Abstract:
Integrated systems and met0hods wherein the separation and treatment of produced water may be driven by energy harvested from the produced water.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation in part of International (PCT) Patent Application Serial No. PCT/US2014/012336, filed Jan. 21, 2014, which claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/754,691, filed Jan. 21, 2013. This application also claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 62/023,582, filed Jul. 11, 2014. The entire disclosure of each application identified above is hereby incorporated herein by reference in its entirety for all purposes. 
     
    
     FIELD OF THE TECHNOLOGY 
       [0002]    One or more aspects relate generally to energy production, and more particularly to systems and methods for treating water used in oil and gas extraction. 
       BACKGROUND 
       [0003]    To meet energy and manufacturing needs, oil and gas are routinely extracted from underground sources. Conventional oil and gas extraction is a water intensive process. Produced water is typically unfit for discharge into local water sources and may be injected into underground wells for disposal. Alternatively, produced water may be treated to render it suitable for a variety of uses. 
       SUMMARY 
       [0004]    In accordance with one or more aspects, integrated systems and methods for energy production are disclosed. 
         [0005]    In accordance with one or more aspects, a method for treating produced water may comprise recovering heat energy from the produced water, and using the recovered heat energy to directly drive treatment of the produced water. 
         [0006]    In some aspects, recovering heat energy from the produced water comprises converting heat energy to mechanical energy. The mechanical energy may be used to separate oil and/or contaminants from the produced water. Recovering heat energy from the produced water may further comprise converting the mechanical energy to electrical energy. Recovering heat energy from the produced water may comprise using a heat engine in fluid communication with a generator to convert the recovered heat energy to electrical energy. Recovering heat energy from the produced water may comprise using a thermoelectric generator to convert the recovered heat energy to electrical energy. 
         [0007]    In some aspects, the method may further comprise delivering excess recovered heat energy to an energy network. An energy network may be used to supplement the recovered heat energy or as a backup source of power. In at least some aspects, the heat energy may be recovered prior to separating oil from the produced water. In other aspects, the heat energy may be recovered during treatment of the produced water. 
         [0008]    In accordance with one or more aspects, a system for providing energy to treat produced water may comprise a source of produced water having heat energy, a water treatment subsystem having an energy requirement and fluidly connected downstream of the source of produced water, and an energy recovery subsystem configured to convert a portion of the heat energy from the produced water to mechanical and/or electrical energy, and to supply at least a portion of the energy requirement of the water treatment system. 
         [0009]    In some aspects, the energy recovery subsystem may comprise a generator disposed in communication with a turbine to generate electrical energy. In some non-limiting aspects, the turbine may comprise a two-phase turbine. In at least some aspects, the water treatment subsystem may comprise an oil-water separator and at least one of a microfiltration unit, an activated carbon media unit, a reverse osmosis unit, and an electrodialysis unit. The energy recovery subsystem may comprise a heat engine configured to operate in accordance with a trilateral thermodynamic energy conversion cycle. 
         [0010]    Still other aspects, embodiments, and advantages of these exemplary aspects and embodiments, are discussed in detail below. Moreover, it is to be understood that both the foregoing information and the following detailed description are merely illustrative examples of various aspects and embodiments, and are intended to provide an overview or framework for understanding the nature and character of the claimed aspects and embodiments. The accompanying drawings are included to provide illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification. The drawings, together with the remainder of the specification, serve to explain principles and operations of the described and claimed aspects and embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the disclosed embodiments, and are not intended as a definition of the limits of such embodiments. For purposes of clarity, not every component may be labeled in every drawing. In the following description, various embodiments are described with reference to the following drawings, in which: 
           [0012]      FIG. 1  presents a schematic of a conventional water cycle during oil and gas extraction operations in accordance with one or more embodiments; 
           [0013]      FIG. 2  presents a schematic of a produced water treatment process in accordance with one or more embodiments; 
