WO2018014174A1

WO2018014174A1 - Ultrasonic separation of a production stream

Info

Publication number: WO2018014174A1
Application number: PCT/CN2016/090416
Authority: WO
Inventors: Mahendra Ladharam Joshi; John Andrew Westerheide; Jason Michael Nichols; Stewart Blake Brazil; Catherine JAMES; Jared Markes; Shiguang Li
Original assignee: General Electric Company
Priority date: 2016-07-19
Filing date: 2016-07-19
Publication date: 2018-01-25

Abstract

Ultrasonic separation to separate constituents (oil, water, solids, entrained and dissolved gases) of a stream of a production fluid is described. Use of ultrasonic separation at one or more points in a production stream may allow elimination of tank venting and/or reduction in energy employed for thermal separation, such as in a heater treater. In addition, ultrasonic separation of crude oil or other hydrocarbon production streams may provide demulsification of crudes with reduced or minimal addition of chemicals.

Description

ULTRASONIC SEPARATION OF A PRODUCTION STREAM

BACKGROUND

The subject matter disclosed herein relates to the separation of constituents of a production stream, such as a hydrocarbon production stream.

Separators are a piece of equipment used in oil and gas production processes. In particular, separators are used to breakup well stream oil/water emulsions to facilitate separation of crude oil from water. The separators may also be used to separate solids (inorganic materials including sand) from the liquid stream, as well as remove entrained or dissolved gases from the production stream.

The most common single-well and multiple-well separators are so called “Heater Treater” systems. In such a heater treater, an actively heated section is used to break the oil/water emulsion. The application of heat causes formation of progressively larger water droplets which eventually settle downward to the water section. At that point lighter oil floats at the top of the heated section, and then spills over and out of the vessel. The water may be removed through an external adjustable water leg controlled by a head pressure operated dump valve. In addition, the heater treater helps separate the production fluids into gas and liquid components, which helps reduce the volatility of the oil component.

The effective gas separation limitations of a heater treater with the lighter oils (API gravity 35 to 45) from shale formations results in oil leaving the separator with very high RVP (Reid Vapor Pressure) in the range of 14 psi and higher. In this scenario, hydrocarbon vapors are released from the stored crude oil in storage tanks, leading to a build-up of vapors in the tank head space. The relatively low pressure hydrocarbon vapors typically cannot be extracted and captured cost effectively and are often instead vented to the atmosphere. The value of the vapor is thereby lost when vented to the atmosphere. Further, producers also face regulatory pressures and safety concerns with respect to tank venting.

BRIEF DESCRIPTION

In one embodiment, a method for processing a hydrocarbon production stream is provided. In accordance with this method, the hydrocarbon production stream is flowed through or stored in a vessel or conduit toward which one or more transducers are directed. Ultrasonic waves are generated using the one or more transducers such that the ultrasonic waves pass through the hydrocarbon production stream. Two or more constituents of the hydrocarbon production stream that are separated upon exposure to the ultrasonic waves are differentially handled.

In a further embodiment, a vessel or conduit for separating a hydrocarbon production stream into two or more constituents is provided. In accordance with this embodiment, the vessel or conduit includes: one or more compartments or passages configured to hold a portion of the hydrocarbon production stream； one or more transducers positioned to generate ultrasonic waves in the portion of the hydrocarbon production stream when in operation； and a first outlet in fluid communication with the one or more compartment or passage through which a first constituent of the hydrocarbon production stream is released or flows upon being separated from the portion of the hydrocarbon production stream when exposed to the ultrasonic waves.

In an additional embodiment, an attachable ultrasonic separation component is provided. In accordance with this embodiment, the attachable ultrasonic separation component includes a transducer configured to attach to a vessel or conduit through which a hydrocarbon production stream is stored or flows.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 schematically depicts an ultrasound transducer used to perform ultrasonic separation on a mixed fluid stream, in accordance with aspects of the present disclosure；

FIG. 2 depicts a graph of frequency over time in a frequency sweeping implementation of ultrasonic degassing, , in accordance with aspects of the present disclosure；

FIG. 3 depicts an arrangement of shaped transducers and complementary engineered reflective surfaces for use in ultrasonic separation approaches, in accordance with aspects of the present disclosure；

FIG. 4 depicts a vertical separator implementation employing ultrasonic separation, in accordance with aspects of the present disclosure；

FIG. 5 depicts a horizontal separator implementation employing ultrasonic separation, in accordance with aspects of the present disclosure；

FIG. 6 depicts a heater treater separator implementation employing ultrasonic separation, in accordance with aspects of the present disclosure；

FIG. 7 depicts a production fluid processing and separation flow using retrofitted ultrasonic separation components, in accordance with aspects of the present disclosure；

FIG. 8 depicts a production fluid processing and separation flow using an ultrasonic separation flow cell stage, in accordance with aspects of the present disclosure；

FIG. 9 depicts an example of a flow cell implementation having ultrasonic separation capability, in accordance with aspects of the present disclosure；

FIG. 10 depicts an example of a box-type flow cell implementation having ultrasonic separation capability, in accordance with aspects of the present disclosure；

FIG. 11 depicts a first example of a tube-type flow cell implementation having ultrasonic separation capability, in accordance with aspects of the present disclosure；

FIG. 12 depicts a second example of a tube-type flow cell implementation having ultrasonic separation capability, in accordance with aspects of the present disclosure；

FIG. 13 depicts a third example of a tube-type flow cell implementation having ultrasonic separation capability, in accordance with aspects of the present disclosure；

FIG. 14 depicts an example of a hydrocyclone implementation having ultrasonic separation capability, in accordance with aspects of the present disclosure；

FIG. 15 depicts an example of a flow cell control scheme, in accordance with aspects of the present disclosure； and

FIG. 16 depicts an example of a power input chart suitable for use in the flow cell control scheme of FIG. 15, in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers’specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

Certain embodiments or implementations illustrating aspects of the present disclosure are described and/or depicted with reference to the present figures. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed, but to the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the present invention. Indeed, the present examples are intended to facilitate and simplify explanation of the present approach and to provide useful context for understanding the disclosed subject matter. These description and example should, therefore, not be read to explicitly or implicitly limit application of the described devices and/or techniques to the contexts of the examples.

