Method to prepare virtual assay using nuclear magnetic resonance spectroscopy
Systems and methods are disclosed for providing virtual assays of an oil sample such as crude oil based on nuclear magnetic resonance (NMR) spectroscopy carried out on the oil sample, and the density of the oil sample. The virtual assay provides a full range of information about fractions of the oil sample including naphtha, gas oil, vacuum gas oil, vacuum residue, and other information about the properties of the oil sample. Using the system and method herein, the virtual assay data pertaining to these several fractions of the oil sample and the oil sample itself are obtained without fractionation of the oil sample into the several components.
1. A method for producing a virtual assay of an oil sample, wherein the oil sample is characterized by a density, wherein the oil sample is selected from a group consisting of crude oil, bitumen and shale oil, and wherein the oil sample is characterized by a naphtha fraction, a gas oil fraction, a vacuum gas oil fraction and a vacuum residue fraction, the method comprising:
preparing a solution of the oil sample by mixing the oil sample with a nuclear magnetic resonance (NMR) spectroscopy solvent;
operating an NMR spectrometer with the solution to obtain NMR spectroscopy data by directly analyzing the oil sample without distillation;
entering into a computer, the NMR spectroscopy data, wherein the NMR spectroscopy data is indicative of aromatic content, and optionally one or both of paraffinic content and naphthenic content, of the oil sample, wherein the aromatic content, and the optionally one or both of the paraffinic content and the naphthenic content, are used as one or more analytical values (AVs); and
calculating and assigning, as a function of the one or more AVs, and the density of the oil sample, virtual assay data of the oil sample and the naphtha fraction, the gas oil fraction, the vacuum gas oil fraction and the vacuum residue fractions, the virtual assay data comprising a plurality of assigned assay data values,
wherein the virtual assay data is used to evaluate the oil sample without distillation and is used to determine an appropriate refinery or refining unit,
wherein the virtual assay data comprises:
the plurality of assigned assay data values pertaining to the oil sample including one or more of the aromatic content, C5-asphaltenes content, elemental composition of sulfur and elemental composition of nitrogen, micro-carbon residue content, total acid number and viscosity;
the plurality of assigned assay data values pertaining to the vacuum residue fraction of the oil sample including one or more of the elemental composition of sulfur and the micro-carbon residue content;
the plurality of assigned assay data values pertaining to the vacuum gas oil fraction of the oil sample including one or more of the elemental composition of sulfur and the elemental composition of nitrogen;
the plurality of assigned assay data values pertaining to the gas oil fraction of the oil sample including one or more of the elemental composition of sulfur and the elemental composition of nitrogen, the viscosity, and indicative properties including aniline point, cetane number, cloud point and pour point; and
the plurality of assigned assay data values pertaining to the naphtha fraction of the oil sample including one or more of the aromatic content, elemental composition of hydrogen and the elemental composition of sulfur, paraffin content and octane number.
2. The method of claim 1 , wherein the virtual assay data comprises:
the plurality of assigned assay data values pertaining to the oil sample including the aromatic content, the C5-asphaltenes content, the elemental composition of sulfur and the elemental composition of nitrogen, the micro-carbon residue content, the total acid number and the viscosity;
the plurality of assigned assay data values pertaining to the vacuum residue fraction of the oil sample including the elemental composition of sulfur and the micro-carbon residue content;
the plurality of assigned assay data values pertaining to the vacuum gas oil fraction of the oil sample including the elemental composition of sulfur and the elemental composition of nitrogen;
the plurality of assigned assay data values pertaining to the gas oil fraction of the oil sample including the elemental composition of sulfur and the elemental composition of nitrogen, the viscosity, and the indicative properties including the aniline point, the cetane number, the cloud point and the pour point; and
the plurality of assigned assay data values pertaining to the naphtha fraction of the oil sample including the aromatic content, the elemental composition of hydrogen and the elemental composition of sulfur, the paraffin content and the octane number.
3. The method of claim 2 , wherein the virtual assay data further comprises:
yields of fractions from the oil sample as mass fractions of boiling point ranges, including one or more of naphtha, gas oil, vacuum gas oil and vacuum residue;
composition information of hydrogen sulfide and/or mercaptans in the oil sample and/or corresponding fractions;
elemental compositions of one or more of carbon, hydrogen, nickel, and vanadium;
physical properties of the oil sample and/or corresponding fractions including one or more of API gravity and refractive index; or
indicative properties of the oil sample and/or corresponding fractions including one or more of flash point, freezing point and smoke point.
4. The method of claim 1 , wherein the nuclear magnetic resonance spectrometer employs 1 H active nuclei to derive the aromatic content, and the optionally one or both of the paraffinic content and the naphthenic content.
5. The method of claim 1 , wherein the nuclear magnetic resonance spectrometer employs 13 C active nuclei to derive the aromatic content, and the optionally one or both of the paraffinic content and the naphthenic content.
6. The method of claim 1 , wherein each assigned assay data value is calculated and assigned by a multi-variable polynomial equation with predetermined constant coefficients developed using linear regression techniques, wherein corresponding variables are the one or more AVs, and the density of the oil sample.
7. The method of claim 6 , wherein each assigned assay data value is calculated and assigned by
AD=K AD +X 1 AD *AV+X 2 AD *AV 2 +X 3 AD *AV 3 +X 4 AD *ρ*AV
where:
AD is the assigned assay data value that is a value and/or property representative of an elemental composition value, a physical property or an indicative property;
AV is a single analytical value of the oil sample;
ρ is the density of the oil sample; and
K AD , X1 AD , X2 AD , X3 AD , and X4 AD are constants.
8. The method of claim 6 , wherein each assigned assay data value is calculated and assigned by
AD=K AD +X 1 AD *ρ+X 2 AD *ρ 2 +X 3 AD *ρ 3 +X 4 AD *AV+X 5 AD *AV 2 +X 6 AD *AV 3 +X 7 AD *ρ*AV
where:
AD is the assigned assay data value that is a value and/or property representative of an elemental composition value, a physical property or an indicative property;
AV is a single analytical value of the oil sample;
ρ is the density of the oil sample; and
K AD , X1 AD , X2 AD , X3 AD , X4 AD , X5 AD , X6 AD and X7 AD are constants.
9. The method of claim 1 , wherein the one or more AVs is the aromatic content of the oil sample as determined by the NMR spectroscopy data.
10. A system for producing a virtual assay of an oil sample, wherein the oil sample is characterized by a density, wherein the oil sample is selected from a group consisting of crude oil, bitumen and shale oil, and wherein the oil sample is characterized by a naphtha fraction, a gas oil fraction, a vacuum gas oil fraction and a vacuum residue fraction, the system comprising:
a nuclear magnetic resonance (NMR) spectrometer that outputs NMR spectroscopy data;
a non-volatile memory device that stores calculation modules and data, the data including the NMR spectroscopy data, wherein the NMR spectroscopy data is indicative of aromatic content, and optionally one or both of paraffinic content and naphthenic content, of the oil sample, obtained by NMR spectroscopy of a solution of the oil sample without distillation in an NMR spectroscopy solvent, wherein the aromatic content, and the optionally one or both of the paraffinic content and the naphthenic content, are used as one or more analytical values (AVs);
a processor coupled to the non-volatile memory device; and
a calculation module that is stored in the non-volatile memory device and that is executed by the processor, wherein the calculation module calculates, as a function of the one or more AVs and the density of the oil sample, virtual assay data of the oil sample and the naphtha fraction, the gas oil fraction, the vacuum gas oil fraction and the vacuum residue fraction, the virtual assay data comprising a plurality of assigned assay data values,
wherein the virtual assay data is used to evaluate the oil sample without distillation and is used to determine an appropriate refinery or refining unit,
wherein the virtual assay data comprises:
the plurality of assigned assay data values pertaining to the oil sample including one or more of the aromatic content, C5-asphaltenes content, elemental composition of sulfur and elemental composition of nitrogen, micro-carbon residue content, total acid number and viscosity;
the plurality of assigned assay data values pertaining to the vacuum residue fraction of the oil sample including one or more of the elemental composition of sulfur and the micro-carbon residue content;
the plurality of assigned assay data values pertaining to the vacuum gas oil fraction of the oil sample including one or more of the elemental composition of sulfur and the elemental composition of nitrogen;
the plurality of assigned assay data values pertaining to the gas oil fraction of the oil sample including one or more of the elemental composition of sulfur and the elemental composition of nitrogen, the viscosity, and indicative properties including aniline point, cetane number, cloud point and pour point; and
the plurality of assigned assay data values pertaining to the naphtha fraction of the oil sample including one or more of the aromatic content, elemental composition of hydrogen and the elemental composition of sulfur, paraffin content and octane number.
11. The system as in claim 10 , wherein the virtual assay data comprises:
the plurality of assigned assay data values pertaining to the oil sample including the aromatic content, the C5-asphaltenes content, the elemental composition of sulfur and the elemental composition of nitrogen, the micro-carbon residue content, the total acid number and the viscosity;
the plurality of assigned assay data values pertaining to the vacuum residue fraction of the oil sample including the elemental composition of sulfur and the micro-carbon residue content;
the plurality of assigned assay data values pertaining to the vacuum gas oil fraction of the oil sample including the elemental composition of sulfur and the elemental composition of nitrogen;
the plurality of assigned assay data values pertaining to the gas oil fraction of the oil sample including the elemental composition of sulfur and the elemental composition nitrogen, the viscosity, and the indicative properties including the aniline point, the cetane number, the cloud point and the pour point; and
the plurality of assigned assay data values pertaining to the naphtha fraction of the oil sample including the aromatic content, the elemental composition of hydrogen and the elemental composition of sulfur, the paraffin content and the octane number.
12. The system as in claim 11 , wherein the virtual assay data further comprises:
yields of fractions from the oil sample as mass fractions of boiling point ranges, including one or more of naphtha, gas oil, vacuum gas oil and vacuum residue;
composition information of hydrogen sulfide and/or mercaptans in the oil sample and/or the corresponding fractions;
elemental compositions of one or more of carbon, hydrogen, nickel, and vanadium;
physical properties of the oil sample and/or the corresponding fractions including one or more of API gravity and refractive index; or
indicative properties of the oil sample and/or the corresponding fractions including one or more of flash point, freezing point and smoke point.
13. The system of claim 10 , wherein the nuclear magnetic resonance spectrometer employs 1 H active nuclei to derive the aromatic content, and the optionally one or both of the paraffinic content and the naphthenic content.
14. The system of claim 10 , wherein the nuclear magnetic resonance spectrometer employs 13 C active nuclei to derive the aromatic content, and the optionally one or both of the paraffinic content and the naphthenic content.
15. The system of claim 10 , wherein each assigned assay data value is calculated by the calculation module with a multi-variable polynomial equation with predetermined constant coefficients developed using linear regression techniques, wherein corresponding variables are the aromatic content, and the optionally one or both of the paraffinic content and the naphthenic content, and the density of the oil sample.
16. The system of claim 15 , wherein each assigned assay data value is calculated by the calculation module with a function:
AD=K AD +X 1 AD *AV+X 2 AD *AV 2 +X 3 AD *AV 3 +X 4 AD *ρ*AV
where:
AD is the assigned assay data value that is a value and/or property representative of an elemental composition value, a physical property or an indicative property;
AV is a single analytical value of the oil sample;
ρ is the density of the oil sample; and
K AD , X1 AD , X2 AD , X3 AD , and X4 AD are constants.
17. The system of claim 15 , wherein each assigned assay data value is calculated by the calculation module with a function:
AD=K AD +X 1 AD *ρ+X 2 AD *ρ 2 +X 3 AD *ρ 3 +X 4 AD *AV+X 5 AD *AV 2 +X 6 AD *AV 3 +X 7 AD *ρ*AV
where:
AD is the assigned assay data value that is a value and/or property representative of an elemental composition value, a physical property or an indicative property;
AV is a single analytical value of the oil sample;
ρ is the density of the oil sample; and
K AD , X1 AD , X2 AD , X3 AD , X4 AD , X5 AD , X6 AD and X7 AD are constants.
18. The system of claim 17 , wherein the one or more AVs is the aromatic content of the oil sample as obtained by the NMR spectroscopy.