CA2972383C - Processes and systems for generating steam from produced water - Google Patents

Abstract

Processes are provided for generating steam from produced water in a hydrocarbon recovery system. The processing comprises inputting a produced water stream having an initial concentration of unwanted components [UC]i at an initial temperature (Ti) above 80°C and an initial pressure (Pi) above atmospheric pressure and treating the produced water stream to produce a treated water stream having a treated concentration of unwanted components [UC]t, a treated temperature (Tt) and a treated pressure (Pt). Treating the produced water stream comprises separating oil emulsion from the produced water stream to produce a separated produced water stream, and removing oil from the separated produced water stream using a column flotation unit (CFU) to produce the treated water stream having a [UC]t lower than [UC]i. Steam generation is then carried out using the treated water stream in a steam generator. The treated water stream has [UC]t lower than [UC]I, Tt within 50°C or 40% of Ti, and Pt within 10% or 0.2 MPa of Pi. Systems for doing same are also provided.

Description

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Processes And Systems For Generating Steam From Produced Water Field Of The Invention The invention relates to processes and systems for treating produced water and more specifically to processes and systems for treating produced water sufficiently such that the treated water may be used to generate steam in hydrocarbon recovery.
Background In hydrocarbon recovery (or production) operations steam is used, for example, in extracting heavy oil through cyclic steam stimulation, steam flooding, or steam-assisted gravity drainage (SAGD). The cost of steam generation, the capital and operating Jo expenditures for the water treatment and steam generation facility and the associated generation of emissions each impact the viability of a hydrocarbon recovery operation.
Water produced from a hydrocarbon production facility, referred to as produced water or production water, may be treated and recycled for use in steam generation.
Recycling of produced water requires overall removal of suspended solids, dissolved solids and of scale-forming chemicals, among other ions and chemical compounds, that affect the operation of steam generating systems. Conventional processes are complex and expensive when handling the specific chemistry of produced water and other oil and gas effluents.
Produced water is typically received at a high temperature and pressure, both of which must be reduced before being treated using conventional processes and systems.
This typically involves the use of heat exchangers to reduce the temperature of the produced water before treatment to remove oil and emulsions, suspended solids, dissolved solids and scale-forming chemicals such as calcium, magnesium and silica, before the treated water is then re-heated and re-pressurized in advance of steam generation. The cooling, re-heating and the re-pressurization of the treated water requires significant energy consumption and equipment to carry out.
The current economic climate, with low oil prices, is driving the need to lower the cost of hydrocarbon production. More stringent environmental regulations on carbon emissions and waste streams further underscore the need for new technologies that will increase productivity without significantly impacting the bottom line, and reduce the facilities operation costs by simplifying facilities, decreasing pipe network, increasing modularization and/or shortening construction cycles.
Summary Of The Invention In one illustrative embodiment, the present invention provides for a process for generating steam from produced water in a hydrocarbon recovery system, the processing comprising:
inputting a produced water stream having an initial concentration of unwanted components [UC]i at an initial temperature (Ti) above 80 C and an initial pressure (Pi) above atmospheric pressure, treating the produced water stream to produce a treated water stream having a treated concentration of unwanted components [UC]t, a treated temperature (Tt) and a treated pressure (Pt), wherein treating the produced water stream comprises:
separating oil emulsion from the produced water stream to produce a separated produced water stream; and removing oil from the separated produced water stream using a column flotation unit (CFU) to produce the treated water stream having a [UC]t lower than [UC]i; and generating steam from the treated water stream in a steam generator, wherein:
[UC]t is lower than [UC]i;
Tt is within 50 C or 40% of Ti; and Pt is within 10% or 0.2 MPa of Pi.
In a further embodiment of the process or processes outlined above, Ti is above 130 C
and Pi is >1MPa and Tt is above 80 C.
In a further embodiment of the process or processes outlined above, Ti is from and Pi is >1MPa and up to 3.1 mPa and Tt is greater than 130 C and Pt is >1MPa.

2 In a further embodiment of the process or processes outlined above, the Pt is at least at the steam saturation pressure.
In a further embodiment of the process or processes outlined above, the unwanted components are in the form of oil and grease, total suspended solids, turbidity, silica, hardness, soluble organics and/or total dissolved solids.
In a further embodiment of the process or processes outlined above, the [UC]i for oil and grease is 200 mg/L or more.
In a further embodiment of the process or processes outlined above, the [UC]t for oil and grease is about 2 mg/L or less.
In a further embodiment of the process or processes outlined above, the [UC]i for total suspended solids is about 100 mg/L or more.
In a further embodiment of the process or processes outlined above, the [UC]t for total suspended solids is about 5 mg/L or less.
In a further embodiment of the process or processes outlined above, the [UC]i for turbidity is about 250 NTU or more.
In a further embodiment of the process or processes outlined above, the [UC]t for turbidity is about 5 NTU or less.
In a further embodiment of the process or processes outlined above, the [UC]i for silica is about 250 mg/L or more.
In a further embodiment of the process or processes outlined above, the [UC]t for silica is about 50 mg/L or less.
In a further embodiment of the process or processes outlined above, the [UC]i for hardness is about 25 mg/L or more.
In a further embodiment of the process or processes outlined above, the [UC]t for hardness is about 15 mg/L or less.

3 In a further embodiment of the process or processes outlined above, the [UC]i for soluble organics is about 500 mg/L.
In a further embodiment of the process or processes outlined above, the [UC]t for soluble organics is about less than about 500 mg/L.
In a further embodiment of the process or processes outlined above, the process or processes further comprise using an ion exchange reaction to remove unwanted components in the form of iron and/or hardness.
In a further embodiment of the process or processes outlined above, the process is free of a cooling step for reducing the initial temperature of the produced water stream and is to free of a de-pressurization step for reducing the initial pressure of the produced water stream.
In a further embodiment of the process or processes outlined above, the steam generator generates steam from the treated water stream having a steam quality of at least 80%, 90% or 100%.
In a further embodiment of the process or processes outlined above, the steam generator is a once-through steam generator (OTSG) or a flash steam generator (FSG).
In a further embodiment of the process or processes outlined above, treating the produced water stream further comprises exposing the treated water stream to a flocculation reaction to further remove unwanted components.
In another illustrative embodiment, the present invention provides for a system for treating produced water and generating steam using the treated water for use in hydrocarbon recovery, wherein the produced water has an initial concentration of unwanted components [UC]i at an initial temperature (Ti) above 80 C and an initial pressure (Pi) above atmospheric pressure, and wherein the treated water has a treated concentration of unwanted components [UC]t, a treated temperature (Tt) and a treated pressure (Pt), the system comprising:
a produced water input;

