Metering system for three-phase oil flow in horizontal pipeline
10527470 ยท 2020-01-07
Assignee
Inventors
Cpc classification
G01F1/74
PHYSICS
International classification
G01F1/74
PHYSICS
Abstract
An apparatus, method and non-transitory computer readable medium method are described for identifying the phase fractions and flow-rate of a petroleum carrying pipeline with three-phase wavy-stratified flow. A set of semi-cylindrical electrodes are mounted on the internal surface of a pipe to monitor the total capacitance and resistance of the three-phase contents. The phase fractions are determined by relating the resistance and capacitance to the phase-angles associated with the interfaces between water, oil and gas phases of the mixture. To calculate the flow rate, measured capacitances from two sets of electrodes with known separation distance are cross-correlated to determine time delay. Communications circuitry transmits the measurements to a remote control center for monitoring. Calculated and measured results demonstrate close agreement. The percentage error exhibited by the proposed inclined capacitive plate technique is calculated and compared with published values.
Claims
1. An apparatus for measuring water, oil and gas volumes within a cylindrical horizontal pipeline and the velocity of the oil flowing in the pipeline, wherein the pipeline has a circular cross-sectional area of radius (Rad), and an axial length (Z), the apparatus comprising: the pipeline including a plurality of pipe sections, wherein at least one pipe section has an internal structure including a first semi-cylindrical conducting sheet covering a portion of the internal surface of the pipe section and a second semi-cylindrical conducting sheet covering an opposing portion of the internal surface of the pipe section, wherein each semi-cylindrical sheet has radius (Rad) and axial length z.sub.0, wherein the at least one pipe section is installed a first location within the pipeline, wherein a gap (2) exists between an edge of the first semi-cylindrical conducting sheet and a corresponding edge of the second semi-cylindrical conducting sheet; a conductive terminal installed along the central axial line of the first semi-cylindrical conducting sheet and a corresponding conductive terminal installed at the central axial line of the second semi-cylindrical conducting sheet, wherein each conductive terminal is placed on the external surface of the pipe section and protrudes through the pipe section to electrically contact a respective semi-cylindrical sheet; and a control unit comprising: a power supply to apply a positive DC voltage at the first terminal and a negative DC voltage at the second terminal; a switch connected between the power supply and the first terminal; a controller having circuitry configured to control the switch; measuring circuitry connected to the conductive terminals to measure the capacitance and resistance between the terminals, the resistance of the semi-cylindrical sheets; and processing circuitry configured determine the respective volumes of water, oil and gas in the pipe sections based on the capacitance and resistance measurements and to calculate the velocity of the oil flowing in the pipeline, and wherein the processing circuitry is further configured to calculate the capacitance measurement of the water based on the measured resistance and the equations:
a.sub.n=.sub.0*{Cos()cot(.sub.2n)Sin()}
b.sub.n=.sub.0*{Cos()cot(.sub.2n)+Sin()}
.sub.2n=(2n+1)radians, with n=0, 1, 2 . . . N,
.sub.n=.sub.2n radians.
2. The apparatus of claim 1, wherein the processing circuitry is further configured to calculate the total resistance and the total capacitance of the semi-cylindrical sheets based on the following equations:
3. The apparatus of claim 1, wherein the water content has a height (hw) measured along the vertical radius of the cross section of the pipe section, wherein the oil content has a height (ho) measured along the vertical radius of the cross section of the pipe section, wherein the gas has a height (hg) measured along the vertical radius of the cross section of the pipe section, wherein 2Rad=hw+ho+hg, and wherein the processing circuitry is further configured to calculate the respective heights of the oil, water and gas within the pipe section.
4. The apparatus of claim 1, further comprising: a second pipe section having a second internal structure installed at a second location within the pipeline, the second internal structure separated by a distance (d) from the first internal structure, wherein second capacitance measurements are made at the second location at a time (.sub.0), wherein (.sub.0) is the time elapsed between a capacitance measurement at the first location and a capacitance measurement at the second location, and wherein the processing circuitry is configured to calculate the velocity of the oil flowing in the pipeline based on the equation velocity=d/.sub.0 and the capacitance measurements of the first pipe section and the second capacitance measurements of the second pipe section.
5. The apparatus of claim 4, wherein the processing circuitry is configured to calculate the volume of oil flowing per unit time, based on:
V.sub.g=1Rad.sup.2Rad.sup.2cos(1)sin(1)
V.sub.b=3Rad.sup.2Rad.sup.2cos(3)sin(3)
6. The apparatus of claim 1, further comprising: wherein the control unit is located within a recessed compartment on the external surface of the pipe section; wherein wiring connects the conductive terminals to the controller; wherein a cover protects the control unit, wiring and conductive terminals, wherein the cover is hermetically sealed to the surface of the pipe section.
7. The apparatus of claim 5, wherein the control unit further comprises a communications unit having communications circuitry capable of transmitting the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second sections to a remote control center using wired or wireless communication.
8. The apparatus of claim 5, wherein the control unit further comprises a communications unit having communications circuitry capable of transmitting the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second sections to a remote computing station using wires embedded within the plurality of pipeline sections.
9. The apparatus of claim 5, wherein the control unit further comprises a communications unit having communications circuitry capable of wirelessly transmitting the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second sections to a remote terminal unit (RTU), wherein the remote terminal unit transmits the measurements to a remote control center by wireless communication, wherein the wireless communication is at least one of microwave communications (WiMAX), 3G, 4G, LTE, Wifi, LAN, WAN and satellite communications.
