U.S. patent application number 11/335846 was filed with the patent office on 2006-08-17 for down hole physical upgrading of heavy crude oils by selective energy absorption.
Invention is credited to Raymond S. Kasevich.
Application Number | 20060180304 11/335846 |
Document ID | / |
Family ID | 36190473 |
Filed Date | 2006-08-17 |
United States Patent
Application |
20060180304 |
Kind Code |
A1 |
Kasevich; Raymond S. |
August 17, 2006 |
Down hole physical upgrading of heavy crude oils by selective
energy absorption
Abstract
The present invention utilizes the ability of electromagnetic
energy at the appropriate frequency to selectively deposit thermal
energy in the heavy oil for precise control of cracking temperature
throughout a given volume of material. Selective electromagnetic
energy absorption in the heavy crude oil provides energy efficient
transfer of heat at the molecular level and thereby insures precise
temperature control throughout the treatment volume. This allows
for optimization of the visbreaking process using electromagnetic
energy.
Inventors: |
Kasevich; Raymond S.; (Great
Barrington, MA) |
Correspondence
Address: |
DORSEY & WHITNEY LLP;INTELLECTUAL PROPERTY DEPARTMENT
50 SOUTH SIXTH STREET
MINNEAPOLIS
MN
55402-1498
US
|
Family ID: |
36190473 |
Appl. No.: |
11/335846 |
Filed: |
January 19, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60645154 |
Jan 19, 2005 |
|
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Current U.S.
Class: |
166/248 ;
166/302; 166/66.5 |
Current CPC
Class: |
E21B 36/04 20130101;
E21B 43/2401 20130101 |
Class at
Publication: |
166/248 ;
166/302; 166/066.5 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Claims
1. A system for use in treating heavy crude oil underground, the
system comprising: a borehole in an area in which crude oil exists
in the ground; an electromagnetic energy applicator positioned
within the borehole in the vicinity of the heavy crude oil to be
treated; a cable attached to the electromagnetic energy applicator
to supply electromagnetic energy to the applicator; an
electromagnetic energy generator attached to the cable to generate
electromagnetic energy to be supplied to the applicator; and a
product return pipe running through the borehole, the product
return pipe comprised of: a distal end positioned in the vicinity
of the electromagnetic energy applicator through which oil or other
products may be recovered; and a proximal end on or near the
surface of the ground.
2. The system of claim 1 wherein the applicator is an antenna
array.
3. The system of claim 1 wherein the applicator is a solenoid
antenna.
4. The system of claim 1 wherein the applicator is a helical
antenna.
5. The system of claim 1 in which at least one of the cable and
applicator are attached to the product return pipe.
6. The system of claim 1 in which the product return pipe is
connected to a storage or processing facility.
7. The system of claim 1 further comprising: a wellhead at the
surface of the borehole, the wellhead comprising: a bellows
connected to the applicator structure in such a way that the
bellows supports the weight of the applicator.
8. The system of claim 7 further comprising a sealable opening for
the introduction of gas to the wellhead and borehole.
9. A method for treating heavy crude oil underground, the method
comprising the steps of: positioning an electromagnetic energy
applicator in a borehole in the vicinity of heavy crude oil;
generating electromagnetic energy; applying the electromagnetic
energy to the heavy crude oil with the applicator to achieve
thermal cracking; and recovering heavy crude oil through a product
return pipe.
10. The method of claim 9, further comprising the steps of:
controlling the electromagnetic energy applied to the heavy crude
oil in order to upgrade the heavy crude oil in situ.
11. The method of claim 9, in which the electromagnetic energy is
applied to heavy crude oil in oil shale.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority from U.S. provisional
patent application No. 60/645,154, which was filed on Jan. 19,
2005, and which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the use of
electromagnetic energy to subject heavy crude oil to mild thermal
cracking conditions, thereby lowering the viscosity, pour point,
and specific gravity of the oil and rendering it easier to recover
and handle. More particularly, this invention relates to methods
for applying electromagnetic energy to heavy oils in the reservoir
to promote in situ upgrading and facilitate recovery. This
invention also relates to systems to apply electromagnetic energy
to heavy oils in situ.