4 a treatment device for treating the produced water to reduce the concentration of unwanted components [UC]i, wherein the treatment device comprises a column flotation unit (CFU) for treating the produced water; and a steam generator for producing steam using the treated water;
wherein [UC]t is lower than [UC]i;
Tt is within 50 C or 40% of Ti; and Pt is within 10% or 0.2 MPa of Pi.
In a further embodiment of the system outlined above, the treatment device further comprises an electro-flocculation system in communication with the CFU.
In one illustrative embodiment, the present invention provides for a facility for treating produced water to provide treated water and for generating steam for use in hydrocarbon recovery from the treated water, wherein the produced water has received emulsion treatment, wherein the produced water has an initial concentration of unwanted components ([UC]i), an initial temperature (Ti) that is above 80 C, and an initial pressure (Pi) that is above atmospheric pressure, and wherein the treated water has a treated concentration of unwanted components ([UC]t), a treated temperature (Tt), and a treated pressure (Pt), the facility comprising:
a produced water input;
a treatment device comprising a flotation type unit for treating the produced water to reduce the concentration of the unwanted components; and a steam generator for generating steam from the treated water, wherein:
the facility is free of a lime softening unit and occupies a reduced footprint, [UC]t is lower than [UC]i,

5 Tt is within 50 C or 40% of Ti, and Pt is within 10% or 0.2 MPa of Pi.
In one illustrative embodiment, the present invention provides for a process for generating steam from produced water in a hydrocarbon recovery system, the processing comprising:
inputting a produced water stream into a treatment device comprising a flotation type unit , wherein the produced water stream has received emulsion treatment, and wherein the produced water stream has an initial concentration of unwanted components ([UC]i) and an initial temperature (Ti) which is above the normal boiling point of the produced water at an inlet to the flotation type unit;
producing a treated water stream from the produced water stream by passing the produced water stream through the treatment device, the treated water stream having a treated concentration of unwanted components ([UC]t) and a treated temperature (Tt);
and generating steam from the treated water stream in a steam generator;
wherein producing the treated water stream comprises passing the produced water stream through the flotation type unit such that the [UC]t for silica is between about 30 ppm and about 300 ppm and the treated water stream is compatible with the steam generator without requiring a lime softening step.
In one illustrative embodiment, the present invention provides for a system for treating produced water to provide treated water and for generating steam from the treated water for use in hydrocarbon recovery, wherein the produced water has received emulsion treatment, wherein the produced water has an initial concentration of unwanted components ([UCli), and wherein the treated water has a treated concentration of unwanted components ([UC]t), the system comprising:
a produced water input;
a treatment device comprising a flotation type unit for treating the produced water to reduce the concentration of unwanted components; and 5a a steam generator for producing steam using the treated water;
wherein:
the produced water has an initial temperature (Ti) which is above the normal boiling point of the produced water at an inlet to the flotation type unit, the treated water has a treated temperature (Tt), and the treatment device comprising the flotation type unit is configured such that the [UC]t for silica is between about 30 ppm and about 300 ppm and the treated water stream is compatible with the steam generator without requiring a lime softening unit.
In one illustrative embodiment, the present invention provides for a facility for treating produced water to provide treated water and for generating steam for use in hydrocarbon recovery from the treated water, wherein the produced water has received emulsion treatment, wherein the produced water has an initial concentration of unwanted components ([UC]i), and wherein the treated water has a treated concentration of unwanted components ([UC]t), the facility comprising:
a produced water input;
a treatment device comprising a flotation type unit for treating the produced water to reduce the concentration of unwanted components; and a steam generator for generating steam from the treated water, wherein:
the facility is free of a lime softening unit and occupies a reduced footprint, the produced water has an initial temperature (Ti) which is above the normal boiling point of the produced water at an inlet to the flotation type unit, the treated water has a treated temperature (Tt), and the treatment device comprising the flotation type unit is configured such that the [UC]t for silica is between about 30 ppm and about 300 ppm and the treated water stream is compatible with the steam generator without requiring a lime softening unit.
5b In one illustrative embodiment, the present invention provides for a process for generating steam from produced water in a hydrocarbon recovery system, the processing comprising:
inputting a produced water stream into a treatment device comprising a flotation type .. unit , wherein the produced water stream has received emulsion treatment, and wherein the produced water stream has an initial concentration of unwanted components ([UC]i) and an initial temperature (Ti) which is below the normal boiling point of the produced water at an inlet to the flotation type unit;
producing a treated water stream from the produced water stream by passing the io produced water stream through the treatment device, the treated water stream having a treated concentration of unwanted components ([UC]t) and a treated temperature (Tt);
and generating steam from the treated water stream in a steam generator;
wherein producing the treated water stream comprises passing the produced water stream through the flotation type unit such that the [UCjt for silica is between about 30 ppm and about 300 ppm and the treated water stream is compatible with the steam generator without requiring a lime softening step.
In one illustrative embodiment, the present invention provides for a system for treating produced water to provide treated water and for generating steam from the treated water for use in hydrocarbon recovery, wherein the produced water has received emulsion treatment, wherein the produced water has an initial concentration of unwanted components ([UC]i), and wherein the treated water has a treated concentration of unwanted components ([UC]t), the system comprising:
a produced water input;
a treatment device comprising a flotation type unit for treating the produced water to reduce the concentration of unwanted components; and a steam generator for producing steam using the treated water;
wherein:
5c õ
the produced water has an initial temperature (Ti) which is below the normal boiling point of the produced water at an inlet to the flotation type unit, the treated water has a treated temperature (Tt), and the treatment device comprising the flotation type unit is configured such that the [UC]t for silica is between about 30 ppm and about 300 ppm and the treated water stream is compatible with the steam generator without requiring a lime softening unit.
In one illustrative embodiment, the present invention provides for a facility for treating produced water to provide treated water and for generating steam for use in hydrocarbon recovery from the treated water, wherein the produced water has received emulsion treatment, wherein the produced water has an initial concentration of unwanted components ([UC]i), and wherein the treated water has a treated concentration of unwanted components ([UC]t), the facility comprising:
a produced water input;
a treatment device comprising a flotation type unit for treating the produced water to reduce the concentration of unwanted components; and a steam generator for generating steam from the treated water, wherein:
the facility is free of a lime softening unit and occupies a reduced footprint, the produced water has an initial temperature (Ti) which is below the normal boiling point of the produced water at an inlet to the flotation type unit, the treated water has a treated temperature (Tt), and the treatment device comprising the flotation type unit is configured such that the [UC]t for silica is between about 30 ppm and about 300 ppm and the treated water stream is compatible with the steam generator without requiring a lime softening unit.
5d _ Brief Description Of The Drawings Embodiments of the present invention will be described, by way of example, with reference to the drawings and to the following illustrative description, in which:
Figure 1 is a schematic illustrating a prior art embodiment for treating produced water for steam generation;
Figure 2 is a schematic illustrative of one embodiment of a process for treating produced water and generating steam utilizing a compact flotation unit (CFU);
Figure 3 is a schematic illustrative of a further embodiment of a process for treating produced water and generating steam utilizing a compact flotation unit (CFU);
Figure 4 is a schematic illustrative of one embodiment of a process for treating produced water and generating steam utilizing an electro-flocculation (EF) reaction;
Figure 5 is a schematic illustrating a pilot system for testing the CFU as described in Example 1;
Figure 6 is a schematic illustrating a pilot system for testing WLS removal described in Example 1; and Se Figure 7 is a schematic illustrating a pilot system for testing the EF unit described in Example 2.
Detailed Description Described herein are processes, systems, apparatuses, techniques and embodiments suitable for treating producing water by removing unwanted components such that the treated produced water is suitable for use in steam generation in a hydrocarbon production facility. It will be appreciated that the processes, systems, apparatuses, techniques and embodiments described herein are for illustrative purposes to intended for those skilled in the art and are not meant to be limiting in any way. All reference to dimensions, capacities, embodiments, substitutions, modifications, optional features or examples throughout this disclosure, including the Figures, should be considered non-limiting and a reference to an illustrative and non-limiting embodiment or an illustrative and non-limiting example. For simplicity and clarity of illustration, reference is numerals may be repeated among the Figures to indicate corresponding or analogous elements. Numerous details are set forth to provide an understanding of the embodiments and examples described herein. The embodiments and examples may be practiced without these details. In other instances, well-known methods, procedures, and components are not described in detail to avoid obscuring the examples described. All 20 ranges referred to herein are intended to be interpreted as being a reference to all values of the range and should be considered a disclosure of all values with each referred to range. The description and claims are not to be considered as limited to the scope of the examples described herein.
Produced water contains unwanted components which should be removed before 25 the treated water may be recycled and used in steam production. In conventional treatment methods, the treatment includes the cooling and depressurization of the produced water followed by the removal of various unwanted components such as oil and grease, total hardness including calcium and magnesium, silica and total organic carbon, before being re-pressurized and re-heated for steam generation. A person of skill in the 30 art will appreciate that water entering a steam generator may also be referred to as boiler feed water (BFW).