10. A method for measuring water, oil and gas volumes within a cylindrical horizontal pipeline and the velocity of the oil flowing in the pipeline, wherein the pipeline has a circular cross-sectional area of radius (Rad), and an axial length (Z), the method comprising: installing, within the pipeline having a plurality of pipe sections, at least one pipe section having an internal structure including a first semi-cylindrical conducting sheet covering a portion of the internal surface of the pipe section and a second semi-cylindrical conducting sheet covering an opposing portion of the internal surface of the section of the pipe section, wherein each semi-cylindrical sheet has radius (Rad) and axial length z.sub.0, so that a gap (2) exists between an edge of the first semi-cylindrical conducting sheet and a corresponding edge of the second semi-cylindrical conducting sheet, installing a first conductive terminal along the central axial line of the first semi-cylindrical conducting sheet and a second conductive terminal at the central axial line of the second semi-cylindrical conducting sheet so that each conductive terminal is located on the external surface of the pipe section and protrudes through the pipe section to electrically contact a respective semi-cylindrical sheet; connecting the conductive terminals to a control unit including a controller having circuitry configured for applying a positive DC voltage at the first terminal and a negative DC voltage at the second terminal and for measuring the resistance and capacitance at the conductive terminals, and the resistance of the semi-cylindrical sheets; the control unit further having processing circuitry for determining the respective volumes of water, oil and gas in the pipe section and calculating the velocity of the oil flowing in the pipeline, and wherein the processing circuitry is further configured to calculate the capacitance measurement of the water based on the measured resistance and the equations:
a.sub.n=.sub.0*{Cos()cot(.sub.2n)Sin()}
b.sub.n=.sub.0*{Cos()cot(.sub.2n)+Sin()}
.sub.2n=(2n+1)radians, with n=0, 1, 2 . . . N,
.sub.n=.sub.2n radians.
11. The method of claim 1, wherein the processing circuitry is configured to calculate the total resistance and the total capacitance of the semi-cylindrical sheets based on the following equations:
12. The method of claim 10, further comprising determining, by the processing circuitry, the capacitance of the water, the water including brine, based on the equation:
Cw=.sub.o.sub.rb/(R)Farad/m and defining the volume of water as having a height (hw) measured along the vertical radius of the cross section of the pipe section, the oil content as having a height (ho) measured along the vertical radius of the cross section of the pipe section, the gas as having a height (hg) measured along the vertical radius of the cross section of the pipe section, wherein 2Rad=hw+ho+hg, and calculating, by the processing circuitry, the respective heights of the water, oil and gas within the pipeline.
13. The method of claim 10, further comprising: installing a second pipe section having a second internal structure at a second location within the pipeline, the second internal structure separated by a distance (d) from the first internal structure, measuring a second capacitance and a second resistance at the second location at a time (.sub.0), wherein (.sub.0) is the time elapsed between a capacitance measurement at the first location and a capacitance measurement at the second location, and calculating, by the processing circuitry, the velocity of the oil flowing in the pipeline based on the equation velocity=.sub.0 and the capacitance and resistance measurements of the first pipe section and the second capacitance and second resistance measurements of the second pipe section.
14. The method of claim 13, further comprising calculating, by the processing circuitry, the volume of oil flowing per unit time, based on:
V.sub.g=1Rad.sup.2Rad.sup.2cos(1)sin(1)
V.sub.b=3Rad.sup.2Rad.sup.2cos(3)sin(3)
15. The method of claim 14, further comprising transmitting, by communications circuitry in the control unit, the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second sections to a remote control center using at least one of wired communication, wireless communication and wires embedded within the plurality of pipeline sections.
16. The method of claim 15, further comprising transmitting, by communications circuitry in the control unit, the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second sections to a remote terminal unit (RTU), wherein the remote terminal unit transmits the measurements to a remote control center by wireless communication, wherein the wireless communication is at least one of microwave communications (WiMAX), 3G, 4G, LTE, Wifi, LAN, WAN and satellite communications.
17. A non-transitory computer readable medium having instructions stored therein that, when executed by one or more processors, cause the one or more processors to perform a method for measuring water, oil and gas volumes within a cylindrical horizontal pipeline and the velocity of the oil flowing in the pipeline, wherein the pipeline has a circular cross-sectional area of radius (Rad) and an axial length (Z), the pipeline having a plurality of pipe sections, at least one pipe section having an internal structure including a first semi-cylindrical conducting sheet covering a portion of the internal surface of the pipe section and a second semi-cylindrical conducting sheet covering an opposing portion of the internal surface of the section of the pipe section, wherein each semi-cylindrical sheet has radius (Rad) and axial length z.sub.0, so that a gap (2) exists between an edge of the first semi-cylindrical conducting sheet and a corresponding edge of the second semi-cylindrical conducting sheet, and a first conductive terminal installed along the central axial line of the first semi-cylindrical conducting sheet and a second conductive terminal installed at the central axial line of the second semi-cylindrical conducting sheet so that each conductive terminal is located on the external surface of the pipe section and protrudes through the pipe section to electrically contact a respective semi-cylindrical sheet; the non-transitory computer readable medium method comprising: applying a positive DC voltage at the first terminal and a negative DC voltage at the second terminal, the conductive terminals connected to a control unit; measuring, by a controller in the control unit and having circuitry configured for measuring, the resistance at the first and second terminals; calculating, by processing circuitry in the control unit, the capacitance measurement of the water based on the measured resistance and the equations:
