U.S. patent application number 11/698556 was filed with the patent office on 2007-08-16 for method for recovery of stranded oil.
Invention is credited to William C. Pfefferle.
Application Number | 20070187093 11/698556 |
Document ID | / |
Family ID | 38367148 |
Filed Date | 2007-08-16 |
United States Patent
Application |
20070187093 |
Kind Code |
A1 |
Pfefferle; William C. |
August 16, 2007 |
Method for recovery of stranded oil
Abstract
The present invention provides a method of recovering stranded
oil wherein heated fluid is injected into a reservoir containing
stranded oil in a region near the reservoir ceiling. The heated oil
drains toward the reservoir floor and is recovered via a production
well.
Inventors: |
Pfefferle; William C.;
(Madison, CT) |
Correspondence
Address: |
Robert L. Rispoli;Precision Combustion Inc.
410 Sackett Point Road
North Haven
CT
06473
US
|
Family ID: |
38367148 |
Appl. No.: |
11/698556 |
Filed: |
January 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60773410 |
Feb 15, 2006 |
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Current U.S.
Class: |
166/257 ;
166/303; 166/50 |
Current CPC
Class: |
E21B 43/2406 20130101;
E21B 43/2408 20130101; E21B 43/243 20130101 |
Class at
Publication: |
166/257 ; 166/50;
166/303 |
International
Class: |
E21B 43/243 20060101
E21B043/243; E21B 43/24 20060101 E21B043/24 |
Claims
1. A method of recovering stranded oil comprising: a) injecting
heated fluid into a reservoir containing stranded oil in a region
near the reservoir ceiling; b) allowing heated oil to drain toward
the reservoir floor; and c) recovering drained oil via a production
well.
2. The method of claim 1 wherein the heated fluid is produced
downhole using a downhole combustor.
3. The method of claim 1 wherein the heated fluid is provided from
the surface and passed downhole.
4. The method of claim 1 wherein the heated fluid is injected via a
horizontal well.
5. The method of claim 4 wherein the horizontal well comprises a
plurality of branches.
6. The method of claim 1 wherein the injected fluid is at a
temperature high enough to result in cracking of the stranded
oil.
7. The method of claim 6 wherein said temperature is greater than
800F.
8. The method of claim 1 wherein the heated fluid is produced by
passage of a fluid through a heated upper layer.
9. The method of claim 8 wherein the fluid to be heated comprises
nitrogen.
10. The method of claim 8 wherein the fluid to be heated comprises
carbon dioxide.
11. The method of claim 1 wherein the heated fluid is produced
downhole by in-situ combustion.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a method for the recovery of
stranded oil left behind in an oil reservoir after recovery of oil
by conventional means.
BACKGROUND OF THE INVENTION
[0002] Oil fields typically are abandoned after oil can no longer
be produced economically by known secondary or tertiary recovery
methods. At this point, the remaining oil in place often represents
as much as two-thirds of the amount originally in place. Of the
remaining oil, about twenty percent is considered technically
recoverable using advanced techniques such as, for example, carbon
dioxide flooding. Unfortunately, for stranded oil in most U.S.
fields, carbon dioxide is not available. Moreover, there is a need
to recover far more stranded oil than can be recovered by known
advanced methods such as carbon dioxide flooding. It is therefore
an object of the present invention to make possible economic
recovery of nearly all the remaining stranded oil in place.
SUMMARY OF THE INVENTION
[0003] The oil coating on the reservoir minerals can be flushed off
much more effectively than by carbon dioxide flooding. By heating
the oil to an elevated temperature along with reservoir
pressurization, the oil can be flushed off of the sand, for
example, in the reservoir. In the present invention, hot fluids are
injected near the top of the reservoir such that fluid flow is
downward toward the reservoir floor by gravity drainage aided by
the downward fluid flow. Inert gases present in injected fluids
provide reservoir repressurization. Preferably, fluid is injected
through a horizontal well to best distribute the flow across the
reservoir ceiling. Advantageously, the hot combustion gases are
produced using a downhole combustor. If available, carbon dioxide
is added to combustion products for sequestration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 depicts an isometric of horizontal injection well
with branches protruding into the reservoir.
DETAILED DESCRIPTION OF THE INVENTION
[0005] In the present invention 10, as shown in FIG. 1, hot fluids
such as steam or combustion gases may be produced at the surface
and injected downhole via injection well 12. However, heat losses
advantageously may be reduced by generating the heated fluids
downhole as by a downhole combustor with fuel and air supplied from
the surface. Combustion gases produced by downhole combustion
typically are reduced in temperature by addition of an inert fluid
such as nitrogen or carbon dioxide. Steam may be produced by
spraying water into the hot combustion products. Hot fluids also
may be generated by in-situ combustion with air supplied from the
surface.
[0006] Hot fluid is provided near the reservoir ceiling 14 using
any conventional method known in the art such that the flow forms a
gas blanket layer which flows downward toward the reservoir floor.
Thus heated oil drains toward the reservoir floor 16. Typically the
fluid is injected via a horizontal well 18. To distribute the fluid
over a wider area, the horizontal well may have horizontal branches
20 as shown in FIG. 1.
[0007] Temperature of the injected fluid in most cases is below
that which would result in significant cracking of the oil.
However, if significant reduction in the oil viscosity is desired,
the temperature of the injected fluid is controlled to a value
which will result in cracking of the oil. Temperatures high enough
for cracking can be provided by use of in-situ combustion. Cracking
of the oil is desirable where the viscosity of the stranded oil is
higher than that originally produced in primary production. Oil
draining to the reservoir floor may be recovered through an
existing production well. However, it may be advantageous to
provide a new horizontal production well located on or near the
reservoir floor.
[0008] After the heated fluid has heated an upper portion of the
reservoir flushing the oil downward, heat from oil depleted layers
may be utilized to heat a cold fluid such as nitrogen or carbon
dioxide thus providing heated fluid for recovery of oil from lower
levels.
[0009] While the present invention has been described in
considerable detail with reference to a preferred method for the
recovery of stranded oil left behind in an oil reservoir after
recovery of oil by conventional means as described herein, other
methods exhibiting the characteristics taught herein are
contemplated. Therefore, the spirit and scope of the invention
should not be limited to the description of the preferred
embodiment described herein.
* * * * *