6 Removal of a portion of these unwanted components is necessary to allow for steam generation without substantial scale formation. Scale formation often leads to operability problems, for example producing an insulating effect which in turn may result in frequent shut downs and boiler tube failures. In order to reduce the overall energy expenditure as well as reduce the footprint of the hydrocarbon production facility it is desirable to avoid, or at least reduce the need, for cooling and de-pressurizing the produced water before unwanted components are removed. This reduces the magnitude of the energy required to re-heat and re-pressurize the treated water.
After emulsion is recovered from a hydrocarbon reservoir and treated for coarse to oil-water separation, produced water is typically obtained at temperatures of between about 80 - 250 C at various points in the process and contains unwanted components that should be removed before the produced water may be recycled and used in steam generation. In a conventional system 100, such as that shown in Figure 1, the produced water from emulsion treatment 102 is cooled, using for example a series of heat exchangers 104, before it is subjected to de-oiling 106 and water treatment 108. Emulsion treatment 102 typically comprises units such as degassers, treaters and free water knockout (FWKO). De-oiling 106 typically comprises several units, such as a skim tank for gravity separation, a flotation type unit, such as an Induced Gas Flotation (IGF), for further removal of suspended solids, and a filtration type unit such as an oil removal filter (ORF).
Water treatment 108 typically includes a warm lime softener (WLS) which increases the pH of the water, may remove hardness in the form of calcium and magnesium as carbonate precipitates, and removes silica. The WLS is typically followed by an ion exchange unit where additional removal of Ca", Mg" and iron ions occurs. The decrease in temperature of the produced water stream entering de-oiling 106 is necessary in conventional systems and processes for several reasons, for example, operation of the various treatment/filtration units (e.g. Skim tank, IGF and WLS) at high pressure would be economically unfavorable when compared to operation at atmospheric pressure.
As well, many of the treatment units require lower temperature for effective operation.
A heat recovery step 110 is then employed, for example, with a number of heat exchangers, to recover at least some of the enthalpy lost from the prior cooling steps through heat integration. The pressure is also increased through pumping. As is clearly evident, a significant input of energy and equipment is required to re-heat the treated water exiting the water treatment 108 and to re-pressurize the treated water before being input into the

7 steam generator. Typical feedwater in a steam generator is usually between about 180-200 C. Steam generation 112 often includes a once-through steam generator (OTSG) followed by a steam separator.
It has been determined that a process may be used that permits the treatment of produced water to remove unwanted components at or near initial produced water temperatures and pressures thereby allowing for the use of the treated produced water in steam generation while significantly conserving the enthalpy in the system and meeting desirable boiler feed water specifications.
In various embodiments, the present invention provides for processes and systems for treating produced water for eventual use in steam generation that do not require the need for a significant reduction in temperature and/or pressure before unwanted components are removed thus avoiding the need for significant re-pressurization and re-heating of the treated water before being fed into a steam generator. These processes allow for the produced water to be treated at temperatures and pressures at or near those of the initial produced water temperature and initial produced water pressure.
Compact Flotation Unit & Removal of Lime Softener In a series of embodiments of processes encompassed by the present invention, a flotation type unit such as but not limited to, a compact flotation unit (CFU) is used to replace the skim tank, ISF/IGF and ORF thereby reducing the overall equipment footprint and complexity of the de-oiling operation central processing facility (CPF).
Leveraging flotation type technology for de-oiling of the produced water has been shown to be capable of achieving all, or at least substantially all, the functionalities of the individual conventional units and replaces the skim tank, ISF/IGF and ORE with a single piece of equipment, for example the CFU. In addition, by utilizing a flotation unit such as a CFU, the produced water can be processed and treated at temperatures and pressures greater than about 80 C and atmospheric pressure. This in turn means that produced water entering the de-oiling section of the facility no longer requires cooling and as a result, may be processed at or near the initial temperatures and initial pressures of the produced water. The CFU
enables the throughput of a produced water containing both silica and having hardness to be treated, where the hardness is later removed, if required, through a hardness removal unit such as an ion exchange unit. Achieving suitable oil and turbidity removal, while

