GB1585305A - Detection of impurities in fluid flowing in refinery pipeline or oil production operations using nuclear techniques - Google Patents
Detection of impurities in fluid flowing in refinery pipeline or oil production operations using nuclear techniques Download PDFInfo
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- GB1585305A GB1585305A GB4804377A GB4804377A GB1585305A GB 1585305 A GB1585305 A GB 1585305A GB 4804377 A GB4804377 A GB 4804377A GB 4804377 A GB4804377 A GB 4804377A GB 1585305 A GB1585305 A GB 1585305A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/221—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by activation analysis
- G01N23/222—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by activation analysis using neutron activation analysis [NAA]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/07—Investigating materials by wave or particle radiation secondary emission
- G01N2223/074—Investigating materials by wave or particle radiation secondary emission activation analysis
- G01N2223/0745—Investigating materials by wave or particle radiation secondary emission activation analysis neutron-gamma activation analysis
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/60—Specific applications or type of materials
- G01N2223/616—Specific applications or type of materials earth materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/60—Specific applications or type of materials
- G01N2223/637—Specific applications or type of materials liquid
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/60—Specific applications or type of materials
- G01N2223/652—Specific applications or type of materials impurities, foreign matter, trace amounts
Description
(54) DETECTION OF IMPURITIES IN FLUID FLOWING
IN REFINERY PIPELINE OR OIL PRODUCTION
OPERATIONS USING NUCLEAR TECHNIQUES
(71) We, TEXACO DEVELOPMENT CORPORATION, a corporation organised and exisiting under the laws of the State of Delaware, United States of America, of 135 East 42nd Street, New York, New York 10017, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
The present invention relates to nuclear techniques for detecting salt water and sulfur impurities in petroleum refining and producing operations.
Petroleum products often contain small concentrations of undesirable impurities, such as chlorine, sulfur and other elements. For example, even relatively small concentrations of salt water in crude oil can often cause major problems during refining operations. The amount of sulfur in petroleum or fuel oil must be closely monitored for processing and environmental reasons.
A recent article in Analytical Chemistry, Volume 48, Number 9, August, 1974 page 1223 and following, deals with determining the amount of sulfur in oil using neutron capture gamma ray spectroscopy. However, it has been found with the present invention that for crude oil of varying and unknown chlorine content, the sulfur readings are varied due to the varying chlorine content. The isotope 32S, upon capture of thermal neutrons, emits relatively low intensity 8.64, 7.78, 7.42, 7.19, 6.64 and 5.97 MeVsgamma radiation in addition to the relatively intense 5.42 MeV radiation. The isotope 3 Cl, upon capture of thermal neutrons, emits 7.79, 7.42, 6.64 and 6.11 MeV gamma radiation. The second and first escape peaks of the 6.64 and 6.11 MeV chlorine capture gamma radiation fall at energies 5.62 and 5.60 MeV, respectively.These escape peaks essentially overlap the primary sulfur capture peak at 5.43 MeV. Due to these overlapping energy peaks, unless the chlorine level in a sample were known and constant, sulfur readings obtained with this prior art technique were not accurate: However, the salt water (and thus chlorine) content of crude oil varies from well to well as well as during the production life of a well for a number of reasons. So far as is known, the only way prior to the present invention to determine chlorine content of crude oil was by chemical analysis.
Briefly, the present invention relates to a new and improved method and apparatus for determining the presence of chlorine and sulfur in a fluid conduit. The fluid may be crude oil at a wellhead, loading dock or other location, or refined product, feed stock or waste water to dispose of at a refinery.
This invention provides a method for determining the concentrations of chlorine and sulfur of a fluid flowing in a conduit comprising: bombarding the fluid with neutrons, which are slowed down and thereafter engage in thermal neutron capture reactions with materials in the fluid; obtaining a gamma ray energy spectrum of the gamma rays arising in response to said thermal neutron capture reactions; obtaining a measure of the concentration of chlorine in the fluid and substantially simultaneously obtaining a measure of the concentration of sulfur in the fluid from the gamma ray energy spectrum; and utilizing said measure of the concentration of chlorine to provide a measure of the concentration of salt water in the fluid.
This invention also provides apparatus for analysis of a fluid flowing in a conduit comprising: bombarding means attached to a wall of said conduit for bombarding the fluid with neutrons, which are slowed down and thereafter engage in thermal neutron capture reactions with materials in the fluid: means for obtaining a gamma ray energy spectrum of the gamma rays arising in response to said thermal neutron capture reactions; means attached to a wall of said conduct at a distance from said bombarding means for obtaining a measure of the concentration of chlorine in the fluid from the gama ray energy spectrum; means for obtaining a measure of the concentration of sulfur in the fluid from the gamma ray energy spectrumsubstantially simultaneously with the measure of the concentration of chlorine, and means for utilizing said measure of the concentration of chlorine to provide a measure of the concentration of salt water in the fluid.
