EP4627186A1

EP4627186A1 - Feed water system, water processing system, and associated systems & methods

Info

Publication number: EP4627186A1
Application number: EP23833855.2A
Authority: EP
Inventors: Hank James SOWERS
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-11-30
Filing date: 2023-11-30
Publication date: 2025-10-08
Also published as: GB2625053A; GB202218035D0; WO2024115913A1

Abstract

A feed water system for use in supplying a feed water input to a water processing system comprises a borehole arrangement extending from surface to a downhole location. The borehole arrangement is configured for fluid communication with a hydrocarbon reservoir and a geothermal reservoir. A fluid conduit arrangement is configured to transport produced water from the hydrocarbon reservoir and water from the geothermal reservoir towards surface. The fluid conduit arrangement is at least partially disposed within the borehole, and comprises a first conduit configured to receive produced water from said hydrocarbon reservoir and a second conduit isolated from said first conduit and configured to receive water from said geothermal reservoir. The water processing system comprises one or more reactors for converting the feed water input into steam output and a concentrate output.

Description

FEED WATER SYSTEM, WATER PROCESSING SYSTEM, AND ASSOCIATED SYSTEMS & METHODS

FIELD

This relates to a feed water system, to a water processing system; and associated systems and methods.

BACKGROUND

Many industries require large volumes of energy and/or water in order to operate. While there is a continuing need to meet this and future demand for energy, there is also a desire to increase the use of recycling technologies that reduce industries carbon footprint by better managing the use of hydrocarbons, and hydrocarbon-based products.

In the oil and gas production industry, for example, the desire to increase efficiency and environmental sustainability has seen the development of a number of reservoir stimulation techniques aimed towards increasing the recovery of oil from a given reservoir, known as Enhanced Oil Recovery (EOR), and thereby reduce the overall environmental impact. In some instances, EOR operations may involve the stimulation of the reservoir by the injection of a gas, e.g. nitrogen or carbon dioxide gas, into the reservoir. In other instances, EOR operations may involve a chemical injection process. In other instances, EOR operations may involve the introduction of heat using steam, this generally known as thermal EOR.

While such techniques have proved successful in increasing the amount of oil that can be recovered, challenges remain with conventional equipment and techniques in terms of their efficiency and environmental impact.

Other areas where challenges remain with conventional equipment and techniques in terms of their efficiency and environmental impact include those directed to the provision of drinking water, the provision of de-mineralised water for industrial processes, those directed to the provision of minerals, in particular but not exclusively rare-earth minerals used in electronics, batteries and the like, and/or nitrates used for example in agriculture and/or medical industry. SUMMARY

Aspects of the present disclosure relate to a feed water system, in particular a feed water system for use in supplying a feed water input to a water processing system; to a water processing system; and to associated systems and methods.

According to a first aspect, there is provided a feed water system for use in supplying a feed water input to a water processing system, the feed water system comprising: a borehole arrangement extending from surface to a downhole location, wherein the borehole arrangement is configured for fluid communication with a hydrocarbon reservoir and a geothermal reservoir; and a fluid conduit arrangement configured to transport produced water from said hydrocarbon reservoir and water from said geothermal reservoir towards surface, wherein the fluid conduit arrangement is at least partially disposed within the borehole, and wherein the fluid conduit arrangement comprises: a first conduit configured to receive produced water from said hydrocarbon reservoir; and a second conduit isolated from said first conduit and configured to receive water from said geothermal reservoir.

Beneficially, the feed water system facilitates cogeneration of water, e.g. brine, from a geothermal reservoir (“geothermal water”) and water from a hydrocarbon reservoir (“produced water”), for supply to the water processing system. As will be described further below, the water processing system utilises the residual thermal energy from the geothermal water and/or the produced water to provide at least part of the thermal energy required to convert the feed water input into steam, such steam being, for example, injected into the hydrocarbon reservoir as part of a thermal enhanced oil recovery (EOR) operation. The feed water system is thus particularly beneficial with hydrocarbon reservoirs or fields comprising hydrocarbon reservoirs containing oil and in particular “heavy” oil in which production can be enhanced using thermal EOR operation. Radiated heat from the geothermal water may also assist in the flow of oil from the hydrocarbon reservoir. By providing access to both geothermal water and produced water - either individually or in combination - the feed water system facilitates the use of the geothermal water and produced water and their associated residual thermal energy in the water processing system, obviating or at least mitigating the need to consume significant amounts of external energy to power the water processing system as well as the investment required to construct, operate and/or maintain the external power supply systems. This, in turn, permits amongst other things thermal EOR operations to be carried out in hydrocarbon production systems which would otherwise be unsuitable or uneconomic for EOR operations. Further, this may permit the operational life of a hydrocarbon reservoir to be extended and/or an abandoned reservoir to be brought back into production.

Alternatively the water processing system may utilises the residual thermal energy from the geothermal water and/or the produced water to provide at least part of the thermal energy required to convert the feed water input into steam, such steam being, for example, in the provision of drinking water, the provision of de-mineralised water for industrial processes, those directed to the provision of minerals, in particular but not exclusively rare-earth minerals used in electronics, batteries and the like, and/or nitrates used for example in agriculture and/or medical industry.

The feed water system may comprise or take the form of a borehole completion system.

The feed water system may comprise or take the form of a hybrid feed water system, for example a hybrid produced water and/or geothermal feed water system.

Beneficially, the feed water system is configured and/or operable to receive produced water from the hydrocarbon reservoir and/or water, e.g. brine, from the geothermal reservoir and transport the water to surface.

As described above, the feed water system comprises a borehole arrangement extending from surface to a downhole location, wherein the borehole arrangement is configured for fluid communication with a hydrocarbon reservoir and a geothermal reservoir.

The borehole arrangement may comprise one or more boreholes. One or more of the boreholes may be configured to intersect both the hydrocarbon reservoir and the geothermal reservoir.

For example, the borehole arrangement may comprise a single borehole, the single borehole configured to intersect both the hydrocarbon reservoir and the geothermal reservoir.