The terminology used herein is for describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” , “comprising” , “includes” and/or “including” , when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Although the terms first, second, primary, secondary, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, but not limiting to, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments or from the discussion attributed to the respective features. As used herein, the term "and/or" includes any, and all, combinations of one or more of the associated listed items.

Certain terminology may be used herein for the convenience of the reader in understanding the relative relationships between components, particularly as they may be illustrated in a given example. However, such terminology is not to be taken as a limitation on the scope of the invention. For example, words such as “upper” , “lower” , “left” , “right” , “front” , “rear” , “top” , “bottom” , “horizontal” , “vertical” , “upstream” , “downstream” , “fore” , “aft” , and the like； merely describe the configuration shown in the figures. Indeed, the element or elements of an embodiment of the present invention may be oriented in other directions and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise.

The present discussion relates to the use of ultrasonic separation to process produced resource streams, such as produced hydrocarbon streams (e.g., crude oil) , having various constituents. Such ultrasonic separation can facilitate separation of the primary constituent of interest (e.g., oil or other hydrocarbons) from other constituents (e.g., water, hydrocarbon or other gases, solids) . In certain implementations, the disclosed ultrasonic separator component may be installed (either as an existing or add-on component) as part of a multi-phase separator system (s) that would provide enhanced separation of >95％of gases in the crude oil stream, ppm level residual oil in produced water stream, and separation of > 99.9％solids contained in the crude oil and/or produced water. Similarly, such ultrasonic separation capability may be installed as part of a flow cell, hydrocyclone, and so forth used to process or degas a stream of production fluid flowing between production nodes.

Conventionally, gravity and/or heat are employed as part of the separation process, such as in a so called “heater treater” or gravity settling tank. In particular, in the context of heat treatment, heating the produced fluids promotes oil/water separation and generally has the effects of: reducing the viscosity of the oil； increasing the mobility of the water droplets； increasing the settling rate of the water droplets； increasing droplet collisions and thereby increasing coalescence； weakening or rupturing the film on water droplets due to water expansion and enhancing film drainage and coalescence； and increasing the difference in densities of the comingled fluids, which further enhances water settling time and separation. As discussed herein, the application of ultrasonics (defined herein as non-acoustic frequencies greater than 15 kHz, such as in the range of 20 kHz to 2,000,000 Hz) to enhance separation facilitates certain of these separation approaches. As a result, in the context of heat treatment, application of ultrasonic energy can reduce the energy required for thermal separation. Similarly, in contexts where oil coagulants or other chemicals are added in the separation process to facilitate separation of the oil and water constituents, the use of such coagulants may be reduced or eliminated.

In particular, when ultrasonic energy is applied to facilitate oil/water separation as discussed herein, burner firing in existing heater treaters may be reduced or eliminated. Further, in such implementations, reduced level of residual solids in the produced water stream allow the reuse/recycling of water. In addition, in certain of these approaches, the separated oil stream has a reduced Reid vapor pressure (RVP) relative to conventional approaches, allowing efficient capture of valuable volatile organic compounds (VOCs) in the sales gas stream and safer storage/transportation of oil without air emissions.

As discussed herein, a variety of geometry’s and/or configurations of ultrasonic separation equipment are described. Depending on the implementation, the ultrasonic separation equipment may be provided internal or external to a heater treater separator system, a gravity separator tank, a pipeline, conduit, outlet, or inlet, resent in a processing flow, a hydrocyclone, and so forth. When reading the present discussion, it should be understood that power ratings and frequencies provided herein are related as non-limiting examples, and are provided simply to convey examples of possible suitable operational ranges for achieving desired separation goals.

By way of further example and to illustrate certain of the present concepts, FIG. 1 depicts a simplified view of a vessel or conduit 10 in which a mixed fluid of water 12 and oil droplets 14 is present. In the depicted example, an ultrasonic transducer 20, such as an element formed from one or more transducers that convert supplied electrical energy to mechanical vibrations at ultrasonic (i.e., non-acoustic) frequencies (i.e., > 20 kHz) , is provided either integral with, external to, or internal to a wall of the conduit 10. Such a transducer 20 may operate using any suitable transduction mechanism, including but not limited to piezoelectric or capacitive transducer mechanisms. In certain implementations, a separate and distinct reflector element (not shown) may be provided opposite the transducer 20 to facilitate reflection of the ultrasonic waves. In such implementations, the provided reflector, when present, may be an active reflector that is designed (e.g., shaped, and/or fabricated using wave reflective materials) as a reflective surface for the ultrasonic waves.

In certain present implementations, the ultrasonic waves generated by the transducer 20 help facilitate the separation of the oil 14 and water 12, such as by causing clumping of the oil droplets 14, which can help in this or other (e.g., downstream) separation processes. For example, when exposed to the ultrasonic waves, the oil droplets may be more likely to coalesce or merge, thereby moving the oil droplet size distribution toward larger droplets and enhancing separation as larger oil droplets are formed. In this manner, the larger droplets may rise more readily in the fluid column, providing quicker and more complete separation of the oil and water constituents. Depending on the implementation, the coagulated oil droplets may be trapped and separated using conventional mechanisms, such as a skimming process in a separator which skims separated oil from the topmost zone of the fluid column. As may be appreciated, the use of ultrasonic separation to facilitate separation of water and oil in this manner may allow for the reduction or elimination of oil coagulants (or other chemicals) that might otherwise be added to improve oil/water separation efficiency and/or to reduce the residual oil level in waste water.

