 pumps feed water 2 into OO unit 4, in which the feed water is separated into OO permeate (flowing through OO permeate feed line 9) and OO concentrate (flowing through OO concentrate feed line 8), and into unit 5 NF, in which the feed water is separated into NF permeate (flowing through the NF permeate feed line 13) and NF concentrate (flowing through the NF concentrate feed line 7). The feed water pressure to the OO and NF nodes can be adjusted (for example, using a booster pump for the incoming OO flow, or a pressure reducing valve for the incoming NF flow) to match the operating pressures of the OO modules of the OO modules of node 4 and the NF of the NF modules of node 5 (NF modules are usually operate at lower pressures than 00 modules). In some cases, the feed pump 3 pumps a portion of the feed water (e.g., MB) into the mixing system through the bypass line 6. Valves V1 and V2 are at least partially open to remove the OO concentrate and NF concentrate, respectively, from the demineralization unit. Usually, the diverted streams of OO-concentrate and NF-concentrate merge into the water area (for example, sea) via lines 8 and 7, respectively. The NF permeate may be further pumped into the RO permeate in a mixing system to form a combined OO/NF permeate stream flowing through line 16. In some cases, the combined RO/NF permeate stream also includes MB and/or a fine particle stabilizer concentrate ( added to feed lines 6 and/or 26, respectively).

Fluids produced from production wells 21 and 21' are passed to field equipment 54 via flowlines 28 and 28', which may optionally be connected to a main product line (not shown). Produced fluids are separated in the field equipment 54 into an oil stream, a gas stream, and an admixture of produced water (SW) stream.

As shown above, the boundary values and preferred boundary values for the composition

- 15 042122 mixed low-salinity injected water flow (e.g., boundary values and preferred boundary values for TWTS, concentrations of one or more individual ions, concentration of individual ions by ion type, ratio of individual ion concentrations, ratio of individual ion concentrations by ion type, or concentrations of one or more more additives for stabilizing fines in the mixed brackish injection water) are introduced into the control unit, thereby determining operating ranges and one or more preferred operating ranges for mixed brackish injection water compositions to achieve FOR for the first or second regions of the oil-bearing layer 23 of the reservoir while providing protection against the risk of deterioration of the reservoir properties of the reservoir in the first and second regions of the oil-bearing layer 23 at different levels corresponding to these regions. When there is a risk of acidification or scaling in the reservoir, operating ranges and preferred operating ranges for mixed brackish injection water stream compositions also reduce the risk of acidification and scaling in the reservoir. The operating ranges and preferred operating ranges for the mixed brackish injection water flow compositions for the first and second reservoir regions are independent of each other because the reservoir degradation risk is determined by the different reservoir rock compositions in the first and second reservoir regions.

Typically, different formulations for mixed low-salinity injection water (TSWT, concentrations of one or more individual ions, concentrations of individual ions by ion type, ratios of individual ion concentrations, ratios of individual ion concentrations by ion type, or concentration of one or more additives to stabilize fine particles) correlated with different blend ratios in the combined RO/NF permeate stream. Different compositions are also correlated with different compositions for a combined RO/NF permeate stream (including compositions for a combined RO/NF permeate stream comprising MB and one or more fine particle stabilizer additives). These correlations can be entered into the control unit, whereby the control unit can control the operation of the demineralization plant to change the ratio of the mixture components of the streams of NF and RO permeate for the combined RO/NF permeate stream and the amounts of optional MB or concentrate for stabilizing fines introduced into the combined an RO/NF permeate stream to produce mixed brackish injection water compositions that meet operating range requirements, or preferred operating range requirements for the first or second reservoir regions.

The system of claim 1 may be used to inject brackish injection water sequentially into injection wells 20 and 20', respectively (in any order). At the same time, the system in Fig. 1 may be used to form a mixed flow of brackish injection water for injection into an injection well 20 having a composition within the operating range for the first reservoir region. Accordingly, the valve V7 on the discharge line 60 is open and the valve V7' on the discharge line 60' is closed. After the first brackish injection water plug is injected into the injection well 20, the system shown in FIG. 2 may be used to form a mixed flow of brackish injection water having a composition in accordance with the operating range for the second reservoir region and to inject a plug of the second brackish injection water into the injection well 20'.