a.sub.n=.sub.0*{Cos()cot(.sub.2n)Sin()}
b.sub.n=.sub.0*{Cos()cot(.sub.2n)+Sin()}
.sub.2n=(2n+1)radians, with n=0, 1, 2 . . . N,
.sub.n=.sub.2n radians; calculating the total resistance and the total capacitance of the semi-cylindrical sheets based on the following equations:
Cw=.sub.o.sub.rb/(R)Farad/m defining, by the processing circuitry, the volume of water as having a height (hw) measured along the vertical radius of the cross section of the pipe section, the oil content as having a height (ho) measured along the vertical radius of the cross section of the pipe section, the gas as having a height (hg) measured along the vertical radius of the cross section of the pipe section, wherein 2Rad=hw+ho+hg, and calculating, by the processing circuitry, the respective heights of the water, oil and gas within the pipeline; measuring at a time (0), second capacitance and second resistance at a second pipe section having a second internal structure and located at a second location within the pipeline, the second internal structure separated by a distance (d) from the first internal structure, wherein (.sub.0) is the time elapsed between a capacitance measurement at the first location and a capacitance measurement at the second location, and calculating, by the processing circuitry, the velocity of the oil flowing in the pipeline based on the equation velocity=.sub.0, the capacitance and resistance measurements of the first pipe section and the second capacitance and second resistance measurements of the second pipe section; calculating, by the processing circuitry, the volume of oil flowing per unit time, based on the equation:
V.sub.g=1Rad.sup.2Rad.sup.2cos(1)sin(1)
V.sub.b=3Rad.sup.2Rad.sup.2cos(3)sin(3) transmitting, by communications circuitry in the control unit, the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second sections to a remote control center using wired or wireless communication.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) A more complete appreciation of this disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
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DETAILED DESCRIPTION
(23) In the drawings, like reference numerals designate identical or corresponding parts throughout the several views. Further, as used herein, the words a, an and the like generally carry a meaning of one or more, unless stated otherwise. The drawings are generally drawn to scale unless specified otherwise or illustrating schematic structures or flowcharts.
(24) Furthermore, the terms approximately, approximate, about, and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween.
(25) In a three-phase horizontal pipeline, the different densities of the oil, gas and water drive the brine layer to the bottom, oil layer to the middle and gas-layer to the top of the flow.
(26) The water may be brine and the gas may be natural gas, ethane, butane, propane, carbon dioxide, air or mixtures of the gases. These layers have distinct separating planes for a steady state flow. Referring to
(27) Aspects of the present disclosure are directed to an apparatus and methods for measuring water, oil and gas volumes within a cylindrical horizontal pipeline and the velocity of the oil flowing in the pipeline. The apparatus is non-invasive, which preserves the integrity of the pipeline.
(28) The following aspects present a simple non-intrusive inclined capacitive plate technique to calculate the capacitance and resistance of three-phase mixture.
(29) In some aspects, a non-intrusive inclined capacitive plate technique is used to calculate the capacitance and resistance of a three-phase wavy-stratified flow. The monitored section of the pipeline includes two semi-cylindrical electrodes mounted on the inside surface with each electrode covering nearly one half of the pipeline. To calculate the capacitance and resistance of this semi-cylindrical capacitor, a processor divides the cross-sectional area of the electrode assembly into N pairs of inclined chords, where the magnitude of N is limited by the expected accuracy and computational resources. An oppositely polarized low-frequency signal is applied to the electrodes. Once calibrated, the measured capacitances represent the total capacitances of the gas, oil and water mixture within the pipe. The measured resistance is primarily that of the water layer, as the water layer has the lowest resistivity of the three phases. Correlating the capacitances and resistances with the phase angles associated with the phase separation plane yields the calculation of the phase fractions.
(30) In some aspects, the pipe section is made of Plexiglas.
(31) In another aspect, the semi-cylindrical electrodes are mounted on the external surface of the pipe.
(32) In some aspects, an apparatus and method are described which calculate the volume of oil-gas-brine under steady state conditions by measuring both the conductance and the capacitance of the flow inside the pipe. Two electrodes, each having the form of a conducting metallic sheet, are each placed to cover one half of the internal surface of the pipe, with a gap between the sheets. The two electrodes are used to measure the conductance of the mixture of oil, gas and water/brine, which conductance is primarily due to the brine content, and to measure the compound capacitance of the three substances.
(33) In some aspects, a method for calculating the flow velocity is based on the measurement of the values of capacitance at different locations in a correlative flow method to determine the speed of flow. The correlative flow measurement is based on measurements of the conductivity of the water in the flow. Analysis results demonstrate that the above measurements are sufficient to calculate the volume of each of the three phases in the pipe.
(34) According to a first embodiment shown in
(35) Referring to
(36) Oil pipelines are made from stainless steel or carbon steel pipes, cast iron or wrought iron pipes, or plastic pipes, such as polyethylene (PE) pipes, polyamide-11 (PA-11) thermoplastic pipes, polyamide-12 (PA-12) thermoplastic pipes. (See Pipeline Materials, PHMSA-Pipeline and hazardous materials safety administration, May 3, 2017, https://www.phmsa.dot.gov/technical-resources/pipeline/pipeline-materials). Pipe sections for measuring the phase fractions and the flow velocity may be made of Plexiglas.
(37) The pipeline includes a plurality of pipe sections, shown as 106 and 108 in
(38) The gap region is filled in with sand glue (as an insulator) so that when saline water (brine) partially fills the pipe, the conducting sheets are not short circuited.