The present ultrasonic approaches may also facilitate or enhance approaches that demulsify oil (e.g., crude oil having API gravity ≤ 25) using chemicals. In particular, the mixture of production fluids in question in embodiments discussed herein may take the form of, or include, oil-in-water emulsions or water-in-oil. Oil-in-water emulsions are typically promoted by basic pH and water-in-oil emulsions are typically promoted by acidic pH. In conventional chemical demulsification treatments, demulsifiers are believed to displace the natural stabilizers present in the interfacial film around the water droplets. This displacement is brought about by the adsorption of the demulsifier (e.g., ethylene oxides and polypropylene oxides of alcohol, ethoxylated phenols, ethoxylated alcohols and amines, ethoxylated resins, ethoxylated nonylphenols, polyhydric alcohols, sulphonic acid salts, and so forth) at the interface, which influences the coalescence of water droplets through enhanced film drainage. Ultrasonic separation, as discussed herein, will reduce the amount of demulsification chemicals (i.e., demulsifiers) needed to demulsify a given production stream.

In addition, the ultrasonic frequencies may be employed to facilitate the removal of small, suspended gas bubbles (e.g., bubbles of hydrocarbon gases) from the oil and water constituents. In particular, as the ultrasonic waves propagate from the radiating surfaces of transducer 20 (and reflector if present) into the fluid medium, alternating high-pressure (i.e., compression) and low-pressure (i.e., rarefaction) cycles may occur. These rapid changes in pressure in the liquid result in cavitation. In certain degassing applications, waves of low to moderate amplitude (e.g., less than 50 microns) may be most suitable.

In particular, during the low-pressure cycles, the ultrasonic waves create small vacuum bubbles or voids in the liquid. Dissolved gas migrates into the vacuum (i.e., low-pressure bubbles) as a function of the large surface area of the bubbles and thereby increase the size of the bubbles. The sonication waves shake smaller bubbles resting below the liquid surface to rise through the liquid, releasing the entrapped gas to the environment when reaching the surface. By way of example, the Reid vapor pressure (RVP) of crude oil, which may be at 15 PSI originating from the well head, can be effectively reduced to 11 PSI in this example.

To facilitate the degassing process, it may be useful to provide a low pressure or vacuum over the liquid surface, if practical and/or to heat the liquid (such as in a heater treater context) . Likewise, a shallow container (relative to the depth of the transducers 20 and/or absence of turbulent agitation of the liquid may be beneficial. In this manner, the ultrasonic processes discussed herein may also be employed to reduce the level of dissolved or entrained gas below the natural equilibrium level of the liquid medium, potentially removing 95％ (or greater) of entrained gases in a crude oil production stream. Based on the implementation, the removed gases (e.g., hydrocarbon gases) may be captured and sold or otherwise removed from the process flow.

In certain implementations, degassing of a production fluid may be enhanced by sweeping the ultrasonic frequency employed, i.e., by employing a frequency sweep with a fixed frequency deviation and sweep rate. Such frequency sweeping enhances cavitation activity, and thereby enhances degassing. As an example, and turning to FIG. 2, a center frequency of 104 kHz is employed with a sweep bandwidth of 4 kHz (i.e., f ＝ 104 kHz ± 2kHz) .

With the discussion in mind, various aspects of transducer and reflector shape and design will be discussed. In particular, depending on the implementation, transducer elements used in the separation of oil, water, and gas may be shaped so as to facilitate separation. Likewise, the reflective surfaces, when present, may be engineered or configured so as to enhance wave reflection and fluid separation.

An example of an arrangement of shaped transducers 20 configured and shaped to correspond to a complementary engineered reflective surface 22 is shown in FIG. 3, where an ultrasonic-facilitated degassing application is illustrated. In this example, shaped transducers 20 are illustrated in complementary arrangement with an engineered reflective surface 22 that corresponds to the shape of the transducers so as to maximize the effectiveness of the reflective surface 22 in a separation application. Such engineered or shaped reflective surfaces may be useful in creating a partially confined reflective surface inside a primary or secondary separation stage of a separator. In particular, a given partially confined geometry may be implemented via an engineered reflective surface 22 with an omnidirectional shape or geometry for the reflection of ultrasonic waves directed to the surface by the transducers 20.

In the depicted example ultrasonic waves generated by the transducers 20 and reflected by complementary reflective surface 22 help force dissolved or entrained gas 24 out of a separated oil product 26 as bubbles. In this example, the engineered reflective surface 22 for the depicted transducer geometry, in combination with the transducer elements 20, are positioned so as to have a spacing between the transducer elements 20 and reflective surface 22 that provides a pre-defined pathway or clearance for the generated gas bubbles to rise and collect in the head space, which may facilitate removal or collection of the gas component.

With the preceding in mind, FIGS. 4-6 depict various high-level schematic illustrations of the use of ultrasonic separation as discussed herein in the context of an integral separator. Turning to FIG. 4, a vertical separator 40 arrangement is depicted. In this example, a primary inlet 42 is depicted along with an inlet diverter 44. In this example, a production stream, such as a production fluid pumped from a subterranean environment, may flow into the separator 40 via the inlet 42. In an unseparated state, the production stream may contain a target fluid, such as a hydrocarbon fluid (e.g., oil) , water (in which the target fluid may be mixed or emulsified) , dissolved or entrained gases within one or both of the water and target fluid, and solids or particulates carried suspended in the fluids.