8 _ maintaining the produced water stream at an elevated pressure and temperature in a multistage flotation unit, allows for the simplification of the conventional process scheme and corresponding facility. In some embodiments, the flotation unit may also be utilized in debottlenecking existing operations where oil removal targets from the produced water stream are not consistently met, or where hydraulic capacity may be limited.
An example of such a facility is shown with reference to Figure 2 detailing an embodiment of a central processing facility (CPF) system 200 encompassed by the present invention. As shown in Figure 2, a high efficiency flotation unit, for example, a CFU 205, has replaced the skim tank, ISF/IGF and ORF. It will be appreciated by those skilled in the art that the section of the CPF containing these units is often termed the de-oiling section. The system 200 enables the removal of heat exchangers 104 that were previously required prior to the de-oiling of the produced water. In some embodiments, heat exchangers 207 may be desirable to increase the temperature of the treated water exiting one of the CFU 205 or a hardness removal unit 209. For example, heat exchangers 207, in a heat integration step, may employ enthalpy from another location within the process, for example an emulsion cooling step (not shown) prior to emulsion treatment 202.
It is a widely held belief within the SAGD industry that in order to re-use produced water as boiler feed water, both silica and hardness need to be removed prior to steam generation in order to prevent scaling in steam generators, for example OTSGs.
The most widely accepted practice in industry is to use a Lime Softener (LS) such as a warm lime softener (WLS) to achieve removal of these contaminants. However, and without wishing to be bound by theory, it is theorized by the inventors that silica may not cause severe scaling issues, particularly if minimal hardness is present. A LS operation is expensive due to chemical consumption, disposal treatment, and the use of high maintenance equipment. Elimination of the LS can reduce: the capital cost for new facility phases, the volume of required waste disposal, chemical and maintenance costs, and the overall facility environmental footprint. Detailed in the examples below are the results of various experiments performed to challenge the industry's belief that silica removal to the generally accepted level of about 50 ppm is required prior to steam generation. Generally, about 100-300 ppm silica is observed in produced water returning from reservoir, and validate that more efficient produced water treating can be achieved without lime softening at high temperature and high pressure produced water treatment conditions.

9 Due to the current industry standard of 76-82% steam quality mode of operation of the OTSGs for steam generation downstream of the water treatment system, the hardness removal unit 209 (for example an ion exchange unit or an EF reactor) may still be used for the removal of Ca2+ and Mg2+ ions. To prevent the silica from precipitating out of the solution, a high pH should be maintained in the range of 7-12. Removing hardness from the produced water tends to keep the silica in solution since the silica generally reacts with hardness to produce species with low solubility and as such the silica will now not react and produce highly water insoluble compounds.
By redesigning of the conventional processing template by removing the traditional de-oiling system as well as the conventional water treatment system which includes lime softening, to instead now utilize a CFU 205 in conjunction with the removal of lime softening, the system 200 can be operated at temperatures and pressures greater than 80 C and atmospheric pressure, respectively. It will be appreciated by those skilled in the art that a CFU could be replaced by other flotation type units that could achieve similar performance to that described herein. Flotation units, such as a CFU, may also be described as high efficiency flotation units.
In another embodiment, as shown in Figure 3, the ion exchange unit may be eliminated from the system 300, by leveraging a different steam generation technology downstream, such as flash steam generation 312 (FSG). FSG comprises higher pressure heat exchange decoupled from the phase change process (occurring in the flash tank) to produce dry steam at pressure for steam-assisted gravity drainage (SAGD) operations. In this embodiment, it is possible to eliminate a conventional system of water treatment 108 as described above all together with this steam generation technology because boiling of produced water and the accompanying deposit of scale is eliminated or significantly reduced from the equipment while still achieving high quality steam production. A person of skill in the art will appreciate that a number of options exist for steam generation from de-oiled produced water without need for additional water treatment ,in addition to flash steam generation which has previously been described.
It will be appreciated that modifications, amendments and/or alterations to the systems, methods and concepts described herein may be carried out and are intended to be within the scope and spirit of the invention.

Electro-flocculation In a further series of embodiments of processes of the invention, an electro-flocculation (EF) process is applied, thereby treating the produced water at high temperature and pressure to remove the majority of unwanted components (contaminants) and enabling recycling of the treated water for use in steam generation.
In electro-flocculation (EF), or electro-coagulation (EC), an electrical current is applied to cause metallic ions, such as Fe2+ or AP, to dissolve in an aqueous solution and then form hydroxide, or other, flocs at an appropriate pH, usually without the need of polymer addition. These flocs serve to remove the contaminants in the water by various to mechanisms, such as absorption. Contaminants include scale forming minerals, such as calcium, magnesium, SiO2 and insoluble organics, hydrocarbons, suspensions and emulsions, in the quantities observed in SAGD produced water as understood by those familiar in the art.
In a typical EF unit, there are a series of metal sheets referred to as electrodes, which generally are arranged in pairs of two, one anode and one cathode. At least one of the anode or cathode is sacrificial and is made from materials such as iron, aluminum, zinc, or magnesium. The ions thereof migrate into the electrolyte and bond with or adhere to the impurities to floc, or precipitate, these impurities with suitable pH
changes. The primary reaction occurring at the anode is metal dissolution, as well as the potential oxidation of the metal ion to a higher oxidation state when exposed to oxygen.
The main cathodic reaction is hydrogen evolution. It will be appreciated that the main reactions in electro-flocculation utilizing iron (Fe) anodes are as follows:
Fe(s) 4 Fe2+0q) + 2e- (1) 2H20(I) + 2e- -3 H2(g) + 20H(at) (2) Fe2+(aq) + 20H-0q) 4 Fe(OH)2(s) (3) A person skilled in the art will appreciate that Ohm's and Faraday's laws provide the basic operational and essential framework for EF. One embodiment of the process and system of the present invention involves integration of the EF technology into a SAGD
facility to remove contaminants in produced water prior to entering a steam generator.
An EF process as referred to in this application comprises an electro-chemical or EF

reactor, pH adjustments, mixing, and separation stage. Potential embodiments are detailed below and are intended to be illustrative of aspects of the invention and are not intended to be limiting:
In one embodiment, shown in Figure 4, the system 400 includes an EF unit 414 downstream of the emulsion treatment 402. The system 400, enables the removal of heat exchangers 104 that were previously required prior to the de-oiling of the produced water, such that the produced water entering the system 400 is at an elevated temperature and pressure as compared with the conventional system described in Figure 1 above.