Alternatively, the borehole arrangement may comprise a plurality of boreholes. Where the borehole arrangement comprises a plurality of boreholes, one or more of the boreholes may be configured to intersect both the hydrocarbon reservoir and the geothermal reservoir. Alternatively or additionally, the borehole arrangement may comprise at least one borehole which intersects the hydrocarbon reservoir and at least one borehole which intersects the geothermal reservoir.

At least one of the boreholes of the borehole arrangement may be at least partially lined (“completed”) with bore-lining tubing, such as casing. The bore-lining tubing may be disposed within the borehole. An annulus between the outside of the bore-lining tubing and the inside of the borehole may be lined with cement. Alternatively or additionally, the bore-lining tubing may be supported within the borehole by a tubing hanger or the like.

In particular embodiments, at least one of the boreholes is wholly lined, i.e. to total depth (TD). However, in other embodiments at least one of the boreholes may be at least partially un-lined (i.e. “open hole” or having an “open hole portion”).

At least one of the boreholes may comprise or take the form of a vertical borehole.

Alternatively or additionally, at least one of the borehole may comprise or take the form of an angled, lateral, kick out or horizontal borehole (referred to as a horizontal borehole).

The borehole arrangement may comprise a borehole fluid communication arrangement for providing fluid communication with the hydrocarbon reservoir and the geothermal reservoir. In use, the borehole fluid communication arrangement may facilitate ingress of produced water from the hydrocarbon reservoir and water, e.g. brine, from the geothermal reservoir.

The borehole fluid communication arrangement may comprise one or more perforations in the borehole. At least one of the perforations may be configured, e.g. positioned, shaped and/or dimensioned, to provide fluid communication between the hydrocarbon reservoir and the borehole. At least one of the perforations may be configured, e.g. positioned, shaped and/or dimensioned, to provide fluid communication between the geothermal reservoir and the borehole.

Alternatively or additionally, the borehole fluid communication arrangement may comprise one or more inflow control device, such as a valve, port, sleeve or the like.

As described above, the system comprises a fluid conduit arrangement disposed within the borehole, the fluid conduit arrangement comprising a first conduit configured to receive produced water from the hydrocarbon reservoir.

The first conduit may comprise or take the form of a tubing, e.g. a tubing string comprising a plurality of tubing sections coupled together. The first conduit may comprise or take the form of metallic tubing. The first conduit may comprise or take the form of production tubing.

The fluid conduit arrangement may comprise a single first conduit. Alternatively, the fluid conduit arrangement may comprise a plurality of first conduits, e.g. 2, 3 4, 5, 5 or more first conduits.

The first conduit may comprise or take the form of insulated tubing.

Beneficially, the provision of insulated tubing retains the thermal energy within the system as it passes from/into the hydrocarbon reservoir. As described above, the feed water system comprises a fluid conduit arrangement disposed within the borehole, the fluid conduit arrangement comprising a second conduit configured to receive water, e.g. brine, from the geothermal reservoir.

The second conduit may comprise or take the form of a tubing, e.g. a tubing string comprising a plurality of tubing sections coupled together. The second conduit may comprise or take the form of metallic tubing. The second conduit may comprise or take the form of production tubing.

The fluid conduit arrangement may comprise a single second conduit. Alternatively, the fluid conduit arrangement may comprise a plurality of second conduits, e.g. 2, 34, 5, 5 or more second conduits.

The second conduit may comprise or take the form of insulated tubing.

Beneficially, the provision of insulated tubing retains the thermal energy within the system as it passes from/into the geothermal reservoir.

In particular embodiments, the borehole arrangement may comprise a single bore having said fluid conduit arrangement disposed at least partially therein. Alternatively, the borehole arrangement may comprise a plurality of boreholes, with one or more boreholes having one or more first conduits and with one or more boreholes having one or more second conduits.

The feed water system may comprise a packer arrangement.

The packer arrangement may comprise a first packer.

The first packer may be configured to engage the borehole, in particular embodiments the bore-lining tubing, so as to prevent the production fluid from the hydrocarbon reservoir from bypassing the first packer and/or to direct the production fluid from the hydrocarbon reservoir into the first conduit.

The first packer may be configured so that the first conduit and the second conduit can pass through the first packer. For example, the first packer may comprise one or more axial throughbores for receiving the first and second conduits therethrough. The first packer may comprise a first axial throughbore for receiving the first conduit therethrough. The first packer may comprise a second axial throughbore for receiving the second conduit therethrough. Alternatively, the first packer may comprise a first fluid communication passage which connects at respective ends to sections of the first conduit and a second fluid communication passage which connects at respective ends to sections of the second conduit.

The first packer may comprise or take the form of a dual string packer.

The packer arrangement may comprise a second packer.

The second packer may be configured to engage the borehole so as to prevent fluid from the geothermal reservoir from bypassing the second packer and/or to direct fluid from the geothermal reservoir into the second conduit.

The second packer may be configured so that the second conduit can pass through the second packer. For example, the second packer may comprise an axial throughbore for receiving the second conduit therethrough. Alternatively, the second packer may comprise a fluid communication passage which connects to the second conduit.

The second packer may comprise or take the form of a single string packer.

In use, the first packer may define an upper packer, that is closer to surface, and the second packer may define a lower packer, that is more distal from surface and the first and second packers may permit zonal isolation in the borehole between fluid from the geothermal reservoir and fluid from the hydrocarbon reservoir. According to a second aspect, there is provided a water processing system configured for coupling to the feed water system of the first aspect, the water processing system comprising: a reactor arrangement comprising one or more reactors, wherein the reactor arrangement is configured and/or operable to convert a feed water input comprising produced water from a hydrocarbon reservoir and geothermal water from a geothermal reservoir into a steam output and a concentrate output.

The water processing system may be configured and/or operable to receive the feed water input from the feed water system and convert this feed water input into a steam output for use in a downstream operation.