The production stream, upon entering the vertical separator 40, may be diverted through a downcomer 50 to a spreader 52 within the tank encompassing the separator components. In the depicted example, within the tank the production fluid is separated into an oil zone 60 and a water zone 62. Separation of the production fluid into these

zones

60, 62 is facilitated by an ultrasonic transducer 20 and, in the depicted example, an opposing reflector 22 which respectively propagate and reflect ultrasonic waves through the production fluid to facilitate separation of the oil 60 from water 62. In one implementation, the oscillator circuit employed with the transducer 20 is capable of tuning to frequencies of 15 kHz or greater, such as between 15,000 and 2,000,000 cycles per second.

The separated oil at the top of zone 60 in the depicted example is substantially free of water and the topmost portion spills over a separator to a second compartment, shown in Inset A. Within the second compartment, the oil (here shown as 60A) is subjected to ultrasonic energy via ultrasonic horn assembly 64. The horn assembly may be a tapering or shaped metal component that facilitates the transfer of the acoustic energy to oil 60A, thereby facilitating the release or separation of dissolved or entrained gases from the oil 60A as discussed herein. Gas or vapor released from the oil 60A may rise through a chimney 78 to the head space of the separator assembly 40.

With this in mind, the separator assembly 40 of FIG. 4, three outlets are provided for controlling the release of the separated constituents of the production stream. In the depicted example, a water level control valve 80 is shown that may be operated to maintain or control the level of water in the separator assembly 40. Similarly, an oil level control valve 82 is shown that may be operated to maintain or control the level of oil in the separator assembly 40. Lastly, a pressure control valve 84, shown here in combination with a mist extractor 86, may be used to control the pressure in the headspace by allowing the continuous or periodic release of gas and vapor from the separator 40.

Turning to FIG. 5, a horizontal separator 90 arrangement is depicted. In this example, a primary inlet 42 is depicted along with an inlet diverter 44. As in the preceding example, a production stream flows into the separator 90 via the inlet 42 and contains a target fluid, such as a hydrocarbon fluid (e.g., oil) , as well as water, dissolved or entrained gases, and suspended solids or particulates.

The production stream, upon entering the horizontal separator 90, may settle in a gravity settling section 92. Within the settling section 92, a layer of oil and/or oil emulsion 60 may form over a water layer 62. Separation of the production fluid into these layers or

zones

60, 62 is facilitated by one or more ultrasonic transducers 20 and, in certain embodiments, opposing reflectors (not shown) which respectively propagate and reflect ultrasonic waves through the production fluid to facilitate separation of the oil 60 from water 62. In one implementation, the oscillator circuit employed with the transducer 20 is capable of tuning to frequencies of 15 kHz or greater, such as between 15,000 and 2,000,000 cycles per second.

The separated oil in layer 60 in the depicted example is substantially free of water and the topmost portion spills over a separator to a second compartment, shown in Inset B. Within the second compartment, the oil (here shown as 60A) is subjected to ultrasonic energy via ultrasonic horn assembly 64. The horn assembly may be a tapering or shaped metal component that facilitates the transfer of the acoustic energy to oil 60A, thereby facilitating the release or separation of dissolved or entrained gases from the oil 60A as discussed herein. Gas or vapor released from the oil in

layer

60 or 60A may rise to the head space of the separator assembly 90.

With this in mind, the separator assembly 90 of FIG. 5, three outlets are provided for controlling the release of the separated constituents of the production stream. In the depicted example, a water level control valve 80 is shown that may be operated to maintain or control the level of water in the separator assembly 90. Similarly, an oil level control valve 82 is shown that may be operated to maintain or control the level of oil in the separator assembly 90. Lastly, a pressure control valve 84 may be used to control the pressure in the headspace by allowing the continuous or periodic release of gas and vapor from the separator 90.

With the preceding configurations in mind, FIG. 6 depicts a heater treater 100 that incorporates the ultrasonic separation functionality discussed above. In particular, the heater treater 100 includes an inlet 42 through which a production fluid mixture of oil, water, and dissolved or entrained gas are introduced into the heater treater 100. Unlike the previous example, the heater treater 100 includes a thermal component e.g., a burner 102 used to heat the mixture of production fluids. By way of example, the burner 102 may conventionally generate 0.5 MM to 2.5 MM Btu/hour heating energy for oil/water separation. In this example, the heated production fluids are subjected to ultrasonic separation as well, as shown in the ultrasonic separation region depicted in the right-hand portion of the heater treater 100, which may reduce or eliminate the burner firing, resulting in saved energy, emission reduction, and demulsification of the oil.

As in the preceding examples, a transducer 20 (or multiple transducers) , and reflector 22 when present, generate and/or propagate ultrasonic waves that facilitate separation of an oil layer 60 and water layer 62 in an initial separation region. Oil spilling over a skimmer barrier proximate the reflector 22 may divert separated oil 60A to a second separation region. The separated oil 60A may be subject to additional ultrasonic waves in the second separation energy to facilitate the removal of dissolved gas within the oil 60A. Separate and degassed oil may then be removed from the heater treater 100 via an outlet 106. Gas may similarly be purged or released via an outlet 108 while separated water may be released via an outlet 110.

Use of ultrasonics to facilitate separation of production fluids into constituent elements may be implemented as an add-on (e.g., attachable) component to existing systems in addition to integral (i.e., built-in) implementations. By way of example, and turning to FIG. 7, a processing system 150 for handling production fluids pumped from a well is schematically illustrated. In this example, a production or pumping system 152 pumps a full (i.e., unseparated) well stream of mixed or complex production fluids 154 (e.g., a mix of oil, water, and dissolved or entrained gases) to a three-phase separator 156, in this instance via a pipeline 158. In one implementation, the separator 156 is operated at 40 psig or other suitable pressures.