The control unit may monitor the pressure sensors 23 (or 23') for any increase in pressure in the injection wells 20 (or 20') near the oil-bearing interval 22 in the first reservoir region 56 (or second reservoir region 56'). Alternatively, or additionally, the control unit may monitor flow sensor Q9 downstream of pressure pump(s) 24 for any reduction in flow. Both an increase in pressure in the injection well and a decrease in the flow rate at the outlet of the injection pump(s) 24 may be evidence of an unacceptable drop in well injectivity due to deterioration of the reservoir properties of the formation. The maximum allowable increase in pressure in the injection well 20 (or 20') and/or the maximum allowable decrease in the flow rate in the injection line 60 (or 60') can be entered into the control unit (where these values are compared with the allowable decrease in injectivity of the well). If the pressure in the injection well 20 (or 20') near the oil-bearing interval rises to a value approaching or reaches the maximum allowable pressure increase, or the flow after the injection pump(s) in the injection line 60 (or 60') drops to a value approaching to or reaches the maximum allowable flow rate reduction, the control unit may select a preferred operating range for the mixed brackish injection water composition that is predicted to reduce the risk of reservoir degradation in the first region (or second region) of the reservoir layer 22. For example, preferred operating ranges for mixed brackish injection water compositions may be defined by one or more of the following: upper bounds for TSRW; upper limit values for the content of divalent

- 16 042122 cations (in particular, the content of calcium cations); or upper limit values for one or more fine particle stabilization additives. The control unit may then control the operation of the demineralization unit by adjusting the composition of the combined RO/NF permeate stream 16 so that the mixed brackish water has a composition within the preferred operating range for the first (or second) reservoir region. For example, the control unit can achieve this by commanding: to increase the amount of RO permeate discharged through the RO permeate discharge line 11 by increasing the opening degree of the throttle valve V4; to increase the content of divalent cations in the composite low-salinity injection water stream by increasing the amount of MB mixed with the combined RO/NF permeate stream by increasing the opening degree of the throttle valve V5; or to increase the amount of fines stabilization concentrate in the brackish water composite stream 18 by increasing the opening degree of the throttle valve V6. The control unit can monitor the effect of changes in the operation of the demineralization plant on the flow rate or composition of the brackish injection water stream 18 (using flow sensor Q9 or sensor S7, respectively) to determine how adjustments to the operation of the plant have affected the flow rate and composition of the mixed brackish injection water within the preferred operating range for the first (or second) area of the reservoir and, if necessary, can make further adjustments to the operation of the demineralization unit to obtain compositions that fall into a more preferred operating range, providing additional assurance against the risk of deterioration of the reservoir properties of the reservoir. Thus, the system in Fig. 1 has a control unit with a feedback loop that provides the system with a mixed flow of brackish injection water, the composition of which prevents or reduces the risk of deterioration of reservoir properties in the first (or second) region of the oil-bearing layer of the productive formation.

After injecting a low pore volume of the mixed low-salinity injection water into the injection well 20 (or injection well 20'), a displacement aqueous fluid, such as produced water (WW) or a mixture of MB and BW, is injected into the injection well 20 (or 20') lines 60 (or 60') to advance the small pore volume plug, and hence the disconnected oil zone, to the production well 21 (or 21').

The system of claim 1 can also be used to provide a low-salinity injection water stream that is simultaneously injected into the injection wells 20 and 20'. In this case, both valves V7 and V8 are in the open position. In this state, the control unit determines the operating range overlap for the brackish injection water composition, defined by the boundary values for the overlap area between the operating ranges defined for the brackish injection water compositions for the first and second reservoir regions. The control unit also determines one or more preferred overlapping operating ranges for the low-salinity injection water composition that continue to achieve FOR from the first and second areas of the reservoir while providing one or more increased levels of assurance against the risk of deterioration of reservoir properties in the first and second 23. The preferred operating range(s) for the brackish injection water composition is defined by the boundary values for the overlap area between the preferred operating ranges for brackish injection water compositions for the first and second reservoir regions. The control unit can monitor the readings of the pressure sensors 23 and 23', monitoring any increase in pressure in the injection wells 20 and 20' adjacent to the oil-bearing interval 22 in the first region 56 and the second region 56' of the reservoir. Alternatively, or additionally, the control unit may monitor the readings of the flow sensor Q9, located on the main pressure line 59 at the outlet of the pressure pump(s) 24, monitoring any reduction in flow. An increase in pressure in either of the injection wells 20 and 20', or a drop in flow in the main injection line, may be indicative of an unacceptable drop in well injectivity due to degradation of the reservoir properties of the formation. Values for the maximum allowable increase in pressure in the injection wells 20 and 20' and/or the maximum allowable flow rate drop in the main injection line 59 can be entered into the control unit (where these values are compared with the allowable decrease in well injectivity). If the pressure in the injection well 20 and/or 20' near the oil-bearing interval increases to a value approaching or reaching the maximum allowable pressure increase, or the flow in the main injection line after the injection pump(s) drops to a value approaching the maximum allowable flow drop or reaching it, the control unit may select a preferred override operating range for the composition of the mixed brackish injection water stream that is predicted to reduce the risk of reservoir degradation in the first or second regions of reservoir 22. For example, preferred overlapping operating ranges for mixed brackish injection water compositions may be defined by one or more of the following: higher limits for TSRW; or higher

