Method for storing and transporting crude oil
Disclosed is a method for transporting blended crude oils comprising the steps of; (a) admixing a first crude oil with a second, different crude oil to form a crude oil admixture; (b) determining a first value representing the content of unprecipitated asphaltenes in the admixture; (c) holding the admixture for a period of time at standard conditions; (d) determining a second value representing the content of unprecipitated asphaltenes in the admixture; and (e) either: (i) transporting the admixture if the second value is the same as or within a predetermined range of the first value; or (ii) taking remedial action to prevent asphaltene precipitation prior to transporting if the second value is outside a predetermined range from the first value. Also disclosed is a method for estimating the storage stability of stored crude oils and crude oil admixtures.
1. A method for transporting blended crude oils comprising the steps of;
(a) admixing a first crude oil with a second, different crude oil to form a crude oil admixture;
(b) determining a first value representing the content of unprecipitated asphaltenes in the admixture; (c) holding the admixture for a period of time at standard conditions;
(d) determining a second value representing the content of unprecipitated asphaltenes in the admixture; and
(e) taking remedial action to prevent asphaltene precipitation prior to transporting the admixture if the second value is outside a predetermined range from the first value,
wherein the determining of a first or second value representing the content of unprecipitated asphaltenes in the admixture is done using a sensor that is a fiber optic attenuated total reflectance probe.
2. The method of claim 1 wherein the admixture is transported through a pipeline, pipes or in tanks.
3. The method of claim 1 wherein a processor makes real time relative concentration determinations of asphaltenes in the admixture.
4. The method of claim 3 wherein the fiber optic attenuated total reflectance probe has an exposed surface in contact with the admixture.
5. The method of claim 4 wherein the processor determines absorbance from the sensor data as a function of wavelength.
6. The method of claim 1 wherein the remedial actions include the addition of an additive, which prevents or mitigates the precipitation of asphaltenes, to the admixture.
7. The method of claim 4 wherein the data from a fiber optic attenuated total reflectance probe is UV absorbance data.
8. The method of claim 7 wherein the UV absorbance data is absorbance in the range of from about 220 nm to about 800 nm.
9. The method of claim 8 wherein the UV absorbance data is absorbance in the range of from about 220 nm to about 400 nm.
10. The method of claim 1 wherein steps (a), (b), (c) and (d) are performed using a model crude oil blend.
11. The method of claim 10 wherein step (e) further comprises making a large scale blend based upon the model crude oil blend prior to taking remedial action.