BACKGROUND OF THE INVENTION
[0003] Heavy crude oil presents problems in oil recovery and
production. Crude oils of low API gravity and crude oils having a
high pour point present production problems both in and out of the
reservoir. Extracting and refining such oils is difficult and
expensive. In particular, it is difficult to pump heavy crude oil
or move it via pipelines.
[0004] Various methods to ameliorate the disadvantages of heavy
crude oil are used today. For example, the oil industry reduces
surface handling problems by blending heavy crude oil with light
oils and liquid proprane gas to make them easily handled in
pipelines and storage facilities. This method has drawbacks,
however, as it does not assist in the initial recovery of the oil,
and it is expensive.
[0005] A process called "visbreaking," or mild thermal cracking,
may also be used to reduce the viscosity of heavy crude oil.
"Visbreaking" is an oil refinery process for increasing the
pumpability of heavy crudes. It typically is accomplished by
heating heavy crude oil in a furnace. The process is characterized
by mild decomposition, minimum coke formation and the retention of
the cracked product in the original feed stock. The resultant
mixture has viscosity, pour point, and specific gravity values that
are lower than the original oil. However, ask applied today,
visbreaking cannot be used on oil in situ.
[0006] The present invention applies visbreaking new contexts and
for new purposes, and proposes improved methods for the application
of visbreaking. In the present invention, visbreaking is
accomplished using electromagnetic energy to heat the heavy crude
oil, rather than heating it in a furnace. Furthermore, the present
invention is suitable for use in the treatment of oil in situ. Such
treatment permits the upgrade of the oil in reservoir and assists
in the recovery of the oil.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention utilizes the ability of
electromagnetic energy at the appropriate frequency to selectively
deposit thermal energy in the heavy oil for precise control of
cracking temperature throughout a given volume of material.
Selective electromagnetic energy absorption in the heavy crude oil
provides energy efficient transfer of heat at the molecular level
and thereby insures precise temperature control throughout the
treatment volume. This allows for optimization of the visbreaking
process using electromagnetic energy.
[0008] Proper selection of frequency and power duration results in
the rapid cracking of heavy hydrocarbons to any degree desired by
electromagnetic energy absorption. When the desired degree of
cracking is reached, the hot oil matrix provides a significantly
different set of electrical properties which can be measured on the
surface during the "electromagnetic visbreaking process." (EVP) to
insure precise down hole temperature and power control.
[0009] This proposed EVP provides efficient energy absorption and
control of thermal cracking of heavy oils for in-situ upgrading.
The application of low power (a few ten's of kilowatts)
electromagnetic energy to the formation for visbreaking will
provide mild decomposition of the heavy oil, minimum coke formation
and the retention of the cracked product in the original feedstock.
The resultant mixture has viscosity, pour point, and specific
gravity values which are lower than those of the original oil.
[0010] The present invention several promising applications. It can
be used to upgrade heavy crude oil in situ. It can also assist in
the recovery of heavy crude oil from reservoirs. Further, the
present invention can be used to more efficiently recovery
hydrocarbons from oil shale, such as that present in the Western
United States.
[0011] In one embodiment of the invention, a system may be provided
for use in treating heavy crude oil underground. The system may
comprise a borehole in an area in which crude oil exists in the
ground, an electromagnetic energy applicator positioned within the
borehole in the vicinity of the heavy crude oil to be treated, a
cable attached to the electromagnetic energy applicator to supply
electromagnetic energy to the applicator, an electromagnetic energy
generator attached to the cable to generate electromagnetic energy
to be supplied to the applicator, and a product return pipe running
through the borehole, the product return pipe comprised of a distal
end positioned in the vicinity of the electromagnetic energy
applicator through which oil or other products may be recovered and
a proximal end on or near the surface of the ground.