- 17 042122 boundary values for the content of divalent cations (in particular, the content of calcium cations); or higher values for one or more fine particle stabilization additives. Further, the control unit may control the operation of the demineralization unit to adjust the composition of the combined RO/NF permeate stream 16 so that the composition of the mixed brackish water falls within the preferred override operating range. This can be achieved by the procedure described above. Similarly, the control unit can monitor the effect of a change in the operation of the demineralization unit on the flow rate or composition of the brackish water stream 18 (using flow sensor Q9 and sensor S7, respectively) to determine whether the changes in the operation of the plant have managed to introduce the flow rate and compositions of the mixed brackish injection water. within the preferred overlapping operating range and to determine if the well injectivity decline has stabilized and, if necessary, may make further changes to the operation of the unit to introduce compositions within the more preferred overlapping operating range, providing more reliable guarantees against the risk of deterioration of reservoir reservoir properties in the first and second reservoir regions.

In FIG. 2 shows a modified integrated system that simultaneously injects the first low-salinity injection water stream into the first area of the reservoir and the second low-salinity injection water stream into the second area of the reservoir, and the compositions of the first and second low-salinity waters differ (i.e., are determined by different operating ranges) the system shown in Fig. 2 differs from the complex system shown in FIG. 1 in that the mixing system has different flow paths to form a first and second combined RO/NF permeate stream flowing through lines 16 and 16'; an optional fines stabilization concentrate tank 50 having a concentrate main line 51 equipped with a pump and concentrate branch lines 26 and 26' each having an adjustable flow valve V8 and V8' respectively, and which can optionally transferring the particle stabilization concentrate to the first and second combined RO/NF permeate streams, respectively; an optional sea water bypass (MB) having branch lines 6 and 6', each respectively equipped with an adjustable flow valve V5 and V5', which can, in some cases, transfer MB to the first and second combined RO/NF- permeate; an injection system for injection wells 20 and 20', wherein the injection system has first and second dedicated injection lines 18, 18' for conveying the first and second mixed brackish water streams to injection wells 20 and 20', respectively, and each of the first and second injection lines 18 and 18' has one or more pressure pumps 24 and 24', respectively; and a control unit for controlling the operation of the demineralization unit and mixing the first and second brackish injection waters in the mixing system. The system also includes production equipment in fluid communication with the first and second flow lines 28, 28' of production wells 21, 21'.

The complex system shown in Fig. 2 has valves V1-V8 and V5'-V8' and different flow lines (piping) configured to form the flow paths described above. The valves V1-V8 and V5'-V8' may be throttle valves and their opening degree may be set by the control unit (ie fully open, fully closed and various intermediate positions). Accordingly, the control unit can control the flows and pressures in the membrane unit by controlling the supply pump 3, valves V1-V4, valves V5 and V5', valves V6 and V6' and valves V7 and V7', or any combination thereof.

The flow sensors Q1-Q9 and Q5'-Q9' are used to determine the flow rates in the various paths of the complex system. Flow data can be sent from flow sensors Q1-Q9 and Q5'-Q9' to the control unit via electrical signal lines (dotted lines in Fig. 1) or via wireless communication channels, such as Wi-Fi or Bluetooth. In some cases, flow sensors Q1 and Q2 on RO concentrate and NF concentrate transfer lines 8 and 7, respectively, may not be used.

To determine the total concentration of dissolved ions (TSDTS) and / or the concentration of individual ions or individual ions by ion types (for example, multivalent cations or divalent cations), ion concentration sensors in the drain streams of the NF concentrate and RO concentrate (sensors S4 and S5) are also used. ), in different mixed streams (sensors S1, S2, S3 and S6) and in the first and second composite brackish injection water streams (sensors S7 and S7'), respectively. The ion concentration data is also sent to the control unit via electrical signal transmission lines) or via wireless communication channels, such as Wi-Fi or Bluetooth. In some cases, sensors S4 and S6 on NF concentrate and RO concentrate transfer lines 7 and 8, respectively, may not be used. The S6 sensor on the optional fine particle stabilizer concentrate feed line 26 may also not be used if the additive concentration in the concentrate tank has been previously measured and remains unchanged over time (in this case, the measured concentration of additive in the concentrate can be entered into the control unit). It also appears that the sensors S1, S2 and S3 on the optional seawater bypass 6, on the feed branch 9

- 18 042122

The RO permeate, and branch feed line 13 NF permeate, respectively, can be omitted when the compositions of the MB, RO permeate, and NF permeate are predictably kept substantially constant over time.