(39) When the pipeline type is conductive, such as carbon steel or iron, the internal structure is preferably insulated from the pipeline internal surface by an insulating backing. Non-limiting examples of insulating materials suitable for use as insulating backings in the present disclosure are glass, porcelain, plastic or composite polymers. Preferably, the portion of the pipeline in which the conducting sheets are installed include an insulating liner such as a thermoplastic sheet covering the inside circumference of the pipeline under the conducting sheets. When the pipeline section is made of Plexiglas, no insulating backing is needed.
(40) A conductive terminal is 103 installed along the central axial line of the first semi-cylindrical conducting sheet and a corresponding conductive terminal 105 is installed at the central axial line of the second semi-cylindrical conducting sheet, wherein each conductive terminal is placed on the external surface of the pipe section (as shown in
(41) The lengths of the conductive terminals are chosen to provide an external contact, to extend through the pipeline wall and to extend through the insulating material (when used) to contact the semi-cylindrical conducting sheet. In a non-limiting example, when the pipe wall thickness is 20 mm, the conductive terminal may be about 40 mm in length.
(42) When the pipeline type is conductive, the conductive terminals insulated from the pipeline internal surface by a non-conductive bushing. Non-limiting examples of insulating materials suitable for use as insulating bushings in the present disclosure are glass, porcelain, nylon or composite polymers.
(43) The gaps (2) at the top and bottom of
(44) A control unit (150, 350) is shown in
(45) In a non-limiting example, the controller may include a calibrated LCR meter with a power supply to apply an alternative voltages with f=1-KHz and V0=1 v to first at the second conductive terminals 103, 105. A non-limiting illustration of an LCR meter suitable for performing the measurements at the conductive terminals is shown in
(46) The control unit 150a, 150b is located within a recessed compartment on the external surface of the pipe section as shown in
(47) Referring to
(48) In the present disclosure, the volumes of the phase fractions are determined by relating the phase angles with calculated and measured values of capacitances and resistances of the three-phase content. To achieve this using an inclined capacitive plate technique, the surfaces of the electrodes are divided into an N-number of inclined pair of chords.
(49)
(50) The procedure for measuring the oil, gas and brine volumes is based on the fact that the brine has finite conductivity and high dielectric constant .sub.rb, while both oil and the gas have zero conductivity and low dielectric constants, .sub.ro and .sub.rg respectively. These properties are shown in Table 1.
(51) TABLE-US-00001 TABLE 1 Material properties at 25 C. Relative Dielectric Constant (.sub.r), Conductivity (), Viscosity (V), Specific Gravity (SG)/Density (D) SG or V Material .sub.r (S/m) D(Kg/m.sup.3) (Pa s) Gas (air) 1 3 10.sup.15 D 1.2 1.8 10.sup.5 Oil (ESCAID 110) 2.4 1 10.sup.8 SG 0.79-0.81 1.5-1.75 (<PPM 500) Brine-water 78 3.2 D 1010 1 10.sup.3
(52) Applying a DC voltage across the poles (103, 105) of the two sheets as shown in
(53) The processing circuitry is configured to calculate the capacitance using the resistance measurements by using the equations:
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and
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wherein is the conductivity of the brine or water; .sub.0 is the dielectric constant of water; and .sub.r is the relative dielectric constant of the brine, wherein is the angle subtended by a sector from the center of the pipe section to the edge of the gap; N is the number of chords subtended by an angle 2, wherein N is an even number and an integer; 1 is the angle from the center of the pipe section to the top of the oil volume, 2 is the angle from the center of the pipe section to the top of the water volume and
a.sub.n=.sub.0*{Cos()cot(.sub.2n)Sin()}
b.sub.n=.sub.0*{Cos()cot(.sub.2n)+Sin()}
.sub.2n=(2n+1)radians,
with n=0, 1, 2 . . . N,
(56)
and .sub.n=.sub.2n radians;
(57) The processor 358 is configured to analyze the measurements and calculate the total resistance and the total capacitance of the semi-cylindrical sheets based on the following equations:
(58)
(59) The processing circuitry is further configured to determine the capacitance measurement based on equation (2):
C.sub.w=.sub.o.sub.rb/(R)Farad/m(2)
wherein .sub.0=8.854 e12, (s/m) is the conductivity of the element under measurement; .sub.r0 is to the dielectric constant of the oil; and .sub.rb is the dielectric constant of the brine and a and b dimensions are shown in
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(61) The total capacitance Cp (F/m) of the oil-gas-brine mixture between the two conducting sheets is measured by the measuring circuitry 357 shown in
(62)
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(64) TABLE-US-00002 TABLE 2 Calibration to known and measured values Calculated Finite Electrode- Cap. Known Difference location (Eq.11) Capacitances Method Semi-cylindrical capacitor with 100% gas contents Inside pipeline 104.9 pF/m 104.95 pF/m 103.43 pF/m surface (FIG. 1) 117.69 pF/m Outside 117.08 pF/m 116.41 pF/m pipeline surface Semi-cylindrical capacitor with .sub.3 = 45 water contents Inside pipeline 1001.9 pF/m 958 pF/m 999.9 pF/m surface (FIG. 1) Outside 212.7 pF/m 215.8 pF/m 214.8 pF/m pipeline surface
(65) A second pipe section 108 having a second internal structure installed at a second location within the pipeline is installed at a distance (d) from the first internal structure 106 as shown in
(66) In order to calculate the oil volume flowing in the pipe, the velocity of the flow inside the pipe must be measured. Second capacitance measurements are made at the second location at a time (.sub.0), wherein (.sub.0) is the time elapsed between a capacitance measurement at the first location and a capacitance measurement at the second location. The velocity is calculated by cross correlating between the measured Cp at two different locations, represented by 106 and 108 in
(67) The processing circuitry is configured to calculate the velocity of the oil flowing in the pipeline based on the equation velocity=d/.sub.0 and the capacitance measurements of the first pipe section and the second capacitance measurements of the second pipe section, based on the equation:
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wherein Rad is the pipe radius and Vg, and Vw are the gas and water volumes respectively, given by:
V.sub.g=1Rad.sup.2Rad.sup.2cos(1)sin(1)
V.sub.b=3Rad.sup.2Rad.sup.dcos(3)sin(3).
