Methods for expanding and enriching hydrocarbon diluent pools

1. A method for the controlled production and distribution of butane enriched diluents so as not to violate pre-defined limits selected from butane content, volatility, density, and combinations thereof comprising:

a) providing a diluent stream having a flow rate, a line pressure, a butane content, a volatility and a density;

b) providing a variable rate butane injection unit in fluid connection with said diluent stream;

c) obtaining values for one or more parameters of said diluent stream selected from butane content, volatility, density, and combinations thereof;

d) calculating a target rate of injecting butane into said diluent stream based upon the one or more parameter values in step (c) so as not to violate the foregoing pre-defined limits; and

e) injecting butane into the diluent stream from the butane injection unit at a pressure greater than said diluent stream pressure, and an actual injection rate less than or equal to said target rate calculated in step (d).

2. The method of claim 1 , further comprising periodically repeating steps (c) and (d) and adjusting the injection rate in step (e) based upon the most recent calculation from step (d).

3. The method of claim 1 wherein said pre-defined limits include butane content and volatility, and said parameter values obtained in step (c) include butane content and volatility.

4. The method of claim 1 wherein said pre-defined limits include density, and said parameter values obtained in step (c) include density.

5. The method of claim 1 wherein said pre-defined limits include butane content, volatility and density, and said parameter values obtained in step (c) include butane content, volatility and density.

6. The method of claim 1 wherein said diluent flow rate varies over time, the method further comprises obtaining said flow rate, and step (d) is performed based upon the flow rate obtained in step (c).

7. The method of claim 2 wherein:

i) said variable rate butane injection unit comprises a supply of butane at a butane pressure greater than said diluent stream pressure, and an on-off valve and regulating valve between said supply of butane and said diluent stream, and

ii) said rate adjustment step comprises modulating the orifice size in said regulating valve.

8. The method of claim 1 wherein in step (c):

i) said volatility is obtained by measuring the volatility of said diluent stream;

ii) said butane content is obtained by measuring the butane content of said diluent stream; and

iii) said density is obtained by receiving a density measurement from an external source.

9. The method of claim 1 wherein in step (c):

i) said volatility is obtained by measuring the volatility of said diluent stream using a manometer; and

ii) said butane content is obtained by measuring the butane content of said diluent stream using liquid chromatography.

10. The method of claim 1 further comprising:

a) providing an informational database on which are stored said pre-defined limits;

b) providing one or more information processing units logically programmed to:

i) receive said parameter values for volatility, butane content and density of said diluent stream;

ii) calculate said target butane injection rate based upon said flow rate, volatility, butane content and density of said diluent stream and said pre-defined limit stored in said information database; and

iii) control said actual butane injection rate so as to correlate with said target butane injection rate.

11. The method of claim 1 , further comprising providing a pipeline comprising two or more sequential batches of differing petroleum products, wherein at least one of said batches comprises said diluent stream.

12. The method of claim 1 wherein the butane content of said diluent stream after said butane injection step (e) is between 5.0% and 7.0%.

13. The method of claim 1 wherein the diluent comprises natural gas condensate.

14. The method of claim 1 wherein the API gravity of said diluent stream after said butane injection step (e) is between 46 and 86.

15. The method of claim 1 , wherein one or more of said values is obtained by generating a spectral response of said diluent stream using absorption spectroscopy with a near infrared analyzer, and comparing said spectral response to a chemometric dataset specific for said value in said diluent stream.

16. The method of claim 15 , wherein said chemometric dataset is built by taking two or more samples of said diluent from a pipeline; measuring said physical property of the samples offline; simultaneously with taking the two or more samples, obtaining a spectral response of the diluent in the pipeline using absorption spectroscopy with a near infrared analyzer; and correlating the spectral response with the value of the samples.

17. The method of claim 1 , further comprising blending said diluent with crude oil.

18. A method for the controlled production and distribution of a butane enriched diluent stream so as not to violate pre-defined limits for butane content, comprising:

a) providing a diluent stream having a flow rate, pressure, butane content, volatility and density;

b) providing a variable rate butane injection unit in fluid connection with said diluent stream;

c) obtaining a parameter value for the butane content of the diluent stream upstream and/or downstream of said injection unit;

d) calculating a target rate of injecting butane into said diluent stream based upon the parameter value for the butane content in step (c), so as not to violate the foregoing pre-defined limits for butane content; and

e) injecting butane into the diluent stream from the butane injection unit at a pressure greater than said diluent stream pressure, and an actual injection rate less than or equal to the target rate calculated in step (d).

19. The method of claim 18 , further comprising periodically repeating steps (c) and (d) and adjusting the injection rate in step (e) based upon the most recent calculation from step (d).

20. A method for the controlled production and distribution of a butane enriched diluent stream so as not to violate pre-defined limits for volatility, comprising:

a) providing a diluent stream having a flow rate, pressure, butane content, volatility and density;

b) providing a variable rate butane injection unit in fluid connection with said diluent stream;

c) obtaining a parameter value for the volatility upstream and/or downstream of said injection unit;

d) calculating a target rate of injecting butane into said diluent stream based upon the volatility obtained in step (c), so as not to violate the foregoing pre-defined limit for volatility;

e) injecting butane into the diluent stream from the butane injection unit at an actual injection rate less than or equal to said target rate calculated in step (d).

21. The method of claim 20 , further comprising periodically repeating steps (c) and (d) and adjusting the injection rate in step (e) based upon the most recent calculation from step (d).