In the shown in FIG. 2, the RO permeate feed line 9 splits to form first and second branch RO permeate feed lines 9' and 9. Similarly, the NF permeate feed line 13 splits to form the first and second branch feed lines 13' and 13 of the NF permeate. The NF permeate flowing through the first NF permeate branch feed line 13' may be further injected into the RO permeate flowing through the first RO permeate branch feed line 9' to form a first combined RO/NF permeate stream flowing through line 16' . Similarly, the NF permeate flowing through the second NF permeate branch feed line 13 may be further injected into the RO permeate flowing through the second RO permeate branch feed line 9 to form a second combined RO/NF permeate flow through the line 16. In some cases, the first combined RO/NF permeate stream flowing through line 16' and the second combined RO/NF permeate stream flowing through line 16 are supplemented with MB and/or fines stabilization concentrate through lines 6, 6' and/or 26, 26' respectively. The resulting first and second mixed brackish injection waters are then injected into the injection wells 20, 20' drilled into the first and second oil-bearing regions of the reservoir, respectively, through the injection lines 18, 18', respectively. It appears, however, that the NF permeate, RO permeate, optional sea water, and optional fines stabilization concentrate used to form the first and second brackish injection waters may be combined in any order, including at a single confluence for each of the first and second mixed low-mineralized injected waters.

As shown above, the boundary values for the compositions of the first and second mixed low-salinity injected water are entered into the control unit, thereby determining the operating ranges for the first and second mixed low-salinity injected waters, which ensure the achievement of FOR for the first and second areas of the oil-bearing layer 23 of the productive formation, while reducing the risk of deterioration of the reservoir properties of the formation.

The control unit may control the operation of the demineralization unit to change the blend ratio of the RO permeate and NF permeate streams for the first and second combined RO/RO permeate streams and the amounts of optional MB or fines stabilizer concentrate blended into the first and second combined RO/ NF-permeate, to obtain, respectively, compositions for the first and second mixed brackish injection water corresponding to the operating ranges for the first and second areas of the oil-bearing layer of the productive formation.

Preferred limit values can be entered into the control unit, where these preferred limit values define the preferred operating ranges (second, third, etc. operating ranges) for the compositions of each of the first and second mixed brackish injection waters, which can further reduce the risk of deterioration. reservoir properties of the formation in the first and second regions of the productive formation, while maintaining an acceptable enhanced oil recovery (EOR) from the first and second regions of the productive formation.

Accordingly, the control unit may monitor the pressure sensors 23 and 23', monitoring any increase in pressure in the injection wells 20, 20' near the oil-bearing intervals 22, 22', or monitoring the flow sensors Q9 and Q9' located after the injection pump(s) 24 , 24' of the dedicated injection lines 18, 18' of the injection system, monitoring any reduction in flow rate (both parameters may indicate an unacceptable decrease in well injectivity due to deterioration of the reservoir properties of the formation). The values for the maximum allowable increase in pressure in the injection wells 20, 20' and/or the maximum allowable decrease in flow in the dedicated injection lines 18, 18' can be entered into the control unit (where these values are correlated with an acceptable decrease in well injectivity). If the pressure in the injection well 20 and/or 20' near the oil-bearing interval increases to a value approaching or reaching the maximum allowable pressure increase, or the flow after the injection pump(s) in the dedicated injection lines 18 and/or 18' drops to a value, approaching or reaching the maximum allowable flow rate reduction, the control unit may select an alternative operating range for the composition of the first and/or second mixed brackish injection water (for example, one of the second, third, etc. operating ranges), which, according to the forecast, reduce the risk of deterioration of the reservoir properties of the formation. For example, alternative operating ranges for the compositions of the first and/or second mixed brackish injection waters can be defined by one or more of the following conditions: higher boundary values for TWR; higher limit values for the content of divalent cations (in particular, the content of calcium cations); or higher limit values for one or more fine particle stabilization additives. Further, the control unit may change the operation of the demineralization unit of the integrated system to control the composition of the first and/or second mixed injection water so that it falls into an alternative operating range. To do this, for example, the control unit can send commands to divert a certain amount of OO-permeate through the line 11 reset OO-19 042122 permeate. The control unit may also change the operation of the complex system to increase the content of divalent cations in the first and/or second combined RO/NF permeate stream, by increasing the amount of MB added to the first and/or second combined RO/NF permeate stream, and/or increasing the amount of fines stabilization concentrate added to the combined first and/or second RO/NF stream (by changing the opening degree of one or more throttle valves V5, V5', V8 and V8'). The control unit may monitor the effect of changes in operation of the complex system in terms of flow rate on the composition of the first and/or second mixed brackish injection water streams using flow sensors Q9 and sensor S7 or flow sensor Q9' and sensor S7', to determine whether as a result of changes in the operation of the installation, to bring the compositions of the first and second mixed injection waters within the preferred operating range, and, if necessary, may make additional changes in the operation of the installation to achieve compositions that are within the preferred operating range. The control unit may also monitor the flow rates of the first and/or second mixed brackish injection water flows in the injection lines 18 and 18' at the outlet of the injection pumps 24 and 24', and/or downhole pressure in the injection wells 20 and 20' using pressure sensors 23 and 23', respectively, to determine if the well has stabilized or increased injectivity. If not, the control unit may change the operation of the complex system so that the composition of the first and/or second mixed low-salinity injection water falls within another additional preferred operating range for the first and/or second reservoir regions. Thus, the system shown in Fig. 1 has a feedback control unit that allows the system to change the composition of the first and second mixed brackish injection water stream so as to reduce the risk of deterioration of the reservoir properties while maintaining the EOR from the reservoir.