Beneficially, the water processing system utilises the residual thermal energy from the geothermal water and/or the produced water to provide at least part of the thermal energy required to convert the feed water input into steam, such steam being, for example, injected into the hydrocarbon reservoir as part of a thermal enhanced oil recovery (EOR) operation. The feed water system is thus particularly beneficial with hydrocarbon reservoirs or fields comprising hydrocarbon reservoirs containing oil and in particular “heavy” oil in which production can be enhanced using thermal EOR operation. Radiated heat from the geothermal water may also assist in the flow of oil from the hydrocarbon reservoir. By providing access to both geothermal water and produced water - either individually or in combination - the feed water system facilitates the use of the geothermal water and produced water and their associated residual thermal energy in the water processing system, obviating or at least mitigating the need to consume significant amounts of external energy to power the water processing system as well as the investment required to construct, operate and/or maintain the external power supply systems. This, in turn, permits amongst other things thermal EOR operations to be carried out in hydrocarbon production systems which would otherwise be unsuitable or uneconomic for EOR operations. Further, this may permit the operational life of a hydrocarbon reservoir to be extended and/or an abandoned reservoir to be brought back into production.

In contrast to conventional thermal EOR systems in which the majority of thermal energy is lost (or in the case of thermal energy purposefully dissipated by cooling as part of the water processing operation), in the present water processing system the thermal energy of the geothermal water and the produced water is utilised in the conversion of the feed water input to the steam output. Thus, in contrast to conventional techniques, the feed water input is not cooled; rather the feed water is directed to the reactor, with the residual thermal energy of the feed water input being utilised in the production of the steam output.

The water processing system may also facilitate the extraction of solids from the geothermal water, e.g. brine, and/or the produced water.

For example, the water processing system may be utilised to take in water with high mineral and/or solids content, and convert this low quality saline water into high pressure de-mineralised steam for example for enhanced oil recovery operations or to provide purified water for oilfield or other industrial process use and a concentrate output containing the solids.

Beneficially, the removal of solids from the geothermal water obviates or at least mitigates fouling of the geothermal water conveyance systems and wells, which may otherwise occur due to precipitation of materials such as silica within the geothermal water.

Alternatively or additionally, the water processing system may also facilitate the processing of saline or contaminated waste water from other oilfield operations such as co-generation blow down, WTP & STP evaporation ponds, fracking operations or sand washing programs which normally render water undesirable for reuse for agriculture, human or wildlife uses or even disposal by deep well injection, reducing the burden on the environment and natural resources.

In use, the steam output can be used in a number of applications, including for example re-injection into a hydrocarbon reservoir as part of an enhanced oil recovery operation, for thermal water purification, as a mechanical motivator in a power generation process, or as utility steam for other industrial processes.

The water processing system may comprise, may be coupled to or operatively associated with the water processing system, or components of the water processing system, described in WO 2017/208023, the contents of which are incorporated in its entirety by way of reference.

As described above, the water processing system comprises a reactor arrangement comprising one or more reactors.

The water processing system may comprise a single reactor.

In particular embodiments, the water processing system comprises a plurality of reactors. The water processing system may comprise two reactors, three reactors, four reactors or more than four reactors. In particular embodiments, the water processing system comprises four reactors.

The reactors may be coupled in series, i.e. the concentrate output, e.g. brine, from a given reactor of said one or more reactors may form a feed water input to at least one other of the reactors.

As described above, the reactor arrangement is configured to receive the feed water input, the reactor configured to convert the feed water input into a steam output for use in a downstream operation.

The reactor may be configured to produce a high pressure steam output. The reactor may be configured to produce a steam output with over 98% vapour content. The reactor may be configured to produce a steam output with over 99% vapour content. The reactor may be configured to produce a steam output with over 99.5% vapour content. The reactor may be configured to produce a steam output of 100% vapour content, or substantially 100% vapour content.

As described above, the water processing system may be configured and/or operable so that reactor arrangement receives a feed water input from the feed water system, the reactor arrangement configured to convert said feed water input from the feed water system into a steam output.

The steam output may be used in a downstream operation. For example, the downstream operation may comprise the generation of electricity. For example, the water processing system may comprise, may be coupled to an electricity generator arrangement, the steam output from the reactor arrangement being directed to the electricity generator arrangement.

The electricity generator arrangement may comprise one or more electricity generators. In particular embodiments, at least one of the electricity generators may comprise or take the form of an organic Rankine Cycle generator such as a micro ORC.

Alternatively or additionally, the downstream operation may comprise a steam flood operation, such as may be utilised in an enhanced oil recovery (EOR) operation.

The reactor may be configured and/or operable to convert the feed water input into a concentrate output.

The concentrate output may comprise or take the form of a concentrated brine, e.g. a concentrated brine slurry.

The concentrate output may contain one of more of: Silica; Lithium; Calcium, e.g. Ca++; Sodium; Chloride, e.g. Cl'; and/or Magnesium.

The water processing system may comprise a heat exchanger arrangement.

The heat exchanger arrangement may comprise one or more heat exchangers.

Each heat exchanger may be coupled to or form part of one or more of the reactors.

One or more of the heat exchangers may comprise or take the form of a plate heat exchanger.

The heat exchanger may be configured and/or operable to receive the steam output from the reactor. The heat exchangers may be configured and/or operable to output a condensate output.

The condensate output may be output from the water processing system. For example, the condensate output may be combined with the concentrate output from the water processing system to, for example, facilitate injection or re-injection of the concentrate output into the borehole.

The water processing system may be configured so at least one of the heat exchangers receives, e.g. via a control valve arrangement, at least a portion of the concentrate output from one or more of the reactors. For example, the concentrate output, or at least part of the concentrate output, from a given reactor may be circulated back to the same reactor, for example via the heat exchanger, or directed onwards to one or more other of the reactors.

Beneficially, circulating the concentrate output from a given reactor back to the same reactor may facilitate the production of a concentrate output with a determined quality and/or maximise or at least improve the thermal recovery efficiency.

The water processing system may comprise one or more further reactor. The one or more further reactor may be configured and/or operable to receive the concentrate output from a given reactor and convert a portion of the concentrate output into steam. The steam output from the further reactor may be combined with the steam output from one or more other of the reactors.

The water processing system may comprise, may be coupled to or operatively associated with a heat generator arrangement.

