U.S. patent application number 12/460102 was filed with the patent office on 2009-11-12 for treatment of cesium-containing fluids.
Invention is credited to Robert L. Sloan, Harry D. Smith, JR., Kevin W. Smith.
Application Number | 20090277633 12/460102 |
Document ID | / |
Family ID | 46327252 |
Filed Date | 2009-11-12 |
United States Patent
Application |
20090277633 |
Kind Code |
A1 |
Smith; Kevin W. ; et
al. |
November 12, 2009 |
Treatment of Cesium-Containing Fluids
Abstract
Cesium solutions are treated in a cavitation device to increase
their temperature and facilitate the removal of water from them.
The context is normally an oil well fluid or a mining solution. The
concentrated solutions can be reused, in the case of oil well
fluids, or more easily handled for recovery of the elemental cesium
or cesium in the form of a salt. Thermal energy is saved by using
the concentrate or the water vapor to heat various streams within
the system.
Inventors: |
Smith; Kevin W.; (Houston,
TX) ; Sloan; Robert L.; (Katy, TX) ; Smith,
JR.; Harry D.; (Montgomery, TX) |
Correspondence
Address: |
William L. Krayer
1771 Helen Drive
Pittsburgh
PA
15216
US
|
Family ID: |
46327252 |
Appl. No.: |
12/460102 |
Filed: |
July 14, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11703950 |
Feb 8, 2007 |
7568523 |
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12460102 |
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11352889 |
Feb 13, 2006 |
7201225 |
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11703950 |
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60652549 |
Feb 14, 2005 |
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60652711 |
Feb 14, 2005 |
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Current U.S.
Class: |
166/267 |
Current CPC
Class: |
B01D 17/047 20130101;
E21B 21/063 20130101; B01D 17/044 20130101; B01D 17/042
20130101 |
Class at
Publication: |
166/267 |
International
Class: |
E21B 43/40 20060101
E21B043/40 |
Claims
1-28. (canceled)
29. Method of processing a used oil well fluid containing cesium
comprising (a) optionally filtering said used oil well fluid, (b)
passing said used oil well fluid through a heat exchanger to
increase its temperature utilizing waste heat from an engine, (c)
powering a cavitation device with said engine, (d) passing said oil
well fluid through said cavitation device to further increase the
temperature thereof, (e) passing said used oil well fluid into a
flash tank to separate steam and vapor from said used oil well
fluid and to obtain a concentrated fluid, (f) removing at least a
portion of said concentrated fluid from said flash tank, and
reusing said at least a portion of said concentrated fluid as a
source of cesium in an oil well fluid.
30. Method of claim 29 including recycling at least a portion of
said oil well fluid after step (d) through said cavitation device
to further increase its temperature prior to passing it into said
flash tank.
31. Method of claim 29 including recycling at least a portion of
said concentrated fluid from said flash tank into said cavitation
device.
32. Method of claim 29 wherein said steam or vapor obtained in step
(e) is used in a heat exchange device to recover at least a portion
of its heat energy.
33. Method of claim 29 wherein said steam or vapor obtained in step
(e) is used as a component of a new oil well fluid.
34. Method of claim 30 wherein said oil well fluid containing
cesium at the end of step (f) is recovered from said oil well and
is processed as a used oil well fluid in an iteration of the steps
of claim 29.
35-39. (canceled)
Description
RELATED APPLICATION
[0001] This application is a division of copending application Ser.
No. 11/703,950 which is a continuation-in-part of application Ser.
No. 11/352,889, filed Feb. 13, 2006, now U.S. Pat. No. 7,201,225,
which in turn claims the benefit of provisional applications
60/652,549 filed Feb. 14, 2005 and 60/652,711 filed Feb. 14,
2005.
TECHNICAL FIELD
[0002] A cavitation device (shockwave power reactor) is used to
prepare oil well completion and workover fluids containing cesium,
using spent, used, or dilute fluids containing cesium, which
commonly contain solids and other dissolved materials. The prepared
solutions contain recycled cesium in the form of dissolved cesium
formate, dissolved cesium chloride, or other dissolved cesium salts
in concentrations useful for achieving a desired density for use in
regenerated completion and workover fluids.