It appears that if a low pore volume mixed first brackish injection water (or second brackish injection water) plug of low pore volume was injected into the injection well 20 (or 20'), a dedicated injection line 18 for the injection well 20 (or a dedicated injection line 18' for the injection well 20 ') can be used to pump bottom water (BW) or a mixture of MB and BW as an aqueous displacement fluid to move a plug of mixed low-salinity injection water, and hence a disconnected oil zone, towards production well 21 (or towards production well 21 '). Accordingly, the RO-permeate and NF-permeate streams are no longer required for the injection well 20 (or 20'), and can be directed to produce one or more mixed brackish injection water streams for at least one injection well drilled into an additional productive area. formation.

Claims (36)

1. A method for increasing oil recovery from the first region and the second region and permeability by injecting the first mixed low-salinity injected water of variable composition into the first region of the oil-bearing formation and the second mixed low-salinity injected water of variable composition into the second region of the oil-bearing formation, in which the first mixed low-salinity injected water is obtained for injection into at least one injection well drilled into the first region of the oil-bearing formation; a second mixed brackish injection water is obtained for injection into at least one injection well drilled into the second region of the oil reservoir, the first region and the second region having the first rock composition and the second rock composition, respectively, the first risk of deterioration of oil recovery when exposed to brackish injection water is due to the first the composition of the rock and the second risk of impaired oil recovery when exposed to brackish injected water is due to the second composition of the rock, while the first risk and the second risk are distinguished and controlled by monitoring at least one of an increase in pressure in the injection well and / or a decrease in flow after the injection pumps, and The first mixed low-salinity injection water and the second mixed low-salinity injection water each contain nanofiltration permeate (NF) and reverse osmosis (RO) permeate, controlled mixing with the high-salinity feeder oy water; maintaining the composition of the first mixed brackish injection water within a first predetermined operating range by adjusting the amounts of NF permeate and RO permeate in response to the reduction in injectivity; response to reduced injectivity; - 20 042122 wherein the first predetermined operating range and the second predetermined operating range increase oil recovery from the first region and the second region and permeability when the first mixed brackish injection water is injected into the first region and the second mixed brackish injection water is injected into the second region. 2. The method of claim 1, wherein the first mixed brackish injection water and the second mixed brackish injection water each comprise sea water. 3. The method according to claim 1 or 2, wherein the first mixed low-salinity injection water and the second mixed low-salinity injection water each additionally contain fines stabilization additives. 4. The method according to any one of the preceding paragraphs, in which the first mixed brackish injection water is injected into at least one injection well drilled into the first region of the oil reservoir; and simultaneously injecting a second mixed low-salinity injection water into at least one injection well drilled into the second region of the oil-bearing formation. 5. The method according to any one of claims 1 to 3, in which the first mixed brackish injection water is injected into at least one injection well drilled into the first region of the oil reservoir; and injecting the second mixed low-salinity injection water into at least one injection well drilled into the second region of the oil-bearing formation, the first mixed low-salinity injection water being injected before injection of the second mixed low-salinity injection water. 6. The method according to any of the preceding paragraphs, in which the oil-bearing formation additionally contains a third region of the productive formation, which has a risk of deterioration in oil recovery when exposed to brackish injected water, different from the risk of deterioration in oil recovery in the first region and the second region, and when implementing the method, a third mixed brackish injection water for injection into at least one injection well drilled into the third region of the oil reservoir; and injecting a third mixed brackish injection water into at least one injection well drilled into the third region of the oil-bearing formation; and maintaining the composition of the third mixed brackish injection water within a third predetermined operating range that enhances oil recovery from the third region and injection permeability of the third mixed brackish injection water. 7. The method of claim 6, wherein the first mixed brackish injection water, the second mixed brackish injection water, and the third mixed bland injection water are injected into at least one injection well at the same time. 8. The method according to claim 6, wherein the first mixed low-salinity injection water, the second mixed low-salinity injection water and the third mixed low-salinity injection water are injected into at least one injection well one after the other. 