The heat generator arrangement may be operatively associated with the reactor. The heat generator arrangement configured to supply thermal energy, e.g. a remaining thermal energy, required to convert the feed water input into the steam output. The heat generator arrangement may be configured to increase the temperature of the feed water input, and thereby convert the feed water input into steam.

The water may enter the reactor at or near to the vaporisation temperature. The temperature will be dependent on the process pressure. Additional heat from 5% to 90% of the total needed to make steam at the given pressure may then be supplied.

The heat generator arrangement may be configured to increase the temperature of the feed water input to a temperature at which mineral ions contained within the feed water input, such as dissolved calcium and/or magnesium ions, are precipitated from the feed water input as insoluble salts. By way of example, the temperature may range from 15 psi @ 250 degrees F to 2500 psi @ 670 degrees F.

The heat generator arrangement may comprise a heat source.

The heat generator arrangement may be configured and/or operable to transfer heat from and/or via a heat transfer medium. For example, the heat transfer medium may comprise or take the form of molten salt. The heat source may be generated from burning fossil fuel. The heat source may, for example but not exclusively, be generated from burning natural gas, waste gas and/or diesel fuel. The heat source may comprise an electrical heat source. The heat source may, for example, comprise an electric heater. In particular embodiments, the heat source may comprise an electric heater powered from the power utility grid or by PV solar cells. The heat source may also comprise a renewable energy heat source. The heat source may comprise a concentrated solar power (CSP) thermal source. The heat source may comprise a geothermal energy source. The heat source may comprise waste process heat.

The water processing system may comprise, may be coupled to or operatively associated with a pump arrangement.

The pump arrangement may comprise one or more pump configured and/or operable to pump the concentrate output from the one or more reactors, e.g. to an outlet or, where the system comprises a plurality of reactors to one or more other of the reactors. The water processing system may comprise a chemical additive supply for adding additives to the feed water, i.e. upstream of the feed water being directed into the reactor.

The chemical additives may comprise one or more of: a corrosion inhibitor; a scale inhibitor; and an oxygen scavenger.

The chemical additives may comprise a polymer, e.g. an EOR polymer.

The water processing system may comprise a chemical additive supply for adding additives to the steam output.

The chemical additives may comprise a polymer, e.g. an EOR polymer.

As described above, the system is configured to produce a steam output.

The steam output may be utilised in a downstream operation. For example, the steam output may be subject to a further processing operation, e.g. may be cracked into hydrogen (e.g. for use as a hydrogen fuel source) and/or oxygen for use in another industrial application.

The water processing system may comprise, may be coupled to or operatively associated with a storage arrangement. The storage arrangement may comprise one or more storage vessel. The storage arrangement may be configured and/or operable to store the condensate output.

The water processing system may comprise, may be coupled to or operatively associated with a chemical supply for supplying a chemical to the concentrate output. The chemical supply may comprise a source of a thickener agent. The chemical supply may be coupled to the storage arrangement.

The pump arrangement may comprise a pump connected to or operatively associated with the storage arrangement. The pump may be configured and/or operable to pump concentrate output, e.g. thickened brine, from the storage vessel of the storage arrangement. In use, the concentrate output may be output from the system and directed for further processing, for example to extract

The water processing system may comprise a flocculation arrangement.

The flocculation arrangement may comprise one or more flocculation tanks.

The flocculation arrangement may be configured and/or operable to receive the concentrate output from the storage arrangement.

The water processing system may comprise, may be coupled to or operatively associated with a chemical supply for supplying a chemical to the flocculation arrangement. The chemical supply may comprise a source of a clarifying agent. The chemical supply may be coupled to the flocculation arrangement.

The water processing system may be modular, comprising a plurality of modules. Each module may for example comprise a reactor and a heat exchanger. Each module may further comprise or may be coupled to a pump of the pump arrangement.

As described above, the water processing system is configured to utilise the thermal energy of the feed water input to partially power the conversion of the feed water input to the steam output.

The feed water input may take the form of water from the feed water system alone.

Alternatively, the feed water input may comprise a first feed water component in the form of water from said feed water system and a second feed water component from one or more further sources.

The second feed water component may comprise water from one or more of: an EOR wellhead separator; a package boiler blowdown system; a co-generation blowdown system; an enhanced oil recovery (EOR) system; a Heat Recovery Steam Generator (HRSG) system; a Once Through Steam Generator (OTSG) system; condensate from a steam separator; and/or waste water.

The water processing system may comprise or take the form of a closed-loop system.

Beneficially, the provision of a closed-loop system means that harmful to hydrogen sulphide gas is not released to the surrounding atmosphere.

According to a third aspect, there is provided a system comprising: the feed water system of the first aspect; and the water processing system of the second aspect.

A fourth aspect relates to a method for supplying feed water to a water processing system using the feed water supply system of the first aspect.

According to a fifth aspect, there is provided a water processing method comprising: providing a water processing system according to the second aspect; and operating the water processing system to convert the feed water input from the feed water supply system to a steam output and a concentrate output.

Operation of the water processing system may produce a condensate output.

According to a sixth aspect, there is provided a downhole completion system comprising: a borehole arrangement extending from surface to a downhole location, wherein the borehole arrangement is configured for fluid communication with a hydrocarbon reservoir and a geothermal reservoir; and a fluid conduit arrangement configured to transport produced water from said hydrocarbon reservoir and water from said geothermal reservoir towards surface, wherein the fluid conduit arrangement is at least partially disposed within the borehole, and wherein the fluid conduit arrangement comprises: a first conduit configured to receive produced water from said hydrocarbon reservoir; and a second conduit isolated from said first conduit and configured to receive water from said geothermal reservoir.