Produced water flows into the EF unit 414, for example an iron reactor, where Fe2+
to dissolves in the produced water. The pH is adjusted to facilitate the formation of hydroxide flocs, which bind to the contaminants within the produced water. The reaction may require a suitable residence time with optional mixing, within a residence unit 416.
The residence unit 416 may be piping or an additional vessel. These flocs are removed in a separation vessel 418. The separation vessel 418 may include filtration or flotation or other separation methods. In another embodiment, the separation vessel 418 may be a high efficiency flotation unit such as a CFU. Optionally, the system 400 may further include a hardness removal unit 409 such as ion exchange vessels (e.g., SAC/WAC), and a unit 420 for removing excess iron and/or organics, as EF has been shown to increase the iron concentration in produced water and doesn't reduce soluble organic contaminants. While zo Figure 4 shows unit 420 after the separation vessel 418, this unit may also be positioned after the separation vessel. In one embodiment, unit 420 may be a two-stage process where excess iron is removed through an ion exchange unit and organics are removed using a chemical oxidation process. A skilled person in the art would understand there are numerous suitable options for both iron and organics removal.
In a further embodiment, where the produced water entering the system 400 comprises large quantities of free floating oil, an additional oil removal unit (not shown) may be included upstream of the EF unit 414. In some instances, free floating oil in the produced water may inhibit electro-flocculation because free oil may form a layer on the electrode surface. This layer may inhibit iron solubility at the electrodes.
The system shown in Figure 4 is operable at or near the initial produced water temperature and pressure conditions, thereby obviating the need to cool and de-pressurize the produced water entering the system 400 and then re-heat and re-pressurize the treated water prior to inputting for use in steam generation 412, In addition, the EF processes and systems described herein allow for both high temperature / high pressure de-oiling and high temperature / high pressure treatment of the produced water. Implementation of the electro-flocculation systems and processes described herein also allows for a significant reduction in the CPF footprint by removing extraneous equipment, for example decreasing the reliance on storage tanks and various treatment vessels. This can also reduce both capital and operating expenses. A
person of skill in the art will appreciate that operation of EF processes and systems could be reconfigured and continue to operate at high pressure and high temperature as described herein.
Examples Example 1 - Compact Flotation & Removal of Warm Lime Softener CFU Test Skid:
A portable compact flotation unit (CFU) test skid containing several flotation stages was used to demonstrate the oil removal capabilities under varying test conditions. The type of CFU utilized in this skid is described in Advances in Compact Flotation Units (CFUs) for Produced Water Treatment by hatnagar, M. &
Sverdrup, C.
J. Offshore Technology Conference Asia held in Kuala Lumpur, Malaysia, 25-28 March 2014 (OTC-24679-MS). A person of skill in the art will appreciate that other CFUs may also be used. A low shear pump at the inlet to the skid was utilized for a lower pressure and temperature test, but was not utilized during a higher pressure and temperature test.
A series of hoses connected the test skid to an existing SAGD central processing facility (CPF) at Foster Creek in Northern Alberta. A chemical injection pump enabled a variety of flocculants to be dosed into the skid unit. The test skid also allowed for a variety of flotation gases to be tested. The separated oil and gas were recycled back to the CPF
for processing separately from the de-oiled water. Sample valves and tubing allowed for the sampling of process fluid at different locations within the test skid.

In the de-oiling process using the CFU testing skid, the produced water input into the skid had the following compositional characteristics:
Pressure: ranged from atmospheric to greater than 1000 kPag Temperature: ranged from about 90 C to about 150 C
Oil content: ranged from about 0 ppm to about 500 ppm of oil in water during normal operation, at upset conditions oil content could reach up to about 5,000 ppm Turbidity: ranged from about 1 NTU to about 300 NTU during normal operation, at upset conditions turbidity could reach up to about 1,000 ppm As described in the application above, the use of a multi-stage flotation type unit that is capable of removing oil in water at high temperature and high pressure operations can either substitute for or eliminate skim tanks, gas flotation units and oil removal filters. A
substantial reduction in land footprint is possible compared to the conventional de-oiling facility design.
Trial locations were selected in the de-oiling area of the plant and downstream of the FWKO, as shown in Figure 5 which depicts the CFU test skid installation 610 in the facility. Several CFU trials were completed using samples taken at various tie points downstream of the free water knock out (FWKO) in the existing CPF to demonstrate the ability to remove oil and turbidity at high temperature and pressure. The following parameters were adjusted to determine suitable operating parameters of the CFU:
1. Number of stages in operation was varied by controlling flotation gas injection.
2. Type, temperature and flow rate of the flotation gas 3. Reject water flow rate 4. Inlet water flow rate 5. Flocculant injection: chemical type and concentration Oil removal and removal efficiency was demonstrated for each of the produced water samples that were analyzed for oil in water concentration as measured by a TD-500 hand held analyzer (supplied by Turner Designs Hydrocarbon Instruments).

Test samples were taken at the following tie in points: FWKO outlet 630, treater outlet 640, skim tank inlet 650, and ISF inlet 660. Typically, the duration of each test was about 1-2 weeks. The dotted line on Figure 5 illustrates the various tie in points from the CPF system to the test skid 610.
The conventional de-oiling process is able to reduce the oil in water to less than ppm and turbidity to less than 10 NTU under typical operation conditions and the current system responds well to upset conditions. Comparatively, the tested multi-stage compact flotation unit was able to achieve both similar oil removal efficiency and turbidity reduction at the outlet 670 as the current entire conventional de-oiling process.

10 In particular, comparable oil removal to the conventional de-oiling train shown in Figure 1 was seen at conventional operational temperatures and pressures, while improved oil removal was seen at higher temperatures and pressures. Operating at higher pressure and temperature required slightly higher dosage of flocculent compared to operation at the current lower temperature and pressure conditions, likely due to polymer degradation at higher temperatures and higher oil demand. A person of skill in the art will appreciate that any of a number of established polymers, flocculants, or a combination thereof, for CFUs may be used in the processes and systems described herein.
Removal of Lime Softening (LS):
While the testing procedure and theory focused mainly on silica concentration, the follow-on effects of LS unit elimination were also investigated. The LS unit affects the concentration of other compounds and elements such as magnesium (added to LS
as Mg(OH)2 for silica removal), calcium (added as Ca(OH)2 for pH adjustment in LS) and also total organic carbon (TOG), to name a few. The testing discussed below allowed for the observation of secondary and tertiary effects as well as reactions that are difficult to account for theoretically. Additionally, the chemical composition of boiler feed water derived from the typical water treatment train in a conventional CPF and boiler feed water derived from a CPF with the LS absent was monitored. In theory, where there is no LS, the boiler feed water will react differently when exposed to the conditions at which steam is produced. Some or all of the scale composition, deposition rate and formation mechanism will most likely show different characteristics.