9. A method according to any one of the preceding claims, wherein at least one of the first predetermined operating range, the second predetermined operating range, or the third predetermined operating range specifies a sulfate level of less than 100 mg/l. 10. The method according to any one of claims 1 to 9, wherein the first predetermined operating range and the second predetermined operating range comprise one or more boundary values for the composition of the first mixed low-salinity injection water and the composition of the second mixed low-salinity injection water, respectively, wherein said one or more boundary values contain at least one of an upper limit or a lower limit for parameters including at least one of total dissolved solids, salinity, ionic strength, concentration of one or more individual ions, concentration of individual ions by one or more types of ions, ratios of individual ions by ion type, ratios of individual ions, or any combination of these parameters. 11. A method for producing a single low-mineralized injected water of variable composition for injection into at least one injection well drilled into the first region of the oil-bearing formation, and at least one injection well drilled into the second region of the oil-bearing formation, to increase oil recovery, in which overlapping operating range for a single mixed low-salinity injected water, moreover, the overlapping operating range is defined by the boundary values for the area of overlap of several specified operating ranges for the compositions of mixed low-salinated injected waters for the first region and the second region of the oil-bearing formation, while these several specified operating ranges increase oil recovery from the first region and the second region of the oil reservoir, increasing the permeability in the first region and the second region, wherein at least one injection well is drilled into the first region and at least - 21 042122 at least one injection well is drilled into the second region, and the reservoir rock of the first region has the first rock composition, the reservoir rock of the second region has the second rock composition, and the first risk of deterioration of oil recovery when exposed to brackish injected water is due to the first rock composition, and the second the risk of deterioration of oil recovery when exposed to brackish injected water is due to the second composition of the rock, and while the first risk and the second risk are distinguished and controlled by monitoring at least one of the increase in pressure in the injection well and / or decrease in flow after the injection pumps, and a single mixed brackish injection water contains nanofiltration permeate (NF) and reverse osmosis permeate (OO); obtaining a single injection fluid with a composition within an overlapping operating range by controlled mixing of at least one of the RO permeate and the NF permeate with the highly saline feed water; and maintaining the composition of the single injection fluid within the overlapping operating range by adjusting the amounts of NF-permeate and RO-permeate in response to the decrease in injectivity. 12. The method of claim 11, wherein a single injection fluid is injected into the first region and into the second region. 13. The method of claim 11 or 12, wherein the first region and the second region are different regions or reservoir rock layers within the oil reservoir. 14. The method according to any one of paragraphs. 11-13, in which the first rock composition and the second rock composition are different. 15. The method according to any one of claims 11 to 14, wherein the boundary values of the single mixed brackish injection water comprise at least one of an upper limit or a lower limit for parameters including at least one of total dissolved solids, salinity, ionic strength, the concentration of one or more individual ions, the concentration of individual ions by one or more types of ions, the ratio of individual ions by type of ion, the ratio of individual ions, or any combination of these parameters. 16. System for injecting a single mixed brackish injection water of variable composition into at least one injection well drilled into the first region of the oil reservoir, and injection of a single mixed brackish injection water into at least one injection well drilled into the second region of the oil reservoir, to increase an oil recovery unit, including a demineralization unit, containing a reverse osmosis (OO) unit, configured to obtain a mixed flow of OO-permeate and transfer the mixed flow of OO-permeate to a mixing system, and a nanofiltration unit (NF), configured to obtain a mixed flow of NF permeate and transferring the mixed flow of NF-permeate to the mixing system; a mixing system comprising an RO permeate feed line, an NF permeate feed line, an RO permeate discharge line, an NF permeate discharge line, a confluence configured to mix the RO permeate and NF permeate to form a single mixed brackish injection water, and a discharge line configured to transfer a single mixed low-salinity injection water to the injection system; and an injection system comprising an injection line having at least one injection pump configured to supply a single mixed injection water to: 1) at least one injection well drilled into the first region of the oil-bearing formation, and 2) at least one injection well a well drilled into the second region of the oil reservoir, and a control unit configured to control the amount of at least one of the blended RO permeate stream or the blended NF permeate stream mixed at the confluence; and maintaining the composition of the single mixed brackish water stream within the overlap operating range defined by the boundary values for the overlap region of the first predetermined operating range and the second predetermined operating range, wherein the first predetermined operating range and the second predetermined operating range determine the compositions of the single mixed brackish injection water for the first region and the second region of the oil-bearing formation, and the first predetermined operating range and the second predetermined operating range define compositions for increasing oil recovery from the first region and the second region and permeability in the first region and the second region. - 22 042122 17. The system of claim 16, wherein the first predetermined operating range and the second predetermined operating range are stored in a control unit configured to determine an overlapping operating range using the first predetermined operating range and the second predetermined operating range. 