The fluid is bombarded with fast neutrons from a neutron source which are slowed down and thereafter engage in thermal neutron capture reactions with materials in the fluid, giving rise to thermal neutron capture gamma rays. The energy spectra of the thermal neutron capture gamma rays are obtained, from which a measure of the concentration of chlorine and sulfur in the fluid may be ascertained. If the salinity of the salt water is known, the concentration of salt water within the fluid is accordingly determined. Alternatively, since substantially all the chlorine in fluids being sampled will usually be present as sodium chloride, the measure of the amount of chlorine will in such cases be in itself a measure of the amount of salt water.
Also, if the fluid contains a gas, e.g. a hydrogen-containing gas, homogeneously mixed therein, the percentage of gas or gas oil ratio (GOR) may be determined according to the present invention.
Figure 1 is a schematic block diagram of apparatus according to the present invention;
Figure 2 is a graphical illustration of a typical thermal neutron capture gamma ray spectrum for crude oil;
Figure 3 is a schematic diagram of an alternative construction of a part of the apparatus shown in Figure 1;
Figures 4 and 5 are graphical illustrations of the ratio of chlorine neutron capture gamma ray count to hydrogen neutron capture gamma ray count in a fluid with the present invention;
Figure 6 is a further graphical illustration of net counts of chlorine neutron capture gamma rays as a function of percent chlorine in a fluid obtained with the present invention;
Figure 7 is a graphical illustration of percent standard deviation of results of the present invention as a function of percent chlorine in a fluid; and
Figure 8 is a graph by which the chlorine and sulfur content of a fluid are simultaneously determined for a fluid as a function of the ratio of chlorine neutron capture gamma ray count and sulfur neutron capture gamma ray count, respectively, from the fluid to the hydrogen neutron capture gamma ray count from the fluid.
Relatively small concentrations of salt water in crude oil can often cause major problems in the crude oil refining process. The present invention relates to the detection in a flowing crude oil stream or other petroleum conduit of concentrations of chlorine as low as several parts per million with statistical accuracies of +15 percent or better. The present invention is based upon the bombardment or irradiation of a flowing stream of crude oil with neutrons
and the detection of gamma radiation emitted by the element chlorine upon capture of thermal neutrons. For a given thermal neutron flux, the yield of chlorine capture radiation is proportional to the concentration of chlorine in the flowing stream of crude oil.If it is known or assumed that all chlorine is in the form of NaCl and if the water salinity is known, then the intensity of chlorine capture radiation is a direct indication of salt water concentration.
Gamma radiation resulting from thermal capture (n,y) reactions is "prompt" in the sense that it is emitted within microseconds after the capture event. This is in contrast to
"delayed" gamma radiation resulting from "activation" type reactions which is emitted from milliseconds to years after the reaction. Since thermal neutron capture radiation is almost instantaneous, the velocity and volume flow rate of the crude oil stream do not affect the measurement. Another advantage of the present invention is that resulting from
showing of the fast neutrons originally emitted are involved, a chemical source rather than
an evacuated envelope accelerator type neutron generator source can be used. Chemical
sources are relatively inexpensive and, of course, require no associated electronics or maintenance.
Theory and sensitivity calculations
The counts C recorded by a gamma ray detector during time T (seconds) is given by the
equation C-- EBNoT (1) where
E = the efficiency of the detector
B = the branching ratio of the counted gamma radiation
N = the nuclear density of the isotope of interest # = the capture cross section for the reaction of interest (cm2) = the thermal neutron flux (neutrons/cm2 - sec) The detector efficiency term E can be expressed as E=Kbef (2) where
K = a constant depending upon the source-detector geometry
E = total efficiency of the detector to the counted gamma radiation
B = the fraction correction for the absorption of gamma radiation within the sample
f = the peak to total ratio for the gamma radiation of interest
For the Cl35 (n, y) reaction, #Cl = 33.6 barns. The nuclear density Ncl is given by the equation Nci = (Pci IC1-35 O)/(Ac1100) = Pci Q 2.15 10-4 (3) where
cl = percent by weight of elemental chlorine in the fluid
1Cl-35 = isotopic fraction of Cl35=.755
Q = Avogadro's number Aci = atomic weight of Cl35 = 35
The gamma radiation of interest for chlorine are encompassed with Window 1 (Figure 2) and their MeV levels along with their corresponding branching ratios B are
(MeV)
Gamma ray energy B
7.79 0.078
7.42 0.140
6.64 0.144
6.11 0.214 L: = 0.576 All of the above gamma radiations in Window 1 will be counted so that the sum of branching ratios Bci = 0.576 (4) will be used in Equation (1) to compute Cc1.
For a 5" (diameter) x 5" NaI(Tl) cylindrical crystal, the E = 1.4 for counted gamma radiation in the 5.75-8.0 MeV range and since this range contains not only photo but escape peaks, f ~ 0.8. Therefore ( f)c= 1.12 (5)
Substituting Equations (2) through (5) into Equation (1) and subscripting C to designate the Cl35(n,y) reaction yields Cc1 = (1.12 KClbCl).0.576.(2.15.10-4 Pci Q)33.6#Cl.TCl = 0.466 Pci Q cl Tci Kcl
The prior art article discussed above has measured sulfur content in crude oil using the
S32(n,y) reaction. For S32(n,y) os= 0.51 barons.The nuclear density Ns is given by the equation Ns = (Ps 1s32 O)/(AS . 100) = PS Q 2.95 10- (7) where Ps = percent by weight of elemental sulfur within the oil
IS-32 = isotopic fraction of S32 = 0.95
Q = Avogadro's number
As = atomic weight of S32 = 32
The predominant gamma radiation of interest from the S32 (n,y) reaction is 5.42 MeV with Bs = 0.42 (8)
For the technique used in this article using a 3" x 3" NaI(Tl) detector
(E f)s = 0.4 (9)
Substituting Equations (2), (7), (8) and (9) into (1) and subscripting C to desginate the
S32(n, y) reaction yields
CS = (.04 Ksbs) 0.42 (2.95 10-4 PsQ) 0-51 wS T
= 2.52 10-6 P5 Qs Ts K5 bs (10)
From Equations (6) and (10), we have
If a geometry similar to that in Figure 1 of the prior art article were used to measure the chlorine content in crude oil, the geometric factors Kci . bci = Ks . b5 (12)
Also referring to the results of the prior art reference, for a controlled sample it was found that for Ps = 1% and Ts = 2000 seconds (33.3 minutes), Cs = 763 counts using a Cf252 source emitting 5. 105 neutrons per second. If the chlorine measurement is made using a source emitting 5 . 107 neutrons per second, P)cJs = 102 (13)
Substituting the above values from this article along with Equations (12) and (13) into
Equation (11) yields Cci = 7.03 x 104 Pci Tcl (14) which relates the counts recorded in a 5.75-8.0 MeV window resulting from the Cl35(n,y) reaction to the percent (by weight) of elemental chlorine in the crude oil for a counting time Tc. In the prior art reference, it was estimated that the Cn, the background recorded in the energy window 5.75 to 8.0 MeV is approximately 37 counts per second.
Figure 1 shows an apparatus A according to the present invention with a neutron source S and a detector D mounted in suitable sockets 10 and 12, respectively, of a counting chamber
C mounted in a crude oil flow line 14. The detector D is preferably a 5" x 5" NaI(Tl) cylindrical crystal coupled to a photomultiplier tube T. The source S shown is a Cf2' neutron source emitting 5 x 107 neutrons per second, although it should be understood that a different source material, such as actinium-beryllium or americium-beryllium could be used, if desired.
The chamber C preferably should be constructed of some material which contains no elements producing appreciable capture gamma radiation above 5.0 MeV. Aluminum or certain fiberglass-epoxy materials would be suitable, although iron, which produces 9.30 and 7.64 MeV gamma radiation through (n,y) reactions, should be avoided. It should be noted that the chamber C is designed such that the detector D and source S are physically isolated in the sockets 10 and 12 from the crude oil. This eliminates the possibility of contaminating the crude oil if the source S should leak and also permits the detector D and source S to be removed without interrupting the flow of crude oil.
The physical shape of the chamber C is not critical as long as the source S and detector D are surrounded by at least several inches of fluid. In certain situations it might be desirable to coat the inside of the chamber C with a material of high thermal neutron cross capture cross section, such as boron. This would reduce the thermal neutron interactions with the walls of the chamber and also prevent the escape from the chamber of thermal neutrons that might react with elements outside the chamber producing additional "background" radiation. Boron (boron carbide mixed with epoxy resin) would be ideal for this application since it has a large thermal neutron capture cross section (o = 775 barns) and a capture reaction which produces no radiation above 5.0 MeV.
The detector D produces scintillations or discrete flashes of light whenever gamma rays pass therethrough, while the photomultiplier tube T generates in response to each such scintillation a voltage pulse proportional to the intensity of the scintillation. A conventional preamplifier circuit 16 amplifies the pulses from the photomultiplier tube T and furnishes the amplifier pulses to a further amplifier stage 18. A B+ power supply 20 is provided for the preamplifier 16, and a high voltage power supply 20 is provided for the photomultiplier tube T.
The output pulses from the amplifier 18 are furnished to a gain stabilizer cirucuit 24 which is calibrated to respond to the energy level of a selected reference peak in the gamma ray energy spectrum, such as the 2.23 MeV energy peak of hydrogen in Window 2 (Figure 2). It should be understood, however, that other gamma ray energy peaks may be used for gain stabilization, if desired. The gain stabilizer circuit 24 is an automatic gain control circuit which responds to energy level of pulses at the calibrated peak level and adjusts the gain of all energy level pulses from the photomultiplier tube T to compensate for gain shift or variations in tube T and other circuitry of the apparatus of the present invention due to power supply voltage fluctuations and/or temperature effects.
The output pulses from gain stabilizer circuit 24 are supplied to a pulse height or multi-channel analyzer 26. The pulse height analyzer 26 may be of conventional design as known in the art and having, for example, four or more channels or energy divisions corresponding to quantizations or energy ranges of the pulse heights of the input pulses, if desired. The pulse height analyzer 26 functions to sort and accumulate a running total of the incoming pulses into a plurality of storage locations or channels based on the height of the incoming pulses which, it will be recalled, is directly related to the energy of the gamma rays causing the pulse. The output of the pulse height analyzer 26 in the case of the present invention consists of count pulses occurring in each of three energy ranges or windows as depicted in Figure 2.It should also be understood the three appropriately biased single channel analyzers may be used in place of the multi-channel 26, if desired.
The output from the pulse height analyzer 26 may be stored on a suitable memory device for subsequent processing, or alternatively, may be supplied directly, over an appropriate number of lines, to a computer 28, which obtains a measure of the concentration of chlorine or salt water in the fluid in the line 14, in a manner to set forth, from the number of chlorine counts, and the length of time for such count. Further, the computer 28 simultaneously determines, from the output of analyzer 26, a measure of the concentration of sulfur in the fluid in line 14, and the percentage of gas in such fluid. The results of such computations may be stored or displayed, as desired with a recorder 30 or other suitable display device.
Figure 2 shows a typical capture gamma ray spectrum 32 recorded using the equipment of
Figure 1 for a stream of crude oil containing small amounts of chlorine and sulfur. The intense peak of 2.23 MeV results from the capture of thermal neutrons by hydrogen in the crude oil and is used, as set forth above, as an energy reference peak by the gain stabilizer circuit of Figure 1. Figure 2 also shows the energy settings of the multi-channel analyzer 26.
The first setting, identified as "Window 1", extends from 5.75 to 8.0 MeV and includes photoelectric and escape peaks from the 7.79, 7.42, 6.64 and 6.11 MeV radiation from the Cl35 (n,y) Cl36 reaction as well as the 7.78, 7.42, 7.19, 6.64 and 5.97 MeV peaks from sulfur.
The second setting, indentified as Window 2. extends from 2.00 to 2.50 MeV and includes the 2.23 MeV hydrogen capture peak. The third setting, identified as Window 3, extends from 5.00 to 5.75 MeV and includes the 5.42 MeV sulfur capture peak.
Determination of chlorine content
A. No Free Hydrogen-containint Gas in the Crude Oil
If it is assumed that there is no free hydrogen-containing gas in the flowing stream of crude oil, the counts recorded in window 1, CI, for a count time T is given by the Equation Cl = Cci + C1B (17) where Co = counts due only to the C135 (n,y) Cl36 reaction ClB = the background counts in Window l due to all gamma radiation other than that
from the chlorine capture reaction Cci can be expressed as
Cci = PclKcLT (18) where Pci = the percent (by weight) of elemental chlorine contained in the crude oil KCl = a calibration constant depending upon the source strength, source-detector
spacing, detector efficiency, and geometry of the counting chamber
T = the count time in seconds
Substituting Equation (18) into Equation (17) and solving for Pcl yields
Theoretical Cl detection sensitivity of the apparatus A is summarized in Figure 6 which shows a plot of Cci versus Pci from Equation (14) using a count time T = 2000 seconds and KCl = 7.03 x 104. The grid at the top of the plot can be used to determine CCl as a function of percent water cut and the salinity of the water in ppm NaCl.The use of Figure 6 can best be illustrated by the following example:
Percent water in oil flow = 0.01%
Salinity of water = 50,000 ppm NaCl
This concentration of water and salinity corresponds to a concentration (by weight) of 0.000303% elemental chlorine and will produce Ccl = 4.8 x 104 net counts for a count time
T = 2000 seconds (33.3 minutes).
It is now of interest to determine the statistical accuracy to which chlorine concentration can be measured. The percent standard deviation SD of the measured count Ccl is given by the equation
SD = [(Cci + [2 . Cn . TCl)/Cl] X 100 (20) where CB is the background count rate in the 5.75 to the 8.0 MeV window in counts per second. It was stated earlier that Cn was estimated to be 37 counts per second for a 3" x 3"
NaI(Tl) detector and a Cf252 source emitting a 5 x 105 neutrons/second. For a 5" x 5"
NaI(Tl) detector, 5 . 107 neutron/second source, and TCl = 2000 seconds, the quantity
2 . Cu . Tci = 2. 37 . 2000 (Esx.s/E3x3) .
= 2.37 . 2000 (1.4/0.4) 102 = 5.19 . 107 and Equation (20) reduces to
SD = [(Cci + 5.19 . 107)/Cl] X 100 (21)
Figure 7 shows a plot of SD from Equation (21) using Equation (14) to relate CCl to Pcl -l with the percent water cut - salinity grid again included at the top of the plot. Again using the example of 0.010/o water cut at a salinity of 50,000 ppm NaCl, it can be seen from Figure 7 that the chlorine concentration can be measured to a standard deviation of #15 percent.
B. Free Gas in the Flowing Stream of Crude Oil
If a homogeneous mixture of gas is present in the flowing stream of crude oil, C1 is now given by the Equation
Cl = (Ccl + C1B) . G(G) (22)
= (KciPciT + ClB) . G(Pc,.) (22a) where G(PG) is a term dependent upon the hydrogen content of the crude oil-gas mixture which is, in turn, dependent upon Pc, the percent gas content of the crude oil. Likewise, the total counts recorded in window 2, C2, is given by the Equation C2 = (CH + C2D) .G(PG) (23) where
CH = count rate in the Window 2 due to H(n,y)2H activity C2u =the background counts in window 2 due to gamma radiation other than that
resulting from neutron capture in hydrogen
Solving Equations (22a) and (23) for Pci yields
where C1/C2 is the ratio of gross counts recorded in window 1 to window 2 during a count time T. The remaining terms on the right hand side of Equation (24) are determined when the system is calibrated.Specifically, ClB/T is determined by filling the chamber C with crude oil containing no free gas
and no chlorine and recording the gross count in window 1 (estimated to be
37 counts per second, as set forth above) (CH+C2B)/T is also the gross count rate recorded in window 2 with the counting chamber
filled with crude oil containing no free gas and no chlorine Kci is determined by (a) filling the count chamber with crude oil containing no
free gas and a known concentration Pci of chlorine, (b) recording Cl for a
time T and (c) solving equation (19) for Kci using C1i3 as determined above.
It should be noted that Equation (24) does not contain the gas term G(PG) and is, therefore, independent of the amount of free gas in the fluid.
Subtracting Equation (22) from Equation (23) and solving for G(PG) yields G(PG) = [C2-C1] [(CH+C2B) - (KClPciT+Cl )] (25) where
(C2-C,) is the difference in gross counts recorded in windows 2 and 1, respectively,
for time T
(CH+C2B) is predetermined in the calibration procedure above
Kcl and C1B are also predetermined in the calibration procedure above Pci is determined from equation (24)
As mentioned earlier, G(PG) is indicative of the percent gas content of the flowing stream of crude oil, if the free gas is homogeneously mixed in the fluid stream.
Simultaneous measurement of chlorine and sulfur content
With the present invention, it has also been found possible to determine the effects of variation in the fluid sulfur content upon the chlorine concentration measurement, and the precision to which sulfur concentration in the fluid can be measured. A series of gamma ray spectra was measured after adding known incremental amounts of chlorine (as Nacre) and sulfur (as H2SO4) to tap water in the counting chamber C using a source-detector spacing of 8".The results are illustrated in Figures 4 and 5, the combined data from which are summarized in Figure 8. Rcf, which is the ratio of counts in Window 1 to counts in Window 2, is plotted along the abcissa. Rs, the ratio of counts in Window 3 from 5.000 to 5.75 MeV (which includes the 5.42 MeV radiation from thermal neutron capture in sulfur) to the counts in Window 2, is plotted along the ordinate. Data points are denoted by (i, j) where and j are the grams of chlorine and sulfur, respectively, added to the fluid. Adjacent to each data point is the quantity (me,, M5) where M and M5 are the masses (in grams) of chlorine and sulfur, respectively, added to the fluid.The grid is constructed by least-squares fitting straight lines through the data and is labeled in grams and ppm or percent of the element added. The concentrations of chlorine and sulfur are also shown in parts per million and percent. respectively. Typical observed standard deviations are shown for Rc, and Rs for a 20 minute count. For this count time, the sulfur concentration can be determined to +0.08 percent. Results similar to those shown in Figure 8 can be expected using oil as a base fluid since oil and water have similar neutron moderation properties.
Once the R5 versus R,, grid has been constructed for a given counting chamber. the chlorine and sulfur content of an unknown fluid can be obtained from the measurement of R5 and Rc, It can be seen that Rc, is affccted to some extent by the sulfur content of the fluid. This is a result of the low intensity, high energy capture radiation from sulfur whose primary and escape peaks fall within the "chlorine" Window 1 (Figure 2). Likewise, it can be seen that Rs is also affected by the chlorine content of the fluid. This results from the escape peaks of the 6.64 and 6.11 MeV chlorine capture radiation that fall within the "sulfur" Window 3.It is apparent, however, that sulfur and chlorine and chlorine concentrations can be determined uniquely by recording Rs and Rce simultaneously and using the grid of Figure 8.
Thus, with the present invention, it is possible to obtain simultaneous measurements of chlorine and sulfur in a flowing stream of crude oil (or waste water), provided three energy windows of interest in the measured gamma ray spectrum are obtained. As set forth above, they are:
Window 1 5.75 MeV to 8.00 MeV
Window 2 2.00 MeV to 2.50 Mev
Window 3 5.00 MeV to 5.75 MeV
As described above, the ratio of counts recorded in Window 1 to the counts recorded in
Window 2, Rcr, increases linearly for a given sulfur concentration and (for concentrations of the subject element less than a few percent) with the chlorine content of the fluid and is independent of the hydrogen index or density of the fluid.The ratio of counts recorded in
Window 3 to Window 2, Rs, also increases linearly (again, for a given chlorine content for concentrations of the subject element less than a few percent) with the sulfur content of the fluid. It is possible, therefore, to measure Rce and Rs simultaneously and obtained elemental concentrations of both chlorine and sulfur from a plot Rs versus Rcf.
It should be understood that the techniques described above are not necessarily confined to a counting chamber geometry. In the event that the subject measurement must be made in a flow line without cutting the pipe or without diverting a portion of the stream to a counting chamber as described above, it would still be possible to make and estimation of the chlorine content (albeit not as precise) by locating the source S and detector D against the pipe 14 on opposite sides of it.
The neutron source S and detector D are mounted on the outside of the exisiting flow line 14 by means of a suitable clamp device C, or other suitable pipe attachment means, as shown in Figure 3. The remainder of the apparatus of Figure 3 corresponds to that of Figure 1 and thus is not shown. However, this apparatus is connected to the preamplifier 16 and photomultiplier tube T in the manner set forth above for Figure 1. Measurements have been made indicating that ppm concentrations of chlorine and 0.1 percent concentrations of sulfur can be detected using this "through-pipe" technique of Figure 3; however, for a given count time, the precision to which the through-pipe measurements can be made is not as good as that obtained using a counting chamber.
From the foregoing, it can be seen that the present invention provides for the simultaneous measurement of chlorine and sulfur and can be used in various producing operations such as
(1) Monitoring chlorine and sulfur content at a well head. The chlorine measurement
could be used to monitor the percentage of water in the fluid produced from the well
if the salinity of the produced water is known.
(2) Monitor chlorine and sulfur at a loading dock.
(3) Monitor the chlorine and sulfur content of water prior to disposal.
In refining operations, the proposed technique can be used to
(1) Monitor sulfur and chlorine in a feed stock.
(2) Monitor sulfur and/or chlorine content of refined products.
Among the primary advantages of the present invention are:
1. Concentrations of chlorine as small as 0.0001 percent (by weight) can be detected in a
flowing stream of crude.
2. The chlorine concentration measurement is independent of the linear flow velocity or
the volume flow rate of the crude oil.
3. The technique is ideally suited for remote. continuous monitoring in the sense that
the system requires minimal maintenance and relatively simple electronic equip
ment.
4. By stabilizing the gain of the gamma ray detector automatically on a suitable peak
with gain stabilizer 24, the system will require minimal adjustment and can be
operated by unskilled personnel.
5. The system can also give a quantitative indication of the free gas content of the crude
oil, (a) if the free gas/liquid mixture is homogeneous and (b) if the linear flow
velocities of the liquid and gas phases are the same.
WHAT WE CLAIM IS:
1. A method for determining the concentrations of chlorine and sulfur of a fluid flowing in a conduit comprising: bombarding the fluid with neutrons, which are slowed down and
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (26)
1. A method for determining the concentrations of chlorine and sulfur of a fluid flowing in a conduit comprising: bombarding the fluid with neutrons, which are slowed down and
thereafter engage in thermal neutron capture reactions with materials in the fluid; obtaining a gamma ray energy spectrum of the gamma rays arising in response to said thermal neutron capture reactions; obtaining a measure of the concentration of chlorine in the fluid and substantially simultaneously obtaining a measure of the concentration of sulfur in the fluid from the gamma ray energy spectrum; and utilizing said measure of the concentration of chlorine to provide a measure of the concentration of salt water in the fluid.
2. A method as claimed in claim 1, wherein the fluid is feed stock in a petroleum refining conduit.
3. A method as claimed in claim 1, wherein the fluid is refined product in a petroleum refining conduit.
4. A method as claimed in claim 1, wherein the fluid is crude oil in a well head conduit at an oil well.
5. A method as claimed in claim 1, wherein the fluid is crude oil at a loading dock.
6. A method as claimed in claim 1, wherein the fluid is waste water for disposal.
7. A method as claimed in any one of claims 1 to 6, wherein substantially all the chlorine in the fluid is present as sodium chloride, and wherein the measure of the concentration of salt water is obtained from the measure of the concentration of chlorine.
8. A method as claimed in any one of claims 1 to 7, wherein a hydrogen-containing gas is present in the fluid in the conduit, and including utilizing said measure of the concentration of chlorine to provide a measure of the percent gas content in the fluid.
9. A method as claimed in any one of claims 1 to 8, wherein said step of obtaining a gamma ray energy spectrum includes making a gamma ray count in the energy range of from 5.0 MeV to 8.0 MeV.
10. A method as claimed in any one of claims 1 to 9, including making a gamma ray count in the energy range of from 2.0 MeV to 2.50 MeV to include the 2.23 MeV capture reaction of hydrogen, and using said last-mentioned count as a reference for gain stabilization.
11. A method as claimed in any one of claims 1 to 10, wherein said bombarding is effected by neutrons emitted by a neutron source attached to the conduit.
12. A method as claimed in any one of claims 1 to 10, wherein said bombarding is effected by neutrons emitted by a neutron source disposed outside the conduit in a recess in the conduit wall.
13. Apparatus for analysis of a fluid flowing in a conduit comprising: bombarding means attached to a wall of said conduit for bombarding the fluid with neutrons, which are slowed down and thereafter engage in thermal neutron capture reactions with materials in the fluid; means attached to a wall of said conduit at a distance from said bombarding means for obtaining a gamma ray energy spectrum of the gamma rays arising in response to said thermal neutron capture reactions: means for obtaining a measure of the concentration of chlorine in the fluid from the gamma ray energy spectrum; means for obtaining a measure of the concentration of sulfur in the fluid from the gamma ray energy spectrum substantially simultaneously with the measure of the concentration of chlorine, and means for utilizing said measure of the concentration of chlorine to provide a measure of the concentration of salt water in the fluid.
14. Apparatus as claimed in claim 14, wherein said bombarding means is mounted adjacent a petroleum refinery feed stock conduit.
15. Apparatus as claimed in claim 14, wherein said bombarding means is mounted adjacent a petroleum refinery refined product conduit.
16. Apparatus as claimed in claim 14, wherein said bombarding means is mounted adjacent a well head crude oil conduit at an oil well.
17. Apparatus as claimed in claim 14, wherein said bombarding means is mounted adjacent a crude oil conduit at a loading dock.
18. Apparatus as claimed in claim 14, wherein said bombarding means is mounted adjacent a waste water disposal conduit.
19. Apparatus as claimed in any one of claims 13 to 18, wherein substantially all the chlorine in the fluid is present as sodium chloride, and wherein the measure of the concentration of salt water is obtained from the measure of the concentration of chlorine.
20. Apparatus as claimed in any one of claims 13 to 19, wherein a hydrogen-containing gas is present in the fluid in the conduit, and including means for utilizing said measure of the concentration of chlorine to provide a measure of the percent gas content in the fluid.
21. Apparatus as claimed in any one of claims 13 to 20, wherein said means for obtaining a gamma ray energy spectrum includes making a gamma ray count in the energy range of from 5.0 MeV to 8.0 MeV.
22. Apparatus as claimed in any one of claims 13 to 21, including means for making a gamma ray count in the energy range of from 2.0 MeV to 2.50 MeV to include the 2.23
MeV capture reaction of hydrogen. and means for using said last-mentioned count as a reference for gain stabilization.
23. Apparatus as claimed in any one of claims 13 to 22, wherein said means for bombarding is attached to the exterior of said conduit.
24. Apparatus as claimed in any one of claims 13 to 22, wherein said means for bombarding is inserted into a recess in the conduit wall outside said conduit.
25. A method for analysis of a fluid flowing in a conduit, substantially as described herein with reference to the accompanying drawings.
26. Apparatus for analysis of a fluid flowing in a conduit, substantially as described herein with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US74807276A | 1976-12-06 | 1976-12-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1585305A true GB1585305A (en) | 1981-02-25 |
Family
ID=25007876
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB4804377A Expired GB1585305A (en) | 1976-12-06 | 1977-11-18 | Detection of impurities in fluid flowing in refinery pipeline or oil production operations using nuclear techniques |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS53105290A (en) |
| CA (1) | CA1088680A (en) |
| DE (1) | DE2754143A1 (en) |
| FR (1) | FR2373055A1 (en) |
| GB (1) | GB1585305A (en) |
| IT (1) | IT1113805B (en) |
| NL (1) | NL7713414A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107796861A (en) * | 2016-09-05 | 2018-03-13 | 中国石油化工股份有限公司 | The detection method of content of organic chloride in crude oil containing free water |
| CN116341764A (en) * | 2023-05-24 | 2023-06-27 | 中国石油大学(华东) | Method and system for predicting mixed oil concentration distribution of finished oil pipeline based on historical data |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4200789A (en) * | 1978-06-29 | 1980-04-29 | Texaco Inc. | Measuring oil and water cuts in a multiphase flowstream with elimination of the effects of gas in determining the liquid cuts |
| US4190768A (en) * | 1978-06-29 | 1980-02-26 | Texaco Inc. | Determining the water cut and water salinity in an oil-water flow stream by measuring the sulfur content of the produced oil |
| EP0007759A1 (en) * | 1978-07-21 | 1980-02-06 | United Kingdom Atomic Energy Authority | Method of and apparatus for measuring the water content of crude oil |
| US4365154A (en) * | 1980-03-06 | 1982-12-21 | Texaco Inc. | Detection of impurities in a fluid containing free gas using nuclear techniques |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2744199A (en) * | 1952-11-28 | 1956-05-01 | Exxon Research Engineering Co | Determination of halogen in oil streams |
| US2983817A (en) * | 1956-07-23 | 1961-05-09 | Gulf Research Development Co | Neutron-capture, gamma-ray prospecting method |
-
1977
- 1977-11-18 GB GB4804377A patent/GB1585305A/en not_active Expired
- 1977-11-21 CA CA291,301A patent/CA1088680A/en not_active Expired
- 1977-12-05 DE DE19772754143 patent/DE2754143A1/en not_active Ceased
- 1977-12-05 NL NL7713414A patent/NL7713414A/en not_active Application Discontinuation
- 1977-12-05 IT IT3038777A patent/IT1113805B/en active
- 1977-12-06 JP JP14650777A patent/JPS53105290A/en active Pending
- 1977-12-06 FR FR7736642A patent/FR2373055A1/en active Granted
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107796861A (en) * | 2016-09-05 | 2018-03-13 | 中国石油化工股份有限公司 | The detection method of content of organic chloride in crude oil containing free water |
| CN107796861B (en) * | 2016-09-05 | 2021-01-01 | 中国石油化工股份有限公司 | Method for detecting content of organic chlorine in crude oil containing free water |
| CN116341764A (en) * | 2023-05-24 | 2023-06-27 | 中国石油大学(华东) | Method and system for predicting mixed oil concentration distribution of finished oil pipeline based on historical data |
| CN116341764B (en) * | 2023-05-24 | 2023-09-26 | 中国石油大学(华东) | Method and system for predicting mixed oil concentration distribution of finished oil pipeline based on historical data |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2373055A1 (en) | 1978-06-30 |
| DE2754143A1 (en) | 1978-06-08 |
| FR2373055B1 (en) | 1983-04-29 |
| CA1088680A (en) | 1980-10-28 |
| JPS53105290A (en) | 1978-09-13 |
| IT1113805B (en) | 1986-01-27 |
| NL7713414A (en) | 1978-06-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |