Method for measurement of crude oil and bitumen dead oil viscosity and density

1. A method for determining viscosity of oil in a sample, comprising:

extracting the oil from the sample using a volatile polar first solvent;

using a portion of the extracted oil to determine a concentration factor of oil in the sample;

determining a dry weight of the extracted oil using the concentration factor;

adding a second solvent to a remaining portion of the extract, the second solvent less volatile than the first solvent;

removing the first solvent from the remaining portion of the extract;

taking a series of sub-samples from the remaining portion of the extract and sequentially removing different amounts of the second solvent from each sub-sample;

measuring solvent concentrations and viscosity values of the solvent-oil mixtures of each sub-sample; and

based on the measured solvent concentrations and viscosity values of each sub-sample, determining the second-solvent-free viscosity of the oil in the sample.

2. The method of claim 1 , wherein determining the second-solvent-free viscosity of the oil in the sample comprises using a fitting algorithm.

3. The method of claim 1 , wherein the first solvent has a lower boiling point than at least 50% of the oil contained in the sample.

4. The method of claim 1 , wherein the second solvent has a lower boiling point than a least 50% of the oil contained in the sample.

5. The method of claim 1 , wherein the second solvent is selected to prevent light end loss from the oil during removal of the first solvent and to facilitate the removal of the first solvent.

6. A method for determining viscosity of oil in a sample comprising:

extracting oil from the sample using a first solvent to form an extract a, wherein the first solvent is a polar volatile solvent having a lower boiling point than at least 50% of the oil in the sample;

removing substantially all of the first solvent from a small portion of the extract a to form an extract b;

determining an amount of oil in the solvent-free extract b;

adding a predetermined amount of a second solvent to the remainder of extract a to make an extract c, wherein the second solvent is a less volatile solvent than the first solvent and has a lower boiling point than at least 50% of the oil in the sample;

removing, from the extract c, substantially all of the first solvent while retaining the second solvent to form an extract d;

allowing a different amount of the second solvent to volatilize from each of a series of sub-samples taken from the extract d;

measuring a viscosity and second solvent concentration in each of the sub-samples; and

based on the measured viscosity of each of the sub-samples and the measured solvent concentrations of the second solvent from each of the sub-samples, determining the viscosity of the oil from the sample, the viscosity representing the viscosity of the oil free of the second solvent.

7. The method of claim 6 , wherein the first solvent is dichloromethane (DCM).

8. The method of claim 6 , wherein the second solvent is toluene.

9. The method of claim 6 , wherein the solvent concentration is determined using gas chromatography or gas chromatography-mass spectrometry.

10. The method of claim 6 , wherein determining the viscosity of the second-solvent-free oil from the sample comprises combining respective viscosity values measured on each of the extracts using viscosity mixing rules or non linear fitting algorithms to derive the second-solvent-free oil viscosity.

11. The method of claim 6 , wherein the second solvent is selected to prevent light end loss from the oil during removal of the first solvent and to facilitate the removal of the first solvent.

12. A method for measuring density of oil in a sample, comprising:

extracting the oil from the sample using a volatile polar first solvent;

using a portion of the extracted oil to determine a concentration factor of oil in the sample;

calculating a dry weight of the extracted oil using the concentration factor;

adding a second solvent to a remaining portion of the extract, the second solvent less volatile than the first solvent;

removing the first solvent from the remaining portion of the extract;

sequentially removing different amounts of the second solvent from each of a series of sub-samples taken from the remaining portion of the extract;

measuring solvent concentrations and density values of the solvent-oil mixtures of each sub-sample; and

based on the measured solvent concentrations and density values of each sub-sample, determining a second-solvent-free density of the oil in the sample.

13. The method of claim 12 , further comprising determining a second-solvent-free API gravity of the oil in the sample based on the determined second-solvent-free density of the oil.

14. The method of claim 12 , wherein determining the second-solvent-free density of the oil in the sample comprises using a fitting algorithm.

15. The method of claim 12 , wherein the first solvent has a lower boiling point than at least 50% of the oil contained in the sample.

16. The method of claim 12 , wherein the second solvent has a lower boiling point than at least 50% of the oil contained in the sample.

17. The method of claim 12 , wherein the second solvent is selected to prevent light end loss from the oil during removal of the first solvent and to facilitate the removal of the first solvent.

18. A method for determining a value of a property of oil in a sample, comprising:

extracting the oil from the sample using a volatile polar first solvent;

using a portion of the extracted oil to determine a concentration factor of oil in the sample;

determining a dry weight of the extracted oil using the concentration factor;

adding a second solvent to a remaining portion of the extract, the second solvent less volatile than the first solvent;

removing the first solvent from the remaining portion of the extract;

taking a series of sub-samples from the remaining portion of the extract and sequentially removing different amounts of the second solvent from each sub-sample;

measuring solvent concentrations and values of the property of the solvent-oil mixtures of each sub-sample; and

based on the measured solvent concentrations and property values of each sub-sample, determining a second-solvent-free value of the property for the oil in the sample.

19. The method of claim 18 , wherein the property is a physical property of the oil.

20. The method of claim 19 , wherein the physical property is a viscosity of the oil.

21. The method of claim 19 , wherein the physical property is a density of the oil.

22. The method of claim 19 , wherein the physical property is an interfacial tension of the oil.

23. The method of claim 18 , wherein the property is a bulk chemical property of the oil.

24. The method of claim 23 , wherein the bulk chemical property is a total acid number of the oil.

25. The method of claim 18 , wherein the first solvent is dichloromethane (DCM) and the second solvent is toluene.

26. The method of claim 18 , wherein determining the property of the second-solvent-free oil from the sample comprises combining the property values measured on each of the extracts using mixing rules or non linear fitting algorithms to derive the second-solvent-free oil value of the property.

27. The method of claim 18 , wherein the second solvent is selected to prevent light end loss from the oil during removal of the first solvent and to facilitate the removal of the first solvent.