18. The system according to any one of claims 16 or 17, in which the mixing system contains a tank containing a concentrated aqueous solution of at least one additive for stabilizing fine particles; and a fines stabilization concentrate feed line, wherein the mixing system is configured to transfer at least one fines stabilization additive into a single mixed brackish injection water through the fines stabilization concentrate feed line. 19. The system of claim 18, wherein the mixing system further comprises a metering pump configured to dose at least one fines stabilization concentrate into the single mixed brackish injection water. 20. The system of claim 19 wherein the metering pump is in signal communication with a flow meter and configured to control the concentration of at least one fines stabilization additive in the single mixed brackish injection water to conform to a concentration profile of at least at least one additive to stabilize fine particles using a signal from a flow meter. 21. The system according to any one of claims 18 to 20, wherein the control unit is configured to control the amount of at least one fines stabilization additive supplied to at least one location from: 1) a mixing system confluence or 2) an injection system lines; and maintaining the composition of the single mixed brackish water within an overlapping operating range by adjusting the amount of the at least one fine particle stabilization additive. 22. The system of claims 16-21, wherein the overlapping operating range comprises upper limits and lower limits for the concentration of at least one fine particle stabilizing additive corresponding to the overlapping concentrations of at least one fine particle stabilizing additive common to the first and second preset operating ranges. 23. A system according to any one of claims 16-22, wherein the demineralization plant is located on the onshore site and the mixing system is located on the offshore site. 24. The system according to any one of claims 16-23, in which the injection system further comprises a number of branch injection lines connected to a single subsea manifold, and the injection line is connected to a single subsea manifold, and a number of branch injection lines connect a single subsea manifold at least with one injection well drilled into the first region of the oil reservoir and at least one injection well drilled into the second region of the oil reservoir. 25. The system according to claim 24, in which the control unit is additionally configured to open valves in the discharge line and a single subsea manifold; and transmitting, by opening the valves, a single mixed flow of brackish water from the injection line to at least one injection well drilled into the first region and at least one injection well drilled into the second region. 26. The system according to claim 24, in which the control unit is additionally configured to: selectively open valves in the discharge line and a single subsea manifold; transmitting, by opening the valves, a single mixed flow of brackish water from the injection line to at least one injection well drilled into the first region; selectively changing the state of valves in the injection line and a single subsea reservoir after the transfer of a single mixed flow of brackish water from the injection line to at least one injection well drilled into the first region; and transmitting, by selectively changing the state of the valves, a single mixed brackish water flow from the injection line to at least one injection well drilled into the second region. 27. The system of any one of claims 16-26, wherein the mixing system further comprises one or more sensors configured to determine a composition parameter of the single mixed brackish injection water stream. 28. The system of claim 27, wherein the composition parameter includes a total dissolved solids concentration, a chloride anion concentration, a bromide anion concentration, a calcium cation concentration, a magnesium cation concentration, a potassium cation concentration, a nitrate anion concentration, a sulfate anion concentration, or a flow rate of one or more from an OO permeate blend stream, an OO permeate divert stream, an NF permeate blend stream, or an effluent - 23 042122 flow NF-permeate. 