U.S. patent application number 13/835104 was filed with the patent office on 2013-10-10 for process of reducing viscosity of heavy crude oil by removal of asphaltene using a precipitating agent.
The applicant listed for this patent is NANO DISPERSIONS TECHNOLOGY INC.. Invention is credited to Socrates Acevedo, Carolina Blanco, Jean Carlos Bravo, Maria Briceno, Antonio Cardenas, Carlos Espinoza, Eduardo Lima.
Application Number | 20130264247 13/835104 |
Document ID | / |
Family ID | 49291459 |
Filed Date | 2013-10-10 |
United States Patent
Application |
20130264247 |
Kind Code |
A1 |
Cardenas; Antonio ; et
al. |
October 10, 2013 |
PROCESS OF REDUCING VISCOSITY OF HEAVY CRUDE OIL BY REMOVAL OF
ASPHALTENE USING A PRECIPITATING AGENT
Abstract
A process and system for reducing the viscosity of heavy and
extra heavy crude oils, and more particularly to a process for
reducing the viscosity of heavy and extra heavy crude oils by means
of total or partial oil deasphalting using a precipitating agent in
order to obtain an upgraded crude oil of lower viscosity that can
be pumped without the use of diluents. The upgrading also includes
a reduction in metals and sulfur associated with asphaltene
removal. The process consists of relatively simple equipment such
as static mixers and stirred tanks and operation temperature is low
and pressure is moderate.
Inventors: |
Cardenas; Antonio; (Panama
City, PA) ; Bravo; Jean Carlos; (Panama City, PA)
; Blanco; Carolina; (Panama City, PA) ; Briceno;
Maria; (Panama City, PA) ; Espinoza; Carlos;
(Panama City, PA) ; Acevedo; Socrates; (Caracas,
VE) ; Lima; Eduardo; (Panama City, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NANO DISPERSIONS TECHNOLOGY INC. |
Panama City |
|
PA |
|
|
Family ID: |
49291459 |
Appl. No.: |
13/835104 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61622197 |
Apr 10, 2012 |
|
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|
Current U.S.
Class: |
208/309 |
Current CPC
Class: |
C10G 21/003 20130101;
C10G 2300/302 20130101 |
Class at
Publication: |
208/309 |
International
Class: |
C10G 21/00 20060101
C10G021/00 |
Claims
1. A method of reducing a viscosity of heavy and extra heavy crude
oils at an oilfield site by partially removing asphaltenes to
produce a pumpable upgraded oil, the method comprising: combining a
heavy or extra heavy crude oil and a feed precipitant, wherein a
volumetric precipitant to crude oil ratio is in a range from about
1 to about 2; precipitating and separating asphaltenes from the
combination crude oil and precipitant; separating the precipitated
asphaltenes to form an oil slurry comprising the asphaltenes and
precipitant, and a liquid stream comprising precipitant and a
remaining volume of the crude oil; and separating the liquid stream
to produce the upgraded oil and a first precipitant stream, wherein
a yield of upgraded oil is about 90% by weight or more with respect
to the heavy or extra heavy crude oil.
2. The method of claim 1, further comprising: washing the oil
slurry with additional precipitant; separating the washed oil
slurry to produce an asphaltenes stream and a second precipitant
stream; and drying the asphaltenes stream to produce a solid
asphaltene product, and a third precipitant stream.
3. The method of claim 2, wherein at least one of the first,
second, and third precipitant streams is recycled as feed
precipitant.
4. The method of claim 2, wherein at least one of the first,
second, and third precipitant streams is recycled as additional
precipitant to wash the oil slurry.
5. The method of claim 2, wherein the second precipitant is
combined with the liquid stream before separation of the liquid
stream.
6. The method of claim 1, wherein the heavy or extra heavy crude
oil and precipitant is combined using static mixers.
7. The method of claim 6, wherein the crude oil and precipitant are
combined at temperatures of about 80.degree. C. (176.degree. F.) or
below, and pressures between 40 and 60 psig to maximize asphaltene
precipitation.
8. The method of claim 1, wherein the step of precipitation
utilizes one or more stirred or agitated tanks to induce asphaltene
precipitation, or to remove crude oil occluded in the precipitated
asphaltene particles.
