Method of assessing asphaltene inhibitor efficiency
View Patent ↗Methods of assessing asphaltene inhibitor/dispersant efficiency are disclosed. Also disclosed are methods of assessing solvent/dispersant/cleaner efficacy for remediating asphaltene deposition. The methods are useful in facilitating the production, transportation, storage, and separation of crude oil and natural gas, and more particularly, for preventing the undesired deposition of asphaltene from crude oil.
1. A method of assessing asphaltene inhibitor/dispersant efficacy in a crude oil, the method comprising:
a) weighing a first coupon; immersing the first coupon or a portion thereof into a first sample for a first selected time period, the first sample comprising an aliquot of the crude oil; adding a precipitant to the first sample within the first selected time period; removing the first coupon from the first sample at the end of the first selected time period; and drying and weighing the first coupon;
b) weighing a second coupon; immersing the second coupon or a portion thereof into a second sample for a second selected time period, the second sample comprising an aliquot of the crude oil and an asphaltene inhibitor/dispersant; adding the precipitant to the second sample within the second selected time period; removing the second coupon from the second sample at the end of the second selected time period; and drying and weighing the second coupon;
c) determining the weight of asphaltenes deposited on the first coupon and the weight of asphaltenes deposited on the second coupon; and
d) determining the % asphaltene deposition inhibition via equation (1),
%
Inhibition
=
100
×
(
1
-
Weight
of
asphaltenes
deposited
on
the
second
coupon
Weight
of
asphaltenes
deposited
on
the
first
coupon
)
,
(
1
)
wherein an increased % inhibition indicates a more effective inhibitor/dispersant.
2. The method of claim 1 , wherein step a) and step b) each comprise the three sequential events of:
precipitant addition, having a time of addition;
soak time after precipitant addition; and
drying time after soaking.
3. The method of claim 2 , wherein
the time of addition is greater than 0 minutes to 48 hours;
the soak time is 30 minutes to 30 days; and
the dry time is 1 hour to 48 hours.
4. The method of claim 1 , wherein the volume of crude oil in the first sample ranges from 1-1000 mL, and the volume of crude oil in the second sample ranges from 1-1000 mL.
5. The method of claim 1 , wherein the first selected time period and the second selected time period are of substantially the same duration.
6. The method of claim 1 , wherein steps a)-d) are carried out over a time period of 2 hours to 33 days.
7. The method of claim 1 , wherein the volume of precipitant added to each of the first and second samples is determined by titration of the crude oil with the precipitant prior to assessing the asphaltene inhibitor/dispersant efficacy.
8. The method of claim 1 , wherein the volume of precipitant added to each of the first and second samples corresponds to the Onset Volume±20%.
9. The method of claim 1 , wherein the precipitant is added dropwise to each of the first and second samples over the first and second selected time periods.
10. The method of claim 1 , wherein the precipitant is added all at once to each of the first and second samples over the first and second selected time periods.
11. The method of claim 1 , wherein steps a) and b) are conducted in parallel such that the first and second selected time periods are of the same duration and occur together in real time.
12. The method of claim 1 , wherein the first sample and the second sample are each substantially closed to the atmosphere during the first and second selected time periods.
13. The method of claim 1 , wherein each of the first and second samples are stirred or agitated during at least a portion of the first and second selected time periods.
14. The method of claim 1 , wherein the asphaltene inhibitor/dispersant is selected from the group consisting of aliphatic sulphonic acids; alkyl aryl sulphonic acids; aryl sulfonates; lignosulfonates; alkylphenol/aldehyde resins and similar sulfonated resins; polyolefin esters; polyolefin imides; polyolefin esters with alkyl, alkylenephenyl or alkylenepyridyl functional groups; polyolefin amides; polyolefin amides with alkyl, alkylenephenyl or alkylenepyridyl functional groups; polyolefin imides with alkyl, alkylenephenyl or alkylenepyridyl functional groups; alkenyl/vinyl pyrrolidone copolymers; graft polymers of polyolefins with maleic anhydride or vinyl imidazole; hyperbranched polyester amides; polyalkoxylated asphaltenes, amphoteric fatty acids, salts of alkyl succinates, sorbitan monooleate, polyisobutylene succinic anhydride, and any combination thereof.
15. The method of claim 1 , wherein the precipitant is a liquid precipitant selected from a linear, branched or cyclic alkane solvent, or a combination thereof.
16. The method of claim 15 , wherein the liquid precipitant is pentadecane(s), tetradecane(s), tridecane(s), dodecane(s), undecane(s),decane(s), nonane(s), octane(s), heptane(s), hexane(s), pentane(s), or any combination thereof.
17. The method of claim 1 , wherein the precipitant is a gas precipitant selected from the group consisting of methane, ethane, propane, butane, carbon dioxide, nitrogen, helium, argon, krypton, xenon, neon, and any combination thereof.
18. The method of claim 1 , wherein the method is carried out on-site at an oil field.
19. The method of claim 1 , wherein each sample is heated to a temperature in the range of room temperature to 80° C.
20. The method of claim 1 , wherein each sample is cooled to a temperature in the range of room temperature to −15° C.
21. The method of claim 1 , wherein each sample is under a pressure in the range of atmospheric pressure to 20,000 psi.
22. A method of assessing asphaltene inhibitor efficacy in crude oil, the method comprising:
a) weighing a first coupon; immersing the first coupon or a portion thereof into a first sample for a first selected time period, the first sample comprising an aliquot of the crude oil; adding a precipitant to the first sample within the first selected time period; removing the first coupon from the first sample at the end of the first selected time period; and drying and weighing the first coupon;
b) weighing a second coupon; immersing the second coupon or a portion thereof into a second sample for a second selected time period, the second sample comprising an aliquot of the crude oil and an asphaltene inhibitor/dispersant, wherein the alphaltene inhibitor/dispersant is selected from the group consisting of aliphatic sulphonic acids; alkyl aryl sulphonic acids; aryl sulfonates; lignosulfonates; alkylphenol/aldehyde resins and similar sulfonated resins; polyolefin esters; polyolefin imides; polyolefin esters with alkyl, alkylenephenyl or alkylenepyridyl functional groups; polyolefin amides; polyolefin amides with alkyl, alkylenephenyl or alkylenepyridyl functional groups; polyolefin imides with alkyl, alkylenephenyl or alkylenepyridyl functional groups; alkenyl/vinyl pyrrolidone copolymers; graft polymers of polyolefins with maleic anhydride or vinyl imidazole; hyperbranched polyester amides; polyalkoxylated asphaltenes, amphoteric fatty acids, salts of alkyl succinates, sorbitan monooleate, polyisobutylene succinic anhydride, and any combination thereof; adding the precipitant to the second sample within the second selected time period; removing the second coupon from the second sample at the end of the second selected time period; and drying and weighing the second coupon;
c) determining the weight of asphaltenes deposited on the first coupon and the weight of asphaltenes deposited on the second coupon; and
d) determining the % asphaltene deposition inhibition via equation (1),
%
Inhibition
=
100
×
(
1
-
Weight
of
asphaltenes
deposited
on
the
second
coupon
Weight
of
asphaltenes
deposited
on
the
first
coupon
)
,
(
1
)
wherein an increased % inhibition indicates a more effective inhibitor.