At the separator 156, the well stream production fluids 154 are separated into separate water, oil, and gas constituents. As discussed in preceding example, the gas component 160 may be removed, such as to a pipeline or to be flared and the water component 162 may be removed in a controlled manner, such as via controlled operation of a water release valve 80. The oil component 164 may also be removed from the separator 156, such as via controlled operation of an oil release valve 82, to a downstream tank or storage vessel 170. With respect the tank 170, oil 164 may be removed from this vessel for transport via a pipeline or truck loading valve 172. In addition, a pressure relief device 174 may be provided proximate the headspace and set to automatically release gas to the atmosphere or a capture device when a set point (e.g., 0.25 psig) is met or exceeded.

In the depicted example, the components of the processing system 150 may be conventional in operation, with no built in ultrasonic functionality. However, to upgrade such a system 150, external ultrasonic generators (i.e., ultrasonic separators 180) may added at points along the fluid path to facilitate separation of oil, gas, and water fluid components. For example, in the depicted arrangement, ultrasonic generating cuffs or sleeves may be fitted externally around existing pipe infrastructure, inlets, or outlets so as to position transducers (and reflector elements if present) on an existing pipe, conduit, or vessel. Alternatively, in some implementations, a section of pipe or vessel with integrated ultrasonic components may be used to upgrade an existing pipe or vessel infrastructure, such as by replacing an existing section of pipe, an inlet, or an outlet that does not include such ultrasonic separation components. When operated, the external ultrasonic separators 180 may apply ultrasonic waves (with or without a corresponding reflector) to the fluid within the proximate pipe or vessel structure to facilitate separation of fluid or fluids and gases as discussed herein.

By way of example, in the arrangement shown in FIG. 7, an externally applied ultrasonic separator 180A is provided on the pipe 158 transporting the well stream production fluid 154 to separator 156 for three-phase separation. In this implementation, the well stream production fluid 154, after passing through the ultrasonic separator 180A, may already have undergone some degree of separation (e.g., coagulation of oil droplets, formation of gas bubbles, and so forth) prior to reaching the separator 156, thus improving the separation and/or reducing the time required for separation of the constituents. Likewise, to the extent that the separator 156 employs other, potentially energy intensive, treatments to enhance separation (e.g., heat) , or chemical treatments to break emulsions, these treatments may be reduced or eliminated.

In the depicted example, a second external ultrasonic separator 180B is also depicted, in this instance downstream from the separator 156 on the oil line leading to the vessel 170. In this implementation, the ultrasonic separator 180B may apply ultrasonic waves to the oil component 164 being moved to the tank 170 so as to facilitate the degassing of the oil component 164, as discussed herein, thereby reducing the gas content of the oil 164 in the tank 170, which may reduce or eliminate the need for venting gas from the tank 170. In the depicted example, a gas stream 190 resulting from the application of ultrasonic energy by the ultrasonic separator 180B may be separately disposed of or merged (as shown in FIG. 7) with the gas removed in the separator 156.

Similarly, a third external ultrasonic separator 180C may be provided downstream from the separator 156 on the water line. In such an implementation, the ultrasonic separator 180C applies ultrasonic waves to the separated water component 162 being removed from the separator 156 so as to facilitate the separation of any remaining oil component 164 from the water 162. In such an implementation, any recovered oil 164 may be returned to the separator 156 to be merged with the bulk of the separated oil 164.

Turning to further implementations, FIG. 8 depicts a more detailed embodiment employing ultrasonic separation implemented in flow cells between a mixing tank 200 and settling tank 202 of a production environment. In this example, various pumps 208, temperature and pressure gauges 206, flow meters 212, backpressure regulators 204 (for regulating gas discharge) , and valves 210 are employed for circulating, sampling, and/or discharging production fluids 154 (and/or oil constituent 164) that are flowed between the mixing tank 200 and settling tank 202. In one implementation, flow rate through the circulation loop may be 3 GPM.

In one embodiment the mixing tank 200 may mix a production fluid 154 via one or more of an agitator 220 turned by a motor 222 (e.g., an electrical motor) and/or gas bubbles introduced via a gas stream flowed through a sparger 224 to generate bubbles in the mixture 154. In one implementation, such a mixing tank 200 may be at 5 bar and have a volume of approximately 75 L.

In the depicted example, as part of the circulation loop, fluids are flowed through a flow cell 230 upon which one or more ultrasonic transducers 20 act to perform ultrasonic separation on the fluid flowing through the flow cell 230. The fluid emerging from the ultrasonic separation flow cell may, in the depicted example pass through a cyclone 240, which separates gas from liquid constituents of the stream. Liquid constituents are pass through to the settling tank 202. After settling of constituents of the production fluid 198, certain constituents may be recirculated to the mixing tank 200.

With respect to the flow cell 230, FIG. 9 depicts an example of an implementation consistent with the environment shown in FIG. 8. In this example, an oil inlet valve 210A controls inflow of oil or other produced fluids to one or more laminar cells 250. Inflow may be controlled so as to maintain a desired liquid level 242 within the flow cell 230. One or more transducers 20 apply ultrasonic waves to the fluid within the flow cell 230, facilitating separation of fluid constituents (e.g., oil and water) as well as dissolved or entrained gas within the liquid constituents. On the outlet end of the flow cell 230, valve 210B may control outflow of oil 164 to the cyclone 240 through an oil outlet 286. Likewise, a gas out line 252 may direct separated gas to the cyclone 240 overflow to be removed or disposed of with a gas component separated at the cyclone 240.