9. The method of claim 1, wherein the oil slurry and liquid stream
are separated in a separation vessel comprising hydro-cyclones or
centrifuges, wherein the precipitation of small solid asphaltene
particles is induced by inertial forces many times the
gravitational force, which operates to reduce residence time in the
separation vessel.
10. The method of claim 2, wherein the asphaltene stream is dried
by dryers.
11. The method of claim 1, wherein the first precipitant stream is
separated from the upgraded oil using a flash separator or
distillation tower.
12. The method of claim 1, further comprising: stripping the
upgraded oil by stream stripping to produce stripped upgraded oil
and a fourth precipitant stream.
13. The method of claim 12, wherein the fourth precipitant stream
is recycled as feed precipitant.
14. The method of claim 12, wherein the stripped upgraded oil has a
higher viscosity than the unstripped upgraded oil due to the
removal of precipitant.
15. The method of claim 1, wherein a volumetric yield of the
upgraded oil is greater than 92% with respect to the heavy or extra
heavy crude oil.
16. The method of claim 1, wherein the upgraded oil exiting the
process has less than 5% by weight of light component depending on
a target viscosity of the upgraded oil.
17. The method of claim 1, wherein the upgraded oil has a higher
API gravity compared to heavy or extra heavy crude oil, wherein a
difference in API gravity comprises at least 3 API gravity
units.
18. The method of claim 1, wherein the upgraded oil comprises a
significant reduction of metals and sulfur from crude oil.
19. The method of claim 2, wherein a precipitant loss in the dried,
solid asphaltene product is less than 1% by weight.
20. The method of claim 1, wherein the feed precipitant comprises a
light gasoline or natural gasoline.
21. The method of claim 1, wherein the feed precipitant comprises a
solvent and one or more additives formulated according to a
chemical makeup of the heavy or extra heavy crude oil.
22. The method of claim 21, wherein the one or more additives are
selected from the group consisting of light paraffinic hydrocarbons
or oxygenated hydrocarbons.
Description
RELATED APPLICATION
[0001] The present application claims the benefit of U.S.
Provisional Application No. 61/622,197, filed Apr. 10, 2012, which
is incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
[0002] The invention is generally directed to reducing the
viscosity of heavy and extra heavy crude oils, and more
particularly to a process for reducing the viscosity of heavy and
extra heavy crude oils by means of total or partial oil
deasphalting using a precipitating agent in order to obtain an
upgraded crude oil of lower viscosity that can be pumped without
the use of diluents. The upgrading also includes a reduction in
metals and sulfur associated with asphaltene removal. The process
consists of relatively simple equipment such as static mixers and
stirred tanks and operation temperature is low and pressure is
moderate.
BACKGROUND OF THE INVENTION
[0003] Crude oil contains four different hydrocarbons including
paraffins, napthenes, aromatics, and asphaltenes. Paraffins, or
alkanes, are saturated hydrocarbons that consist only of hydrogen
and carbon atoms, having the general formula C.sub.nH.sub.2n+2. All
bonds are single bonds, and the carbon atoms are not joined in
cyclic structures but instead form a simple chain. They make up
from about 15 to about 60% of crude oil, and on average about 30%.
Resins or naphthenes, otherwise known as cycloalkanes, are alkanes
that have one or more rings of carbon atoms in the chemical
structure of their molecules. They make up from about 30 to about
60% of crude oil, and on average about 49%. Aromatics, or arenes,
are hydrocarbons with alternating double and single bonds between
carbon atoms forming rings. Aromatics make up from about 3 to about
30% of crude oil, and on average about 15%.
[0004] Asphaltenes consist primarily of carbon, hydrogen, nitrogen,
oxygen, and sulfur, as well as trace amounts of vanadium and
nickel. The C:H ratio is approximately 1:1.2, depending on the
asphaltene source. Asphaltenes are defined operationally as the
n-heptane (C.sub.7H.sub.16)-insoluble, toluene
(C.sub.6H.sub.5CH.sub.3)-soluble component of a carbonaceous
material such as crude oil, and are the sticky, black, highly
viscous residue of distillation processes. They make up the
remainder of crude oil, and on average from about 3 to about 10% of
the crude oil; however heavy oils can contain 10% or more, with a
high C:H ratio. Due to the aggregation of asphaltenes, they are the
most significant contributor to the viscosity of crude oil
affecting its viscosity.