BACKGROUND OF THE INVENTION
[0003] In oil and other hydrocarbon production operations,
completion, drilling and workover fluids are typically circulated
down the string of tubes and upwards around the outside of the
tubes, contacting the formation surface of the wellbore from which
the hydrocarbons are to be produced. Part of the fluid may be lost
into the formation, and frequently the fluid is diluted by
indigenous fluid entering from the formation. The salts and other
additives in the completion or workover fluid are either partially
lost or diluted, or both, as a result of contact with the
formation. It is desirable in many instances to use additives which
contribute a degree of density to the completion or workover fluid;
that is, a dense brine will be able more efficiently to remove
loose rock and sand, for example, which otherwise might clog the
perforations in the pipe, thus impeding hydrocarbon production. As
a relatively heavy alkali metal, cesium works well as a densifying
agent in completion and workover fluids, but it is expensive, and,
as with any other material which must ultimately be disposed of,
should be recycled to the extent reasonably possible. This
invention is directed specifically to the recycling of cesium as a
densifying agent in completion, drilling and workover fluids and to
similar treatment of solutions of cesium obtained in the mining of
cesium.
[0004] As used herein, the term "heavy brine components" means
calcium, zinc, ammonium and/or cesium as cations and chloride,
formate and particularly bromide as anions from any source. Typical
sources include cesium chloride or formate, calcium chloride,
sodium chloride, sodium bromide, calcium bromide, zinc chloride,
zinc bromide, ammonium chloride, and mixtures thereof as well as
their cation and anion forming moieties from other sources.
[0005] Many oil well fluids contain polymers added for various
purposes including to increase viscosity to help remove solids from
the well and to retard the fluid loss into the formation. Polymers
may be considered contaminants for various types of recycling, and
in any event are difficult to remove, particularly when they are
present with substantial quantities of solids.
[0006] Oil well muds generally include large proportions of solids,
making their disposal difficult; also they contain additives which
are beneficially recovered and recycled. Disposal is also difficult
for other common oil well fluids such as water/oil (or oil/water)
emulsions of widely varying composition including muds; recovering
the more valuable components of emulsions for recycling or other
use has been very difficult
[0007] Not least among the difficulties of dealing with dilute,
spent or used oil well fluids is the mundane but expensive task of
trucking the fluids from remote producing wells to distant
environmentally approved disposal sites or processing plants. Quite
apart from the utter waste of materials, the cost of hauling dilute
brines and other oil well fluids for disposal is a serious
counterproductive burden to the producer. A related point is that
if the excess water in dilute fluids is not eliminated or recovered
for various purposes, the volume of fluid at the wellsite continues
to increase, requiring more and more additives to render it useful.
Such additions are costly, as are the facilities necessary to store
the additional fluid.
[0008] As our invention is capable of concentrating and remediating
any or all of the above described oil well fluids--brines, heavy
brines, polymer-containing fluids, completion and workover fluids,
drilling fluids, muds, and emulsions--we may refer to these
collectively herein as "oil well fluids." Similar fluids are used
in the production of natural gas in gas wells, and accordingly we
intend to include such fluids in the term oil well fluids. Oil well
fluids generally may include high solids contents, but muds in
particular may include solids commonly in the range of up to about
45% by volume. Such high solids content is detrimental to any
conventional distillation process which might be considered to
treat an oil field mud for recycling. Likewise emulsions are not
conducive to conventional distillation as a separate procedure.
Conventional distillation methods of concentrating dilute and
particularly contaminated solutions including heavy brine
components result in scaling and other difficulties which
ultimately frustrate the economics of recycling. A more economical
method is needed for recycling the components of oil well
fluids.
[0009] Common alkali metal salts such as sodium or potassium
chloride, bromide or formate have long been used in oil well
completion, drilling and workover fluids (collectively herein
called oil well fluids). The more unusual cesium salts have been
found particularly useful where a denser fluid is needed.
Conventional distillation methods of concentrating dilute and
particularly contaminated solutions of cesium salts result in
scaling and other difficulties which ultimately frustrate the
economics of recycling.
[0010] Because of the particular difficulties of handling and
dewatering cesium solutions, and because of their expense and the
unique environmental aspects of cesium, this application is
directed specifically to the concentration of cesium solutions and
recycling where appropriate. A more economical method of recycling
cesium is needed for oil well fluids.
SUMMARY OF THE INVENTION
[0011] This invention regenerates dilute and contaminated cesium
solutions by passing them through a cavitation device which
generates shock waves to heat the solution and remove moisture,
thereby concentrating the solution and any small solids present.
Preferably the cavitation device is one manufactured and sold by
Hydro Dynamics, Inc., of Rome, Ga., most preferably the device
described in U.S. Pat. Nos. 5,385,298, 5,957,122 6,627,784 and
particularly 5,188,090, all of which are incorporated herein by
reference in their entireties. In recent years, Hydro Dynamics,
Inc. has adopted the trademark "Shockwave Power Reactor" for its
cavitation devices, and we use the term SPR herein to describe the
products of this company and other cavitation devices that can be
used in our invention.
[0012] The solution may be treated with similar or other additives
to achieve a desired density, crystallization temperature, or an
appropriate or desired balance with other cations and anions.
[0013] Unlike a conventional distillation process, the shockwave
power reactor (SPR) preserves the ratios of the cations and anions,
and solids, in the solution to each other, while simply removing
water. A conventional distillation process would tend to scale out
some of the constituents. This ability can be used to provide
greater control over the process of reconstituting oil well
completion and workover fluids.
[0014] Our invention includes the step of filtering the fluid
prepared by the cavitation device. Typically, the dilute,
contaminated, or used oil well fluids are filtered before they are
stored or processed by distillation. Our invention renders the
filtration process more efficient by postponing it until after the
used fluid is passed through the cavitation device. Thus our
invention includes a process of preparing a recycled
cesium-containing oil well fluid comprising passing the fluid
through a cavitation device and then filtering it.
[0015] In one aspect, our invention comprises passing the
cesium-containing fluid through a cavitation device and then
filtering the fluid thus concentrated. A conventional distillation
process will generally be preceded by filtration in order to
minimize the scaling and deposition effects incident to the
presence of undissolved solids. Because the cavitation device will
operate with as high as 80% solids, filtration can be performed
more efficiently on the smaller volumes obtained after passing
through the cavitation device.
[0016] Our invention includes a method of treating a downhole
formation comprising introducing into a well an oil well fluid
containing cesium, whereby the fluid becomes diluted so that it
contains less than the desired concentration of cesium, circulating
the fluid from the well, and passing at least a portion of the
fluid through a cavitation device to remove moisture therefrom and
produce a regenerated fluid containing a higher concentration of
cesium in said fluid. Commonly the oil well fluid will contain at
least 2.5% cesium by weight. Our invention will restore the
concentration of one which has been diluted by circulating in the
well bore and/or contact with the formation--that is, it may be
restored to 2.5% or higher.
SUMMARY OF THE INVENTION
[0017] This invention treats dilute and contaminated solutions and
slurries, particularly such solutions and slurries containing
cesium, by passing them through a cavitation device to facilitate
the removal of water.
[0018] Unlike a conventional distillation process, the SPR
preserves the ratios of the cations and anions, as well as the
solids, to each other in the solution that enters the SPR, while
facilitating the removal of water. A conventional distillation
process would tend to scale out some of the constituents in more or
less difficulty predictable portions and relationships. The fact
that in our process the ratios of the non-aqueous components remain
essentially the same can be used to provide greater control over
the process of reconstituting oil well completion and workover
fluids. Either before or after passing through the SPR, the
solution may be treated with additives to restore the original
density, crystallization temperature, or balance of cations and
anions, or to adjust the individual concentrations of components to
respond to new conditions found in the well. Since the operator may
rely on the SPR to preserve the ratios of the solid and dissolved
components to each other in the fluid that enters the SPR, any
distortion of the ratios caused by the formation or wellbore can be
adjusted or compensated for either before the fluid enters the SPR
or after it leaves, without concern for a further distortion of the
ratios caused by the SPR. This would not be the case with any
device or process step that might result in scaling. If the
conserved components are to be used in a different well requiring
different ratios of components to each other, the operator again
may rely on the SPR not to alter the existing ratios, and make any
necessary adjustments accordingly.
[0019] Definition: We use the term "cavitation device," or "SPR,"
to mean and include any device which will impart thermal energy to
flowing liquid by causing bubbles or pockets of partial vacuum to
form within the liquid it processes, the bubbles or pockets of
partial vacuum being quickly imploded and filled by the flowing
liquid. The bubbles or pockets of partial vacuum have also been
described as areas within the liquid which have reached the vapor
pressure of the liquid. The turbulence and/or impact, which may be
called a shock wave, caused by the implosion imparts thermal energy
to the liquid, which, in the case of water, may readily reach
boiling temperatures. The bubbles or pockets of partial vacuum are
typically created by flowing the liquid through narrow passages
which present side depressions, cavities, pockets, apertures, or
dead-end holes to the flowing liquid; hence the term "cavitation
effect" is frequently applied, and devices known as "cavitation
pumps" or "cavitation regenerators" are included in our definition.
Steam generated in the cavitation device can be separated from the
remaining, now concentrated, water and/or other liquid which
frequently will include significant quantities of solids small
enough to pass through the reactor. The term "cavitation device"
includes not only all the devices described in the above itemized
U.S. Pat. Nos. 5,385,298, 5,957,122 6,627,784 and 5,188,090 but
also any of the devices described by Sajewski in U.S. Pat. Nos.
5,183,513, 5,184,576, and 5,239,948, Wyszomirski in U.S. Pat. No.
3,198,191, Selivanov in U.S. Pat. No. 6,016,798, Thoma in U.S. Pat.
Nos. 7,089,886, 6,976,486, 6,959,669, 6,910,448, and 6,823,820,
Crosta et al in U.S. Pat. No. 6,595,759, Giebeler et al in U.S.
Pat. Nos. 5,931,153 and 6,164,274, Huffman in U.S. Pat. No.
5,419,306, Archibald et al in U.S. Pat. No. 6,596,178 and other
similar devices which employ a shearing effect between two close
surfaces, at least one of which is moving, such as a rotor, and/or
at least one of which has cavities of various designs in its
surface as explained above.
[0020] Our invention includes the optional step of filtering the
fluid prepared by the SPR. Typically, in the prior art, the dilute,
contaminated, or used oil well fluids are filtered before they are
stored or processed by distillation. Our invention enables the
postponement of filtration until after the used fluid is
concentrated by passing through the SPR to heat it and facilitate
removal of vapor from a flash tank or a vent; filters and the
filtration process can therefore be engineered more efficiently to
handle smaller volumes of liquid with higher concentrations of
solids. Thus our invention includes a process of preparing a
recycled oil well fluid comprising passing the fluid through a
cavitation device and then filtering the concentrated fluid thus
obtained. Persons skilled in the art will readily see that
filtering significant quantities of solids after water removal
rather than before contrasts dramatically with a distillation
process. Of course it may be desirable in some cases to filter
before passing the fluid into the SPR, or to filter both before and
after.
[0021] It will be seen that our invention includes a method of
conserving components of a used oil well fluid containing oil well
fluid components comprising (a) concentrating said oil well fluid
by passing said oil well fluid through a cavitation device to heat
the fluid and facilitate removal of vapor or moisture therefrom and
to obtain a concentrated oil well fluid containing oil well fluid
components in concentrations higher than said used oil well fluid,
(b) optionally adjusting the composition of said concentrated oil
well fluid by adding at least one moiety, increment, or amount of
at least one component of said concentrated oil will fluid to
increase the concentration thereof in said concentrated oil well
fluid, and (c) reusing the concentrated oil well fluid so adjusted.
By a moiety, we mean an additive amount, i.e. any additional amount
of the component in question.
[0022] Our invention also includes a method of conserving
components of a used oil well fluid containing oil well fluid
components comprising (a) concentrating said oil well fluid by
passing said oil well fluid through a cavitation device to obtain a
concentrated oil well fluid containing oil well fluid components in
concentrations higher than said used oil well fluid, (b) filtering
the composition of said concentrated oil well fluid, and (c)
reusing the concentrated oil well fluid.