With the preceding flow cell design in mind, FIGS. 10-13 depict various other flow cell configurations suitable for ultrasonic separation as discussed herein. Turning to FIG. 10, a configuration similar to that described in FIG. 9 is shown. In particular, FIG. 10 depicts a box-type flow cell design. In this example, crude oil 278 flows into the flow cell 230 via an inlet 280. A series of transducers 20 (here eight transducers 20) controlled or stimulated by an ultrasonic generator 282 apply ultrasonic waves to the crude oil 278, facilitating separation of liquid (e.g., oil and water) and gas components of the crude oil 278. As in preceding example, the ultrasonic generator or circuit is capable of tuning to any specified frequency between 1,000 to 2,000,000 cycles per second.

Separated gas may migrate to the head space 280, where it can be released by a gas outlet 284. Depending on the implementation, gas volume corresponding to the head space may be between 20％-50％of the enclosed flow cell volume, while the liquid volume may, correspondingly be between 80％-50％of the volume. Liquid components may be pumped out of the flow cell 230 (such as via pump 208) though an outlet (e.g., oil outlet 286) . A level meter 290 may be present to control the level of crude oil 278 (i.e., liquid level) in the flow cell 230, such as by controlling the inflow and/or outflow of the crude oil 278 with respect to the flow cell 230. For example, the level meter 290 may control operation of the pump 208 so as to maintain a desired liquid level within the flow cell 230.

With respect to an example of an implementation of the box-type flow cell 230 of FIG. 10, in one embodiment, eight 150 watt (W) ultrasonic transducers 20 are employed, each tunable in the range of 10％to 100％and providing a total rated power of 1200 W and a maximum power of 1500 W. The transducers 20, in one implementation operate at a frequency of 25 kHz (or other suitable ultrasonic frequencies. In one implementation, the transducers 20 have an interface diameter of ～63 mm. In one example, the transducers 20 may be mounted or attached externally to the flow cell vessel 230 (e.g., the bottom of the vessel) so as to shake or vibrate all or part of the vessel at ultrasonic frequencies when operated. In such an approach, the vibrations, which facilitate separation of the crude oil 278 and gas, reach the crude oil 278 indirectly.

Turning to FIGS. 11 and 12, two vertical tube-type flow cell designs are depicted, a first with the transducer elements installed at the bottom of the vertical tubes (FIG. 11) and a second with the transducer elements installed at the top of the vertical tubes (FIG. 12) . In these examples, the vertical tubes corresponding to the base flow cell unit are linked in series, allowing sequential separation steps with each downstream step or tube corresponding to a separation performed on a more refined fluid stream (e.g., oil with less water and/or entrained or dissolved gas in the stream) . Though two tubes are shown in each example, more than two tubes may be linked in the depicted manner for a given flow cell design or alternatively, a single tube may be provided and employed.

Turning to FIG. 11, the first tube-type design depicts a flow cell 230 having two tubes 300. The leftmost depicted vertical tube 300A receives a product fluid (e.g., crude oil 278) via an inlet 280 provided toward the bottom of the tube 300A. The crude oil 278 may be pumped into or pumped out of the fluid cell 230 by a suitable mechanical pump to cause the oil 278 (or other production fluid) to flow through the tube or tubes 300 forming the flow cell 230. At the top of each tube 300, gas outlets 284 allow separated gas to flow outward, such as to a collection location or flare site. In each tube 300, separated or degassed oil flows out of an oil outlet 286 at the top of the tube 300, with the outlet 286 of the downstream terminal tube 300B feeding a storage vessel (e.g., a settling tank) or a pipeline and the outlets of other tubes (e.g., the initial tube 300A or intervening tubes) feeding the next tube in the sequence.

Ultrasonic separation of fluid and/or gas constituents within each tube 300 is facilitated by a transducer element 20 (such as the depicted multi-stage ultrasonic horn elements) . The transducer elements 20 may be operated or controlled by an ultrasonic generator 282 configured to cause generation of ultrasonic waves at the transducers. In the implementation of FIG. 11, the transducer elements 20 are depicted toward the bottom of each tube 300, and thus facilitate separation of fluid and gas components of the production stream (e.g., crude oil 278) at the bottom of the tubes.

Alternatively, as shown in FIG. 12, a similar multi-tube flow cell 230 implementation may be provided but with the transducer elements (i.e., the ultrasonic horn elements) toward the top of each tube 300. In such an implementation, fluid and gas separation of components of the production stream (e.g., crude oil 278) are separated near the top of each tube 300.

With respect to an example of an implementation of the tube-type flow cells 230 of FIGS. 11 and 12, in certain embodiments a two-tube configuration may be employed with a respective multi-stage transducer (such as the depicted ultrasonic horns) present in each tube. In one such implementation, the transducers 20 provide a total power of 2100 W (such as by employing a 1200 W rated transducer in one tube and a 900 W rated transducer in the other) , each tunable in the range of 10％to 100％. The transducers 20, in one implementation operate at a rated frequency of 20 kHz (or other suitable ultrasonic frequencies. In a degassing implementation, gas space within a tube may be 60％and oil space 40％. As noted above, additional tubes can be added in series if needed.

Turning to FIG. 13, in a third tube-type design ultrasonic transducers 20 are provided in-line with respect to a pipeline 310 through which a production fluid (e.g., crude oil 278) flows. In one embodiment, the pipeline 310 may be the pipeline through which the output of a separator, discussed elsewhere herein, flows. As shown in the depicted example, the pipeline may include, or be retrofitted with, one or more chambers 312 along its length which may accommodate transducer elements 20, such as the depicted ultrasonic horns. As in the preceding example, the transducers 20 may be driven by an ultrasonic generator 282.