           [0014]      FIG. 3  presents a schematic of a produced water treatment process in accordance with one or more embodiments; 
           [0015]      FIG. 4  presents an energy flow diagram of systems and methods in accordance with one or more embodiments; 
           [0016]      FIG. 5  presents an example of heat recovery using a working fluid to exchange and recover heat in accordance with one or more embodiments; 
           [0017]      FIG. 6  presents a schematic of a generator suitable for transforming heat energy transferred from a well fluid to electrical energy in accordance with one or more embodiments; 
           [0018]      FIG. 7  presents an energy flow diagram of systems and methods in accordance with one or more embodiments; 
           [0019]      FIG. 8  presents a schematic of a thermoelectric generator in accordance with one or more embodiments; 
           [0020]      FIG. 9  presents a schematic of an integrated separator-heat exchanger in accordance with one or more embodiments; and 
           [0021]      FIG. 10  presents a schematic of an integrated separator-heat exchanger in accordance with one or more embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Various embodiments described herein are not limited in their application to the details of construction and the arrangement of components as set forth in the following description or illustrated in the drawings. One or more embodiments are capable of being practiced or carried out in various ways beyond those exemplarily presented herein. 
         [0023]    Treatment of produced water has become increasingly attractive in view of the expense and potential environmental drawbacks relating to water use and disposal. Onsite treatment of produced water has various challenges, however, particularly the large energy demand associated with such operations. Gas wells are often located in remote locations, limiting access to large energy grids. Operating and fueling on-site generators to supply the energy required for treatment can be cost prohibitive. In accordance with one or more embodiments disclosed herein, systems and methods may beneficially extract heat energy from produced water and use it to power onsite treatment of the produced water. This integration may enable greater efficiency of overall oil and gas extraction operations. While some disclosed embodiments relate specifically to produced water associated with oil and gas extraction, one or more aspects may be applied to any source of water to be treated. For example, heat may be extracted from water associated with geothermal applications as well as from various industrial or refinery water streams. In some embodiments, heat may be recovered from process streams associated with metal casting or the manufacture of cement, iron, steel, aluminum and glass. The recovered energy may then be used to treat the water from which the heat was extracted. The following discussion regarding energy recovery and its use in water treatment may therefore be applied to any source of water to be treated. 
         [0024]    A schematic of a water cycle in a conventional oil and gas extraction operation is presented in  FIG. 1 . In a first step  110 , injected water may be used to drive oil or gas to the surface at a well head. The injected water and/or the existing water in the formation surfaces as a mixture, or emulsion, known as “produced water” that includes the oil and gas products. A typical water to oil ratio may be about 5-10:1 but may vary greatly. Temperatures at the depth under the earth&#39;s surface where oil and gas yielding formations exist are generally high, which causes the water to become heated. In some embodiments, the produced water may be at a temperature in the range of about 100° F. to about 750° F. In some specific non-limiting embodiments, the produced water may be at about 170° F. 
         [0025]    In a second step  120  of the water cycle, the water portion and oil portion of the produced water are separated by various unit operations, as discussed in greater detail below with reference to  FIG. 2 . In a third step  130  of the water cycle, portions of the separated water stream may undergo different treatment operations depending on their intended use. If the water is intended for reinjection to permanent well disposal or for waterflooding, then further treatment may be minimal. For example, in a fourth step  140  of the illustrated water cycle, a portion of the produced water is reinjected for waterflooding to enhance water production. Alternatively, minimally treated produced water may be injected in an underground well for disposal (not shown). If the intended use requires an improved water quality, such as for irrigation, then a more robust water treatment may be required as discussed in greater detail below with reference to  FIG. 3 . 