A systematic and controlled testing procedure was developed in order to validate the concepts behind the theory mentioned above. The testing procedure employed several step changes (phases) as silica concentration in a water stream intended for steam generation was increased to develop a better understanding of the chemistry and operability of the system. As mentioned previously, though silica is the main factor controlled for in each phase of testing, other chemical effects were also monitored. A pilot system 700 for testing LS removal, in this case warm LS (WLS), is shown in Figure 6. The pilot system took advantage of low and high silica source tie points to achieve overall targeted silica concentrations between about 40 ppm and 300 ppm measured as SiO2 for delivery to an OTSG.
A low silica source water was derived from the existing water treatment train that employs a WLS to reduce the silica concentration to a range typically between about 30 ppm and about 50 ppm. More specifically this tie point 780 is located immediately following the WLS, which ensures that only the effects of the WLS unit were considered and not additional water treatment units preceding it. A high silica source was derived from a tie point 790 prior to the WLS tank; this source stream is also known as de-oiled produced water as known to those skilled in the art and the industry. To target a certain concentration for each phase of testing the two source streams (pre- and post-WLS) were mixed at various ratios.
A WLS test skid 710 was set up to replicate the unit operations that follow WLS in a typical water treatment train. This includes a filtration unit and several ion exchange unit steps that together decrease the total suspended solids (TSS) and hardness of the mixed high silica produced water. The test skid 710 enabled control over the test parameters, as well as allowed for isolation of the test skid 710 from central processing facility operations.
Currently, conventional thinking suggests that controlling hardness concentration is critical as it is directly associated with the scale formation rate. In addition, for preventing silica based deposition, the control of ion exchange operations is also considered critical.
The filter prior to the ion exchange units was included in the test skid 710 for the removal of TSS, turbidity and to some extent 'free' oil, as known to those skilled in the art.
The hardness level was controlled to levels below what are currently targeted in the existing water treatment facility that employs a LS unit for example, <0.5 ppm. Even if the LS is eliminated, hardness may be maintained at <0.5 ppm. The heightened levels of substrates (e.g., silica, sodium silicate) that could bind with hardness to produce precipitation will push the reaction towards the product side, thus, even fairly low levels of hardness could be detrimental to control of scale deposition. Nevertheless, the rate of scale formation, operation time between mechanical cleaning (pigging) cycles of the boilers and cost savings observed from the elimination of LS from operations were all considered for setting success criteria.
The results have shown flexibility in the level of silica control which suggests that the current level of silica control practiced in the industry is unnecessary.
The results have shown that a relaxing of current silica control practices and full by-pass of the WLS are all to possible without causing detrimental effects to the operability of the CPF. A person of skill in the art will appreciate that other combinations of filters, ion exchange units, and other equipment could be used as an alternative to the test set-up described herein and shown in Figure 6.
Testing began by passing a low silica stream (30-50ppm) from existing facilities through the WLS test skid, providing boiler feed water for steam generation and establishing a baseline (over a 2 week period) for steam generation at an inlet temperature of about 125 C to about 130 C. Samples of boiler feed water (BFW) and blowdown (BD) from the steam generator were regularly acquired and analyzed for content including silica, iron, hardness, pH, conductivity, oil & grease, carbonate/bicarbonate, total dissolved solids, chlorides/sodium, turbidity, TOC, dissolved organic carbon, sulfates and TSS. Infrared thermal scans were completed after two weeks of baseline operation, and at least as frequently as incremental step changes of silica concentration were made.
Once the baseline data was gathered as described above, the OTSG feed was switched incrementally (about every 3 months) to higher silica concentration water blends (e.g., 100 ppm, 150 ppm silica). The OTSG continued operating at the same conditions as set out in the baseline operation. Chemicals (chelant and sulfite) were dosed as per rates equivalent to the current conventional facilities practice, as will be understood by a person of skill in the art.
The OTSGs were inspected after boiler feedwater streams with the varying silica concentrations were tested for steam generation. The OTSG scale load was measured to be more than what is observed in existing facility operations. However, given that the integrity and functionality of the OTSG was not compromised, BFW having increased silica concentrations was shown to successfully generate steam.
The produced water entering the inlet of the test skid unit was shown to have average values ranging from 10-1000 ppm oil and grease, 20-1000 NTU Turbidity and hardness of 1-50 ppm. The treated water at the outlet of the test skid prior to entering an OTSG was shown to have average values below about 5 ppm oil and grease, 10 NTU

Turbidity, and 0.2 ppm hardness.
The concentration of silica at the inlet and outlet of the test skid was essentially 1() unchanged. Testing of variations in the silica concentration of BFW
ranging from 100ppm to a maximum concentration of about 300pm will be tested in further experiments.
However, as noted above, higher silica concentrations in BFW have been shown to successfully generate steam indicating that the improved system 200 can be successfully implemented.
In experiments performed, it was observed that the boiler can be operated at commercial conditions for 250 days under a 90 ppm ¨ 280 ppm range of silica concentrations, compared to industry's practice of operating at a concentration of about <
50 ppm silica. All monitored parameters and inspections indicated that the test boiler utilized for the experiments was in good condition with no integrity issues.
The boiler tube conditions remained consistent with those obtained prior to LS removal. The treated water at the outlet of the test skid prior to entering the OTSG showed the same quality as the treated water in the existing water treatment train that employs a WLS (the exception being the higher silica concentrations tested), with average treated water outlet values below about 5 ppm oil and grease, 10 NTU turbidity, and 0.2 ppm hardness.
Example 2 - Electro-flocculation A trial was performed at a SAGD facility at Foster Creek in Northern Alberta to confirm that the EF technology described in Figures 4 can remove the necessary contaminants found in SAGD produced water to a similar degree as the current de-oiling water treatment process at atmospheric conditions. A pilot system 800 for testing an EF
.. unit 810 in a CPF is shown in Figure 8. Using an EF test skid 810, operating on the theoretical principles previously described, we were able to successfully treat a source of produced water over the course of 2 weeks of testing period with typical industry contaminant concentrations for SAGD produced water, e.g., 0-500 mg/L oil, 1-300 NTU, 100-800 mg/L TSS, 100-300 mg/L silica, 10-50 mg/L hardness (as CaCO3), 400-600 mg/L
soluble organics (TOC). A person of skill in the art will appreciate that typical contaminant concentrations will vary depending on the type of reservoir and hydrocarbon recovery operations. The EF test skid 810 was configured for testing atmospheric conditions and at a temperature between about 20-60 C, lower than the about 90 C operating temperature of the facility, and so the produced water was let cool prior to entering the EF unit 810.
Contaminant removal was successfully demonstrated at these conditions.
The test skid and process described herein, was comprised mainly of a pH pre-adjustment, an EF unit (also referred to as an iron reactor in this example), pH after-adjustment, a mixing chamber, and filtration to remove flocs. When in the reactor, iron(II) enters the solution and forms iron(II) hydroxide flocs. A person of skill in the art will appreciate that some iron(III) may be produced by oxidation of iron with air at the surface of the basin. Microbubbles are also formed which attach to the flocs and float them to the top of the reactor. A rectifier produced a constant current across the electrode plates within the reactor. The operating voltage is generally between about 4 and 10 V.
Variation in the conductivity of the feed water is compensated for by changes in the voltage during normal operation. The number of electrodes was varied depending on conductivity of the feed water being tested, with more electrodes used for lower conductivity water feeds. pH
adjustments varied as appropriate to facilitate floccing. pH was pre-adjusted between 6-8 by dosing with acid (e.g., HCI) when applicable for proper iron dissolution and pH after-adjustment to between 9 and 10 was performed by dosing with caustic (e.g., NaOH) to facilitate large Fe(OH)2 floc formation without the addition of other chemicals.
Inlet produced water was comprised of the following approximate contaminant concentration ranges during testing: 200-500 mg/L oil, 100-800 mg/L TSS, 100-mg/L silica, 10-50 mg/L hardness (as CaCO3), 400-600 mg/L soluble organics (TOC).
The conductivity of the produced water was between 2-4 mS/cm. These levels may vary during normal process operation. The testing demonstrated average oil removal of >99%, TSS removal of 98%, silica removal of 96%, hardness removal of 72%, and TOC
removal of 50%, generating a treated water suitable for steam generation. A
person of skill in the art will appreciate that water contamination parameters targeted for steam generation will vary depending on the particular source water and hydrocarbon recovery operations being performed.
Testing supports the feasibility of designing and building a process system incorporating EF technology as shown in Figures 4. EF technology provides a number of advantages over current practices, including a significant reduction in capital and operating expenditures.
Based on results from the on-site tests, electro-flocculation is suitable for replacing the conventional de-oiling and water treatment equipment up to WAC
polishers, working at atmospheric pressure. Such a configuration is shown in Figure 4.
to The Applicants predict based on the testing conducted to date, that solubility of almost all inorganic salts (i.e., Fe(OH)2) will change only slightly when temperature increases to about 135 C or more making operation at high temperature and high pressure feasible. (Yoshio Nishi, Robert Doermig, Handbook of Semiconductor Manufacturing Technology (2007); Selji Sawamura, High-pressure investigations of solubility, Pure Appl. Chem., Vol. 79, No. 5, pp. 861-874, (2007); and L. M.
Dorfman, G.
E. Adams; Reactivity of the Hydroxyl Radical in Aqueous Solutions, Ohio State University, Columbus, Ohio 43210, (1973). Based on this understanding and the test data described above, EF may be implemented under high temperature, high pressure operating conditions (as shown in Figure 4).
It will be appreciated that various modifications, changes, adaptations and substitutions may be made to the embodiments disclosed and claimed herein without departing from the scope and spirit of the invention and such modifications, changes, adaptations and substitutions are intended to be captured by the scope and spirit of the disclosure and claims. The disclosure provides embodiments for the purposes of illustrating the invention and is not intended to limit the scope of the claims.