In the depicted example, within the chambers 312 ultrasonic separation may occur as the production fluid (e.g., crude oil 278) flows through the pipe 310. Headspace may be provided in each chamber and gas released by the ultrasonic separation process may accumulate in the headspace and may be released for collection or flaring via gas outlets 284, for which a suitable diameter may be selected. Thus, the crude oil 278, or other production fluid, may be progressively degassed as it flows through pipe 310. It may also be appreciated that, depending on the implementation, and as can be seen with respect to FIG. 13, the ultrasonic horn direction may be configurable simply by rotating and securing the chamber and transducer assembly with respect to the pipeline 310.

With respect to an example of an implementation of the tube-type flow cell 230 of FIG. 13, in certain embodiments a two-tube configuration may be employed with a respective multi-stage transducer (such as the depicted ultrasonic horns) present in each chamber 312. In one such implementation, the transducers 20 provide a total power of 2100 W (such as by employing a 1200 W rated transducer in one tube and a 900 W rated transducer in the other) , each tunable in the range of 10％to 100％. The transducers 20, in one implementation operate at a rated frequency of 20 kHz (or other suitable ultrasonic frequencies. In a degassing implementation, gas space may be 60％and oil space 40％. Additional chambers and transducer assemblies can be added in series if needed.

A comparison of operational and other aspect of the various flow cell designs described herein is provided in Table 1.

Table 1

Turning to FIGS. 14 and 15, an approach for controlling operation of a flow cell 230 as discussed herein is described. The depicted control scheme may, for example, be suitable for controlling operation of a flow cell 230 so as to maintain a suitable Reid vapor pressure (RVP) in a downstream vessel and/or to reduce the RVP in the downstream vessel that would be observed absent the operation of the flow cell 230. In the depicted example, an ultrasonic power controller 318 based on a microprocessor or on application specific integrated circuit (ASIC) control the flow of power to one or more ultrasonic generators and/or transducers (not shown) positioned to cause ultrasonic separation, as discussed herein, within the flow cell 230.

The controller 318 may be programmed or configured to operate based on various measured parameters of the controlled systems, such as an inlet temperature, an outlet temperature, or a gas outlet temperature (measured by

temperature gauges

320A, 320B, and 320C respectively) , an inlet pressure or an outlet pressure (measured by

pressure gauges

322A and 322B respectively) , and/or an inlet flow, an outlet flow, or a gas outlet flow (measured by

flow meters

324A, 324B, and 324C respectively) . As may be appreciated, measurement of the gas outlet flow (F_g) in addition to the inlet and outlet flows (F₁ and F₂ respectively) may allow for the system balance to be monitored or checked, where F₁ ＝ F_g + F₂.

By way of example, a known or empirically derived reference relationship may be accessed or generated that relates inlet temperature, a specified or desired pressure, pressure difference (e.g., Δ RVP or ΔP) , or pressure ratio between the inlet 280 and outlet 286, a flow rate of oil through the flow cell 230, and an input power for the ultrasonic separation equipment (e.g., the transducers and/or generators) . Example of such reference relationships, here depicted as different curves relating target Reid vapor pressure (or pressure differences or pressure ratios) , ultrasonic input power (e.g., in kW) , and oil flow rate at temperature T₁, are shown in FIG. 15. Thus based on a measured inlet temperature and a specified or desired pressure, pressure difference (e.g., Δ RVP) , or pressure ratio, a known relationship (which may be provided as a corresponding algorithm or formula) may be used by the controller 318 to determine one or both of a suitable input power and/or flow rate to achieve the desired pressure relationship. For example, if flow rate is constant, only the input power may be controlled by controller 318 to achieve the desired pressure relationship. However, if both flow rate and input power are controllable, the controller 318 may control one or both of these parameters to achieve the desired pressure relationship across the flow cell 230. With this in mind, the controller 318 may control the power input to an ultrasonic generator used to facilitate ultrasonic separation based on one or more of a specified or set pressure relationship (e.g., a target RVP, a pressure difference between the inlet and outlet, or a ratio of inlet and outlet pressure) , an inlet flow F₁, an inlet temperature T₁, and so forth.

Turning back to the example control scheme of FIG. 14, in this example the controller 318 may read or receive as an input one or more of inlet temperature (T₁) , inlet flow (F₁) , and inlet pressure (P₁) and based on how much the vapor pressure is to be reduced (e.g., ΔP or ΔRVP 326) , the controller 318 may adjust the power setting of the ultrasonic generator 282 (as shown in FIGS. 10-13) . Feedback control of the controller 318 may be based on one or more of the set or specified vapor pressure (P₂) in the outlet stream, the flow rate (F₁) of the fluid coming into the flow cell 230, the temperature (T₁) of the inlet stream, or other suitable monitored parameters.

Based on the context, certain aspects of the control scheme (or the provided reference relationship) may be adjusted to account for certain implementation specific factors. For example, at higher temperatures (or in heated contexts) , less ultrasonic generation power may be provided or needed as more gas will exit the liquid stream as a function of the higher temperature. Similarly, higher flow rates through the flow cell 230 may justify greater provided ultrasonic generation power due to the higher flow rate corresponding to a larger volume of oil (or other production fluid) being treated. In this context, in certain implementations the equipment utilizing ultrasonic separation may be in fluid communication with a well fluid flow or production stream where the flow speed is controlled by a variable speed drive. In such a context changes in well fluid or oil flow rates may be communicated to the controller 318 prior to or contemporaneous with the changing operation of the variable speed drive so as to optimize the power provided to the ultrasonic generator.

In addition to the preceding example, an ultrasonic flow cell may be combined with a hydrocyclone to facilitate degassing and solid separation of a fluid passed through the hydrocyclone. For example, turning to FIG. 16, a hydrocyclone 350 is depicted in which two multi-stage transducers 20, i.e., ultrasonic horns) are provided, a first transducer 20A installed in the bottom cone section (to facilitate solid separation) and a second transducer 20B installed at oil inlet pipe 280 (to facilitate degassing) . As in preceding example, one or more ultrasonic generators 282 drive the operation of the transducers 20. Thus, in this example, production fluid (e.g., crude oil 278) flows into the hydrocyclone 350 via inlet pipe 280 and is subject to ultrasonic separation at this stage to facilitate degassing. The degassed fluid, and some remaining solids flow down the hydrocyclone 350 and are subject to ultrasonic separation at this stage to facilitate solid separation, with the remaining fluid going out oil outlet 286 and solids or fines dropping out the bottom of the hydrocyclone 350.

Tables 2 and 3, respectively provide parameters associated with the Liquid/Gas Ratio (Table 2) and the Water/Solids Ratio (Table 3) .

Table 2

Table 3

Technical effects of the invention include use of ultrasonic separation to separate constituents (oil, water, solids, entrained and dissolved gases) from a stream of a production fluid. Use of ultrasonic separation at one or more points in a production stream may allow elimination of tank venting and/or reduction in energy employed for thermal separation, such as in a heater treater. For example, in one implementation it is expected that conventional use of 0.5 to 2.5 MM btu/hr thermal energy with respect to a heater treater may be reduced by 50％along with achieving a 50％reduction in air emissions. In addition, ultrasonic separation of crude oil or other hydrocarbon production streams may provide demulsification of crudes (e.g., API gravity of 25 or lower) with reduced or minimal chemical addition (i.e., addition of demulsifiers) , e.g., a 50％reduction in added demulsifiers.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

A method for processing a hydrocarbon production stream, comprising:

flowing or storing the hydrocarbon production stream in a vessel or conduit toward which one or more transducers are directed；

generating ultrasonic waves using the one or more transducers such that the ultrasonic waves pass through the hydrocarbon production stream； and

differentially handling two or more constituents of the hydrocarbon production stream that are separated upon exposure to the ultrasonic waves.
The method of claim 1, wherein the vessel or conduit comprises one of a separator vessel, a heater treater, a pipeline, a flow cell, or a hydrocyclone.
The method of claim 1, wherein the ultrasonic waves are at a frequency greater than or equal to 15 kHz.
The method of claim 1, wherein differentially handling the two or more constituents comprises collecting venting, or flaring a separated gas portion released from a hydrocarbon liquid stream which is flowed to a downstream location.
The method of claim 1, wherein differentially handling the two or more constituents comprises directing a separated water portion through a first outlet and directing a separated hydrocarbon portion through a second outlet.
The method of claim 1, wherein differentially handling the two or more constituents comprises settling out solid particles from a liquid stream portion.
The method of claim 1, further comprising reducing the amount of added heat used to separate the constituents of the hydrocarbon production stream relative to separating the hydrocarbon production stream without generating ultrasonic waves.
The method of claim 1, further comprising reducing the amount of demulsifiers added to the hydrocarbon production stream relative to separating the hydrocarbon production stream without generating ultrasonic waves.
The method of claim 1, further comprising reducing the amount of oil coagulants added to the hydrocarbon production stream relative to separating the hydrocarbon production stream without generating ultrasonic waves.
The method of claim 1, wherein generating ultrasonic waves comprises sweeping an ultrasonic frequency over which ultrasonic waves are generated using a fixed frequency deviation and sweep rate.
The method of claim 1, further comprising:

controlling an input power to an ultrasonic generator used to generate the ultrasonic waves based on one or more of a target vapor pressure downstream of the transducers, a pressure relationship upstream and downstream of the transducers, an inlet temperature of the vessel or conduit, or a flow rate of the hydrocarbon production stream.
A vessel or conduit for separating a hydrocarbon production stream into two or more constituents, comprising:

one or more compartments or passages configured to hold a portion of the hydrocarbon production stream；

one or more transducers positioned to generate ultrasonic waves in the portion of the hydrocarbon production stream when in operation； and

a first outlet in fluid communication with the one or more compartment or passage through which a first constituent of the hydrocarbon production stream is released or flows upon being separated from the portion of the hydrocarbon production stream when exposed to the ultrasonic waves.
The vessel or conduit of claim 12, further comprising:

a controller configured to provide an input power to an ultrasonic generator in communication with the one or more transducers, wherein the controller controls the input power based on one or more of a target vapor pressure downstream of the transducers, a pressure relationship upstream and downstream of the transducers, an inlet temperature of the vessel or conduit, or a flow rate of the hydrocarbon production stream.
The vessel or conduit of claim 12, wherein the one or more compartments or passages comprise a pipeline, a flow cell chamber, a hydrocyclone interior, a multi-phase separator compartment, a heater treater compartment.
The vessel or conduit of claim 12, wherein the one or more transducers are configured to generate ultrasonic waves at a frequency greater than or equal to 15 kHz.
The vessel or conduit of claim 12, wherein the first outlet comprises a gas outlet through which a separated hydrocarbon gas constituent is collected or released.
The vessel or conduit of claim 12, wherein the first outlet comprises a water outlet through which a separated water portion is directed.
The vessel or conduit of claim 12, wherein the one or more transducers are configured to generate ultrasonic waves by sweeping an ultrasonic frequency over which ultrasonic waves are generated using a fixed frequency deviation and sweep rate.
The vessel or conduit of claim 12, further comprising a second outlet in fluid communication with the one or more compartment or passage, wherein the first constituent of the hydrocarbon production stream is released or flows through the first outlet and a remaining hydrocarbon stream flows through the second outlet.
An attachable ultrasonic separation component, comprising:

a transducer configured to attach to a vessel or conduit through which a hydrocarbon production stream is stored or flows.
The attachable ultrasonic separation component of claim 20, wherein the transducer is configured to attach to an inlet or outlet of a multi-phase separator, a heater treater, a flow cell, or a hydrocyclone.