It should be understood that the features defined above in accordance with any aspect of the present disclosure or below in relation to any specific embodiment of the disclosure may be utilised, either alone or in combination with any other defined feature, in any other aspect or embodiment of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 shows a feed water system for use in supplying a feed water input to a water processing system and a water processing system comprising the feed water system;

Figure 2 shows a diagrammatic view of the feed water system shown in Figure 1 ;

Figure 3 shows a side view of the feed water system shown in Figure 1 ;

Figures 4 and 5 show a separator arrangement of the water processing system shown in Figure 1;

Figures 6 and 7 show diagrammatic views of the water processing system shown in Figure 1;

Figure 8 shows an alternative feed water system for use in supplying a feed water input to a water processing system; and

Figure 9 shows an alternative reactor arrangement utilising a heat generator arrangement.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to Figures 1 and 2 of the accompanying drawings, there is shown a feed water system, generally denoted 10, for use in supplying a feed water input FW to a water processing system, generally denoted 12.

As shown, the feed water system 10 comprises a borehole arrangement, generally denoted 14, which extends downwards from a wellhead W and which intersects the hydrocarbon reservoir HR and the geothermal reservoir GR, and a fluid conduit arrangement, generally denoted 16, which is disposed within the borehole arrangement 14 and which is configured to transport production fluid PF (containing oil O, gas G and produced water PW) from the hydrocarbon reservoir HR and geothermal water GW from the geothermal reservoir GR to surface where it is processed by the water processing system 12.

As shown in Figure 1, the water processing system 12 comprises a separator arrangement 18 which separates the production fluid PF into the oil output O, gas output G and the produced water PW, the produced water PW then being combined with the geothermal water GW to form a feed water input FW which is processed by a reactor arrangement 20 of the water processing system 12 to produce a steam output S and a concentrate output C.

Beneficially, the feed water system 10 facilitates cogeneration of geothermal water GW, e.g. brine, from the geothermal reservoir GR and produced water PW from the hydrocarbon reservoir HR for supply to the water processing system 12. As will be described further below, the water processing system 12 utilises the residual thermal energy from the geothermal water GW and/or the produced water PW to provide at least part of the thermal energy required to convert the feed water input FW into the steam output S, such steam output S being, for example, injected into the hydrocarbon reservoir H or another hydrocarbon reservoir as part of a thermal enhanced oil recovery (EOR) operation, and the concentrate output C. The feed water system 10 is thus particularly beneficial with hydrocarbon reservoirs or fields comprising hydrocarbon reservoirs containing oil and in particular “heavy” oil in which production can be enhanced using thermal EOR operation. Radiated heat from the geothermal water GW may also assist in the flow of the production fluid PF from the hydrocarbon reservoir H. By providing access to both geothermal water GW and produced water PW - either individually or in combination - the feed water system 10 facilitates the use of the geothermal water GW and produced water PW and their associated residual thermal energy in the water processing system 12, obviating or at least mitigating the need to consume significant amounts of external energy to power the water processing system 12 as well as the investment required to construct, operate and/or maintain the external power supply systems. This, in turn, permits amongst other things thermal EOR operations to be carried out in hydrocarbon production systems which would otherwise be unsuitable or uneconomic for EOR operations. Further, this may permit the operational life of a hydrocarbon reservoir to be extended and/or an abandoned reservoir to be brought back into production.

As shown most clearly in Figure 2, the feed water system 10 comprises a borehole arrangement 22, which in the illustrated feed water system 10 takes the form of a single, drilled, borehole 24 which intersects with, and is configured for fluid communication with, the hydrocarbon reservoir HR and the geothermal reservoir GR. In the illustrated feed water system 10, the borehole 24 has been lined with bore-lining tubing 26 in the form of casing, more particularly a casing string, an annulus A between the outside of the bore-lining tubing 26 and the inside of the borehole 24 being filled with cement 28.

In the illustrated feed water system 10, the borehole 24 takes the form of a vertical borehole. However, it will be understood that the borehole 24 may alternatively take the form of a horizontal borehole and/or the system 10 may comprise a plurality of boreholes, each being vertical or horizontal.

As shown in Figure 2, the borehole arrangement 22 comprises a borehole fluid communication arrangement, generally denoted 30, which facilitates ingress of the production fluid PF from the hydrocarbon reservoir HR and geothermal water GW from the geothermal reservoir GR.

In the illustrated feed water system 10, the borehole fluid communication arrangement 22 comprises perforations 32 which extend through the bore-lining tubing 26 and cement 28 and into the hydrocarbon reservoir HR and perforations 34 which extend through the bore-lining tubing 26 and cement 28 and into the geothermal reservoir GR.

As shown in Figure 2, the fluid conduit arrangement 16 comprises a first conduit 36 configured to receive the production fluid PF from the hydrocarbon reservoir HR and a second conduit 38 isolated from the first conduit 36 and configured to receive the geothermal water GW from the geothermal reservoir GR. In the illustrated feed water system 10, the first and second conduits 36, 38 each take the form of a production tubing string.

Beneficially, the feed water system 10 is configured and/or operable to receive produced water PW via the production fluid PF from the hydrocarbon reservoir and/or geothermal water GW, e.g. brine, from the geothermal reservoir GR and transport these separately to surface. As also shown in Figure 2, and referring now also to Figure 3 of the accompanying drawings, the feed water system 10 comprises a packer arrangement, generally denoted 40, which comprises a first packer 42 and a second packer 44.

As shown in more detail in Figure 3, the first packer 42 comprises one or more sealing members 46 configured to engage the bore-lining tubing 26 so as to prevent the production fluid PF from the hydrocarbon reservoir HR bypassing the first packer 42 and thereby direct the production fluid PF into the first conduit 36. The first packer 42 may take a number of different forms and in the illustrated system 10 the first packer 42 takes the form of a hydrostatic-pressure actuated packer.

In the illustrated system 10, the first packer 42 takes the form of duel string packer having a first fluid communication passage 48 which connects as respective ends to sections of the first conduit 36 and a second fluid communication passage 50 which connects at respective ends to sections of the second conduit 38.

In the illustrated system 10, the section of the first conduit 36 disposed below the first packer 42 takes the form to perforated pipe to facilitate the ingress of the production fluid PF into the first conduit 36.

As also shown in Figure 3, the second packer 44 comprises one or more sealing members 52 configured to engage the bore-lining tubing 26 so as to prevent the geothermal water GW from the geothermal reservoir GR bypassing the second packer 44and thereby direct the geothermal water GW into the second conduit 38. The second packer 44 may take a number of different forms and in the illustrated system 10 the second packer 44 takes the form of a hydrostatic-pressure actuated packer.