Claims (88)

WE CLAIM:

1. A process for generating steam from produced water in a hydrocarbon recovery system, the processing comprising:
inputting a produced water stream which has received emulsion treatment, which has an initial concentration of unwanted components ([UC]i), which has an initial temperature (Tl) above 80°C, and an initial pressure (Pi) above atmospheric pressure;
treating the produced water stream to produce a treated water stream which has a treated concentration of unwanted components ([UC]t), which has a treated temperature (Tt), and which has a treated pressure (Pt), wherein treating the produced water stream comprises removing oil from the produced water stream using a flotation type unit to produce the treated water stream, and generating steam from the treated water stream in a steam generator;
wherein:
[UC]t is lower than [UC]i;
Tt is within 50°C or 40% of Ti; and Pt is within 10% or 0.2 MPa of Pi

2. The process according to claim 1, wherein Ti is above 130°C, Pi is >1MPa and Tt is above 80°C.

3. The process according to claim 1 , wherein Ti is 130-220°C, Pi is >1MPa and up to 3.1 mPa, Tt is greater than 130°C, and Pt is >1MPa.

4. The process according to claim 1, wherein Pt is at least at the steam saturation pressure.

5. The process according to any one of claims 1 to 4, wherein the unwanted components are in the form of oil and grease, total suspended solids, turbidity, silica, hardness, soluble organics, total dissolved solids, or a combination thereof

6. The process according to claim 5, wherein the [UC]i for oil and grease is 10 mg/L or more.

7 The process according to claim 5, wherein the [UC]i for oil and grease is less than about 5,000 mg/L under upset conditions.

8. The process according to any one of claims 5 to 7, wherein the [UC]t for oil and grease is about mg/L or less.

9. The process according to claim 5, wherein the [UC]i for total suspended solids is about 100 mg/L or more.

10. The process according to claim 5 or 9, wherein the [UC]t for total suspended solids is about 5 mg/L or less

11. The process according to claim 5, wherein the [UC]i for turbidity is about 250 NTU or more.

12. The process according to claim 5, wherein the [UC]i for turbidity is less than about 1,000 ppm under upset conditions

13. The process according to any one of claims 5, 11 and 12, wherein the [UC]t for turbidity is about NTU or less.

14. The process according to claim 5, wherein the [UC]i for silica is about 250 mg/L or more.

15. The process according to claim 5 or 14, wherein the [UC]t for silica is about 50 mg/L or less.

16. The process according to claim 5, wherein the [UC]i for hardness is about 10 mg/L or more.

17. The process according to claim 5 or 16, wherein the [UC]t for hardness is about 15 mg/L or less

18. The process according to claim 5, wherein the [UC]i for soluble organics is about 400 mg/L or more.

19. The process according to claim 5 or 18, wherein the [UC]t for soluble organics is less than about 400 mg/L

20. The process according to any one of claims 1 to 19, further comprising using an ion exchange reaction to remove unwanted components in the form of iron, hardness, or a combination thereof.

21. The process according to any one of claims 1 to 20, which is free of a cooling step for reducing tie temperature of the produced water stream prior to the inputting of the produced water stream.

22. The process according to any one of claims 1 to 20, which is free of a cooling step for reducing the temperature of the produced water stream.

23. The process according to any one of claims 1 to 21, wherein the steam generator generates steam from the treated water stream having a steam quality of at least 80%, 90% or 100%.

24. The process according to any one of claims 1 to 22, wherein the steam generator is a once-through steam generator or a flash steam generator.

25. The process according to any one of claims 1 to 24, wherein treating the produced water stream further comprises exposing the treated water stream to a flocculation reaction to further remove unwanted components.

26. The process according to any one of claims 1 to 24, wherein the process is free of a lime softening step for reducing a silica content of the produced water.

27. The process according to any one of claims 1 to 26, wherein the process is free of a silica removing step.

28. The process according to any one of claims 1 to 27, wherein the flotation type unit is a column flotation unit.

29. The process according to any one of claims 1 to 27, wherein the flotation type unit is a compact flotation unit.

30. The process according to any one of claims 1 to 29, which is maintained at a pH of between about 7 and about 12

31. A system for treating produced water to provide treated water and for generating steam from the treated water for use in hydrocarbon recovery, wherein the produced water has received emulsion treatment, wherein the produced water has an initial concentration of unwanted components ([UC]i), an initial temperature (Ti) which is above 80°C, and an initial pressure (Pi) which is above atmospheric pressure, and wherein the treated water has a treated concentration of unwanted components ([UC]t), a treated temperature (Tt), and a treated pressure (Pt), the system comprising:
a produced water input;
a treatment device for treating the produced water to reduce the concentration of the unwanted components, wherein the treatment device comprises a flotation type unit for treating the produced water; and a steam generator for producing steam using the treated water;

wherein:
[UC]t is lower than [UC]i, Tt is within 50°C or 40% of Ti; and Pt is within 10% or 0.2 MPa of Pi

32. The system according to claim 31, wherein Ti is above about 130.degrees.C, Pi is greater than about 1MPa, and Tt is above about 80.degrees.C

33. The system according to claim 31, wherein Ti is between about 130.degrees.C and about 220.degrees.C, Pi is between about 1MPa and about 3.1 mPa, Tt is greater than about 130.degrees.C, and Pt is greater than about MPa.

