Note: Descriptions are shown in the official language in which they were submitted.
63
The present invention relates to a method and system for secondary
recovery of oil by injection of water into injection wells for water flooding
of oil bearing formation with the crude oil recovered from the recovery or
production well being pumped into a concentric tank separator heated by solar
energy for effective separation of gas, oil and water with the gas and oil
being discharged to storage or other point of use and the heated water serving
as an insulator for the inner tank of the separator and being recirculated
back to the injection wells for more effective water flooding
Secondary oil recovery methods and systems have been employed for a
number of years in order to recover a larger percentage of crude oil from the
oil bearing strata or formation. One method and system ~hich has been employed
is water flooding which basically involves the injection of water or other
~lowable medium into an injection well or injection wells spaced from a
production or recovery well so that the flooding medium which is pumped into
the injection well or injection wells under pressure will cause crude oil in
the formation to migrate toward the production well or recovery well thus
enabling it to be pumped to storage in a conventional manner.
An object of the present invention is to provide a secondary recovery
method and system utilizing solar energy combined with a separator for~separat-
~O ing the crude oil pumped from a production or recovery well into gas, oil andwater with the separator including concentric tanks with the inner tank
receiving the crude oil and being heated by the solar energy to facilitate
separation into gas, oil and water with the separator including an outer tank
receiving heated water to serve as an insulator and heat sink for the crude
oil in the inner tank and as a reservoir for heated water to be injected into
the injection well or wells.
Another object of the invention is to provide a secondary recovery
method and system as set forth in the preceding object in which the solar
energy is provided by a solar furnace including a collector panel mounted on
30 top of the separator tank and transferring heat to the water and crude oil ~.
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through a heat exchange fluid circulating through heat exchange tubing.
Still another object of ~he invention is to provide a secondary
recovery method and system as set forth in the preceding objects in which the
separator serves as a temporary storage tank with a dome trap at the upper end
for collecting gas separated from the crude oil and the exterior of the tank
is provided with insulating material to reduce heat loss from the heated crude
and water wi~hin the separator.
Yet another object of the invention is to provide a secondary
recovery method and system using solar energy and a concentric tank separator
which is relatively simple in construction, is low cost in operation and
effectively utilizes solar energy to facilitate recovery of crude oil from an
oil bearing formation.
Figure I is a schematic side elevational view illustrating the
secondary recovery method and system of the present invention
Figure 2 is a plan view of the separator tank assembly with a
portion of the solar furnace and top of the tank being broken away illustrat-
ing the structural details thereof.
Figure 3 is a vertical sectional view, taken substantially upon a
plane passing along section line 3--3 on Fig. 2, illustrating further struc-
2~ tural details of the separator tank.
Referring now specifically to the drawings, the secondary oilrecovery method and system of the present invention is generally designated by
numeral 10 and includes a tank generally designated by the numeral 12 which
serves as a separator and temporary storage for crude oil 14 which is pumped
from a recovery well or production well generally designated by numeral 16 by
a conventional pump jack 18 and downhole pump (not shown) all of which are
conventional components with the tank 12 being the essential component of the
present invention. Also shown in Fig. 1 is an injection well 20 spaced from
the recovery well 16 with a waterline 22 being connected to the injection well
20 in a conventional manner for flooding the oil bearing strata or formation
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to enable a larger percentage of the oil in the formation to be recovered at
the recovery well 16. This flooding technique is well-known and conventional
except that in the present invention, the water injected into the injection
well or wells 20 through the waterline 22 is heated and temporarily stored in
A unique manner to be set forth in detail hereinafter.
The tank 12 includes an inner tank 24 defined by an inner wall 26
and an outer tank 28 defined by an outer wall 30 spaced from the inner wall 26
and in concentric relation thereto. As illustrated, the walLs 26 and 30 are
cylindrical in configuration and concentric but the shape and configuration
thereof may vary. The lower end of the concentric walls 26 and 30 are inter-
connected by a bottom wall 32 which also forms a closure for the bottom of the
inner cank 24. Thus, the bottom 32 forms an imperforate bottom for the tank
12. The top of the tank 12 is closed by a top wall 34 which has a centrally
disposed dome 36 incorporated therein or attached thereto to provide a gas
trap with the dome being in communication with only the inner tank 24. The
crude oil from the well 16 is conveyed to the inner tank 24 by a pipeline 38
and a suitable pump 40, if necessary, depending upon the distance and other
conditions with respect to the relationship of the tank 12 to the recovery
well 16.
~0 As illustrated in Fig. 3, the crude oil 14 in the inner tank 24 is
heated and separated into gas, oil and water with the gas accumulating in the
dome 36 and being conveyed to a storage tank or other point of use by a
pipeline 42 communicating with the dome gas trap 36. The heated crude oil is
discharged to a storage tank through a pipeline 44 and a pump, if necessary,
with the inner end of the pipe 44 communicating with the inner tank 24 at a
point generally at or slightly below the vertical center of the inner tank 24
as indicated by numeral 46 in order to make certain that the upper level of
the crude 14 in the inner tank 24 will normally be disposed above the inlet
point 46 for the heated oil discharge pipe 44. Water that separates from the
heated crude oil will accumulate in the bottom of the inner tank 24 and is
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discharged from the heated inner tank 24 into the outer tank 28 by a plurality
of connecting tubes or pipes 48 which extend radially through the lower end
portion of the peripheral wall 26 as illustrat~d in Fig. 3. The heated water
in the bottom of inner tank 24 and in the outer tank 28 is used as heated
water to inject into the injection well or wells 20 through pipelines 22 and
an appropriate injection pump of conventional construction. Gas is discharged
through the gas pipe 42 to a storage tank or other point of use or sale and
heated crude oil is discharged from the pipe 44 into a storage tank or other
point of use, sale or refinement.
In order to heat the crude oil, a solar furnace generally designated
by numeral 50 is provided on top of the tank 12 although it could be mounted
in other locations adjacent thereto depending upon the manner in which the
tank is supported. As illustrated, the tank is mounted on the ground surface
or partially embedded therein with the supporting arrangement therefor being
conventional. In this embodiment, the solar furnace is mounted on top of the
tank 12 and includes a generally hollow rectangular collector panel generally
designated by the numeral 52 which includes a box-shaped housing 54 having
a transparent cover 56 thereon and receiving a heat exchange coil or tube 58
therein which represents a conventional solar collector with a heat exchange
medium such as "Freon" or any other halogenated hydrocarbon or other heat
exchange fluid. The heat exchange tubing or coil includes vertical tubes 60
and 62 which extend downwardly through the outer tank 28 with a pump 64 being
provided in the downwardly extending tube in which the heat exchange medium
flows from the collector 52 although in some instances, the pump 64 may not
be necessary. The tubes 60 and 62 then extend horizontally from one side of
the outer tank 28 through the inner tank 24 and through the opposite side
of the outer tank 28 as illustrated in Fig. 3 and define a heat exchange coil
generally designated by the numeral 66 in the form of multiple loops disposed
in the inner tank 24 and partially in the outer tank 28 so that solar energy
will be absorbed by the working fluid or heat exchange medium and transferred
63
to the inner and outer tanks to maintain the crude oil and water at a desired
elevated temperature. The elevated temperature may vary but should be at
least 90 F. and may reach approximately 160 F. or 180 F. depending upon the
capability of the solar furnace to collect and transfer solar energy. Also,
an auxiliary heater such as a gas fired heater, oil fired heater, electric
resistance heater, or the like, may be provided in the inner tank as a back-up
heat source in the event a series of cloudy days occur or a prolonged period
of inclement weather occurs. The outer surface of the tank 12 is provided
with insulation 68 around the outer wall 30 and over the top wall, if desired,
in order to reduce heat loss and enable the heat sink formed by the water in
the outer tank 28 to maintain elevated temperature of the crude oil for a
period of time, such as during the night time, so that under average circum-
st~nces, the solar furnace S0 will provide all of the heat necessary to
effectively heat the crude oil and water to more efficiently separate the gas
and water from the crude oil and also heat the water used for injection into
the injection wells thereby more efficiently extracting oil from the oil
formation by flooding the formation with heated water.
The gas entrained in the crude oil usually will maintain an elevated
pressure within the inner tank so that the level of the oil 14 therein is
slightly below the level of the water in the outer tank although the pressure
in the inner tank is relatively low, on the order of 20 to 25 pounds per
square inch. The size, shape and configuration of the solar furnace may
vary depending upon the requirements of each installation inasmuch as the heat
produced depends, at least in part, to the si~e and location of the solar
collector or collectors. Any suitable bracket structure may be provided for
supporting the solar furnace from the top wall of the tank or the solar
collectors may be supported from ground or other supporting structure adjacent
to or even remote from the separator tank 12.
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