CHARACTERIZATION OF CRUDE OIL BY FOURIER TRANSFORM ION CYCLOTRON RESONANCE MASS SPECTROMETRY
20170363602 · 2017-12-21
Inventors
Cpc classification
H01J49/0036
ELECTRICITY
G16C20/30
PHYSICS
International classification
Abstract
A system, method and computer program product are provided for calculating one or more indicative properties, e.g., one or more of the cetane number, octane number, pour point, cloud point and aniline point of oil fractions, from the density and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of a sample of an oil sample.
Claims
1. A system for assigning an indicative property of to a fraction of an oil sample, based upon Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) data, the system comprising: a non-volatile memory device that stores calculation modules and data, the data including FT-ICR MS data indicative of intensities at corresponding mass-to-charge ratio of ions (m/z) derived from the oil sample; a processor coupled to the memory; a first calculation module that calculates the carbon numbers and double hood equivalents from the FT-ICR MS data; a second calculation module that calculates and assigns a FT-ICR MS index value a function of the FT-ICR MS peak intensity and carbon numbers; and a third calculation module that calculates and assigns the indicative property as a function of the FT-ICR MS index value and a density of the oil sample.
2. A system for assigning an indicative property of to a fraction of an oil sample comprising: a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) that outputs FT-ICR MS data; a non-volatile memory device that stores calculation modules and data, the data including FT-ICR MS data indicative of intensities at corresponding mass-to-charge ratio of ions (m/z) derived from the oil sample; a processor coupled to the memory; a first calculation module that calculates the carbon numbers and double bond equivalents from the FT-ICR MS data; a second calculation module that calculates and assigns a FT-ICR, MS index value a function of the FT-ICR MS peak intensity and carbon numbers; and a third calculation module that calculates and assigns the indicative property as a function of the FT-ICR MS index value and a density of the oil sample.
3. A method for operating a computer to assign an indicative property to a fraction of an oil sample based upon Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) data, the method comprising: entering into the computer a density of the oil sample and FT-ICR MS data indicative of intensities at corresponding mass-to-charge ratio of ions (m/z) derived from the oil sample; calculating the carbon numbers and double bond equivalents from the FT-ICR MS data; calculating and assigning a FT-ICR MS index value a function of the FT-ICR MS peak intensity and carbon numbers; and calculating and assigning the indicative property as a function of the FT-ICR MS index value and the density of the oil sample.
4. A method for operating a computer to assign an indicative property to a fraction of an oil sample, the method comprising: obtaining Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) data from a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS), the FT-ICR MS data indicative of intensities at corresponding mass-to-charge ratio of ions (m/z) derived from the oil sample; obtaining a density of the oil sample; entering into the computer the density of the oil sample and the FT-ICR MS data; calculating the carbon numbers and double bond equivalents from the FT-ICR MS data; calculating and assigning a FT-ICR MS index value a function of the FT-ICR MS peak intensity and carbon numbers; and calculating and assigning the indicative property as a function of the FT-ICR MS index value and the density of the oil sample.
5. The method of claim 3 wherein the oil sample is crude oil.
6. The method of claim 3 wherein the oil sample is obtained from an oil well, stabilizer, extractor, or distillation tower.
7. The method of claim 3 wherein the indicative property is a cetane number.
8. The method of claim 3 wherein the indicative property is a pour point.
9. The method of claim 3 wherein the indicative property is a cloud point.
10. The method of claim 3 wherein the indicative property is an aniline point.
11. The method of claim 3 wherein the indicative property is an octane number.
12. The method of claim 3 wherein plural indicative properties are calculated including at least two indicative properties selected from the group consisting of cetane number, pour point, cloud point, aniline point and octane number.
13. The method of claim 3 wherein the indicative property is of a gas oil fraction boiling in the nominal range 180-370° C.
14. The method of claim 3 wherein the indicative property is of a gasoline fraction boiling in the nominal range 36-180° C.
15. The method of claim 4, wherein the masses covered by FT-ICR MS are in the range 150-1400 m/z.
16. The method of claim 4, wherein the carbon numbers detected by FT-ICR MS are in the range 1-60.
17. The method of claim 4, wherein the double bond equivalence calculated by FT-ICR MS are in the range 1-40.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Further advantages and features of the present invention will become apparent from the following detailed description of the invention when considered with reference to the accompanying drawings in which:
[0023]
[0024]
[0025]
[0026]
DETAILED DESCRIPTION OF INVENTION
[0027] A system and method is provided for determining one or more indicative properties of a hydrocarbon sample. Indicative properties (e.g., one or more of cetane number, pour point, cloud point and aniline point) of a gas oil fraction in crude oil samples are assigned as a function of FT-ICR MS measurement of a crude oil sample and the density of the crude oil sample.
[0028] The correlations provide information about gas oil and/or naphtha indicative properties without fractionation/distillation (crude oil assays) and will help producers, refiners, and marketers to benchmark the oil quality and, as a result, valuate the oils without performing the customary extensive and time-consuming crude oil assays. The currently used crude oil assay method is costly in terms of money and time. It costs about $50,000 US and takes two months to complete one assay. With the method and system herein, the crude oil can be classified as a function of FT-ICR MS measurement data, and thus decisions can be made for purchasing and/or processing.
[0029] The systems and methods are applicable for naturally occurring hydrocarbons derived from crude oils, bitumens, heavy oils, shale oils and from refinery process units including hydrotreating, hydroprocessing, fluid catalytic cracking, coking, and visbreaking or coal liquefaction. Samples can be obtained from various sources, including an oil well, stabilizer, extractor, or distillation tower.
[0030] In the system and method herein, a mass spectra is obtained by a suitable known or to be developed FT-ICR MS, and from this spectra signal intensity data is obtained (Y-axis in
[0031] Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) includes two components: an ionization source and a mass analyzer. The ionization source ionizes molecules, while the mass analyzer determines the mass-to-charge ratio (m/z) of ions.
[0032] A number of ionization sources have been used in gas chromatography and mass spectrometry, with some being preferable for gases, others for liquids, and others for solids. Ionization sources for gas chromatography include electron ionization (EI), which uses a glowing filament, which may break down the molecules under study. Inductively coupled plasma ionization (ICP) is a destructive technique which applies heat to reduce a sample to its atomic components. Chemical ionization (CI), a subset of EI, adds gases such as methane, isobutane, or ammonia, producing results that are less damaging to the molecules under study. Direct analysis in real time (DART) ionizes samples at atmospheric pressure using an electron beam. Matrix-assisted, laser desorption ionization (MALDI) is a solid phase process that uses laser energy to ionize molecules off a metal target plate. Electrospray ionization (ESI), is a liquid phase process that produces a fine mist of droplets, as from an atomizer.
[0033] FT-ICR MS frequently relies on ESI or on a related variant, such as atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI). APCI uses a corona discharge from an electrified needle to induce ionization of a solvent, which in turn reacts with the sample molecules to induce a chemical reaction resulting in an ionized sample molecule. APPI uses a photon discharge from high-intensity ultraviolet light to ionize the solvent gas, which in turn ionizes the sample molecules. APCI works well with relatively small, neutral, or hydrophobic compounds, such as steroids, lipids, and non-polar drugs. APPI works well with highly non-polar molecules like napthols and anthracenes.
[0034] Thus, in the petroleum industry, FT-ICR is conducted using ESI, and preferably the APPI variant of ESI. A petroleum sample is diluted in an appropriate solvent and infused into the spectrometer. The liquid sample is evaporated and the components are ionized by ESI or APPI, yielding unfragmented gas phase ions of the sample components. These ions are trapped in the strong magnetic field of the mass analyzer, where their mass-to-charge ratios are determined with high resolution and accuracy. The spectrometer provides a resolution of R>300,000 at m/z 400, which is high enough for routinely separating signals spaced as closely as 3.4 mDa (SH.sub.4 vs. .sup.12C.sub.3), which is essential for the correct assignment of the elemental composition (C.sub.cH.sub.hN.sub.nO.sub.oS.sub.sNi.sub.iN.sub.v) corresponding to each mass signal in petroleum samples. The identified elemental compositions are then classified according to the heteroatoms in their elemental composition, e.g., pure hydrocarbons, mono-sulfur (or mono-nitrogen) species for molecules with one sulfur (or nitrogen) atom, or molecules with any combination of heteroatoms. The corresponding double bond equivalent (DBE) values and carbon numbers are calculated for each identified elemental composition, where the DBE is defined as half the number of hydrogen atoms lacking from a completely saturated molecule with an otherwise identical number of carbon and heteroatoms.
[0035]
[0036] Equation (1) shows the FT-ICR mass spectrometry index, FTMSI, which is calculated in step 225:
[0037] where:
[0038] Intensity=the intensity for each carbon atom.
[0039] The indicative properties (e.g., the cetane number, pour point, cloud point and aniline point of the gas oil fraction boiling in the range 180-370° C. and octane number for gasoline fraction boiling in the range 36-180° C.) of the crude oil can be predicted from the density of whole crude oil (which is determined in step 230), and from the Fourier Transform Ion Cyclotron Resonance Mass Spectrometry index (FTMSI) of crude oil (which was determined in step 225). That is,
Indicative Property=f(density.sub.crude oil,FTMSI.sub.crude oil) (2);
[0040] Equations (3) through (6) show, respectively, the cetane number, pour point, cloud point aniline point of gas oils boiling in the range 180-370° C., and equation (7) shows the octane number of gasoline boiling in the range 36-180° C. that can be predicted from the density and Fourier transform ion cyclotron resonance mass spectrometry index of crude oils. Thus, in step 235, the cetane number is calculated as:
Cetane Number(CET)=K.sub.CET+X1.sub.CET*DEN+X2.sub.CET*FTMSI+X3.sub.CET*FTMSI.sup.2+X4.sub.CET*FTMSI.sup.3 (3);
[0041] In step 240, the pour point is calculated as:
Pour Point(PPT)=K.sub.PPT+X1.sub.PPT*DEN+X2.sub.PPT*FTMSI+X3.sub.PPT*FTMSI.sup.2+X4.sub.PPT*FTMSI.sup.3 (4)
[0042] In step 245, the cloud point is calculated as:
Cloud Point(CPT)=K.sub.CPT+X1.sub.CPT*DEN+X2.sub.CPT*FTMSI+X3.sub.CPT*FTMSI.sup.2+X4.sub.CPT*FTMSI.sup.3 (5)
[0043] In step 250, the aniline point is calculated as:
Aniline Point(AP)=K.sub.AP+X1.sub.AP*DEN+X2.sub.AP*FTMSI+X3.sub.AP*FTMSI.sup.2+X4.sub.AP*FTMSI.sup.3 (6)
[0044] In step 255, the octane number is calculated as:
Octane Number(ON)=K.sub.ON+X1.sub.ON*DEN+X2.sub.ON*FTMSI+X3.sub.ON*FTMSI.sup.2 (7)
[0045] where:
[0046] DEN=density of the crude oil sample;
[0047] FTMSI=Fourier transform ion cyclotron resonance mass spectrometry index (derived from FT-ICR MS data); and
K.sub.CET, X1.sub.CET-X4.sub.CET, K.sub.PPT, X1.sub.PPT-X4.sub.PPT, K.sub.CPT, X1.sub.CPT-X4.sub.CPT, K.sub.AP, X1.sub.AP-X4.sub.AP, K.sub.ON, X1.sub.ON-X3.sub.ON are constants that were developed using linear regression analysis of hydrocarbon data from the APPI mode of FT-ICR MS.
[0048]
[0049]
[0050] Program storage memory 470 and data storage memory 480 can each comprise volatile (RAM) and non-volatile (ROM) memory units and can also comprise hard disk and backup storage capacity, and both program storage memory 470 and data storage memory 480 can be embodied in a single memory device or separated in plural memory devices. Program storage memory 470 stores software program modules and associated data, and in particular stores a density and raw data receiving module 310, peak sorting module 315, heteroatom class export module 320, FTMSI calculation module 325, cetane number calculation module 330, pour point calculation module 340, cloud point calculation module 345, aniline point calculation module 350, and octane number calculation module 355. Data storage memory 480 stores data used and/or generated by the one or more modules of the present invention, including but not limited to density of the crude oil sample, raw data generated by the FT-ICR MS APPI source, and m/z correlations with DEB data and carbon number data.
[0051] The calculated and assigned results in accordance with the systems and methods herein are displayed, audibly outputted, printed, and/or stored to memory for use as described herein.
[0052] It is to be appreciated that the computer system 400 can be any general or special purpose computer such as a personal computer, minicomputer, workstation, mainframe, a dedicated controller such as a programmable logic controller, or a combination thereof. While the computer system 400 is shown, for illustration purposes, as a single computer unit, the system can comprise a group/farm of computers which can be scaled depending on the processing load and database size, e.g., the total number of samples that are processed and results maintained on the system. The computer system 400 can serve as a common multi-tasking computer.
[0053] Computer system 400 preferably supports an operating system, for example stored in program storage memory 470 and executed by the processor 420 from volatile memory. According to the present system and method, the operating system contains instructions for interfacing the device 400 to the calculation module(s). According to an embodiment of the invention, the operating system contains instructions for interfacing computer system 400 to the Internet and/or to private networks.
Example
[0054] Crude oil samples were prepared and analyzed by atmospheric pressure photo ionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) according to the method 200 described herein, and illustrated in
[0055] In step 205, Stock solution 1 is prepared by dissolving a 100 μL sample of the crude oil in 10 mL of toluene (or alternatively, in a 50/50% volume mixture of toluene with methanol, methylene chloride, dichloromethane or tetrahydrofuran). If complete solubility is not attained, based upon visual observation against a light source, methylene chloride is added to achieve a clear solution. The solution is shaken for a minimum of 20 seconds.
[0056] Solution 2 is prepared with a 1:100 dilution of solution 1 in methylene chloride. The miscibility of the solvent mix must be ensured.
[0057] Solution 3 is prepared with a 1:10 dilution of solution 2 in methylene chloride (i.e., 100 μL of solution 2 in 900 μL solvent).
[0058] The dilution ratio depends on the sample and has to be determined empirically on a case-by-case basis, starting from solution 3, then advancing to solution 2 and then to solution 1.
Key Instrument Parameters
[0059] For each analysis of a sample, the operator tunes the spectrometer settings to optimize performance. Key parameters and default settings follow:
[0060] TD (Fid Size): 4M
[0061] Average Spectra: 100
[0062] Source Accumulation: 0.001 s
[0063] Ion Accumulation Time: 0.001 s
[0064] TOF (AQS): variable, depending on sample
[0065] APPI Temperature 250-400° C., depending on sample
[0066] Detection Mode: Broadband
[0067] Low Mass: 150 to 350 m/z
[0068] High Mass: 3000 m/z
Mass Calibration and Performance Check
[0069] The performance of the FT-ICR MS instrument is checked by obtaining a mass calibration in ESI positive mode. This ESI calibration can be used in the APPI mode by exchanging the ESI ion source with the APPI source. The mass calibration remains valid for one day of normal operation as long as the key instrument parameters described above have not been changed. A change of any of the key instrument parameters requires a complete recalibration by switching to the ESI source, calibration, followed by switching back to the APPI source.
Analysis
[0070] In step 210, the analysis begins with Solution 3, which is directly infused into the mass calibrated FT-ICR MS APPI source by a syringe pump. The operator records and averages 100 accumulated scans, which serve as a general basis for fine-tuning the instrument parameters.
[0071] If sufficient signal intensity (10.sup.8 to 10.sup.9 units) is not obtained with Solution 3, the analysis is repeated with Solution 2. If the analysis with Solution 2 still does not yield sufficient signal intensity, the analysis is repeated with Solution 1.
[0072] The operator checks the signal shape at the beginning, middle and end of the mass range. An excessive sample load can be diagnosed by a signal splitting. In case of signal splitting, all signals will appear as two closely aligned signals or, in severe cases, even as a group of signals. When the operator observes such signal splitting, he should dilute the sample until he obtains a good independent signal shape.
[0073] The following pass/fail criteria are applied to the tests. A mass calibration is acceptable when every mass calibrant in the mass range of the sample does not deviate more than ±0.2 ppm from the expected value, except calibrants that are discarded from the list due to either low intensity (below 3 times the baseline noise) or a calibrant signal that is overlapping a contamination signal.
Data Processing Workflow
[0074] Data processing is an extensive exercise involving four different software packages as described below. Data processing can significantly impact the quality of the produced data and therefore must be performed by, or under the direction of an experienced scientist. The trade names of the respective programs are followed by their sources.
[0075] DataAcquisition from Bruker Daltonics of Bremen, Germany. The raw data is checked for sufficient signal shape and intensity as described above and, if necessary, re-measured until sufficient signal shape and intensity are obtained.
[0076] DataAnalysis from Bruker Daltonics of Bremen, Germany. The recorded raw data file is loaded into the DataAnalysis software. In step 215, the peak list is sorted according to increasing m/z values. The m/z values and intensities are then saved as a peak list “text file.”
[0077] Composer from SierraAnalytics of Modesto, Calif. The peak lists are loaded into the Composer software. The Composer software is started and a suitable parameter file is loaded. In step 220, the recalibration is checked by looking at the identified species. The individual series are inspected for consistency, i.e., for missing series and/or interrupted series, which may indicate non-ideal re-calibration. In exceptional cases, recalibration parameters have to be fine tuned until a good fit of the data is obtained. The main heteroatom classes, which are those constituting more than 1 percent of the assigned heteroatom classes, are exported into the Microsoft Excel spreadsheet “Automatic Processing Composer Data.xls.”
[0078] Excel Spreadsheet Automatic Processing Composer Data: This in-house developed spreadsheet processes the elemental compositions calculated by the Composer software and produces all graphs in a final reporting form. An Excel workbook with one summary tab and detail tabs for each identified heteroatom class is created.
[0079] Exemplary constants K.sub.CET, X1.sub.CET-X4.sub.CET, K.sub.PPT, X1.sub.PPT-X4.sub.PPT, K.sub.CPT, X1.sub.CPT-X4.sub.CPT, K.sub.AP, X1.sub.AP-X4.sub.AP, K.sub.ON, X1.sub.ON-X3.sub.ON are were developed using linear regression analysis of hydrocarbon data from the APPI mode of FT-ICR MS, and are given in Table 3.
TABLE-US-00003 TABLE 3 Cetane Pour Cloud Aniline Octane Constants Number Point Point Point Number K −322.2 −266.1 4.5 166.7 128.8 X1 419.0 299.4 −3.4 −119.8 −91.1 X2 −22.9 −180.7 −127.2 51.0 8.8 X3 198.8 558.1 330.6 −123.9 3.2 X4 −175.3 −387.4 −215.0 70.2 —
[0080] A sample of Arabian medium crude with a 15° C./4° C. density of 0.8828 Kg/l was analyzed by APPI FT-ICR MS, using the described method. The mass spectral data is presented in Table 4 and is shown in
[0081] The FT-ICR MS index, FTMSI, is calculated using equation (1) by summing the intensities of the detected peaks and then dividing by 1E+11, with the value in the example calculated as 0.40707.
TABLE-US-00004 TABLE 4 Double Bond Equivalent (DBE) Intensity 0 0 1 0 2 0 3 0 4 3047754803 5 4148548475 6 4106580447 7 4475073884 8 4874039296 9 4852787148 10 4060232629 11 2831278701 12 2726027390 13 2196336212 14 1348225844 15 980497462 16 604773496 17 455374155 18 0 19 0
[0082] Applying equation (3) and the constants from Table 3,
[0083] Applying equation (4) and the constants from Table 3,
[0084] Applying equation (5) and the constants from Table 3,
[0085] Applying equation (6) and the constants from Table 3,
[0086] Applying equation (7) and the constants from Table 3,
[0087] In alternate embodiments, the present invention can be implemented as a computer program product for use with a computerized computing system. Those skilled in the art will readily appreciate that programs defining the functions of the present invention can be written in any appropriate programming language and delivered to a computer in any form, including but not limited to: (a) information permanently stored on non-writeable storage media (e.g., read-only memory devices such as ROMs or CD-ROM disks); (b) information alterably stored on writeable storage media (e.g., floppy disks and hard drives); and/or (c) information conveyed to a computer through communication media, such as a local area network, a telephone network, or a public network such as the Internet. When carrying computer readable instructions that implement the present invention methods, such computer readable media represent alternate embodiments of the present invention.
[0088] As generally illustrated herein, the system embodiments can incorporate a variety of computer readable media that comprise a computer usable medium having computer readable code means embodied therein. One skilled in the art will recognize that the software associated with the various processes described can be embodied in a wide variety of computer accessible media from which the software is loaded and activated. Pursuant to In re Beauregard, 35 USPQ2d 1383 (U.S. Pat. No. 5,710,578), the present invention contemplates and includes this type of computer readable media within the scope of the invention. In certain embodiments, pursuant to In re Nuijten, 500 F.3d 1346 (Fed. Cir. 2007) (U.S. patent application Ser. No. 09/211,928), the scope of the present claims is limited to computer readable media, wherein the media is both tangible and non-transitory.
[0089] The system and method of the present invention have been described above and with reference to the attached figure; however, modifications will be apparent to those of ordinary skill in the art and the scope of protection for the invention is to be defined by the claims that follow.