Patent Publication Number: US-2020299153-A1

Title: Oil-Water Separation Technology Using Phase Separation Reactor

Description:
CLAIM OF PRIORITY 
     This application claims priority to U.S. Provisional Application Ser. No. 62/821,811, filed on Mar. 21, 2019, the entire contents of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to separating multiphase fluids, for example, fluids including an oil phase and a water phase, in fluids processing plants, for example, plants that include phase separation reactors. 
     BACKGROUND 
     Hydrocarbons trapped in subsurface reservoirs in subterranean zones often exist as multiphase fluids, for example, an oil phase and a water phase. Phase separation of such fluids is often necessary as part of multiple operations including, for example, hydrocarbon exploration, refining, distribution, utilization, oily wastewater treatment, spill and accident control. 
     SUMMARY 
     This disclosure describes oil-water separation technology using phase separation reactor. 
     Certain aspects of the subject matter described in this disclosure can be implemented as an apparatus. The apparatus includes a fluid flow pathway and a phase separator. The fluid flow pathway includes a fluid inlet and a fluid outlet. The fluid flow pathway is configured to flow multiphase fluid including an oil phase and a water phase from the fluid inlet to the fluid outlet. The phase separator is spatially positioned relative to the fluid flow pathway to receive the multiphase fluid flowing from the fluid outlet. The phase separator includes a mounting substrate and a separation layer attached to the mounting substrate. The separation layer includes a material switchable between oleophilic and hydrophobic under a first condition and oleophobic and hydrophilic under a second condition. The separation layer is configured to separate the oil phase and the water phase when the separation layer is under either the first condition or the second condition. 
     An aspect combinable with any of the other aspects can include the following features. The separation layer is covalently bonded to the mounting substrate. 
     An aspect combinable with any of the other aspects can include the following features. The separation layer is configured to permit flow of the oil phase through the separation layer and prevent flow of the water phase through the separation layer under the first condition. 
     An aspect combinable with any of the other aspects can include the following features. The separation layer is configured to permit flow of the water phase through the separation layer and prevent flow of the oil phase through the separation layer under the second condition. 
     An aspect combinable with any of the other aspects can include the following features. The mounting substrate includes multiple openings to permit flow of the oil phase or the water phase flowed through the separation layer. 
     Certain aspects of the subject matter described here can be implemented as a phase separation reactor that includes a reactor body and a separation layer positioned within the reactor body. The reactor body defines a multiphase fluid receiving portion configured to receive a multiphase fluid including an oil phase and a water phase. The reactor body defines a separated phase receiving portion configured to receive a separated phase of the multiphase fluid. The separation layer is positioned within the reactor body. The separation layer includes a material switchable between oleophilic and hydrophobic under a first condition and oleophobic and hydrophilic under a second condition. The separation layer is configured to separate the oil phase and the water phase when the separation layer is under either the first condition or the second condition to flow one separated phase through the separation layer and to prevent flow of the other separated phase through the separation layer. 
     An aspect combinable with any of the other aspects can include the following features. A mounting substrate is positioned within the reactor body. The separation layer is attached to the mounting substrate. 
     An aspect combinable with any of the other aspects can include the following features. The separation layer is covalently bonded to the mounting substrate. 
     An aspect combinable with any of the other aspects can include the following features. A first phase outlet is coupled to the separated phase receiving portion. The first phase outlet is configured to flow the separated phase flowed through the separation layer out of the reactor body. 
     An aspect combinable with any of the other aspects can include the following features. A second phase outlet is coupled to the multiphase fluid receiving portion. The second phase outlet is configured to flow the separated phase prevented from flowing through the separation layer out of the reactor body. 
     An aspect combinable with any of the other aspects can include the following features. A baffle is configured to control flow of fluid through the multiphase fluid receiving portion. 
     An aspect combinable with any of the other aspects can include the following features. A fluid flow pathway includes a fluid outlet. The fluid flow pathway is fluidically coupled to the reactor body to flow the multiphase fluid into the reactor body. 
     An aspect combinable with any of the other aspects can include the following features. The multiphase fluid receiving portion is substantially cylindrical. 
     An aspect combinable with any of the other aspects can include the following features. The separated phase receiving portion is substantially conical. 
     An aspect combinable with any of the other aspects can include the following features. The reactor is a single stage reactor. 
     An aspect combinable with any of the other aspects can include the following features. The reactor includes a separation layer treatment unit attached to the reactor body. The separation layer treatment unit carries one or more chemicals configured to switch the material of the separation layer between the first condition and the second condition. 
     Certain aspects of the subject matter described here can be implemented as a phase separation reactor assembly including at least two phase separation reactors fluidically coupled in series. 
     Certain aspects of the subject matter described here can be implemented as a method. A separation layer such as the one described earlier is attached to a mounted substrate. The mounted substrate is positioned inside a phase separation reactor. A multiphase fluid including an oil phase and a water phase is flowed through the phase separation reactor and over the separation layer. The oil phase and the water phase are separated from each other. 
     The details of one or more implementations of the disclosure are set forth in the accompanying drawings and the description that follows. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic of an example of an apparatus including a multiphase fluid separation layer attached to a mounting substrate. 
         FIG. 2  is a schematic of an example of a single stage reactor to separate multiphase fluids. 
         FIG. 3  is a schematic of an example of a dual stage reactor to separate multiphase fluids. 
         FIG. 4  is a schematic of an example of a dual stage reactor with acid/base treatment features. 
         FIG. 5  is a flowchart of an example of a method of making and using a reactor. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     This disclosure describes oil-water separation technology that works based on material surface property rather than gravity or coalescence. In some implementations, a continuous or batch flow reactor is equipped with a filter or mesh coated with super-olephilic or super-olephobic switchable surface material. A multiphase fluid stream that includes an oil phase and a water phase, for example, a stream of hydrocarbons produced from a subsurface reservoir in a subterranean zone, is processed by the reactor as described later. Depending on the material used, oil can be separated from water to purify water or water can be separated from oil to improve oil quality. The reactor function is pH dependent. In some implementations, the reactor can be operated in single or dual stage depending on specific conditions of the multiphase stream. Oil-water separation can be caused using one or more of several types of super-olephilic or super-olephobic switchable surface materials that can be coated or otherwise loaded at the surface of a supporting medium. In all applications, the separation material/medium can be regenerated by switching the surface properties through pH change, this is unique to this technology. 
     The subject matter described here can be implemented to achieve one or more advantages. For example, the phase separation reactor described here can be implemented to separate oily wastewaters resulting from hydrocarbon production or other operations. The quantity of water in oil or oil in water can be reduced. By switching the separation conditions of the separation layer, the same reactor can be used to collect separated oil or separated water. Evaporation ponds can be cleaned from oil. The separation technology can be scaled to any desired level allowing the reactor to be implemented on a large, industrial scale such as a gas separation reactor plant and all components are built to that scale. This separation technology will also be used for the treatment of oily wastewater to remove wide range of oils and oil products, depending on the design, the reactor can be used as a primary oil water separator to replace gravity separators, such as American Petroleum Institute design separators and corrugated plate interceptors, commonly used in oil and gas industries. It can also be designed to work as secondary oil water separators to replace Walnut Shell filters or packed bed filters. 
       FIG. 1  is a schematic of an example of an apparatus  100  including a multiphase fluid separation layer  110  attached to a mounting substrate  108 . For example, the mounting substrate  108  is a plate or similar member that may or may not be flat and that has a fit-for-purpose shape and dimension. The apparatus  100  includes a fluid flow pathway  102  including a fluid inlet  104  and a fluid outlet  106 . In some implementations, the fluid flow pathway  102  can be an elongate tube or a flowline through which multiphase fluid is flowed. The fluid flow pathway  102  flows the multiphase fluid, which includes an oil phase and a water phase, from the fluid inlet  104  to the fluid outlet  104 . 
     A phase separator is spatially positioned relative to the fluid flow pathway  102  to receive the multiphase fluid flowing from the fluid outlet  106 . For example, the phase separator can be positioned within a container into which the fluid flow pathway  102  discharges the multiphase fluid. The phase separator includes the mounting substrate  108  and the separation layer  110  attached to the mounting substrate  108 . In some implementations, the separation layer  110  is covalently bonded to the mounting substrate  108 . The mounting substrate could be made of metal or any other corrosion resistant material that can provide support to the separation layer  110  and withstand the flow conditions without deformation. The mounting substrate  108  and the separation layer can take any shape or angle necessary to support the specific purpose of the reactor. The separation material  110  can be made in various forms including coating of metal mesh, coating of sponge, or coating of loose substrate for use in packed beds, in all cases the mounting substrate will provide physical support to the separation material. 
     The separation layer  110  includes a material switchable between oleophilic (that is, having an affinity to oil) and hydrophobic (that is, having an aversion to water) under a first condition, and oleophobic (that is, having an aversion to oil) and hydrophilic (that is, having an affinity to water) under a second condition. In some implementations, the material in the separation layer is poly(2-vinyl pyridine) and oleophilic/hydrophobic polydimethylsiloxane. When the multiphase fluid is flowed over the separation layer  110  and the material of the separation layer  110  is under the first condition, the separation layer  110  permits the water phase to pass through the separation layer  110  and prevents the oil phase from passing through the separation layer  110 . Conversely, when the multiphase fluid is flowed over the separation layer  110  and the material of the separation layer  110  is under the second condition, the separation layer  110  permits the oil phase to pass through the separation layer  110  and prevents the water phase from passing through the separation layer  110 . The mounting substrate  108  includes multiple openings through which the phase flowed through the separation layer  110  flows. In this manner, the phase separator separates the oil phase and the water phase under either the first condition or the second condition. That is, under either condition, phase separation is implemented. The specific condition determines the phase that is flowed through the separation layer  110  and the phase that is prevented from flowing through the separation layer  110 . 
       FIG. 2  is a schematic of an example of a single stage reactor  200  to separate multiphase fluids. In some implementations, the reactor  200  can be implemented as an industrial-scale reactor having dimensions and other features common to industrial-scale reactors. The reactor  200  includes a reactor body  202  that defines a multiphase fluid receiving portion  204  and a separated phase receiving portion  206 . In some implementations, the reactor body  202  includes a drum having a cross-section and an elongated portion of dimensions sufficient to receive the multiphase fluid and to house the components described here. For example, the portion  204  can be a substantially cylindrical portion with a substantially circular cross-section. For example, the portion  206  can have a substantially conical or truncated conical cross-section. The use of the term “substantially” as a prefix to a shape (for example, circular or conical) indicates a permissible variation from that shape by a quantity that depends, for example, on machining tolerances of machinery used to form the shape. The diameter of a bottom end of the portion  204  can be substantially equal to the larger diameter of a top end of the portion  206 . In construction, the bottom end of the portion  204  and the top end of the portion  206  can be fluidically sealed. By “substantially equal,” it is meant that the diameters of the bottom end of the portion  204  and the top end of the portion  206  can differ from each other by a quantity that allows forming a fluidic seal between the two portions when connected. 
     In some implementations, the reactor  200  includes a separation layer  208  that is substantially identical to the separation layer  110  ( FIG. 1 ) and a mounting substrate  210  that is substantially identical to the mounting substrate  108  ( FIG. 1 ). The separation layer  208  is attached to, for example, covalently bonded to, the mounting substrate  108 . In the example schematic, the separation layer  208  rests on top of the mounting substrate  210 . That is, the mounting substrate  210  serves as a support for the separation layer  208 . In some implementations, other forms of supporting structures (for example, a composite wire mesh or another mounting substrate) can be positioned within the separation layer  210 . In such implementations, the separation layer can surround the mounting substrate. The combination of the separation layer  208  and the mounting substrate  210  can have a cross-sectional shape that is the same as the cross-sectional shape of the bottom end of the portion  204  and the top end of the portion  206 . In addition, the combination can have a diameter that allows the combination to be positioned at the intersection of the bottom end of the portion  204  and the top end of the portion  206  and to prevent the multiphase fluid from flowing past edges of the combination. In some implementations, a fluidic seal can be disposed around the edges of the combination to prevent the multiphase from flowing from the portion  204  to the portion  206  without passing through the separation layer  208 . 
     The portion  206  includes (or defines) a first phase outlet  214  through which the separated phase flowed through the separation layer  208  and the mounting substrate  210  is flowed out of the reactor body  202 . Similarly, the portion  204  includes (or defines) a second phase outlet  216  through which the separated phase prevented from flowing through the separation layer  208  and the mounting substrate  210  is flowed out of the reactor body  202 . In some implementations, the reactor  200  includes a baffle  218 . In some applications, the baffle  218  can hold lighter fluids floating in the portion  204  and prevent them from reaching the outlets controlled by valves  212 ,  216 , which can be controlled externally by the level of the fluid overflow. 
     In operation, the portion  204  can receive a multiphase fluid that includes an oil phase and a water phase. Depending on whether the separation layer  208  is oleophilic and hydrophobic (that is, the first condition) or oleophobic and hydrophilic (that is, the second condition), the separation layer  208  can permit either the water phase or the oil phase to pass through the separation layer  208  and prevent the oil phase or the water phase from passing through the separation layer  208 . The portion  206  can receive the separated phase flowed through the separation layer  208  from the portion  204 . One separated phase can be flowed out of the reactor  200  through the first phase outlet  214  and the other separated phase can be flowed out of the reactor  200  through the second phase outlet  216 . In some implementations, the separated phase that is prevented from flowing through the separation layer  208  can be recirculated into the portion  204  to be once again processed by the separation layer  208 . In this manner, the effectiveness of separation of the multiphase fluid can be improved. 
       FIG. 3  is a schematic of an example of a dual stage reactor to separate multiphase fluids. The reactor  200  is an example of a single stage reactor. A dual stage reactor is a combination of the reactor  200  and another reactor  300  that has substantially the same components as the reactor  200 . A difference between the reactor  200  and the reactor  300  is that the separation layer of one, for example, the reactor  200 , is oleophobic and hydrophilic (that is, the second condition) while the separation layer of the other, for example, the reactor  300 , is oleophylic and hydrophobic (that is, the first condition). Consequently, in this example, the separation layer of the reactor  200  permits flow of water and prevents the flow of oil. Conversely, the separation layer of the reactor  300  permits flow of oil and prevents the flow of water. 
     In some implementations, the reactor  200  and the reactor  300  can be fluidically coupled, for example, using one or more tubular members or pipes. In such implementations, the separated phase prevented from flowing the separation layer of the reactor  200  is flowed into the reactor  300  through the fluidic coupling. The separated phase may include some remnants of the other phase. Such remnants are further separated by the separation layer of the reactor  300 . 
       FIG. 4  is a schematic of an example of a dual stage reactor with acid/base treatment features. In some implementations, the dual stage reactor is similar to the dual stage reactor of  FIG. 3  and includes the reactor  200  and the reactor  300 . In some implementations, the dual stage reactor has two single stage reactors, for example, two of the reactor  200  or two of the reactor  300 . The dual stage reactor can be fluidically coupled as described earlier with reference to  FIG. 4 . 
     In some implementations, a separation layer treatment unit can be attached to each reactor of the dual stage reactor, for example, treatment unit  402  attached to the reactor  200  or the treatment unit  404  attached to the reactor  200 . The treatment unit can include a housing, one or more containers storing components, and flow mechanisms including pumps, valves, pipes and the like. The treatment unit can be operated to switch the separation layer between the first condition and the second condition depending on the phase to be flowed through the separation layer and the phase to be prevented from flowing through the separation layer. The components in the treatment unit to switch the separation layer can include solvents or chemicals, for example, acids and bases that can switch the separation layer between the two conditions by modifying the pH of the separation layer. Since the surface function of the separation material  208  change with pH, the acid/base  402  compartment is used to adjust pH to the optimum pH for the intended phase separation at the first compartment. All fluid (phase  1 ) passed through the separation material  208  will be collected/flow through the outlet  214 , the mix retained in  204  (two phases) then will flow to  404  for another pH adjustment to the optimum pH for the second fluid phase (phase  2 ) to pass through the outlet. The remaining mix of phases can be returned to the inlet of  200  for further processing in another cycle. 
       FIG. 5  is a flowchart of an example of a method  500  of making and using a reactor. The reactor can be the reactor  200  described earlier with reference to  FIG. 1 . At  502 , a separation layer, for example, the separation layer  110 , is attached to a mounted substrate, for example, the mounted substrate  108 . At  504 , the mounted substrate is positioned inside a phase separation reactor, for example, between the portion  204  and the portion  206  of the reactor  200 . At  506 , a multiphase fluid is flowed into the phase separation reactor and over the separation layer  506 . At  508 , the oil phase is separated from the water phase. Some aspects of this disclosure can be implemented to make the reactor  200  without necessarily using the reactor. Some aspects of this disclosure can be implemented to use the reactor  200  without necessarily making the reactor 
     A number of implementations of the disclosure have been described. 
     In some implementations, the oil-water separation techniques described here can be combined with other oil-water separation techniques, for example, gravity-based or coalescence-based techniques. 
     In some implementations, the reactor described in this disclosure can be stationary such that the multiphase fluid is brought to the reactor. In some implementations, the reactor described in this disclosure can be mobile such that the reactor can be transported to the multiphase fluid and implemented on-site. 
     Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure.