Characterization of crude oil and its fractions by fourier transform infrared spectroscopy (ftir) analysis

Abstract

A system and a method are provided for calculating the cetane number, pour point, cloud point, aniline point, aromaticity, and/or octane number of a crude oil and its fractions from the density and Fourier transform infrared spectroscopy (FTIR) of a sample of the crude oil.

We claim: 
     
         1 . A system for evaluating a crude oil sample and calculating an indicative property of a naphtha or gas oil fraction of the crude oil sample without first distilling said naptha or gas oil fraction, the system comprising:
 a Fourier transform infrared spectrophotometer;   a non-volatile memory device that stores calculation modules and data, the data including density of the crude oil sample and Fourier transform infrared spectroscopy data indicative of transmittance values at predetermined increments between a predetermined range for the crude oil sample, the data derived from an analysis of the crude oil by the Fourier transform infrared spectrophotometer;   a processor coupled to the non-volatile memory;   a first calculation module that retrieves the Fourier transform infrared spectroscopy data from the non-volatile memory, that calculates a crude oil Fourier transform infrared spectroscopy index value of the fraction from the transmittance values of the spectroscopy data, and that transfers the calculated Fourier transform infrared spectroscopy index into the non-volatile memory; and   a second calculation module that calculates the indicative property for the fraction of the crude oil from a two-variable polynomial equation with predetermined constant coefficients developed using linear regression techniques, and that stores the indicative property into the non-volatile memory device;   wherein the two variables of the two-variable polynomial equation are the Fourier transform infrared spectroscopy index and the density of the crude oil sample.   
     
     
         2 . The system of  claim 1 , wherein the indicative property is the cetane number. 
     
     
         3 . The system of  claim 1 , wherein the indicative property is the pour point. 
     
     
         4 . The system of  claim 1 , wherein the indicative property is the cloud point. 
     
     
         5 . The system of  claim 1 , wherein the indicative property is the aniline point. 
     
     
         6 . The system of  claim 1 , wherein the indicative property is the aromaticity. 
     
     
         7 . The system of  claim 1 , wherein the indicative property is the octane number. 
     
     
         8 . The system of  claim 1 , wherein the temperature range for the Fourier transform infrared spectroscopy analyzer is 20-80° C. 
     
     
         9 . The system of  claim 1 , wherein the Fourier transform infrared spectroscopy index is that of whole crude oil. 
     
     
         10 . The system of  claim 1 , wherein the Fourier transform infrared spectroscopy index is calculated from FTIR data measured in the wavelength range of 700-4000 cm −1 . 
     
     
         11 . The system of  claim 1 , wherein the Fourier transform infrared spectroscopy data is obtained directly from core and/or drill cuttings material. 
     
     
         12 . A method for evaluating a crude oil sample and calculating an indicative property of a naphtha or gas oil fraction of the crude oil sample without first distilling said naptha or gas oil fraction, the method comprising;
 obtaining the density of the crude oil sample;   providing a Fourier transform infrared spectrophotometer;   subjecting said crude oil sample to Fourier transform infrared spectroscopic analysis using the Fourier transform infrared spectrophotometer and entering measured transmittance values into non-volatile memory of a computer;   using a processor of the computer to calculate a crude oil Fourier transform infrared spectroscopy index value of fraction from the transmittance values; and   using the processor to calculate and record into the non-volatile memory the indicative property for the naptha or gas oil fraction of the crude oil from a two-variable polynomial equation with predetermined constant coefficients developed using linear regression techniques;   wherein the two variables of the two-variable polynomial equation are the Fourier transform infrared spectroscopy index and the density of the crude oil sample.   
     
     
         13 . The method of  claim 12 , wherein the indicative property is the cetane number. 
     
     
         14 . The method of  claim 12 , wherein the indicative property is the pour point. 
     
     
         15 . The method of  claim 12 , wherein the indicative property is the cloud point. 
     
     
         16 . The method of  claim 12 , wherein the indicative property is the aniline point. 
     
     
         17 . The method of  claim 12 , wherein the indicative property is the aromaticity. 
     
     
         18 . The method of  claim 12 , wherein the indicative property is the octane number. 
     
     
         19 . The method of  claim 12 , wherein the temperature range for the Fourier transform infrared spectroscopy analyzer is 20-80° C. 
     
     
         20 . The method of  claim 12 , wherein the Fourier transform infrared spectroscopy index is that of whole crude oil. 
     
     
         21 . The method of  claim 12 , wherein the Fourier transform infrared spectroscopy index is calculated from FTIR data measured in the wavelength range of 700-4000 cm −1 . 
     
     
         22 . The method of  claim 12 , wherein the Fourier transform infrared spectroscopy data is obtained directly from core and/or drill cuttings material.