U.S. patent number 3,881,551 [Application Number 05/406,030] was granted by the patent office on 1975-05-06 for method of extracting immobile hydrocarbons.
This patent grant is currently assigned to Ruel C. Terry, Xerxes T. Stoddard. Invention is credited to Xerxes T. Stoddard, Ruel C. Terry.
United States Patent |
3,881,551 |
Terry , et al. |
May 6, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Method of extracting immobile hydrocarbons
Abstract
A method of extracting immobile hydrocarbons includes the steps
of sinking spaced wells into the hydrocarbon formation, fracturing
the formation near the bottom of the wells to establish subsurface
communication between the wells, passing a heated fluid through the
wells and the hydrocarbon formation to obtain a predetermined
temperature in the formation and finally passing a solvent
material, having the ability to dissolve the immobile hydrocarbon,
through the hydrocarbon formation so that the admixture of the
solvent and hydrocarbon can be brought to the surface and allowed
to solidify into a fuel composition which can be transported at
normal atmospheric conditions in solid form and can be easily
melted into liquid fuel.
Inventors: |
Terry; Ruel C. (Denver, CO),
Stoddard; Xerxes T. (Denver, CO) |
Assignee: |
Ruel C. Terry (Denver, CO)
Xerxes T. Stoddard (Denver, CO)
|
Family
ID: |
23606264 |
Appl.
No.: |
05/406,030 |
Filed: |
October 12, 1973 |
Current U.S.
Class: |
166/272.2;
166/271 |
Current CPC
Class: |
E21B
43/2405 (20130101) |
Current International
Class: |
E21B
43/24 (20060101); E21B 43/16 (20060101); E21b
043/24 () |
Field of
Search: |
;166/272,303,35R,271,268,306 ;299/2,4,6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Novosad; Stephen J.
Attorney, Agent or Firm: Polumbus; Gary M.
Claims
What is claimed is:
1. A method of extracting gilsonite from a gilsonite formation in
the earth comprising the steps of:
establishing injection and removal passages between a surface
location and the gilsonite formation,
establishing sub-surface communication in the gilsonite formation
between the injection and removal passages, and
passing a liquid having a temperature above the melting temperature
of gilsonite and below 500.degree.F through the formation to melt
contacted portions of the gilsonite formation by injecting the
liquid material into the formation through the injection passage
and removing the material along with the melted gilsonite through
the removal passage.
2. A method of extracting gilsonite from a gilsonite formation in
the earth with a solvent material comprising the steps of:
establishing an injection passage and a removal passage between a
surface location and the gilsonite formation,
establishing subsurface communication in the gilsonite between the
passages,
passing a heating fluid through the formation by injecting the
heating fluid into the formation through the injection passage and
removing the heating fluid through the removal passage until the
temperature of the formation is above the melting point of the
solvent material, and
passing the solvent material, which has the capability of
dissolving gilsonite through the formation to dissolve contacted
portions of the gilsonite formation by injecting the solvent into
the formation through the injection passage and removing solvent
along with the dissolved gilsonite through the removal passage.
3. The method of claim 2 further including the step of establishing
an above-surface flow line for fluid communication between said
injection passage and said removal passage, and circulating the
heating fluid through the injection and removal passages, the
gilsonite formation and the flow line until the temperature of the
formation, at least along the path of communication in the
formation between the passages, is above the melting point of the
solvent material.
4. The method of claim 3 further including the steps of providing a
heating unit in the flow line and continuously heating the heating
fluid as it is circulated through the injection and removal
passages, the gilsonite formation and the flow line.
5. The method of claim 3 wherein said solvent material is
circulated through the injection and removal passages, the
gilsonite formation and the flow line after the temperature of the
formation has been brought to a temperature above the melting point
of the solvent material.
6. The method of claim 5 further including the step of
substantially filling the void in the gilsonite formation where the
hydrocarbon has been removed with a backfill material having a
specific gravity greater than the specific gravity of the solvent
material so that the circulating solvent material will float on the
backfill material is engagement with the undersurface of the
remaining gilsonite.
7. The method of claim 2 wherein said solvent material is
paraffin.
8. The method of claim 7 wherein siad heating fluid is circulated
through the gilsonite formation until the temperature of the
gilsonite, at least along the path of communication between the
wells, is approximately 200.degree.F.
9. The method of claim 8, further including the step of preheating
said paraffin to a temperature of approximately 250.degree.F before
it is passed through the gilsonite formation.
10. The method of claim 2 wherein said injection and removal
passages are spaced injection and removal wells and wherein said
injection well has inner and outer longitudinally extending
concentric tubes therein and wherein the heating fluid is injected
into the inner one of said tubes and the solvent materials is later
injected into the inner of said tubes after circulation of the
heating fluid has been terminated.
11. The method of claim 10 further including the steps of placing a
screening device near the bottom of the removal well and preventing
undissolved hydrocarbon particles greater than a predetermined size
from passing to the surface through the removal well.
12. The method of extracting immobile gilsonite from the earth
comprising the steps of:
sinking an injection well and a removal well into the gilsonite
formation at spaced location,
placing inner and outer concentric tubing in each of said injection
and removal wells,
connecting the inner tubing of each well and the outer tubing of
each well with an above-surface flow line having valve means at
opposite ends thereof for selectively establishing communication
between the flow line and one or both of said inner and outer
tubings,
placing a heating unit in communication with the above-surface flow
line,
providing a closable inlet line and a closable outlet line in
communication with said flow line,
opening the gilsonite formation between the bottoms of the wells to
establish a path for fluid communication between the wells,
injecting hot water at a temperature of approximately 250.degree.F
into said inlet line at a rate of approximately 300 gals/min., and
then circulating the hot water through the inner tubing of each
well, the fractured gilsonite formation and the flow line
connecting the inner tubing until the temperature of the gilsonite
formation along the fracture is at least 200.degree.F,
terminating the circulation of the hot water,
injecting liquid paraffin at a temperature of approximately
250.degree.F into said inlet line, circulating the paraffin through
the inner tubing of each well, the fractured gilsonite formation
and the flow line connecting the inner tubing to dissolve the
gilsonite, and continuing the circulation until the paraffin
obtains a dissolved gilsonite content of approximately 20% by
weight,
removing the paraffin-gilsonite composition through the outlet
line, and
allowing the paraffin-gilsonite composition to cool and thereby
solidify into a solid fuel material.
13. A method of extracting gilsonite from a gilsonite formation in
the earth with a solvent material comprising the steps of:
establishing an injection passage and a removal passage between a
surface location and the gilsonite formation,
establishing subsurface communication in the gilsonite formation
between the passages, and
passing a solvent material at a temperature below 230.degree.F.
which has the capability of dissolving gilsonite through the
formation to dissolve contacted portions of the gilsonite formation
by injecting the solvent into the formation through the injection
passage and removing the solvent along with the dissolved gilsonite
through the removal passage.
Description
The present invention generally concerns a method of extracting
immobile hydrocarbons from the earth and more particularly concerns
a method of extracting immobile hydrocarbons from the earth by
converting the hydrocarbons in situ into a flowable state and in a
manner such that the resultant product of the extraction is a solid
fuel composition.
Public utilities supplying gas for fuel find it necessary to
curtail or interrupt deliveries to industrial and commercial
customers when system demands exceed the supply available. These
customers are then required to switch to an alternate fuel, such as
fuel oil, until adequate supplies of gas are again available.
Facilities for alternate fuel are costly and require considerable
space and furthermore, these facilities are generally inadequate to
supply peak load fuel requirements for sustained periods such as
occurs during periods of unseasonably cold weather and periods of
mechanical difficulty in gas distribution systems and the like.
Storage for alternate fuels frequently requires bulky steel tanks
which in some cases are pressurized, and during periods of fuel
shortages, replenishment of the alternate fuel for the tanks
becomes difficult and at times impossible due to temporary
unavailability of tank cars, tank trucks and other vehicles suited
for transporting liquid fuel.
It is accordingly an object of the present invention to provide an
alternate fuel having a high BTU content that does not require tank
cars, tank trucks or other liquid fuele transporting means to
transport the fuel to storage and use locations.
It is another object of the present invention to provide an
alternate fuel material which does not need to be stored in bulky
steel tanks or pressure storage tanks.
It is another object of the present invention to provide a new and
improved alternate fuel which eliminates the need for temporary but
costly shutdowns of industrial and commercial facilities due to
lack of fuel.
It is another object of the present invention to provide a method
of producing a solid fuel composition which is easily transported
without the use of tank cars, tank trucks or other liquid transport
means.
It is another object of the present invention to provide a new and
improved method of extracting immobile hydrocarbons from the
earth.
It is another object of the present invention to provide a method
of extracting immobile hydrocarbons from the earth by in situ
conversion of the immobile hydrocarbon into a liquid state and
flowing the hydrocarbon to a surface location where it is naturally
solidified at atmospheric temperatures.
It is another object of the present invention to provide a method
of extracting immobile hydrocarbons from the earth by passing a
solvent material through the in situ formation of hydrocarbon to
dissolve the hydrocarbon and thereby entrain the hydrocarbon in a
fluid flow to the surface where it is allowed to solidify under
atmospheric conditions.
Viscous hydrocarbons, such as heavy oils, bitumen, tar sands,
asphalts, and asphaltities and the like, are difficult to produce
from native formations using conventional oil field production
practices. Numerous schemes have been tried using pressure, heat,
solvents, etc., to induce mobility and while some of these schemes
have been technical successes, they have been economic failures.
The present invention involves a new and improved method of
extracting viscous or immobile hydrocarbons by converting the
hydrocarbon in situ into a flowable condition so that it can be
removed from the earth in a liquid state. In accordance with the
present invention, an injection well and a removal well are sunk
into the hydrocarbon formation and the hydrocarbon formation is
fractured or otherwise connected between the lower ends of the
wells in a conventional manner to establish communication with the
bottoms of the wells. The immobile hydrocarbon material in the
formation can be converted into a flowable state by passing a
preheated liquid material at a temperature in excess of the melting
point of the hydrocarbon formation through the injection well, the
fractured formation and the removal well to melt the hydrocarbon
and thereby remove it in a liquid state. Preferably, however, the
hydrocarbon material is converted to a flowable state by dissolving
the hydrocarbon with a suitable solvent material which will carry
the dissolved hydrocarbon to the surface in a liquid state. Since
some suitable solvents have melting points above normal atmospheric
temperatures, it is necessary to preheat these solvent materials
and also the hydrocarbon formation so that the solvent material
itself will remain in a flowable condition while dissolving the
hydrocarbon.
The resultant composition of the hydrocarbon material and the
solvent material has a melting point above normal atmospheric
temperatures so that the composition solidifies upon being exposed
to atmospheric conditions. The solid composition is combustible and
thereby forms a new fuel material which overcomes the many
disadvantages of liquid fuel in that it can be readily transported
and stored and does not require the unique equipment necessary to
transport and store liquid fuels. Of course, the solid fuel can be
easily converted into liquid form merely by heating and thereby
becomes ideally suited for use as most conventional liquid
fuels.
Other objects, advantages and capabilities of the present invention
will become more apparent as the description proceeds taken in
conjunction with the accompanying drawings, in which:
FIG. 1 is a diagrammatic vertical section taken through a
hydrocarbon formation to illustrate the initial phases of the
method of the present invention.
FIG. 2 is a diagrammatic vertical section similar to FIG. 1 with
portions removed and illustrating a later phase of the method of
the present invention.
By way of illustration and not limitation, the present invention
will be described in connection with the extraction of gilsonite
from the earth, it being understood that the described method and
resultant solid fuel product would be equally applicable to other
immobile hydrocarbons such as asphalt, grahamite, glance pitch,
tar, bitumens and others.
Gilsonite is a unique crude petroleum that remains a solid at
normal atmospheric conditions. As found in nature, it is usually
pure and is located in a massive, near vertical fracture system
varying in width from a few inches to over 20 feet, and in depth
from surface out-crop to more than 1500 feet. Gilsonite is
relatively soft with a specific gravity of 1.03 to 1.10 at
77.degree.F and with a pour point of 230.degree.F to as high as
approximately 500.degree.F depending upon the specific gravity.
It's heat content is in the range of 18,000 to 18,800 BTU's per
pound. Gilsonite is not flamable below it's melting temperature and
is nontoxic and furthermore, gilsonite is relatively inert to most
chemicals, non-corrosive, and has a low sulfur content.
In extracting gilsonite from the earth in accordance with the
present invention, an injection well 10 and a removal well 12 are
sunk into a gilsonite formation 14 by conventional oil field
drilling techniques. By way of example, the well bores could be 9
inches in diameter, spaced approximately fifty feet apart and sunk
into the earth to the approximate depth of the gilsonite formation.
Of course, the spacing between the wells would vary with the width
of the gilsonite vein and the difficulties encountered in
establishing sub-surface circulation beteen the bottoms of the
wells. The circulation between the bottoms of the wells is
established by conventional oil field practices, which would
include explosive or hydraulic fracturing, pressure solvent
opening, or directional drilling of the gilsonite formation or the
surrounding rock formations. This establishes communication in the
form of passage 16 between the bottoms of the wells through which
fluid will flow.
After the wells have been drilled, a surface casing 18 is set in
each well bore, for example 65/8 inch casing, to an approximate
depth of 50 feet with the casing 18 being set and the lower end
thereof cemented in place. Next, inner tubing and outer liner
tubing 20 and 22 respectively, for example 2 inches and 41/2 inches
in diameter respectively, are suspended in each hole by a
conventional oil field "christmas tree" assembly (not shown) at the
top of each well. Initially, both tubing and liner are extended to
the total depth of each well and left open at the bottom so as to
be in communication with the fracture or passages 16 in the
gilsonite formation 14. To insulate the inner tubing and liner from
the surrounding gilsonite formating and thereby minimize heat loss
during circulation procedures to be described later, the liner is
preferably provided with an inner coating of foamed silicate
insulating material or the like and the annular space between the
liner and the gilsonite formation is filled with a gelled oil or
the like.
The christmas tree assemblies at the top of the wells are
interconnected by a common flow line 24. The connection of the flow
line 24 to each assembly is through a T-joint 26 having one arm 28
in communication with the inner tubing 20 of the associated well
and the other arm 30 in communication with the outer liner 22 of
the associated well. Conventional adjustable valve devices 32a and
32b for the injection well and 34a and 34b for the removal well are
incorporated into the arms of the T-joint to selectively control
the flow of material associated with the inner tubing and outer
liner respectively, through either the inner tubing, the outer
liner or both.
A liquid pump 36 and a conventional liquid heating unit 38 are
incorporated into the flow line 24 so that liquid material can be
continuously pumped through the flow line and heated during the
process. Also, the flow line 24 is provided with an inlet line 40
and an outlet line 42 so that liquid materials can be injected into
the flow line 24 or removed therefrom when desired. Of course,
conventional adjustable valve devices 44 and 46 connect the inlet
and outlet lines, respectively, to the flow line 24 so that the
flow of material can be regulated. Additionally, a control valve 48
is incorporated into the flow line 24 between the inlet and outlet
lines to selectively block the flow line, for example when material
is being withdrawn from the flow line through the outlet line
42.
It will be appreciated that after the wells have been provided with
the aforementioned tubing and connected in communication both
sub-surface and above surface as described, a closed circulating
path is established through the injection well 10, the fractured or
opened up gilsonite formation, the removal well 12 and the flow
line 24.
After the aforementioned closed circulation path is established, a
hot heating liquid such as water or brine is circulated through the
closed circulation path to elevate the temperature of the
gilsonite. If the hot water or brine has a temperature in excess of
the melting point of the gilsonite, the gilsonite can be melted in
place and will flow with the water or brine to the surface through
the removal well 12 so that it can be extracted through the outlet
line 42 from the system.
Preferably, however, the hot water or brine is circulated through
the fractured gilsonite formation at a temperature of approximately
250.degree.F and at a rate of approximately 300 gallons per minute
until the gilsonite formation, at least along the passages 16,
obtains a temperature of, for example, 200.degree.F. Preferably,
the heating liquid would be injected into the formation through the
inner tubing 20 of the injection well 10 via valve 32a and
similarly removed from the formation through the inner tubing 20 of
the removal well 12 via the valve 34a for a reason to be explained
later.
After the gilsonite formation obtains a temperature of
approximately 200.degree.F, the heating liquid circulation is
terminated. At this time a pre-heated liquid solvent material, such
as the heavy or residual fractions of waxy crude oils hereinafter
referred to as paraffin, is circulated through the closed
circulation path. Of course, other solvent materials suitable for
dissolving immobile hydrocarbons similar to gilsonite could also be
used. Examples of these solvents would include crude oil, kerosene,
fuel oil, amyl nitrate, amyl acetate, benzol, toluol, terpentine,
chloroform, carbon disulfide, carbon tetrachloride, naphtha, and
others. The paraffin solvent would preferably have a specific
gravity in the range of 0.85 to 1.1, a melting point in the range
of 65.degree.F to 160.degree.F and be pre-heated to a temperature
of approximtely 250.degree.F before it was pumped into the closed
circulation path via the inlet line 40 and would be directed into
the inner tubing 20 via valve 32a of the injection well and removed
through the inner tubing 20 via valve 34a of the removal well. In
the even the temperature in the circulating path drops below the
melting point of the paraffin, causing the paraffin to freeze in
the tubing, a heating liquid could be injected into the outer
tubing of each well through the inlet line 40, the heating unit 38
and then split by a valve 35b to pass through the common line to
valve 32b connected to the outer tubing of the injection well and a
bypass line 35 via valve 35a and 34b to the outer tubing of the
removal well to again melt the paraffin and establish production
fluid flow. The resultant pressure increase in such a case is
reduced by conventional pressure relief valves in the christmas
tree assemblies. It is preferable that the paraffin solvent be
circulated at a rate of approximately 150 gallons per minute to
maintain the hot temperature of the paraffin through the complete
circuit. It should be noted that gilsonite is known to readily
dissolve in hot paraffin, even though the paraffin temperature may
be well below the melting point of the gilsonite, however, during
the circulating process it is possible that chunks of gilsonite may
break away from the formation and not have a chance to totally
dissolve before it reaches the bottom of the removal well 12. To
prevent such chunks from possibly clogging the removal well, a
conventional screen or perforated joint 50 can be positioned at the
bottom of each well to prevent large chunks of gilsonite from
entering the flow lines of the wells, regardless of circulation
direction, until dissolved.
The paraffin and dissolved gilsonite is circulated through the
closed circuit or circulation path until the gilsonite content of
the circulating mixture reaches a desired level of for example 80%
paraffin and 20% gilsonite by weight. Of course, other percentage
compositions with the gilsonite being as low as approximately 10%
of the total weight may be desirable depending upon the desired
pour point of the resultant solid fuel which will be described
later. Should more than one pass through the circuit be required,
the heating unit 38 serves to maintain the composition mixture
above the necessary temperature for maintainance of fluid flow.
When the circulating mixture attains the desired percentage content
of dissolved gilsonite, the mixture is removed from the circuit
through the outlet line 42. Fresh quantities of hot paraffin are
added to the circuit as necessary and the process can continue
without interruption as production proceeds.
The production procedure continues from the bottom of the mined
area toward the top. Accordingly, periodically the tubing in the
injection and removal wells 10 and 12 must be raised by stages,
FIG. 2, to a point near the bottom face or undersurface 52 of the
gilsonite formation remaining in place. In order to assure that the
circulating paraffin remains in contact with the undersurface 52 of
the gilsonite, the void created by the removed gilsonite must be
filled with a backfill material 34 through inlet 53 via valve 53a
having a specific gravity greater than the paraffin solvent so that
the solvent will float across the top of the backfill material and
thereby remain in dissolving contact with the gilsonite. This hot
backfill material 54 could be water, brine, mud or the like and is
pre-heated to maintain the desired temperature at the undersurface
of the remaining gilsonite.
The production process continues by stages until the gilsonite is
removed up to the economic limit. Upon completion of the
production, the tubing and surface casing may be pulled while the
system is hot using conventional equipment commonly found in oil
fields. The salvaged equipment can thereby be reused in other wells
along the gilsonite formation or at other locations.
The produced mixture of paraffin and gilsonite constitutes a fuel
material having a BTU content of approximately 18,500 to 19,600
BTU's per pound and when exposed to atmospheric conditions, remains
in a solid state. The mixture may be cut or otherwise divided into
convenient sized units, for example, units containing 100,000 BTU's
and in convenient shapes, for example slabs, heavy wall tubes, etc.
The produced fuel may also be prilled, or it may be stored in bulk
by freezing into vats similar to those used in frasch sulfur
mining. If desired, the fuel can be also be melted and the
resultant liquid fuel transported in heated tank trucks or tank
cars as is conventional with other liquid fuels.
The fuel produced as described above, can be produced to
specifications, for example a melting point of 175.degree.F, at the
time it is removed from the circuit. The melting point of the
finished fuel can be set between the melting point of paraffin, for
example 120.degree.F and the maximum melting point of gilsonite,
for example approximately 500.degree.F. Paraffin readily softens at
temperatures encountered in the warm months and thus is troublesome
to store without safeguarding the maximum temperature. Gilsonite,
on the other hand, will not soften at warm month temperatures, but
it is brittle and readily breaks up into explosive dust upon
handling. The fuel processed in accordance with the present
invention eliminates the undesirable characteristics of both
components and may be readily handled, transported and stored with
minimum hazards.
The solid fuel composition resulting from the process of the
present invention in preferred physical sizes and shapes, can be
readily transported by a variety of conveyances normally used for
transportation of inert solids and the finished product may be
stored with a minimum of precautions, for example in sand and
gravel pits near industrial and commercial facilities and plants.
Further, the finished product can be used as fuel oil by using
sufficient heat to convert the product to a flowable liquid. Thus,
the finished product may be readily transported without the
necessity of tank trucks and tank cars and used as other
conventional liquid fuels during prolonged periods of unseasonably
cold weather.
Although the present invention has been described with a certain
degree of particularity, it is understood that the present
disclosure has been made by way of example and that changes in
details of structure may be made without departing from the spirit
thereof.
* * * * *