In the illustrated system 10, the second packer 44 takes the form of single string packer having a fluid communication passage 54 which connects as respective ends to sections of the second conduit 38.

In the illustrated system 10, the section of the second conduit 38 disposed below the second packer 44 takes the form to perforated pipe to facilitate the ingress of the geothermal water GW into the second conduit 38. In use, the first packer 42 defines an upper packer, that is closer to surface, and the second packer 44 defines a lower packer, that is more distal from surface and the first and second packers 42, 44 permit zonal isolation in the borehole 24 between fluid from the geothermal reservoir GR and production fluid PF from the hydrocarbon reservoir HR.

As described above, the water processing system 12 comprises a separator arrangement 18 which separates the production fluid PF into the oil O, gas G and produced water PW, the produced water PW being combined with the geothermal water GW to form a feed water input FW to which is processed by a reactor arrangement 20 of the water processing system 12 to produce a steam output S and a concentrate output C.

Figure 4 of the accompanying drawings shows the separator arrangement 18 in more detail.

As shown, the separator arrangement 18 comprises a separator 56, which in the illustrated embodiment takes the form of a high pressure two phase separator.

In use, the separator 56 receives the production fluid PF from the hydrocarbon reservoir HR and separates this into the produced water PW which forms a first part of the feed water input FW to the reactor arrangement 20, the gas output G and the oil output O.

In the illustrated system 12, the separator 56 is coupled to the first conduit 36 by a flow line 58. Access to the separator 56 is controlled by control valves V1 , V2, V3 and V4. With control valves V1 and V2 open and control valves V3 and V4 closed, the production fluid PF may be directed to the separator 56.

Bypass lines 60, 62 are provided to selectively direct the production fluid PFdirectly to a pipeline (not shown), where desired. Access to the bypass lines 60, 62 is controlled by the control valves V3, V4 and also control valves V5 and V6. As shown in Figure 5, the separator 56 includes, is coupled to, or is operatively associated with, a gauge 64 in the form of an LIC for monitoring the amount of water in the separator 56. The gauge 64 is coupled to a control valve V7.

In use, when the amount of water in the separator 56 detected by the gauge 64 exceeds a selected threshold or as otherwise directed by an operator or control system of the processing system 12, the control valve V7 will open and direct the produced water PW to the reactor arrangement 20. Alternatively, if the water is not needed for the process it can be bypassed to the production pipeline (not shown).

As also shown in Figure 5, the separator 56 includes, is coupled to, or is operatively associated with, a gauge 66 in the form of a PIC for monitoring the amount of gas in the separator 56. The gauge 66 is coupled to a control valve V8.

In use, when the amount of gas in the separator 56 detected by the gauge 66 exceeds a selected threshold or as otherwise directed by an operator or control system of the processing system 12, the control valve V8 will open.

The separator 56 includes, is coupled to, or is operatively associated with, a gauge 68 in the form of an LIC for monitoring the amount of oil in the separator 56. The gauge 68 is coupled to a control valve V9.

In use, when the amount of oil in the separator 56 detected by the gauge 68 exceeds a selected threshold or as otherwise directed by an operator or control system of the processing system 12, the control valve V9 will open so as to direct the oil (and some water) for dehydration or to a production pipeline (not shown). Beneficially, the ability of the system 12 to direct oil back to the production pipeline increases the amount of oil that is recovered from the hydrocarbon reservoir HR.

After leaving the separator 56, the produced water PW from the separator 56 is directed to flow line 70.

As shown, in the illustrated system 12 one or more chemical lines 72 permit chemical additives from chemical store 74 to be added to the produced water PW before it combines with the geothermal water GW carried by flow line 76 to form the feed water input FW to the reactor arrangement 20. Referring now also to Figures 6 and 7 of the accompanying drawings, there is shown diagrammatic and perspective views respectively of the water processing system 12.

As will be described further below, the water processing system 12 is configured and/or operable to receive the feed water input FW from the feed water system 10 and convert this feed water input FW into the steam output S for use in a downstream operation and the concentrate output C.

Beneficially, the water processing system 12 utilises the residual thermal energy from the geothermal water GW and/or the produced water PW to provide at least part of the thermal energy required to convert the feed water input FW into the steam output S, the steam output S then being, for example, injected into the hydrocarbon reservoir HR as part of a thermal enhanced oil recovery (EOR) operation and/or used to power an electricity generator. The water processing system 12 is particularly beneficial with hydrocarbon reservoirs or fields comprising hydrocarbon reservoirs containing oil and in particular “heavy” oil in which production can be enhanced using thermal EOR operation. Radiated heat from the geothermal water GW may also assist in the flow of the production fluid PF from the hydrocarbon reservoir HR. By providing access to both geothermal water GW and produced water PW - either individually or in combination - the feed water system 10 facilitates the use of the geothermal water and produced water and their associated residual thermal energy in the water processing system, obviating or at least mitigating the need to consume significant amounts of external energy to power the water processing system as well as the investment required to construct, operate and/or maintain the external power supply systems. This, in turn, permits amongst other things thermal EOR operations to be carried out in hydrocarbon production systems which would otherwise be unsuitable or uneconomic for EOR operations. Further, this may permit the operational life of a hydrocarbon reservoir to be extended and/or an abandoned reservoir to be brought back into production.

In contrast to conventional thermal EOR systems in which the majority of thermal energy is lost (or in the case of thermal energy purposefully dissipated by cooling as part of the water processing operation), in the present water processing system 12 the thermal energy of the geothermal water GW and the produced water PW is utilised in the conversion of the feed water input FW to the steam output S. Thus, in contrast to conventional techniques, the feed water input FW is not cooled; rather the feed water FW is directed to the reactor arrangement 20, with the residual thermal energy of the feed water input FW being utilised in the production of the steam output S.

As described above, the water processing system 12 also facilitates the extraction of solids from the geothermal water GW, e.g. brine, and/or the produced water PW to produce the concentrate output C.

For example, the water processing system 12 may be utilised to take in water with high mineral and/or solids content, and convert this low quality saline water into high pressure de-mineralised steam - said steam forming the steam output S - for example for enhanced oil recovery operations or to provide purified water for oilfield or other industrial process use and a concentrate output C containing the solids.

Beneficially, the removal of solids from the geothermal water GW obviates or at least mitigates fouling of the geothermal water conveyance systems and wells, which may otherwise occur due to precipitation of materials such as silica within the geothermal water GW.

Alternatively or additionally, the water processing system 12 may also facilitate the processing of saline or contaminated waste water from other oilfield operations such as co-generation blow down, WTP & STP evaporation ponds, fracking operations or sand washing programs which normally render water undesirable for reuse for agriculture, human or wildlife uses or even disposal by deep well injection, reducing the burden on the environment and natural resources.

In use, the steam output S can be used in a number of applications, including for example re-injection into a hydrocarbon reservoir HR as part of an enhanced oil recovery operation, for thermal water purification, as a mechanical motivator in a power generation process, or as utility steam for other industrial processes. The water processing system 12 may comprise, may be coupled to or operatively associated with the water processing system described in WO 2017/208023, the contents of which are incorporated in its entirety by way of reference.

As shown in Figure 6, the reactor arrangement 20 comprises one or more reactors 78 and in the illustrated system 12, the reactor arrangement 20 comprises four reactors 78 coupled in series, i.e. the concentrate output C, e.g. brine, from a given reactor 78 of said one or more reactors 78 forming a feed water input to at least one other of the reactors 78.

The reactor arrangement 20 is configured and/operable to produce a high pressure steam output S. The reactor arrangement 20 may be configured to produce a steam output S with over 98% vapour content and in the illustrated system 12 the reactor arrangement 20 is configured to produce a steam output S of 100% vapour content, or substantially 100% vapour content.

The steam output S may be used in a downstream operation. For example, the downstream operation may comprise the generation of electricity. For example, the water processing system may comprise, may be coupled to an electricity generator arrangement, the steam output from the reactor arrangement being directed to the electricity generator arrangement. The electricity generator arrangement may comprise one or more electricity generators. In particular embodiments, at least one of the electricity generators may comprise or take the form of an organic Rankine Cycle generator such as a micro ORC. Alternatively or additionally, the downstream operation may comprise a steam flood operation, such as may be utilised in an enhanced oil recovery (EOR) operation.

As described above, the reactor arrangement 20 is configured and/or operable to convert the feed water input FW into a concentrate output C. In the illustrated system 12, the concentrate output C comprises or take the form of a concentrated brine, e.g. a concentrated brine slurry and may contain one of more of: Silica; Lithium; Calcium, e.g. Ca++; Sodium; Chloride, e.g. Cl'; and/or Magnesium.

As shown in Figures 6 and 7, the water processing system 12 comprises a heat exchanger arrangement, generally denoted 80, comprising one or more heat exchangers 82. In the illustrated system 12, the heat exchanger arrangement 80 comprises three heat exchangers 80, each heat exchanger 80 being coupled between two of the reactors 78. The heat exchangers 82 may take a variety of different forms and in the illustrated system 12, the heat exchangers 82 take the form of plate heat exchangers.

The heat exchangers 82 are configured and/or operable to receive the steam output S from the associated reactor 78 and output a condensate output COND.

The condensate output COND from each of the heat exchangers 82 is combined in a header 84 before being output from the water processing system 12. As shown in Figure 6, in the illustrated system 12 the condensate output COND is combined with a portion of the concentrate output C and re-injected into the borehole arrangement 12.

As also shown in Figure 6, the water processing system 12 further comprises one or more further reactors 86 and in the illustrated system 12 two further reactors 86 are provided. The further reactors 86 are configured and/or operable to receive the concentrate output C from a given reactor 78 and convert a portion of the concentrate output C into steam. The steam output S from the further reactor 86 may be combined with the steam output S from the previous stage reactor 78 before entering the associated heat exchanger 82.

The water processing system 12 comprises, is coupled to or is operatively associated with a pump arrangement, generally denoted 88.

In the illustrated system 12, the pump arrangement 88 comprises three pumps P1 , P2 and P3 which are configured and/or operable to pump the concentrate output C, via flow lines 90 from each reactor 78 to the next stage reactor 78.

As shown in Figure 6, the pump arrangement 88 further comprises a pump P4 for pumping the concentrate output C, via flow line 92, to a storage tank 94, a pump P5 for circulating the concentrate output C, via flow lines 96, between the storage tank 94 and a flocculation tank 98 and a pump P6 for pumping the concentrate output C, via flow line 100, to concentrate outlet 102. The pumps P1 , P2, P3, P4, P5 and P6 may take a variety of different but in the illustrated system 12 the pumps P1, P2, P3, P4, P5 and P6 take the form of slurry recirculation pumps.

As shown in Figure 6, in the illustrated system 12 a thickener agent TA is added from a supply 104 to the concentrate output C before entering the storage tank 94.

As also shown in Figure 6, in the illustrated system 12 a clarifying agent CA is added from a supply 106 to the concentrate output C after exiting the flocculation tank 98 and before it is combined with the condensate output COND.

As also shown in Figure 6, a chemical additive supply 108 for adding additives ADD to the feed water FW, i.e. upstream of the feed water FW being directed into the reactor arrangement 20. In the illustrated system 12, the chemical additive supply 104 comprises or takes the form of an automated chemical dosing system. A number of different chemical additives ADD may be used, but in the illustrated system 12, the chemical additives ADD comprise one or more of: a corrosion inhibitor; a scale inhibitor; and an oxygen scavenger.

It will be apparent to those of skill in the art that the above embodiments are merely exemplary and that various modifications and improvements may be made thereto without departing from the scope of the disclosure.

For example, Figure 8 of the accompanying drawings shows an alternative feed water system 10’.

As shown in Figure 8, the feed water system 10’ comprises a borehole arrangement, generally denoted 14’, which extends downwards from a wellhead W and which intersects the hydrocarbon reservoir HR and the geothermal reservoir GR, and a fluid conduit arrangement, generally denoted 16’, which is disposed within the borehole arrangement 14’ and which is configured to transport production fluid PF (containing oil O, gas G and produced water PW) from the hydrocarbon reservoir HR and geothermal water GW from the geothermal reservoir GR to surface where it is processed by the water processing system 12. Whereas in the feed water system 10 the borehole arrangement 14 takes the form of a single bore in the system 10’ separate boreholes are provided to respectively access the hydrocarbon reservoir HR and the geothermal reservoir GR.

Figure 9 of the accompanying drawings shows an alternative reactor arrangement, generally denoted 120.

As shown in Figure 9, the reactor arrangement 120 comprises a reactor 178 operable to convert a feed water input FW into a steam output S for use in a downstream operation and a concentrate output C.

As also shown in Figure 9, the reactor 178 comprises, is coupled to, or is operatively associated with a heat generator 198.

In use, the heat generator 198 supplies additional energy required to convert the feed water FW into the required high pressure steam output S.

In the illustrated reactor arrangement 120, the heat generator 198 transfers heat from a secondary liquid heat transfer medium comprising molten salt. However, embodiments of the present disclosure beneficially permit the use of any suitable heat source as the heat generator 198, including for example but not exclusively: a fossil fuel burner; an electrical generator; a concentrated solar power (CSP) thermal source; a solar source; a geothermal source; a waste process heat source or the like, or a combination of these.

In use, the reactor 178 is configured to increase the temperature of the feed water FW to a temperature at which mineral ions, e.g. calcium and magnesium ions, contained within the water input are precipitated as insoluble salts.

In the illustrated arrangement 120, the reactor 178 comprises, is coupled to, or is operatively associated with a heat exchanger 182 and a solids separator 200 and. The solids separator 200 and heat exchanger 182 are disposed between the reactor 178 and the concentrate outlet. In use, the solids separator 200 is operable to filter the concentrate output C while the heat exchanger 182 is operable to recover thermal energy from the concentrate output C, e.g. for use in the reactor 178.

Claims

1. A feed water system for use in supplying a feed water input to a water processing system, the feed water system comprising: a borehole arrangement extending from surface to a downhole location, wherein the borehole arrangement is configured for fluid communication with a hydrocarbon reservoir and a geothermal reservoir; and a fluid conduit arrangement configured to transport produced water from said hydrocarbon reservoir and water from said geothermal reservoir towards surface, wherein the fluid conduit arrangement is at least partially disposed within the borehole, and wherein the fluid conduit arrangement comprises: a first conduit configured to receive produced water from said hydrocarbon reservoir; and a second conduit isolated from said first conduit and configured to receive water from said geothermal reservoir.

2. The feed water system of claim 1 , wherein the borehole arrangement comprises a single borehole configured to intersect both the hydrocarbon reservoir and the geothermal reservoir.

3. The feed water system of claim 1 , wherein the borehole arrangement comprises one or more boreholes.

4. The feed water system of claim 3, wherein the one or more boreholes are configured to intersect both the hydrocarbon reservoir and the geothermal reservoir.

5. The feed water system of claim 3, wherein at least one of the boreholes is configured to intersect the hydrocarbon reservoir and at least one of the boreholes is configured to intersect the geothermal reservoir.

6. The feed water system of any preceding claim, wherein the borehole arrangement comprises a borehole fluid communication arrangement for providing fluid communication with the hydrocarbon reservoir and the geothermal reservoir.

7. The feed water system of claim 6, wherein the borehole fluid communication arrangement comprises one or more perforations in the borehole.

8. The feed water system of any preceding claim, wherein the feed water system comprises a packer arrangement.

9. The feed water system of claim 8, wherein the packer arrangement comprises a first packer configured to engage the borehole so as to prevent fluid from the hydrocarbon reservoir from bypassing the first packer and/or to direct fluid from the hydrocarbon reservoir into the first conduit.

10. The feed water system of claim 9, wherein the packer arrangement comprises a second packer configured to engage the borehole so as to prevent fluid from the geothermal reservoir from bypassing the second packer and/or to direct fluid from the geothermal reservoir into the second conduit.

11. A water processing system configured for coupling to the feed water system of any one of claims 1 to 10, the water processing system comprising: a reactor arrangement comprising one or more reactors, wherein the reactor arrangement is configured and/or operable to convert a feed water input comprising produced water from a hydrocarbon reservoir and geothermal water from a geothermal reservoir into a steam output and a concentrate output.

12. The water processing system of claim 11, wherein the water processing system comprises a heat exchanger arrangement, the heat exchanger arrangement comprising one or more heat exchangers.

13. The water processing system of claim 12, wherein the one or more heat exchangers are coupled to or form part of the one or more reactors.

14. The water processing system of claim 11 , 12 or 13, wherein the water processing system comprises a pump arrangement, the pump arrangement comprising one or more pumps.

15. The water processing system of any one of claims 11 to 14, wherein the water processing system comprises a chemical additive supply for adding additives to the feed water.

16. A system comprising: the feed water system of any one of claims 1 to 10; and the water processing system of any one of claims 11 to 15.

17. A method for supplying feed water to a water processing system using the feed water system of any one of claims 1 to 10.

18. A water processing method comprising: providing a water processing system according to any one of claims 11 to 15; and operating the water processing system to convert the feed water input from the feed water supply system to a steam output and a concentrate output.

19. The method of claim 18, wherein operation of the water processing system produces a condensate output.

20. A downhole completion system comprising: a borehole arrangement extending from surface to a downhole location, wherein the borehole arrangement is configured for fluid communication with a hydrocarbon reservoir and a geothermal reservoir; and a fluid conduit arrangement configured to transport produced water from said hydrocarbon reservoir and water from said geothermal reservoir towards surface, wherein the fluid conduit arrangement is at least partially disposed within the borehole, and wherein the fluid conduit arrangement comprises: a first conduit configured to receive produced water from said hydrocarbon reservoir; and a second conduit isolated from said first conduit and configured to receive water from said geothermal reservoir.