[0012] In another embodiment of the invention, a method for
treating heavy crude oil underground is provided. The method
comprises the steps of positioning an electromagnetic energy
applicator in a borehole in the vicinity of heavy crude oil,
generating electromagnetic energy, applying the electromagnetic
energy to the heavy crude oil with the applicator to achieve
thermal cracking, and recovering heavy crude oil through a product
return pipe.
[0013] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention. As
will be realized, the invention is capable of modifications in
various obvious aspects, all without departing from the spirit and
scope of the present invention. Accordingly, the drawings and
detailed description are to be regarded as illustrative in nature
and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view of a single borehole radiation
type applicator.
[0015] FIG. 2 is a close up view of a portion of the applicator
system.
[0016] FIG. 3 is a perspective view of a portion of another
configuration of a single borehole applicator.
[0017] FIG. 4 is a perspective view of a wellhead for use with the
applicator system.
[0018] FIG. 5 shows a sample of the absorption data from
experiments on the application of electromagnetic energy to large
oil molecules in oil shale.
DETAILED DESCRIPTION
[0019] A variety of different types of down hole electromagnetic
structures may be employed to apply electromagnetic energy to heavy
crude oil in situ. The proper structure for any particular
application depends on a variety of factors, including depth, heat
uniformity, and minimizing the degree of coking and production of
unsaturated hydrocarbons.
[0020] FIG. 1 is a perspective view of a single borehole radiation
type applicator. Applicator system 10 is positioned within borehole
12. Borehole 12 is supported by casing 14. Applicator system 10 is
then used to apply electromagnetic energy to heavy crude oil in the
vicinity of borehole 12.
[0021] Applicator structure 20 is a transmission line retort. For a
point of reference, a typical applicator 20 may be approximately 70
feet long. In a typical configuration, the applicator 20 may be
positioned from between 100 to 600 feet underground in borehole 12.
Radiofrequency ("RF") energy is supplied to applicator 20 by an RF
generator (not shown). The RF generator is connected to applicator
20 via a portion of flexible coaxial cable 30. In turn, the
flexible coaxial cable 30 is connected to a portion of rigid
coaxial cable 32. The coaxial cable may or may not be supported by
ceramic beads, which are desirable at higher temperatures. By this
means, the RF generator supplies RF energy to applicator 20, which
in turn applies RF energy to the target volume to achieve
visbreaking. This allows in situ upgrading of the heavy crude oil
and assists in recovery.
[0022] Recovery of the oil and related products is achieved by
means of production pipe 40. This non-metallic pipe runs from the
production area of borehole 12 through the borehole to surface 16.
At the surface, production pipe 40 is connected via a product
return line to a storage or processing facility (no shown).
[0023] Production pipe 40 provides a firm mounting base for the RF
hardware of applicator system 10. Coaxial cables 30 and 32 can be
attached directly to production pipe 40 using connectors 42.
Applicator 20 also attaches to production pipe 40.
[0024] FIG. 2 is a close up view of a portion of the applicator
system. Applicator structure 20, rigid coaxial cable 32, and
production pipe 40 are all positioned within borehole 12. Typical
dimensions for such a system are shown in FIG. 2. Ceramic support
beads 34 support rigid coaxial cable 32. Further, ceramic pressure
window 36 is placed at the tope of applicator 20.
[0025] FIG. 3 is a perspective view of a portion of another
configuration of a single borehole applicator. In this
configuration, a dipole feed is used. Coaxial feed 38 surrounds
production pipe 40. Ceramic window 36 is placed at the bottom of
coaxial feed 38.
[0026] Although specific examples of applicator structures are
given, it is understood that other arrangements known in the art
could be used as well. Uniform heating may be achieved using
antenna array techniques, such as those disclosed in U.S. Pat. No.