34. The system according to claim 31, wherein Pt is at least at the steam saturation pressure

35. The system according to any one of claims 31 to 34, wherein the unwanted components are in the form of oil and grease, total suspended solids, turbidity, silica, hardness, soluble organics, total dissolved solids, or a combination thereof

36. The system according to claim 35, wherein the [UC]i for oil and grease is 10 mg/L or more

37. The system according to claim 35, wherein the [UC]i for oil and grease is less than about 5,000 mg/L under upset conditions.

38. The system according to any one of claims 35 to 37, wherein the [UC]t for oil and grease is about mg/L or less.

39. The system according to claim 35, wherein the [UC]i for total suspended solids is about 100 mg/L or more.

40. The system according to claim 35 or 39, wherein the [UC]t for total suspended solids is about 5 mg/L or less.

41. The system according to claim 35, wherein the [UC]i for turbidity is about 250 NTU or more.

42. The system according to claim 35, wherein the [UC]i for turbidity is less than about 1,000 ppm under upset conditions

43. The system according to any one of claims 35, 41 and 42, wherein the [UC]t for turbidity is about NTU or less.

44. The system according to claim 35, wherein the [UC]i for silica is about 250 mg/L or more.

45. The system according to claim 35 or 42, wherein the [UC]t for silica is about 50 mg/L or less.

46. The system according to claim 35, wherein the [UC]i for hardness is about 10 mg/L or more.

47. The system according to claim 35 or 46, wherein the [UC]t for hardness is about 15 mg/L or less.

48. The system according to claim 35, wherein the [UC]i for soluble organics is about 400 mg/L or more.

49. The system according to claim 35 or 48, wherein the [UC]t for soluble organics is about less than about 400 mg/L.

50. The system according to any one of claims 31 to 49, further comprising an ion exchange unit for removing unwanted components in the form of iron, hardness, or a combination thereof.

51. The system according to any one of claims 31 to 50, which is free of a cooling unit for reducing the temperature of the produced water stream upstream of the treatment device.

52. The system according to any one of claims 31 to 50, which is free of a cooling unit for reducing the temperature of the produced water stream.

53. The system according to any one of claims 31 to 52, wherein the steam generator generates steam from the treated water stream having a steam quality of at least 80%, 90% or 100%.

54. The system according to any one of claims 31 to 53, wherein the steam generator is a once-through steam generator or a flash steam generator.

55. The system according to any one of claims 31 to 54, which is free of a lime softening unit.

56. The system according to any one of claims 31 to 54, which is free of a silica removing unit.

57. The system according to any one of claims 31 to 56, wherein the flotation type unit is a column flotation unit.

58. The system according to any one of claims 31 to 56, wherein the flotation type unit is a compact flotation unit.

59. The system of any one of claims 31 to 58, wherein the treatment device further comprises an electro-flocculation system in communication with the flotation type unit for the removal of hardness.

60. The system of any one of claims 31 to 59, wherein the treatment device is configured to maintain the treated water at a pH of between about 7 and about 12.

61. A facility for treating produced water to provide treated water and for generating steam for use in hydrocarbon recovery from the treated water, wherein the produced water has received emulsion treatment, wherein the produced water has an initial concentration of unwanted components ([UC]i), an initial temperature (Ti) that is above 80°C, and an initial pressure (Pi) that is above atmospheric pressure, and wherein the treated water has a treated concentration of unwanted components ([UC]t), a treated temperature (Tt), and a treated pressure (Pt), the facility comprising:
produced water input;
a treatment device comprising a flotation type unit for treating the produced water to reduce the concentration of the unwanted components; and a steam generator for generating steam from the treated water, wherein:
the facility is free of a lime softening unit and occupies a reduced footprint, [UC]t is lower than [UC]i, Tt is within 50°C or 40% of Ti, and Pt is within 10% or 0.2 MPa of Pi.

62. The facility according to claim 61, wherein Ti is above about 130°C, Pi is greater than about 1MPa and Tt is above about 80°C.

63. The facility according to claim 61, wherein Ti is between about 130°C and about 220°C, Pi is between about 1MPa and about 3.1 mPa, Tt is greater than about 130°C, and Pt is greater than about 1MPa.

64. The facility according to claim 61, wherein Pt is at least at the steam saturation pressure.

65. The facility according to any one of claims 61 to 64, wherein the unwanted components are in the form of oil and grease, total suspended solids, turbidity, silica, hardness, soluble organics, total dissolved solids, or a combination thereof.

66. The facility according to claim 65, wherein the [UC]i for oil and grease is 10 mg/L or more.

67. The facility according to claim 65, wherein the [UC]i for oil and grease is less than about 5,000 mg/L under upset conditions.

68. The facility according to any one of claims 65 to 67, wherein the [UC]t for oil and grease is about mg/L or less.

69. The facility according to claim 65, wherein the [UC]i for total suspended solids is about 100 mg/L
or more.

70. The facility according to claim 65 or 69, wherein the [UC]t for total suspended solids is about 5 mg/L or less.

71. The facility according to claim 65, wherein the [UC]i for turbidity is about 250 NTU or more.

72. The facility according to claim 65, wherein the [UC]i for turbidity is less than about about 1,000 ppm under upset conditions.

73. The facility according to any one of claims 65, 71 and 72, wherein the [UC]t for turbidity is about NTU or less.

74. The facility according to claim 65, wherein the [UC]i for silica is about 250 mg/L or more.

75. The facility according to claim 65 or 74, wherein the [UC]t for silica is about 50 mg/L or less.

76. The facility according to claim 65, wherein the [UC]i for hardness is about 10 mg/L or more.

77. The facility according to claim 65 or 76, wherein the [UC]t for hardness is about 15 mg/L or less.

78. The facility according to claim 65, wherein the [UC]i for soluble organics is about 400 mg/L or more.

79. The facility according to claim 65 or 78, wherein the [UC]t for soluble organics is less than about 400 mg/L.

80. The facility according to any one of claims 61 to 79, further comprising an ion exchange unit for removing unwanted components in the form of iron, hardness, or a combination thereof.

81. The system according to any one of claims 61 to 80, which is free of a cooling unit for reducing the temperature of the produced water stream upstream of the treatment device.

82. The facility according to any one of claims 61 to 80, which is free of a cooling unit for reducing the temperature of the produced water stream.

83. The facility according to any one of claims 61 to 82, wherein the steam generator generates steam from the treated water stream having a steam quality of at least 80%, 90% or 100%.

84. The facility according to any one of claims 61 to 83, wherein the steam generator is a once-through steam generator or a flash steam generator.

85. The facility according to any one of claims 61 to 84, which is free of a silica removing unit.

86. The facility according to any one of claims 61 to 85, wherein the flotation type unit is a column flotation unit.

87. The facility according to any one of claims 61 to 85, wherein the flotation type unit is a compact flotation unit.

88. The facility according to any one of claims 61 to 87, wherein the treatment device is configured to maintain the treated water at a pH of between about 7 and about 12.