[0005] Light crude oil is liquid petroleum that has low viscosity,
low specific gravity, and high API (American Petroleum Institute)
gravity due to the presence of a high proportion of light
hydrocarbon fractions. API gravity is calculated by dividing 141.5
by the fluid's specific gravity and subtracting 131.5. The New York
Mercantile Exchange (NYMEX) defines light crude oil for domestic
U.S. oil as having an API gravity between 37.degree. API (840
kg/m.sup.3) and 42.degree. API (816 kg/m.sup.3), while it defines
light crude oil for non-U.S. oil as being between 32.degree. API
(865 kg/m.sup.3) and 42.degree. API (816 kg/m.sup.3). The National
Energy Board of Canada defines light crude oil as having a density
less than 875.7 kg/m.sup.3 (more than 30.1.degree. API). The
Mexican state oil company, Pemex, defines light crude oil as being
between 27.degree. API (893 kg/m.sup.3) and 38.degree. API (835
kg/m.sup.3).
[0006] Unlike light crude oil, heavy crude oils are generally not
pumpable due to the high viscosity. Therefore, it is advantageous
to remove the higher viscosity products, i.e. asphaltenes, in order
to pump the remaining, lighter deasphalted crude oil. Light crude
oil is also desired over heavy crude oil because it receives a
higher price than heavy crude oil on commodity markets because it
produces a higher percentage of gasoline and diesel fuel when
converted into products by an oil refinery.
[0007] One method of decreasing the viscosity of heavy crude oil is
via a deasphalting process. Deasphalting is a well-known process
that uses extraction towers and usually propane as a solvent as
depicted in a number of references including, for example, U.S.
Pat. Nos. 2,121,517; 2,192,253; and 2,081,473. Other solvents used
are gasoline, as described in U.S. Pat. No. 2,101,308, alcohols as
described in U.S. Pat. No. 4,592,831, mixtures of propane with
H.sub.2S or CO.sub.2 as described in U.S. Pat. No. 4,191,639,
acetone mixtures as described in U.S. Pat. Nos. 3,975,396, among
others. The list is not exhaustive but shows that many types of
solvents have been used.
[0008] The use of extraction towers is common to almost all
processes, as shown in the descriptions of several commercial
processes such as LEDA, Demex, MDS, ROSE and Solvahl (Speight, J G,
The Chemistry and technology of petroleum, 4ed, CRC Press, Boca
Raton, 2007). The majority of these processes requires high
temperatures and pressures, and often operates at super-critical
conditions. Those processes also operate at higher solvent to crude
oil from 2:1 to 10:1 by volume as stated in many patents, such as,
for example, U.S. Pat. Nos. 2,101,308; 2,152,253; 2,337,448;
2,367,671; 2,850,431; 2,940,920; 3,159,571; 3,364,138; 4,101,415;
4,548,711; 4,290,880, and more specifically normally in the 4:1 to
8:1 volume range. One specific process to produce fluid catalytic
cracking (FCC) feedstock can use lower range solvent to crude oil
ratios between 1:1 to 4:1 by volume, as described in U.S. Pat. No.
5,000,838, but in this process, the solvent recovery is not
complete.
[0009] The principle in all the asphaltenes precipitating processes
from asphaltene containing mixtures, such as crude oils, is the
insolubility of asphaltenes in low alkane carbon solvents (propane
to heptane) and other solvents and mixtures. This is because the
asphaltene molecules are polar and insoluble in non-polar paraffin,
being less soluble in the lowest molecular weight paraffin
(propane) and more soluble in heptanes. The solvent type is related
to the yield and quality of the upgraded oil (hereinafter "UO"). In
general, a process with propane gives lower yields of UO, but of
better quality regarding lighter density and lower metals content.
In some cases, the solvent is subjected to special operating
conditions, which changes the solubility and its precipitating
power. By changing the operating conditions, different products are
obtained as UO, resins and asphaltenes, as described in U.S. Pat.
No. 4,290,880.