5,065,819. Such techniques can be used to minimize coking
conditions at the applicator borehole and avoid excessive electrode
voltage gradients at high power. Arrays reduce excessive voltage
gradients at the borehole by means of mutual coupling. The ability
to separately measure reflected power from each applicator borehole
containing radiator and mutual impedance coupling between any pair
of applicator boreholes insures precise temperature control of the
heated volume.
[0027] Other variations are possible, including non-radiation
structures such as those proposed in J. Bridges, et al., "RF
Heating of Utah Tar Sands," Final Report, IIT Research Institute.
However, such structures are sensitive to high voltage breakdown
and require extensive drilling which is not economical.
[0028] A special wellhead may be used in conjunction with
applicator system 10. Properly designed, the wellhead can be used
to provide safe and efficient delivery of RF energy to the
applicator.
[0029] FIG. 4 is a perspective view of a wellhead for use with the
applicator system. The weight of the down hole applicator (not
shown) rests on a special bellows 46 within the wellhead. This
insures that any heat induced mechanical movements of the down hole
apparatus during energy transfer do not interrupt power flow. An
input opening 44 permits nitrogen to be introduced into the
interior of the wellhead and borehole, further ensuring the safe
application of RF energy. Insulators 45 are positioned above the
bellows 46, and a center conductor expansion joint is positioned on
top of that. At the top of the wellhead, where coaxial cable 30
exits and runs to RF generator 28, a coaxial line seal and vertical
alignment clamp 26 secure the cable to the wellhead. Product return
line 41 carries the product recovered through the system to a
storage or processing facility (not shown), and water extraction
line 43 permits the removal of water from borehole 12.
[0030] The present invention also has application in oil shale
fields, such as those present in the Western United States. Large
oil molecules that exist in such oil shale have been heated in a
series of experiments to evaluate the dielectric frequency response
with temperature. The response at low temperatures is always
dictated by the connate water until this water is removed as a
vapor. Following the water vapor state, the minerals control the
degree of energy absorption until temperatures of about 300-350
degrees centigrade are reached. In this temperature range, the
electromagnetic energy begins to be preferentially absorbed by the
heavy oil. The onset of this selective absorption is rapid and
requires power control to insure that excessive temperatures with
attendant coking do not occur. FIG. 5 shows a sample of the
absorption data from such experiments.
[0031] Because of the high temperature selective energy absorption
capability of heavy oil, it is therefore possible to very carefully
control the bulk temperature of down hole crude oil heated by
electromagnetic energy. The energy requirement is minimized once
the connate water is removed by steaming. It takes much less energy
to reach mild cracking temperatures with electromagnetic energy
than any other thermal means to provide visbreaking.
[0032] Kasevich has published a molecular theory that relates to
the specific heating of heavy of oil molecules. He found that by
comparing cable insulating oils with kerogen (oil) from oil shale,
a statistical distribution of relaxation times in the kerogen
dielectric gave the best theoretical description of how
electromagnetic energy is absorbed in oil through dielectric
properties. With higher temperatures and lowering of potential
energy barriers within the molecular complex a rapid rise in
selective energy absorption occurs.
[0033] In use, a user of an embodiment of the present invention
would position an applicator system in a borehole in an area in
which heavy crude oil exists. The user would position the
applicator structure itself in the borehole in the target area for
application of RF energy. The user would connect the applicator
structure to an RF generator via coaxial cable. A production pipe
would run from the area of production to the surface, and from
there to a storage or processing facility. The user would then
apply RF energy using the RF generator to the applicator, thereby
applying the RF energy to the heavy crude oil in situ. The RF
energy would be controlled to minimize coking and achieve the
desired cracking and upgrading of the heavy crude oil. The
resulting products would then be recovered via the production pipe
and transferred to a storage or processing facility.
[0034] Although the present invention has been described with
reference to preferred embodiments, persons skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *