Disaggregation of asphaltenes in incompatible petroleum oil mixtures

Abstract

The present invention is a method to disaggregate asphaltenes in petroleum oils and oil mixtures by mild heating. The presence of asphaltenes is determined by small angle neutron scattering.

What is claimed is:  
     
         1 . A method to disaggregate asphaltenes in petroleum oils and oil mixtures comprising mild heating.  
     
     
         2 . The method of  claim 1  further comprising the step of determining the presence of asphaltene aggregates by irradiating said petroleum oils and oil mixtures with neutrons and determining small angle neutron scattering (SANS) intensity, I, as a function of wavenumber, q.  
     
     
         3 . The method of  claim 2  wherein said neutron scattering wavenumber, q, is in the range 10 −4  Å −1 ≦q≦1 Å −1 , preferably 10 −3  Å −1 ≦q ≦10 −1  Å −1 .  
     
     
         4 . A method to determine the regimes of compatibility and incompatibility of petroleum oils and mixtures of petroleum oils and/or refinery process streams using fitting of I(q) in  claim 2  to an equation based on a physical model that contains contributions a strongly decaying feature to describe the surface scattering of asphaltene aggregates at low q, a plateau feature with a rolloff at higher q to describe the asphaltene particles, and a constant to describe the high q incoherent scattering.  
     
     
         5 . The method of  claim 4  wherein the equation is given by Equation (1).  
     
     
         6 . The method of  claim 5  wherein the criterion for incompatibility is determined by the concavity of the low-q plateau intensity of the asphaltene particles, I L , as a function of the volume fraction of mixing, φ m .  
     
     
         7 . The method of  claim 5  wherein the criterion for incompatibility is determined by the systematic deviation of I L , as a function of mixing volume fraction from the hard sphere prediction given by Equation (2).  
     
     
         8 . The method of  claim 5  wherein the criterion for incompatibility is determined by the maximum in the correlation length, given by Equation (2).  
     
     
         9 . The method of  claim 5  wherein the criterion for incompatibility is determined by the dominance of the low-q value of the surface scattering intensity, I surf , over the sum of the low-q plateau intensity of the asphaltene particles and the incoherent scattering intensity.  
     
     
         10 . The method of  claim 5  wherein the criterion for incompatibility is determined by the power law exponent, a, exceeding a value of three.  
     
     
         11 . A method to estimate the volume fraction of asphaltene aggregates, φ agg , in incompatible petroleum oil and/or refinery process stream mixtures based on a difference between the low-q plateau intensity corresponding to the asphaltene particles, I L , determined in  claim 5  at different volume fractions of mixing, φ m , and a prediction for the behavior of this intensity expected for spherical particles interacting by contact repulsions.  
     
     
         12 . The method of  claim 11  wherein the equation to estimate the volume fraction of aggregates, φ agg , is given by Equations (2) and (3).  
     
     
         13 . The method of  claim 2  wherein the total surface area of asphaltene aggregates per unit volume of the petroleum oil, S V , is determined from the amplitude of the surface scattering intensity, I surf , from asphaltene aggregates at low wavenumbers, q.  
     
     
         14 . The method of claims  12  and  13  wherein the average length scale, R, associated with the internal structures of the asphaltene aggregates is estimated using Equation (4).