         [0026]      FIG. 2  presents a non-limiting schematic of a method for oil and gas separation from produced water in accordance with one or more embodiments. The produced water  210  may enter an oil/water separation train  200  and may first undergo treatment in a gravity separation device  220  to separate the oil from the water. Various gravity separation devices and other appropriate unit operations will be readily apparent to those of ordinary skill in the art. Typically, gravity separation devices may operate based on the specific gravity differences between oil and water. Given time, the less dense oil will form an oil layer  240  that floats on top of the denser water layer  230 . Likewise, particulate matter will sink to the bottom of the water layer and will be drained out as part of a sludge  250 . Hydrocarbons in a vapor phase may, in some embodiments, be directed through a vapor outlet towards a vapor collection vessel (not shown). The oil  240  and water layers  230  may then be directed to different outlets, with the oil layer collected as a commodity, and the water layer directed toward further separation and treatment. Passage through a single separation device may not complete the separation of oil and water to a satisfactory degree. 
         [0027]    In accordance with one or more embodiments with further reference to  FIG. 2 , the water mixture effluent from device  220  may continue on to another oil water separation unit, for example, an inclined plate separator  260 . In an inclined plate separator, smaller oil droplets that remained in the water layer coalesce on the inclined plates  265  into larger droplets and separate from the water layer to form an oil layer  240  separate from the water layer  230 . The two layers may then be directed to different outlets. The oil layer  240  produced by the inclined plate separator  260  may be removed from the train  200 , and collected as a commodity. The remaining water mixture may continue on to another separation device, for example, an induced gas flotation device  270  and/or a membrane filter  290 . In an induced gas flotation device, gas or air is introduced into the water mixture, coalescing entrained oil particles and bringing them to the surface where they are separated from the water mixture, and reserved as a commodity. 
         [0028]    Conventional oil and gas well operations that involve the introduction of water to drive oil and gas to the surface will generally include oil and water separation processes of which the above are examples. Various unit operations and their arrangements for oil and gas separation may be selected by those skilled in the art with the embodiment described above presented as a non-limiting example. At this stage in the overall extraction operation, an optimal amount of oil has been recovered, the acquisition of which was the general purpose of the operation. The remaining water mixture at this point may be reinjected either into a working oil or gas well, in a process known as waterflooding, to drive out more oil and gas. Alternatively, the water may be reinjected into a disposal well for permanent disposal. 
         [0029]    Further alternative uses for the water may be limited, however, because even after oil and water separation processes are complete, the water mixture may still contain sufficient impurities to make it unfit for most uses according to various state and/or federal water quality standards. After separation from the oil products is complete, the remaining water mixture still retains a high amount of total dissolved solids (TDS). Non-limiting species of TDS found in produced water may include bicarbonate, calcium, chloride, magnesium, potassium, sodium, and sulfate species among others. Therefore, the waste water mixture may also go through a treatment process to prepare it for other uses. 
         [0030]      FIG. 3  presents a schematic of a method for further treatment of a water mixture after oil separation in accordance with one or more embodiments. The water treatment train  300  of the non-limiting embodiment presented may include microfiltration  310 , activated carbon media  320 , and/or a desalination process such as reverse osmosis or electrodialysis  330  unit operations. Microfiltration  310  typically refers to filtration with a membrane pore size ranging from 0.1 to 10 microns. However, other filtration techniques, whether they involve larger or smaller pore sizes, may be substituted for microfiltration. Another method for filtering which may be employed in the water treatment train  300  involves activated carbon media  320 , e.g., activated carbon, to remove contaminants through chemical adsorption. Reverse osmosis  330  may separate contaminants by applying pressure to push a water stream through a selective membrane. Additional or alternative steps in the water treatment train  300  not shown could include coagulation and flocculation, water softening, air stripping, or any other process generally known in the art for treating water. Various combinations of such unit operations may be used for treatment. 
         [0031]    In accordance with one or more embodiments, the result of this water treatment train  300  may be a concentrate flow  340  which comprises a reject stream that includes the impurities, and a product flow  350  which comprises purified water of a quality that may be suitable for a variety of uses. The product flow  350  may be appropriate for a number of end uses which fall within established water quality regulations. In some non-limiting embodiments, the product flow may be used to recharge aquifers, or for agricultural and irrigation purposes. 
         [0032]    As mentioned above, the energy demands associated with water treatment may serve as a barrier to its implementation or the extent thereof. Energy delivery to remote oil and gas fields may be costly and of limited availability. Conventional energy supplies for oil and gas fields include electrical energy from an electricity grid or a series of onsite generators. In an overall extraction operation, energy is generally required to drive a variety of pumps which may bring the flow of produced water to the surface and move it through further unit operations. Energy is also demanded by oil/water separation processes, as well as by any further water treatment processes such as those described above. 
         [0033]    In accordance with one or more embodiments, heat energy from well fluids or other sources of water to be treated may be harnessed to power oil/water separation and other water treatment processes. Treatment of produced water may be driven by heat energy captured from the produced water. Such integration may beneficially allow water treatment and overall oil or gas extraction operations to be performed in a more efficient manner. 
         [0034]    In accordance with one or more embodiments, the temperature of the produced water may vary, such as may depend on geographical location, depth of extraction, and other factors. In some embodiments, the temperature may be relatively low, for example, between about −10 and 200° F. 
         [0035]      FIG. 4  presents a non-limiting schematic of an integrated system and method in accordance with one or more embodiments. System  400  includes oil and gas recovery  440  and water treatment  450  operations. System  400  may also include an energy recovery system  460 , electric generator(s)  470 , and/or an energy supply  420  as discussed below. The energy recovery system  460  may convert heat energy  480  from well fluids  475  to mechanical energy  485  and/or electrical energy  490 . Mechanical energy  485  and electrical energy  490  may be used to operate unit operations of not only the oil/water separation processes  440  but also the further water treatment processes  450 . As discussed further in association with  FIGS. 5 and 6 , the heated well fluid, or heated produced water  475  may be directed to a heat exchanger which may be part of the energy recovery system  460 . As the heat energy flow arrows  480  indicate, the transfer of heat from the well fluids  475  can occur at any point or multiple points along its path. One or more heat energy recovery units may be used. In some embodiments, the heat energy may be recovered prior to or during oil/water separation. For example, units such as those discussed below in relation to  FIGS. 9 and 10  may be used to recover heat energy during oil/water separation. Heat energy may be recovered during a downstream water treatment process. In some non-limiting embodiments, cooling may generally be required prior to surface discharge and upstream of any membrane filtration or biological treatment used for water treatment. 
         [0036]    As will be discussed further below, at least a portion of the heat from the well fluids may be transferred to a working fluid in a heat exchanger as part of the energy recovery system  460  in accordance with one or more embodiments. Various heat exchangers may be implemented which are capable of operating at the involved process conditions. In some non-limiting embodiments, the inlet temperature to the heat exchanger may be about 40 to 100° F. In some embodiments, the outlet temperature from the heat exchanger may be about 45 to 110° F. The heated working fluid may then be vaporized to drive a turbine, or other mechanical transfer device, thus converting the heat energy to mechanical energy in some non-limiting embodiments. Any mechanical transfer device may be used. In some embodiments, a turbine may be used. The turbine should generally be suitable for operation at the involved process temperatures as discussed herein. For example, the turbine may be a Euler turbine or a variable phase turbine. In some non-limiting embodiments, the turbine may be a two-phase turbine commercially available from Energent Corporation (CA). In other embodiments, a screw expander or other mechanical transfer device may be used. 
         [0037]    The mechanical energy of the turbine may then be used directly or to generate electrical energy via a generator  470 . The mechanical energy may be used for driving pump(s)  430 , oil/water separator  440  or water treatment process  450 . Other applicable methods for energy extraction may be recognized by those of ordinary skill in the art. The electrical energy  490  thus produced may then be used to directly supply or supplement the electrical energy requirements of the unit operations  440  and/or  450 . If the produced electricity  490  exceeds system requirements, then the difference may be supplied to grid  420 . Alternatively, if the produced electricity  490  is less than demand, then the difference may be supplied from the grid  420 . 
         [0038]    In accordance with one or more embodiments, the turbine may be used to generate electricity. In some embodiments, the turbine may be used to provide mechanical energy to a water treatment process, for example, to directly move a pump, a mixer or other device. 
         [0039]    In accordance with one or more embodiments, the energy recovery system may transfer mechanical energy to an oil water separator and/or a water treatment process. In some non-limiting embodiments, a rotating shaft may be implemented such that shaft energy may be used directly in an oil separator, for example, to run a mixer, or a flotation unit. 
         [0040]      FIG. 5  presents a non-limiting schematic illustrating a system  500  for the exchange of heat from a well fluid to a working fluid to generate mechanical energy that may be used to operate a mechanical system or provide electricity in accordance with one or more embodiments. Heated fluid from a production well  510  passes through a heat exchanger  520  and transfers a portion of its heat to a working fluid  540 , for example a refrigerant. The heated working fluid vaporizes to turn a turbine  550 . The mechanical energy of the turbine  550  is transformed into electrical energy in a generator  560 . The embodiment depicted in  FIG. 5  may operate based on an organic Rankine cycle or alternative thermodynamic energy conversion cycles such as, for example, a trilateral cycle, a variable phase cycle, or a Kalina cycle. The trilateral cycle, for example, is a thermodynamic cycle involving a substantially perfect temperature matching between the heat source and the working fluid to minimize irreversibility associated with the process and to maximize its efficiency. In contrast with more traditional thermodynamic cycles that encompass expansion of gases, the expansion of liquid may start in the saturated liquid phase forming a mixture of gas and liquid as a result. Alternative working fluids or heat cycles may be substituted for those in  FIG. 5 . 
         [0041]      FIG. 6  presents a non-limiting schematic of a generator  600  suitable for transforming heat energy transferred from a well fluid to electrical energy in accordance with one or more embodiments. Generator  600  may convert heat energy to mechanical energy, which may be subsequently converted to electrical energy. A working fluid, as described above, may evaporate in evaporator  610  after heat is transferred to it from extracted produced water. The evaporated fluid may perform work on a turbine  620 , the mechanical energy of which may be used to produce electricity. The working fluid may then be condensed in condenser  640  before beginning the cycle again. 
         [0042]    In accordance with one or more embodiments, a thermoelectric conversion process may be used instead of a heat engine.  FIG. 7  presents a non-limiting schematic of one such embodiment of an oil and gas recovery operation. System  700  includes a thermoelectric conversion process  760  and an energy supply  720 . Rather than a heat engine described above, a thermoelectric conversion process  760  uses heat  785  from well fluid  795  to produce electricity  790 . In some embodiments, the thermoelectric conversion process  760  may involve a thermoelectric generator described below with reference to  FIG. 8 . The electricity  790  may then be used to power the operations of the system  700 , either driving the pump  730 , powering the oil/water separations  740 , or powering the water treatment process  750 . If more power is produced than required by the system, the balance of the energy may be transferred to the energy supply  720 , e.g. the grid. If the system requires more energy than that produced by the thermoelectric conversion process  760 , then the energy supply  730  will supply the difference. 
         [0043]      FIG. 8  presents a schematic of a thermoelectric generator in accordance with one or more embodiments. Recaptured heat from the produced water may be used to operate a thermoelectric generator  800 . In generator  800 , heat is absorbed by a substrate  810  connected to thermoelectric couples  820 . The thermoelectric couples  820  of thermoelectric semiconductors may be connected electrically in series and thermally in parallel to make a thermoelectric generator. The flow of heat may generally drive the free electrons to produce electrical power from heat. 
         [0044]      FIG. 9  presents a schematic of an integrated separator-heat exchanger in accordance with one or more embodiments. The integrated separator-heat exchanger  900  may comprise a shell  920  and have an inlet  915  for receiving a fluid  910 . The fluid  910  may be produced water. The fluid  910  may be a fluid that has already undergone some treatment. The fluid may separate out into different layers by, for example, gravity separation. The layers may include a water layer  930  and an emulsion layer  940  that may include carbon species or oils. The layers may also include a gas layer  950 . The different layers may be directed to different outlets. For example, the water layer may be directed to outlet  935 . The emulsion layer may be directed to outlet  945 . The gas layer may be directed to outlet  955 . Having exited the integrated separator-heat exchanger  900  the various layers may be directed to further treatment (for example, further separations treatments), storage, or disposed of as waste, according to the requirements of the operation. 
         [0045]    The integrated separator-heat exchanger  900  may also include components for providing heat exchange. For example, the integrated separator-heat exchanger  900  may include perforated baffles  960  that carry a working heat exchange fluid, for example a refrigerant. The refrigerant may be cold refrigerant  970  that receives heat from the fluid  910 . The refrigerant may then exit as hot refrigerant  980 . The heat energy gathered by the refrigerant may then be put to use as discussed elsewhere herein. The integrated separator-heat exchanger  900  may be incorporated into a treatment train, like those discussed in relation to  FIGS. 2 and 3 . 
         [0046]      FIG. 10  presents a schematic of an integrated separator-heat exchanger in accordance with one or more further embodiments. The integrated separator-heat exchanger  1000  may comprise a shell  1020  and have an inlet  1015  for receiving a fluid  1010 . The fluid  1010  may be produced water. The fluid  1010  may be a fluid that has already undergone some treatment. The integrated separator-heat exchanger  1000  may comprise inclined plates  1065  to separate out oil or carbon species by a process like that described in relation to  FIG. 2 . Separated layers or species may be directed to different outlets of the integrated separator-heat exchanger  1000 . For example, solids may be directed to primary solids outlet  1050  and/or secondary solids outlet  1052 . Gas that enters the system may be directed to gas space  1030  and out through outlet/vent  1035 . Oil may exit through outlet  1054  or secondary outlet  1056 . Water may exit through outlet  1058 . The various separated species may then be directed toward further treatment, storage, or be disposed of as waste, according to the requirements of the operation. 
         [0047]    The integrated separator-heat exchanger  1000  may also include components for providing heat exchange. For example, the integrated separator-heat exchanger  1000  may include perforated baffles and/or wall  1070  including tubing for conveying a working heat exchange fluid, for example a refrigerant. The refrigerant may be cold refrigerant  1080  that receives heat from the fluid  1010 . The refrigerant may then exit as hot refrigerant  1085 . The heat energy gathered by the refrigerant may then be put to use as discussed elsewhere herein. Multiple sets of perforated baffles/walls  1070  may be placed throughout the integrated separator-heat exchanger  1000  as required to meet demand. The integrated separator-heat exchanger  1000  may be incorporated into a treatment train, like those discussed in relation to  FIGS. 2 and 3 . The heat extracted by the refrigerant may cool the water-oil mixture processed by the integrated separator-heat exchanger. In some cases, the cool water-oil mixture enhances the oil-water separation process by changing density, viscosity of water and oil and solubility of organic compounds in water. In other cases the cooling effect induces convective currents in the process that are used for improving circulation and water-oil separation. In at least some embodiments, oil-liquid separation processes may be enhanced by extraction of heat from the produced water. 
         [0048]    In accordance with one or more embodiments, energy may be harnessed from produced water and used to drive oil/water separation as well as treatment of the produced water. Recovered energy may be mechanical energy used directly to drive pumps used for water treatment. In other embodiments, mechanical energy may be converted to electrical energy directly used to drive motors used for water treatment. In some embodiments, a thermoelectric generator may be used to convert the recovered heat energy to electrical energy. Recovered energy may be more or less than that required for conveyance and treatment of the produced water. Excess energy may be delivered to an electric energy network which may provide supplemental energy when needed or otherwise serve as a backup source of power. The heat energy from the produced water may be recovered prior to separating oil from the produced water. In other embodiments, the heat energy may be recovered during treatment of the produced water. In at least some embodiments, heat may be extracted for heating and/or cooling applications. Excess recovered heat energy may be delivered to an energy network, such as a heating and/or cooling distribution network. 
         [0049]    In accordance with one or more embodiments, the systems and methods may generally be described as having an energy recovery component or subsystem, followed by a water treatment component or subsystem. 
         [0050]    The embodiments described herein will be further illustrated through the following example which is illustrative in nature and not intended to limit the scope of the disclosure. 
       EXAMPLE 
       [0051]    The following Table illustrates a prophetic example of the electric energy that can be recovered as an oil field is developed and produced water increases. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Item 
                 Unit 
                 Energy Generation Example 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Temperature  
                 F. 
                 160 
                 160 
                 160 
               
               
                 Inlet Water 
                   
                   
                   
                   
               
               
                 Temperature  
                 F. 
                 135 
                 135 
                 135 
               
               
                 Outlet Water 
                   
                   
                   
                   
               
               
                 Flow Rate 
                 bbl/day 
                 500,000 
                 2,500,000 
                 7,000,000 
               
               
                   
                 lps 
                 920 
                 4,601 
                 12,882 
               
               
                 Produced  
                 kW gross 
                 2,600 
                 13,000 
                 36,000 
               
               
                 Power 
                 kW net 
                 2,200 
                 11,000 
                 31,000 
               
               
                 Power for  
                 kW 
                 2,500 
                 12,300 
                 34,500 
               
               
                 Desalination 
                   
                   
                   
                   
               
               
                 Excess Power 
                 kW 
                 (300) 
                 (1,300) 
                 (3,500) 
               
               
                 Annual energy 
                 kWh/y 
                 19,300,000 
                 96,400,000 
                 271,600,000 
               
               
                 Energy Price 
                 $/kWh 
                 $0.17 
                 $0.17 
                 $0.17 
               
               
                 Annual  
                 M$/y 
                 3.3 
                 16.4 
                 46 
               
               
                 Avoided Cost 
                   
                   
                   
                   
               
               
                 Annual  
                 ton CO2/y 
                 5,000 
                 25,000 
                 72,000 
               
               
                 Avoided CO2 
               
               
                   
               
             
          
         
       
     
         [0052]    The results for power generation are based on pilot unit results for the same temperature while the results for desalination are based on a recently run pilot unit using electrodialysis reversal technology for removing the salts. It is observed that in this case with low salinity waters the energy recovered supplies about 90% of the total energy required for water desalination and conveyance for treatment. Energy expenses for desalination are the most significant processing expense in treating the water to render it suitable for reuse. The energy at this site is generated by burning crude oil in a combustion engine. There are also significant environmental benefits by avoiding green house gas emissions from burning the oil. The last row on the Table indicates the Tons of CO2 that will be avoided with the technology as a result of displacing the use of a fossil fuel to generate electric power with a renewable energy source such as natural water heat. The results from the pilot energy recovery unit indicate that the systems are sensitive to the influent temperature to the unit. There is therefore an incentive to harvest the heat before it is dissipated. 
         [0053]    The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “involving,” “having,” “containing,” “characterized by,” “characterized in that,” and variations thereof herein is meant to encompass the items listed thereafter, equivalents thereof, as well as alternate embodiments consisting of the items listed thereafter exclusively. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority. 
         [0054]    While exemplary embodiments have been disclosed, many modifications, additions, and deletions may be made therein without departing from the spirit and scope of the disclosure and its equivalents, as set forth in the following claims. 
         [0055]    Those skilled in the art would readily appreciate that the various parameters and configurations described herein are meant to be exemplary and that actual parameters and configurations will depend upon the specific application for which the embodiments are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the disclosed systems and methods may be practiced otherwise than as specifically described. The present systems and methods are directed to each individual feature described herein. In addition, any combination of two or more such features, if not mutually inconsistent, is included within the scope of the present disclosure. 
         [0056]    Further, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the disclosure. For example, an existing system or method may be modified to utilize or incorporate any one or more aspects of the disclosure. Thus, in some embodiments, embodiments may involve configuring an existing energy extraction system or method to include the integration described herein. For example, an existing system or process may be retrofitted to involve use of heat from produced water to drive treatment of the produced water in accordance with one or more embodiments. Accordingly, the foregoing description and drawings are by way of example only. Further, the depictions in the drawings do not limit the disclosures to the particularly illustrated representations.