(69) During the measurement, the pressure of the oil pump (see
(70) The control unit 350 further includes a communications unit 353 having communications circuitry capable of transmitting the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second pipe sections to a remote control center using wired or wireless communications.
(71) The measurements may be transmitted along the pipeline through wires embedded within the plurality of pipeline sections. Remote terminal units (RTU), as shown in
(72) The remote terminal unit transmits the measurements to the remote control center by wireless communication, wherein the wireless communication is at least one of microwave communications (WiMAX), 3G, 4G, LTE, Wifi, LAN, VLAN, WAN and satellite communications.
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(75) The present invention is not limited to only the two pipeline sections having internal structures. The pipeline may have a plurality of pipe sections placed along the length z of the pipeline so that multiple measurements of the heights of the water, oil and gas and the oil velocity may be taken. The measurements may be transmitted to the remote control center with an identification of the location of each pipe section and other information, such as temperature, wind velocity, damage taken by other sensors in the pipe section.
(76) A second embodiment of a method for measuring the water, oil and gas volumes within a cylindrical horizontal pipeline and the velocity of the oil flowing in the pipeline, wherein the pipeline has a circular cross-sectional area of radius (Rad), and an axial length (Z) is described with respect to
(77) The method comprises installing, within the pipeline having a plurality of pipe sections (106, 108), at least one pipe section having an internal structure including a first semi-cylindrical conducting sheet 102 covering a portion of the internal surface of the pipe section and a second semi-cylindrical conducting sheet 104 covering an opposing portion of the internal surface of the section of the pipe section, wherein each semi-cylindrical sheet has radius (Rad) and axial length z.sub.0, so that a gap (2) exists between an edge of the first semi-cylindrical conducting sheet and a corresponding edge of the second semi-cylindrical conducting sheet.
(78) The method continues by installing a first conductive terminal 103 along the central axial line of the first semi-cylindrical conducting sheet and a second conductive terminal 105 at the central axial line of the second semi-cylindrical conducting sheet so that each conductive terminal is located on the external surface of the pipe section and protrudes through the pipe section to electrically contact a respective semi-cylindrical sheet, then connecting the conductive terminals to a control unit 350, as shown in
(79) The processing circuitry is configured for calculating the capacitance of the water layer based on the measured resistance and the equations:
(80)
and the relationship
(81)
where R and C are the resistance and capacitance of the water layer, wherein .sub.0=8.854 e12, (s/m) is the conductivity of the element under measurement; .sub.r is the dielectric constant of the phase under measurement, and a, b and .sub.0 are measurements as shown in
(82) The method continues by calculating the total resistance and the capacitances of the semi-cylindrical sheets based on the following equations:
(83)
where
a.sub.n=.sub.0*{Cos()cot(.sub.2n)Sin()}
b.sub.n=.sub.0*{Cos()cot(.sub.2n)+Sin()}
.sub.2n=(2n+1)radians,
with n=0, 1, 2 . . . N,
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and .sub.n=#.sub.2n radians and wherein is the angle subtended by a sector from the center of the pipe section to the edges of the gap; N is the number of pairs of chords subtended by an angle 2, 1 is the angle from the center of the pipe section to the top of the oil volume, 2 is the angle from the center of the pipe section to the top of the water volume, .sub.0=the radius of a chord from the axial center of the internal structure as shown in
(85) The method continues by calculating, by the processing circuitry, the respective heights of the water, oil and gas within the pipe section, wherein the volume of water is defined as having a height (hw) measured along the vertical radius of the cross section of the pipe section, the oil content is defined as having a height (ho) measured along the vertical radius of the cross section of the pipe section and the gas is defined as having a height (hg) measured along the vertical radius of the cross section of the pipe section, wherein 2Rad=hw+ho+hg.
(86) The method further continues by installing a second pipe section 108 having a second internal structure at a second location within the pipeline, the second internal structure separated by a distance (d) from the first internal structure as shown in
(87) The method proceeds by measuring a second capacitance and a second resistance at the second location at a time (.sub.0), wherein (.sub.0) is the time elapsed between a capacitance measurement at the first location and a capacitance measurement at the second location, and calculating, by the processing circuitry, the velocity of the oil flowing in the pipeline based on the equation velocity=d/.sub.0 and the capacitance and resistance measurements of the first pipe section and the second capacitance and second resistance measurements of the second pipe section.
(88) Calculating by the processing circuitry of the volume of oil flowing per unit time, is based on the equation:
(89)
wherein Rad is the pipe radius and Vg, and Vw are the gas and water volumes respectively, given by:
V.sub.g=1Rad.sup.2Rad.sup.2cos(1)sin(1)
V.sub.b=3Rad.sup.2Rad.sup.2cos(3)sin(3)
(90) Once the heights of the water, oil and gas and velocity of oil in the pipeline are determined, the method proceeds by transmitting, by communications circuitry in the control unit 350, the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second sections to a remote control center using wired or wireless communication. As described with respect to the first embodiment and shown in
(91) A third embodiment to a non-transitory computer readable medium is described with reference to
(92) The method of the third embodiment comprising applying a positive DC voltage at the first terminal and a negative DC voltage at the second terminal, the conductive terminals connected to a control unit; measuring, by a controller in the control unit and having circuitry configured for measuring, the resistance at the first and second terminals; calculating, by processing circuitry in the control unit, the capacitance based on the measured resistance and the equations:
(93)
and the relationship
(94)
determining, the respective volumes of water, oil and gas in the pipe section and calculating the velocity of the oil flowing in the pipeline; analyzing, by the processing circuitry, the total resistance and total capacitance of the semi-cylindrical sheets based on the equations:
(95)
wherein is the angle subtended by a sector from the center of the pipe section to the edges of the gap; N is the number of chords subtended by an angle 2, wherein N=0, 1, 2, . . . N; 1 is the angle from the center of the pipe section to the top of the oil volume, 2 is the angle from the center of the pipe section to the top of the water volume and
pipe section to the top of the water volume and
a.sub.n=.sub.0*{Cos()cot(.sub.2n)Sin()}
b.sub.n=.sub.0*{Cos()cot(.sub.2n)+Sin()}
.sub.2n=(2n+1)radians,
with n=0, 1, 2 . . . N,
(96)
and
.sub.n=.sub.2n radians;
determining, by the processing circuitry, the capacitance of the water, the water including brine, based on the equation:
Cw=.sub.o.sub.rb/(R)Farad/m
wherein is the conductivity of the brine or water; C is the dielectric constant of the oil; and .sub.rb is the dielectric constant of the brine; defining, by the processing circuitry, the volume of water as having a height (hw) measured along the vertical radius of the cross section of the pipe section, the oil content as having a height (ho) measured along the vertical radius of the cross section of the pipe section, the gas as having a height (hg) measured along the vertical radius of the cross section of the pipe section, wherein 2Rad=hw+ho+hg, and calculating, by the processing circuitry, the respective heights of the water, oil and gas within the pipe section; measuring at a time (0), second capacitance and second resistance at a second pipe section having a second internal structure and located at a second location within the pipeline, the second internal structure separated by a distance (d) from the first internal structure, wherein (.sub.0) is the time elapsed between a capacitance measurement at the first location and a capacitance measurement at the second location, and calculating, by the processing circuitry, the velocity of the oil flowing in the pipeline based on the equation velocity=d/.sub.0, the capacitance and resistance measurements of the first pipe section and the second capacitance and second resistance measurements of the second pipe section; calculating, by the processing circuitry, the volume of oil flowing per unit time, based on the equation:
(97)
wherein Rad is the pipe radius and Vg, and Vw are the gas and water volumes respectively, given by:
V.sub.g=1Rad.sup.2Rad.sup.2cos(1)sin(1)
V.sub.b=3Rad.sup.2Rad.sup.2cos(3)sin(3)
(98) The third embodiment continues by transmitting, by communications circuitry in the control unit, the measurements of the volumes of water, oil and gas in the pipe section and the velocity of the oil flowing in the pipeline between the first and second pipe sections to a remote control center using wired or wireless communication.
(99) A fourth embodiment to an experimental arrangement for measuring the flow rate of a three phase pipeline is described with respect to
Volume of oil/time=(Rad.sup.2V.sub.gV.sub.w)velocity
V.sub.g=1Rad.sup.2Rad.sup.2cos(1)sin(1)
V.sub.w=3Rad.sup.2Rad.sup.2cos(3)sin(3)
where Rad is the pipe radius, V.sub.g and V.sub.w are the volumes and .sub.1 and .sub.3 are phase-angles of the gas and water regions, respectively.
(100) In a non-limiting example, an experimental testing arrangement includes two 1963-liter supply-tanks, a 60 cm long, 1.6 cm radius Plexiglas pipeline and three single-stage 3.5-hp end-suction centrifugal supply/return pumps. Using a data acquisition system, the maximum laminar flow rates achieved for water, oil and air are 0.04 m3.Math.min1, 0.04 m3.Math.min1 and 0.9 m3.min1, respectively. In a non-limiting example, the data acquisition system is LabView.
(101) In a non-limiting example, a Plexiglas (.sub.r=2.7) pipeline with thickness t=0.15 mm, electrode length (Z.sub.0)=20 cm, (in z-axis), angle =0.25 and N=179, the total capacitance and total resistance equations above are used to calculate the total resistance and capacitance of a three-phase near-horizontal pipeline with stratified flow. Referring to Table 1, the water region has highest and highest .sub.r, thus the three parallel conducting paths between the two electrodes are mostly dominated by the water layer. Thus, the total resistance between the electrodes are equivalent to the resistance of the water layer (R.sub.TR.sub.W).
(102) Experimental measurements are described below and a comparison is made to prior art measurements.
(103) In a non-limiting example, measurements were taken on a pipe of radius 3.2 cm and length 150 cm. The measurements for Cp and Rp are normalized to a 1 m length. In a further non-limiting example, measurements were repeated for a pipe of length 25 cm and radius 8 cm. There was agreement between the theory and the experiments as well as with the finite difference (FD) method described by Iqbal. (See M. S. Iqbal, Novel metering system for the three phase flow in horizontal oil pipes under steady flow, 2018 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), INSPEC Accession No. 17880625 DOI: 10.1109/WMCaS.2018.8400621 April 2018, incorporated herein by reference in its entirety).
(104) The present disclosure utilizes equations (1) and (2) for calculating the capacitance and the resistance of multi-layers compositions inside a horizontal pipe especially for composition that occupy distinct layers. Equation (1) is verified against the theoretical development of an empty pipe, and against the more computationally involved Finite Difference (FD) method and experimental measurements.
(105)
(106) Firstly, the capacitance of the empty pipe was measured. This was compared to the result obtained by equations (1) and (2). Secondly, a Finite Difference numerical algorithm was established and the capacitance of the empty pipe was calculated numerically by solving Laplace's equation as detailed by Iqbal. Additionally, the theoretical solution to solving for the capacitance of the empty pipe was formulated. The comparative results are presented in Table 4, which shows very close agreement between the calculation using equation 1 and the theoretical calculation, the finite difference calculation and the experimental results. Thus, equations (1) and (2) verify that the capacitance of the empty pipe can be determined by measuring the resistance in the experimental arrangement.
(107) TABLE-US-00003 TABLE 4 Capacitance per unit length of empty circular pipe Finite Experimental Theoretical Difference (Iqbal) Equation (1) 117.29 pF/m 116.41 pF/m 117.08 pF/m 117.69 pF/m
(108) Next, various volumes of saline water were fed into the pipe and the resistance Rp and capacitance Cp were measured across the two terminals described earlier. Cp is the sum of the capacitance of the water Cw plus the Cg of the gas plus Co of the oil. The Rp is the resistance of the water only which is related to Cw by equation (2). Equation is a fundamental equation in the electromagnetic field theory, (See M. N. Sadiku, Elements of electromagnetics, Sixth edition, chapter 6, Oxford university press, 2015), herein incorporated by reference in its entirety.
(109) Finally, the procedure outlined above in the calculations of the volumetric flow of oil per unit time (correlative flow method) were followed and several experiments were conducted to register the average percentage errors in the results. Table 5 gives the errors reported in the literature obtained using other techniques compared with the present procedure. The present procedure achieved a comparable error ratio with other methods. More details on the procedure may be found in the references above and in M. S. Iqbal. (See also X. Chen and L. Chen, Crude Oil/Natural gas/Water Three-Phase Flow meter, SPE, 63rd annual technical conference and exhibition of the Society of Petroleum Engineers, Houston, Tex., Oct. 2-5, 1988; M. R. Taherian, T. M. Habashy, Microwave Device and Method for Measuring Multiphase Flow, U.S. Pat. No. 5,485,743, Date: Jan. 23, 1996; P. Spedding, G. Donnelly and E. Benard, Three Phase Oil-Water and Gas horizontal co-current flow Part II. Hold up measurement and prediction, Asia Pacific Journal of Chemical Engineering, 2007-2, pp. 130-136, each incorporated herein by reference in its entirety).
(110) TABLE-US-00004 TABLE 5 Comparison of % errors (Room Temperature) Present Source Chen Taherian Spedding Xu Isaksen Qu Technique % Error 5 5 3.7 >5 30 8 6.3
(111) Measurements were made using a setup of a closed pipe system with two pumps to control the flow of oil and brine and one pipe section internally covered with the electrodes as shown in
(112) For an unknown three-phase stratified flow, the measured pipeline resistance (R.sub.TR.sub.W) is superimposed in
(113)
to calculate the predicted capacitances (C.sub.W) contributed by the electrode sections submerged within that water layer. The calculation of C.sub.W versus .sub.3 values are plotted in
(114) TABLE-US-00005 TABLE 3 Comparison of percent-errors (25 C.) Experi- Ref. Ref. Ref. Ref. Ref. Ref. mental [1] [2] [3] [4] [5] [6] results Reported 5% 5% 3.7% >5% 30% 8% 6.3% Error
(See [1] X. Chen and L. Chen, Crude Oil/Natural gas/Water Three-Phase Flow meter, SPE, 63rd annual technical conference and exhibition of the Society of Petroleum Engineers, Houston, Tex., 2-5 Oct. 1988.[2]M. R. Taherian, T. M. Habashy, Microwave Device and Method for Measuring Multiphase Flow, U.S. Pat. No. 5,485,743, Date: 23 Jan. 1996. [3] P. Spedding, G. Donnelly and E. Benard, Three Phase Oil-Water and Gas horizontal co-current flow Part II. Hold up measurement and prediction, Asia Pacific Journal of Chemical Engineering, Vol. 2, No. 2, pp. 130-136, March 2007. [4] L. Al-Hadhrami, S. Shaahid, L. Tund and A. Al-Sarkhi, Experimental study on the flow regimes and pressure gradients of air-oil-water three-phase flow in horizontal pipes, Scientific World Journal, vol. 2014, January 2014. [5] Michel Brard and Ibrahim Babelli, System and Method for Measuring Flow in a Pipeline, U.S. Pat. No. 7,726,185, Date: 1 Jun. 2010. [6] O. Isaksen, Three Phase Pipe Flow Imaging Using a Capacitance Tomography System, IEEE Colloquium on Advances in Sensors for Fluid Flow Measurements, pp 11/1-11/6, 18 Apr. 1996, each herein incorporated by reference in its entirety).
(115) The present disclosure presents a novel technique for estimating and determining the amounts of water and oil in a three-phase flow using simple electrical measurements. The results are comparable with relatively complicated methods reported in the literature.
(116) Next, a hardware description of the control unit according to exemplary embodiments is described with reference to
(117) Further, the claimed advancements are not limited by the form of the computer-readable media on which the instructions of the inventive process are stored. For example, the instructions may be stored on CDs, DVDs, in FLASH memory, RAM, ROM, PROM, EPROM, EEPROM, hard disk or any other information processing device with which the computing device communicates, such as a server or computer.
(118) Further, the claimed advancements may be provided as a utility application, background daemon, or component of an operating system, or combination thereof, executing in conjunction with CPU 700 and an operating system such as Microsoft Windows 7, UNI7, Solaris, LINU7, Apple MAC-OS and other systems known to those skilled in the art.
(119) The hardware elements in order to achieve the computing device may be realized by various circuitry elements, known to those skilled in the art. For example, CPU 700 may be a Xenon or Core processor from Intel of America or an Opteron processor from AMD of America, or may be other processor types that would be recognized by one of ordinary skill in the art. Alternatively, the CPU 700 may be implemented on an FPGA, ASIC, PLD or using discrete logic circuits, as one of ordinary skill in the art would recognize. Further, CPU 700 may be implemented as multiple processors cooperatively working in parallel to perform the instructions of the inventive processes described above.
(120) The computing device in
(121) The computing device further includes a display controller 708, such as a NVIDIA GeForce GT7 or Quadro graphics adaptor from NVIDIA Corporation of America for interfacing with display 710, such as a Hewlett Packard HPL2445w LCD monitor. A general purpose I/O interface 712 interfaces with a keyboard and/or mouse 714 as well as a touch screen panel 716 on or separate from display 710. General purpose I/O interface also connects to a variety of peripherals 718 including printers and scanners, such as an OfficeJet or DeskJet from Hewlett Packard.
(122) A sound controller 720 is also provided in the computing device such as Sound Blaster 7-Fi Titanium from Creative, to interface with speakers/microphone 722 thereby providing sounds and/or music.
(123) The general purpose storage controller 724 connects the storage medium disk 704 with communication bus 726, which may be an ISA, EISA, VESA, PCI, or similar, for interconnecting all of the components of the computing device. A description of the general features and functionality of the display 710, keyboard and/or mouse 714, as well as the display controller 708, storage controller 724, network controller 706, sound controller 720, and general purpose I/O interface 712 is omitted herein for brevity as these features are known.
(124) The exemplary circuit elements described in the context of the present disclosure may be replaced with other elements and structured differently than the examples provided herein. Moreover, circuitry configured to perform features described herein may be implemented in multiple circuit units (e.g., chips), or the features may be combined in circuitry on a single chipset, as shown on
(125)
(126) In
(127) For example,
(128) Referring again to
(129) The PCI devices may include, for example, Ethernet adapters, add-in cards, and PC cards for notebook computers. The Hard disk drive 860 and CD-ROM 866 can use, for example, an integrated drive electronics (IDE) or serial advanced technology attachment (SATA) interface. In one implementation the I/O bus can include a super I/O (SIO) device.
(130) Further, the hard disk drive (HDD) 860 and optical drive 866 can also be coupled to the SB/ICH 820 through a system bus. In one implementation, a keyboard 870, a mouse 872, a parallel port 878, and a serial port 876 can be connected to the system bus through the I/O bus. Other peripherals and devices that can be connected to the SB/ICH 820 using a mass storage controller such as SATA or PATA, an Ethernet port, an ISA bus, a LPC bridge, SMBus, a DMA controller, and an Audio Codec.
(131) Moreover, the present disclosure is not limited to the specific circuit elements described herein, nor is the present disclosure limited to the specific sizing and classification of these elements. For example, the skilled artisan will appreciate that the circuitry described herein may be adapted based on changes on battery sizing and chemistry, or based on the requirements of the intended back-up load to be powered.
(132) The functions and features described herein may also be executed by various distributed components of a system. For example, one or more processors may execute these system functions, wherein the processors are distributed across multiple components communicating in a network. The distributed components may include one or more client and server machines, which may share processing, as shown on
(133) The above-described hardware description is a non-limiting example of corresponding structure for performing the functionality described herein.
(134) In conclusion, a simple inclined capacitive plate apparatus is proposed to determine the phase-fractions and the flow-rate of a three-phase pipeline with wavy-stratified flow. A method relates the measured capacitances and resistances of the mixture with phase angles of water and gas layers to determine the volume ratio. A capacitor with a set of semi-cylindrical electrodes, mounted on the inner or outer surface of the pipe, is used for this purpose. To find the flow-rate, a set of capacitors with known separation distance is used to measure the time-delay required for a surge in the fluid flow to pass through the capacitors. Standard cross-correlation of measured capacitances is used for this purpose. The predicted phase-fractions and flow-rate are experimentally verified and an error rate of 6.3% is observed.
(135) Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically 1 to described herein.
(136) Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications and variances. Additionally, while several embodiments of the present disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. And, those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. Other elements, steps, methods and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure.
(137) The embodiments shown in the drawings are presented only to demonstrate certain examples of the disclosure. And, the drawings described are only illustrative and are non-limiting. In the drawings, for illustrative purposes, the size of some of the elements may be exaggerated and not drawn to a particular scale. Additionally, elements shown within the drawings that have the same numbers may be identical elements or may be similar elements, depending on the context.
(138) Where the term comprising is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun, e.g. a an or the, this includes a plural of that noun unless something otherwise is specifically stated. Hence, the term comprising should not be interpreted as being restricted to the items listed thereafter; it does not exclude other elements or steps, and so the scope of the expression a device comprising items A and B should not be limited to devices consisting only of components A and B. This expression signifies that, with respect to the present disclosure, the only relevant components of the device are A and B.
(139) Furthermore, the terms first, second, third and the like, whether used in the description or in the claims, are provided for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances (unless clearly disclosed otherwise) and that the embodiments of the disclosure described herein are capable of operation in other sequences and/or arrangements than are described or illustrated herein.
(140) While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly it is to be understood that the present invention has been described by way of illustrations and not limitations.