[0010] Most of the deasphalting processes use settling vessels for
the separation of asphaltenes, while in some cases, hydrocyclones
or centrifuges are suggested, as described in, for example, U.S.
Pat. Nos. 3,159,571; and 4,572,781. These technologies aid at
precipitating the smaller particles suspended in the UO. However,
many of these processes are complex, and are not adequately adapted
for oilfield operations.
[0011] An alternative method for transporting or pumping otherwise
unpumpable, high viscosity heavy crude oil is via the use of
diluents. Diluents are diluting agents that thin, or reduce the
viscosity of a fluid to which it is added. For example, diluents
are added to and blended with the heavy crude oil at the oilfield.
The lower viscosity solution is then pumped, trucked, and/or
transported to a refinery, storage facility, or other desired
location, where the solution is broken to separate the crude oil
from the diluent. The diluent is then pipelined or otherwise
transported back for reuse. However, this process requires
additional process steps, such as returning the diluent, that can
be costly. Also, available diluents, such as naphtha, are becoming
increasingly unavailable.
[0012] Therefore, there remains a need to make the process simpler
and readily adapted to oilfield operations, and that does not
require large amounts of additives, such as diluents.
SUMMARY OF THE INVENTION
[0013] Embodiments of the present invention described many of the
drawbacks inherent in the processes described above. Embodiments
are directed to a process that reduces heavy and extra heavy crude
oil viscosity by partial or total deasphalting of such crude oils
producing a high yield of the partially or totally deasphalted
product at the oilfield. The process can significantly reduce, or
in a best case scenario, completely eliminate the use of diluents
for pipeline transport of crude oil. Furthermore, the process is
designed so that it can be readily implemented in oilfield
operations sites requiring moderate pressures and temperatures.
[0014] The present invention includes a process that uses a low
precipitant/crude oil ratio, such as, for example, a 2:1 in volume
ratio or less, and a 1.5:1 in weight ratio or less, and more
particularly about 1:1, compared to ratios of 8:1 in weight or more
of the prior art, to produce upgraded oil with a viscosity suitable
for pumping at ambient temperatures, while maximizing upgraded oil
yield, such as, for example, about 90% or greater volumetric
recuperation, and more particularly about 94% or greater. The
process also produces a reduction in metal and sulfur content of
the upgraded oil obtained related to the asphaltene removal. The
upgraded oil also has an API gravity at least about three degrees
or more greater than an API gravity of the heavy crude oil.
[0015] In this process, precipitant and crude oil come into
intimate contact with a static mixer arrangement, at temperatures
below 80.degree. C. (176.degree. F.) and pressures between 40 and
60 psig. The crude oil/precipitant stream is then taken to an
agitated tank for further mixing and for ensuring sufficient
residence time in order to improve solid precipitation. The
agitated tank content is then drained out of the tank using
suitable equipment that forces it to flow into a high gravity field
device (a hydro-cyclone or a centrifuge). There, the crude
oil/precipitant stream is separated into two currents: a solid free
stream and high solid content slurry which still contains some
upgraded oil and precipitant. The solid free stream is fed to a
flash separator that recovers the precipitant to be reused, and
produces the upgraded oil.
[0016] The high solid content stream goes to a "washing" section
were the solids are washed to recuperate the liquid that remains
occluded in them. This step is critical to increase the volumetric
yield of the process. The washed product goes to a high
gravitational force separator (centrifuge) where two streams are
obtained: one rich in solids (asphaltenes) that goes to a dryer
where the remaining precipitant is recuperated, and a second
current comprising, or alternatively consisting of, dry solids that
can be used for power generation (combustion) or other purposes.
The second stream is a liquid that contains some crude oil and
precipitant that goes to the flash unit to recover the lighter
precipitant and to produce the upgraded oil, which is mixed with
the oil obtained in the first separator. In the flash unit, the
precipitant remaining in the upgraded oil is adjusted to further
reduce viscosity, if required.
[0017] The precipitant used in this process is a light fraction of
crude oil, like light gasoline, that reduces asphaltene solubility
in the crude oil and that can optionally contain some additives
(paraffinic, aromatic or oxygenated compounds) that enhance the
performance of the process as required. The formulation of the
precipitant is such that it fits the type of crude being treated,
as well as the required quality and yield.
[0018] An alternative embodiment of the process includes a battery
of static mixers that blends the extra heavy and heavy crude oil
feed with the stream that leaves the washing section. In this case,
the precipitant enters the washing section, which consists of a
stirred tank and a centrifuge or hydro-cyclones; the solid stream
of the centrifuge goes to a dryer where solids are obtained as a
product and precipitant is recovered. The liquid stream of the
centrifuge goes to the static mixers where it combines with crude
oil as mentioned. The crude oil and precipitant blend that exits
the static mixers goes to an agitated tank to provide for residence
time and then to a separator (hydro-cyclones or centrifuge) where
the liquid stream goes to a flash separator where the precipitant
is recuperated while the bottom stream goes to a steam stripper to
recover the last traces of solvent (if required). From the bottom
of the stripper, upgraded crude oil is obtained. The heavy stream
of the separator goes to the washing section or stirred tank where
precipitant and make-up precipitant are introduced. From there the
combined stream goes to the washing section centrifuge.
[0019] The above summary of the various representative embodiments
of the invention is not intended to describe each illustrated
embodiment or every implementation of the invention. Rather, the
embodiments are chosen and described so that others skilled in the
art can appreciate and understand the principles and practices of
the invention. The figures and the detailed description that follow
more particularly exemplify these embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The invention can be completely understood in consideration
of the following detailed description of various embodiments of the
invention in connection with the accompanying drawings, in
which:
[0021] FIG. 1 is a diagram showing in a schematic way the main
stages of the process of upgrading the crude oil for transport in
pipelines, according to an embodiment of the invention.
[0022] FIG. 2 shows a diagram of a modified version of the process
for upgrading crude oil for pipeline transport.
[0023] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular embodiments described. On the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION
[0024] Referring to FIG. 1, a process 1000 is shown in which crude
oil (1) is blended with a feed precipitant (2) in a set of static
mixers (3). The feed crude oil (1) generally comprises a kinematic
viscosity (dynamic viscosity divided by fluid density) of about
2400 centistokes (cSt) or more. Optionally, water has been removed
from the crude oil before being introduced into process 1000. The
crude oil (1) is at a temperature range of 50 to 100.degree. C.
(122 to 212.degree. F.), with pressures lower than 60 psig and the
volumetric precipitant to oil volume ratio is in a range from about
1 to 1 to about 1 to 2, including for example, 1.25:1 and 1.5:1,
depending on density differences. The weight ratio of crude oil to
precipitant (or solvent) can comprise about 1:1.
[0025] Once blended, the crude oil/precipitant mix is introduced to
a stirred tank (4) to allow for some residence time and growth of
the precipitated particles. The use of light precipitant with
relatively low boiling points (FBP less than 140.degree. C. or
284.degree. F.) helps in the separation and precipitation of
asphaltenes. The asphaltenes are generally present in the agitated
tank (4) as suspended particles and nano-colloids. From the tank
(4), the mixture goes through line (5) to a separator set (6). The
separator (6) uses inertial forces to separate the solid particles
from the liquid upgraded crude oil. The separator (6) can comprise,
for example, one or more hydro-cyclones or centrifuges. Precipitant
is present in both streams.
[0026] From the separator set (6) the liquid exits through line 7
to a "flash" separator or distillation tower (8) to recuperate the
precipitant from the upgraded oil. The "flash" separator (8)
operates at a pressure slightly higher than atmospheric and
temperatures capable of recuperating most of the precipitant. If
needed, the flash tower or separator (8) operation can be adjusted
so that a convenient amount of precipitant remains in the upgraded
oil, to further reduce viscosity as required or desired.
[0027] The precipitant leaves the flash through line 9 to be cooled
down in condensers (not shown) exiting at 35-55.degree. C.
(95-131.degree. F.) and then goes through line 17 to a solvent tank
(18). From tank (18), the precipitant goes through line 19 to line
2 and is recycled and mixed with crude oil (1).
[0028] Referring back to the flash separator (8), the bottom of the
flash drum goes through line 20 into an optional steam stripper
(21) that operates to recuperate traces of precipitant left in the
upgraded oil, if required or desired. The recuperated precipitant
plus steam mix leave the stripper (21) through line 24, where the
mix is condensed (not shown) and the water and precipitant are
separated in a drum (not shown). The recuperated precipitant goes
through line 17 where it mixes with the precipitant from line 9 of
the flash separator 8, and the combined currents return to the
solvent tank (18) as described above. From the precipitant tank
(18), the solvent transits line 19 into line 2 and it is finally
mixed with crude oil (1).
[0029] Referring back to the stripper (21), vapor, in the form of
steam, enters the stripper (21) through line 23. The product of the
stripper (21) is the lower viscosity upgraded oil, which exits
through line 22. Typically, the kinematic viscosity (dynamic
viscosity divided by the density of the fluid) is equal to or less
than about 700 centistokes (cSt). The yield of crude oil in the
upgraded oil is about 92% or greater in volume. It has been
observed that the initial viscosity of the crude oil feed (1) is
independent from, and does not affect, the yield of upgraded
oil.
[0030] The liquid/solid stream, or oil slurry containing the
asphaltenes that leaves the first separator (6) through line 10
goes to an agitated tank (11) where it is very well mixed or washed
with precipitant at low shear rates fed from recycle stream 19
through line 25 with a volumetric flow similar to the one used in
the first contact in the static mixers (3). The mixture of the oil
slurry and the precipitant leaves the agitated tank (11) through
line 12 to a centrifugal separator (13) that operates between 1000
to 6000 g's. The combination of the tank (11) and separator (13)
make up the washing unit of the process, and is shown in FIG. 1
inside a dashed box.
[0031] Two streams leave the separator (13) including a liquid
stream with precipitant and crude oil (14) that goes to the flash
separator (8) to recuperate the precipitant and the upgraded oil as
described above, and a solid stream (15) saturated with precipitant
that goes to a dryer (16) to recuperate the precipitant through
line 17, where the precipitant is condensed and recycled as
described above with respect to line 17. A dry stream (26),
containing mostly asphaltenes (26), can be used to produce energy,
such as by firing at the oilfield site, or for other purposes.
[0032] Additionally, or optionally, precipitant make-up or
additives are introduced, as needed, such as at start-up, through
line 27 that combines with recycled precipitant 19 at line 2, where
it ultimately mixes with the crude oil in line 1.
[0033] Referring now to FIG. 2, in an alternative embodiment, a
process 2000 includes a crude oil feed (50) mixed with a recycled
current (51) that contains precipitant and deasphalted crude oil
recuperated in the washing section exiting the separator (52). This
mixture goes through a static mixers battery (53) and then enters a
stirred tank (54) to allow for residence time. From there, the
liquid-solid mixture exits through line (55) to end in a separation
unit (56), which can comprise a battery of hydro-cyclones or
centrifuges.
[0034] Two streams leave the separator (56); one liquid stream (57)
goes to a flash separator unit or distillation tower (58) where the
solvent (i.e. light precipitant) leaves through line 59 to
precipitant tank (60). The heavy fraction or oil slurry leaves the
separator (56) through line 61 to the wash tank (62) of a wash unit
shown in dotted lines, where it is washed with precipitant from
precipitant tank 60 via line 71. From the wash tank (62) the stream
exits through line (63) to the separator (52) of the wash unit. The
separator (52) discharges the liquid recycled current (51) that
goes to blending with the crude oil as aforementioned.
[0035] The slurry or heavy fraction leaves the separator (52)
through line 64 to the dryer (65). The dryer output consists of two
currents: stream 66, which is the solid product comprising mainly
asphaltenes, similar to line 26 of FIG. 1; and stream (67), which
is recuperated precipitant. This recuperated precipitant is
condensed (condensing section not shown) and sent to a precipitant
tank (60) where it is blended with recuperated precipitant (59)
from flash unit or distillation tower (58) and fed via line 71 to
wash tank (62) as described above.
[0036] The bottom of the flash tower (58) leaves through line 68 to
an optional stripper (69) where the current 68 containing crude oil
and precipitant is stripped with steam (70). From the bottom of the
stripper the upgraded oil (72) is obtained. The recuperated
precipitant plus steam leave the stripper through line 74 where it
is condensed and the water and solvent separated in a drum (not
shown). The precipitant is sent through line 59 to precipitant tank
(60).
[0037] Additionally, or optionally, precipitant make-up or
additives are introduced, as needed, such as into wash agitated
tank 62, through line 76.
[0038] Similar to the process 1000 of FIG. 1, the kinematic
viscosity (dynamic viscosity divided by the density of the fluid)
of the upgraded oil at 72 is equal to or less than about 700
centistokes (cSt). The yield of crude oil in the upgraded oil is
about 92% or greater in volume. It has been observed that the
initial viscosity of the crude oil feed (50) is independent from,
and does not affect, the yield of upgrade oil. Furthermore, the
ratios of precipitant to crude oil at the feed of process 2000 is
also similar to process 1000 of FIG. 1, and can comprise, for
example, a volumetric precipitant to oil volume ratio is in a range
from about 1 to 1 to about 1 to 2, including for example, 1.25:1
and 1.5:1, depending on density differences. The weight ratio of
crude oil to precipitant (or solvent) can comprise about 1:1.
[0039] In embodiments of the invention, the precipitant can
comprise, for example, a light or natural gasoline. The
precipitant's precipitating properties can be modified using
optional additives such as light paraffinic hydrocarbons (pentane,
hexane and heptanes, for example) or oxygenated hydrocarbons (such
as pentanol, butanol, light ketones) that can be added through line
27 in FIG. 1, or line 76 in FIG. 2). The formulation of the final
precipitant is a function of the type of crude oil and the level of
deasphalting required in the process to reach a low enough upgraded
oil viscosity for pipe transportation and the highest yield
possible. Also the vapor pressure of the solvent or precipitant
must be such as to allow an easy separation in the flash columns or
distillation column of the processes.
[0040] In both processes, the stripper is used to recuperate traces
of solvent from the upgraded product; however, depending on the
user's needs, the stripper could be omitted from the process.
EXAMPLE
[0041] In this example the process 1000 shown in FIG. 1 is
followed:
[0042] 100 g of Quifa crude oil from Colombia, whose
characteristics are shown in table 1, is treated with a 100 g of a
light gasoline as precipitant (Flash Boiling Point 260.degree. F.
and 81.1.degree. API) in a precipitant/crude oil ratio of 1/1 in
weight percent. The Quifa and precipitant are well mixed and are
separated in a centrifuge (at 4000 g's). Two streams are produced,
a light stream of 141.1 g which contains precipitant and partially
deasphalted upgraded oil. This stream is subjected to a flash
separation to recuperate precipitant and separate the upgraded oil.
The other stream is 58.9 g of slurry that contains precipitant and
a heavy solids fraction. This heavy fraction is subjected to a
washing operation with 100 g of precipitant in an agitated
tank.
[0043] The washed product is separated in a centrifuge at 4000 g's
and two streams are obtained: a slurry stream of 40.8 g rich in
asphaltenes (18.0%), very little crude oil (6.5%) and precipitant
(75.5%) and a liquid stream of 118.1 g that contains washed crude
oil (20.3%) and solvent (79.7%). The slurry stream is dried and 10
g of solids are obtained and 30.8 g of precipitant are recuperated.
The liquid stream goes to the flash tower, were it is mixed with
the liquid stream from the fist centrifuge. From the flash unit,
169.1 g of the precipitant is recuperated and 90.0 g of upgraded
oil are obtained as a product (characteristics shown in table
1).
TABLE-US-00001 TABLE 1 Characteristics of Quifa crude oil and of
upgraded oil Quifa Crude Oil Upgraded Oil API gravity 13 16
Viscosity (cP @ 30.degree. C.) 2400 650 V (ppm) 119 24 Ni (ppm) 33
7 Yield (% wt) N/A 90
[0044] As demonstrated by this example, the process has a very high
yield of product (90.0% wt) and a volumetric recuperation of 92%.
There is also a substantial reduction in metals.
[0045] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and described in detail. It is understood,
however, that the intention is not to limit the invention to the
particular embodiments described. On the contrary, the intention is
to cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the invention as defined by the
appended claims.
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