29. System for producing a first mixed low-salinity injection water and a second mixed low-salinity injected water of variable composition for injection into at least one injection well drilled into the first region of the oil-bearing formation, and at least one injection well drilled into the second region of the oil-bearing formation , wherein the reservoir rock of the first region has the first rock composition for oil recovery, the reservoir rock of the second region has the second rock composition, and the first risk of deterioration in oil recovery when exposed to low-mineralized injected water is due to the first composition of the rock, and the second risk of deterioration in oil recovery when exposed to low-mineralized injected water is due to the second composition of the rock, and wherein the first risk and the second risk are distinguished and controlled by monitoring at least one of an increase in pressure in the injection well and/or a decrease in flow rate after the injection pumps, and the first mixed low-salinity injected water and the second mixed low-salinated injected water each contain nanofiltration permeate and reverse osmosis permeate, including a demineralization unit containing a reverse osmosis (OO) unit, configured to obtain a mixed flow of OO-permeate and transfer the mixed an OO permeate flow to the mixing system, and a nanofiltration unit (NF) configured to obtain an NF permeate admixture stream and transfer the NF permeate admixture flow to the mixing system; a mixing system comprising a main RO-permeate feed line, a main NF-permeate feed line, an RO-permeate discharge line, an NF-permeate discharge line, a first confluence and a second confluence, and a first discharge line and a second discharge line, wherein the RO discharge line -permeate and the NF-permeate discharge line are fluidly connected to the main RO-permeate feed line, separating to form the first RO-permeate branch line and the second RO-permeate branch line, configured to transfer the admixed RO-permeate flow to the first confluence and the second confluence point, respectively, and the main feed line of the NF-permeate is divided to form the first branch line of the NF-permeate and the second branch line of the NF-permeate, configured to transfer the admixed flow of NF-permeate to the first confluence and the second confluence, respectively, and the first outlet line and the second outlet line are fluidly connected to the first a confluence point and a second confluence and are configured to transfer the first mixed brackish injection water and the second mixed brackish injection water to the injection system; an injection system comprising at least a first dedicated injection line and a second dedicated injection line, each of which has at least one injection pump and, accordingly, are fluidly connected to the first discharge line and the second discharge line of the mixing system, the first the dedicated injection line is configured to transfer the first mixed low-salinity injection water to at least one injection well drilled into the first region of the oil-bearing formation, and the second injection line is configured to transfer the second mixed low-salinity injection water to at least one injection well drilled in the second region of the oil-bearing formation; and a control unit configured to receive the first predetermined operating range and the second predetermined operating range; changing the operation of the demineralization unit to control the amount of at least one stream of the OO permeate blend stream or the NF permeate blend stream blended at the first confluence and the second confluence; and maintaining the compositions of the first mixed brackish water stream and the second mixed brackish water stream within the first predetermined operating range and the second predetermined operating range, respectively, by changing the operation of the demineralization unit. 30. The system of claim 29, wherein at least one of the first mixed brackish injection water or the second mixed brackish injection water comprises sea water or at least one fine particle stabilization additive. 31. The system according to claim 29 or 30, wherein the control unit is configured to inject the first mixed low-salinity injection water and the second mixed low-salinity injection water sequentially one after the other. 32. The system according to claim 29 or 30, in which the control unit is configured to pump the first mixed brackish injection water and the second mixed brackish - 24 042122 injection water at the same time. 33. The system according to any one of paragraphs.29-32, in which the mixing system further includes a tank containing a concentrated aqueous solution of at least one additive for stabilizing fine particles; the main feed line connected to the tank; and a first branch feed line and a second branch feed line, each having a flow valve configured to supply at least one fines stabilization additive as an admixture stream for the first mixed brackish injection water and the second mixed brackish injection water. 34. The system of claim 33, wherein the control unit is further configured to change the operation of the mixing system to control the amount of at least one fines stabilization additive conveyed as an admixture stream for the first mixed brackish injection water and the second mixed bland injection water ; and maintaining the compositions of the first mixed brackish injection water stream and the second mixed brackish injection water stream within a first predetermined operating range and a second predetermined operating range that include boundary values for at least one fines stabilization additive. 35. The system of any one of claims 29-34, wherein the mixing system further comprises one or more sensors configured to determine a composition parameter of the first mixed brackish injection water stream and the second mixed brackish injection water stream. 36. The system of claim 35 wherein said one or more sensors are configured to measure one or more parameters including total dissolved solids concentration, chloride anion concentration, bromide anion concentration, calcium cation concentration, magnesium cation concentration, potassium cation concentration , nitrate anion concentration, sulfate anion concentration, or a flow rate of one or more of: RO permeate blend stream, RO permeate bleed stream, NF permeate bleed stream, or NF permeate bleed stream.