[0023] In another aspect, our invention includes a method of
processing a used oil well fluid comprising optionally filtering
said used oil well fluid, passing the used oil well fluid through a
heat exchanger utilizing waste heat from a power source such as the
exhaust of a Diesel engine, powering a cavitation device with the
power source, passing the oil well fluid through the cavitation
device to increase the temperature thereof, optionally recycling at
least some of said used oil well fluid through said cavitation
device to further increase the temperature of said used oil well
fluid, passing said used oil well fluid into a flash tank to
separate steam and vapor from said used oil well fluid and to
obtain a concentrated fluid, removing at least a portion of said
concentrated fluid from said flash tank, and reusing said at least
a portion of said concentrated fluid in an oil well. The use of a
Diesel engine is not essential; persons skilled in the art will
realize that the cavitation device may be powered by any more or
less equivalent source of mechanical energy, such as a common
internal combustion engine, a steam engine, an electric motor, or
the like. Waste heat from any of these, either in an exhaust gas or
otherwise, may be utilized in a known manner to warm the oil well
fluid before or after passing it through the SPR.
[0024] While the SPR is quite capable of elevating the temperature
of an aqueous solution or slurry to the boiling point (at
atmospheric pressure) of water or higher, it is not essential in
our process for it to do so, as the flash tank may be operated
under a vacuum to draw off vapors at temperatures below the boiling
point of water at atmospheric pressure.
[0025] Also, our invention includes a method of upgrading a cesium
containing solution comprising passing said cesium containing
solution through a cavitation device to remove water therefrom,
thereby obtaining a solution containing a higher concentration of
cesium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1a and 1b show variations of a cavitation device as
utilized in our invention.
[0027] FIG. 2 is a flow sheet illustrating the process for
concentrating an oil well fluid or other fluid.
DETAILED DESCRIPTION OF THE INVENTION
[0028] FIGS. 1a and 1b show two slightly different variations, and
views, of the cavitation device, sometimes known as a cavitation
pump, or a cavitation regenerator, and sometimes referred to herein
as an SPR, which we use in our invention to regenerate solutions
comprising heavy brine components.
[0029] FIGS. 1a and 1b are taken from FIGS. 1 and 2 of Griggs U.S.
Pat. No. 5,188,090, which is incorporated herein by reference along
with related U.S. Pat. Nos. 5,385,298, 5,957,122, and 6,627,784. As
explained in the U.S. Pat. No. 5,188,090 and elsewhere in the
referenced patents, liquid is heated in the device without the use
of a heat transfer surface, thus avoiding the usual scaling
problems common to boilers and distillation apparatus.
[0030] A housing 10 in FIGS. 1a and 1b encloses cylindrical rotor
11 leaving only a small clearance 12 around its curved surface and
clearance 13 at the ends. The rotor 11 is mounted on a shaft 14
turned by motor 15. Cavities 17 are drilled or otherwise cut into
the surface of rotor 11. As explained in the Griggs patents, other
irregularities, such as shallow lips around the cavities 17, may be
placed on the surface of the rotor 11. Some of the cavities 17 may
be drilled at an angle other than perpendicular to the surface of
rotor 11--for example, at a 15 degree angle. Liquid (fluid)--in the
case of the present invention, a solution containing heavy brine
components, or a used mud emulsion, or a used workover fluid, for
example,--is introduced through port 16 under pressure and enters
clearances 13 and 12. As the fluid passes from port 16 to clearance
13 to clearance 12 and out exit 18, areas of vacuum are generated
and heat is generated within the fluid from its own turbulence,
expansion and compression (shock waves). As explained at column 2
lines 61 et seq in the U.S. Pat. No. 5,188,090, "(T)he depth,
diameter and orientation of (the cavities) may be adjusted in
dimension to optimize efficiency and effectiveness of (the
cavitation device) for heating various fluids, and to optimize
operation, efficiency, and effectiveness . . . with respect to
particular fluid temperatures, pressures and flow rates, as they
relate to rotational speed of (the rotor 11)." Smaller or larger
clearances may be provided (col. 3, lines 9-14). Also the interior
surface of the housing 10 may be smooth with no irregularities or
may be serrated, feature holes or bores or other irregularities as
desired to increase efficiency and effectiveness for particular
fluids, flow rates and rotational speeds of the rotor 11. (col. 3,
lines 23-29) Rotational velocity may be on the order of 5000 rpm
(col 4 line 13). The diameter of the exhaust ports 18 may be varied
also depending on the fluid treated. Pressure at entrance port 16
may be 75 psi, for example, and the temperature at exit port 18 may
be 300.degree. F. Thus the heavy brine components containing
solution may be flashed or otherwise treated in the cavitation
device to remove excess water as steam or water vapor. Note that
the position of exit port 18 is somewhat different in FIGS. 1a and
1b; likewise the position of entrance port 16 differs in the two
versions and may also be varied to achieve different effects in the
flow pattern within the SPR.
[0031] Another variation which can lend versatility to the SPR is
to design the opposing surfaces of housing 10 and rotor 11 to be
somewhat conical, and to provide a means for adjusting the position
of the rotor within the housing so as to increase or decrease the
width of the clearance 12. This can allow for different sizes of
solids present in the fluid, to reduce the shearing effect if
desired (by increasing the width of clearance 12), to vary the
velocity of the rotor as a function of the fluid's viscosity, or
for any other reason.
[0032] Operation of the SPR (cavitation device) is as follows. A
shearing stress is created in the solution as it passes into the
narrow clearance 12 between the rotor 11 and the housing 10. This
shearing stress causes an increase in temperature. The solution
quickly encounters the cavities 17 in the rotor 11, and tends to
fill the cavities, but the centrifugal force of the rotation tends
to throw the liquid back out of the cavity, which creates a vacuum.
The vacuum in the cavities 17 draws liquid back into them, and
accordingly "shock waves" are formed as the cavities are constantly
filled, emptied and filled again. Small bubbles, some of them
microscopic, are formed and imploded. All of this stress on the
liquid generates heat which increases the temperature of the liquid
dramatically. The design of the SPR ensures that, since the bubble
collapse and most of the other stress takes place in the cavities,
little or no erosion of the working surfaces of the rotor 11 takes
place, and virtually all of the heat generated remains within the
liquid.
[0033] Temperatures within the cavitation device--of the rotor 11,
the housing 10 and its metal wall 20, and the fluid within the
clearance spaces 12 between the rotor and the housing--remain
substantially constant after the process is begun and while the
feed rate and other variables are maintained at the desired values.
There is no outside heat source; it is the mechanical energy of the
spinning rotor--to some extent friction, as well as the above
described cavitation effect--that is converted to heat taken up by
the solution and soon removed along with the solution when it is
passes through exit 18. The rotor and housing indeed tend to be
lower in temperature than the liquid in clearances 12 and 13. There
is little danger of scale formation even with high concentrations
of heavy brine components in the solution being processed.
[0034] Any solids present in the solution, having dimensions small
enough to pass through the clearances 12 and 13 may pass through
the SPR unchanged. This may be taken into account when using the
reconstituted solution in for oil well purposes. On the other hand,
subjecting the water-soluble polymers to the localized cavitation
process and heating may break them down, shear them, or otherwise
completely destroy them, a favorable outcome for many purposes. The
condition known as "fish-eyes," sometimes caused by the gelling of
water-soluble polymers, can be cured by the SPR. These effects will
take place in spite of the possible presence of significant amounts
of solids.
[0035] Concentrated and heavy or dense brines are more liable to
crystallize in use than dilute brines, and accordingly their
crystallization temperatures are of concern. The crystallization
point of a highly salt-laden solution does not imply merely that a
small portion of the salts may crystallize out, but that the entire
solution will tend to gel or actually solidify, a phenomenon of
great concern during the transportation of such solutions or in
storage, for example. The ability to concentrate heavy brine
components and their ratios to each other in a solution using a
cavitation device leads to better control over crystallization
temperature and the ability to achieve a good balance between
crystallization temperature and density. Complex relationships
between the concentrations and ratios of heavy brine component ions
and other constituents in the solution rather precisely obtained by
our invention means that the crystallization temperature of a
completion or workover fluid can be more readily controlled while
conserving substantially all of the components available to be
saved. Our invention includes a method of achieving a desired
crystallization temperature in a used oil well fluid containing
cesium comprising passing said used oil well fluid through a
cavitation device, thereby obtaining a rejuvenated oil well fluid
having a concentration of cesium greater than that of said used oil
well fluid, and adding at least one salt to said rejuvenated oil
well fluid in an amount calculated to obtain a desired
crystallization temperature in said rejuvenated oil well fluid.
[0036] The ability to concentrate heavy brine components content in
a solution using a cavitation device also leads to better control
over solution density. Relationships between the rather precisely
obtained concentrations of heavy brine component ions and other
constituents in the solution means that the density of a completion
or workover fluid can be more readily matched with the density of
the drilling fluid.
[0037] The ability to concentrate cesium content in a solution
using a cavitation device leads to better control over solution
density. Relationships between the rather precisely obtained
concentrations of cesium ions and other constituents in the
solution means that the density of a completion or workover fluid
can be more readily matched with the density of the drilling fluid.
The ability to concentrate cesium content in a solution using a
cavitation device also leads to better control over crystallization
temperature. As is known in the art of hydrocarbon production,
downhole crystallization can be expensive and troublesome. The
operator should be aware of downhole temperatures and should design
the completion or workover fluid accordingly. Relationships between
the rather precisely obtained concentrations of cesium ions and
other constituents in the solution rejuvenated by our process means
that the crystallization temperature of a completion or workover
fluid can be more readily controlled. In another aspect, our
invention includes filtering the fluid after it is passed through
the cavitation device. In the prior art, where one wishes to store
a cesium containing fluid or distill it to concentrate it,
frequently the solution is filtered first. We can pass the fluid
"as is" through the cavitation device, thus concentrating the
solids along with the dissolved matter, which makes filtration more
efficient in many instances. Density or crystallization temperature
can be adjusted after filtration or before.
[0038] Where the fluid treated is a heavy brine containing cesium,
it will commonly contain at least 2.5% cesium by weight. Our
invention includes a method of treating a hydrocarbon producing
formation comprising introducing into the formation through a well
an oil well fluid containing at least 2.5% by weight cesium,
whereby the fluid becomes diluted so that it contains less than
2.5% cesium by weight, circulating the fluid from the well, and
passing at least a portion of the fluid through a cavitation device
to remove moisture therefrom and produce a regenerated fluid
containing at least 2.5% cesium by weight in said fluid.
[0039] Similar percentages may be found in cesium solutions used in
mining cesium, and our invention may be quite useful for
concentrating cesium solutions in cesium mining.
[0040] In FIG. 2, the dilute solution, slurry or emulsion
(hereafter sometimes a fluid) enters in line 32 from the left, as
depicted. It may come directly from a well, from a hold tank, or
indirectly from another source. The SPR (cavitation device) 30
requires a motor or engine to rotate it. Here, a Diesel engine or
other power source, not shown, powers the SPR and generates hot
exhaust gases, which are passed through the Diesel Exhaust Heat
Exchanger or other waste heat source where Diesel power is not
used, where the thermal energy of the exhaust gas is used to heat
the incoming fluid in line 32 through a heat exchange surface or
other conventional or expedient manner. Optionally the heat
exchanger may be bypassed in a line not shown. The incoming fluid
continues through line 31 to the SPR 30 which may be any cavitation
device described above; for illustrative purposes, it may be
substantially as shown in FIGS. 1a and 1b. A supplemental pump, not
shown, may assist the passage of the fluid. In the SPR 30, the
fluid is heated as described with reference to FIGS. 1a and 1b, and
the heated fluid is passed through line 33 to a (labeled) flash
tank, where steam is separated and removed in line 34.
Alternatively or supplementally, steam or vapor may be vented
through a separate vent not shown to the atmosphere or drawn off
directly from or in a similar vent associated with exit port 18
(FIGS. 1a and 1b). The steam may be recycled in a known manner for
thermal energy preservation, for condensing to make substantially
pure water, put to other useful purposes, or simply flashed to the
atmosphere. Optionally a vacuum may be drawn on the flash tank to
assist in removing the vapor and steam. It is not essential that
the temperature of the fluid exiting from the SPR exceed the
boiling point of water, as a vacuum assist can facilitate the
withdrawal of vapors. Concentrated fluid from the flash tank, in
line 35, can be recycled to the well, or analyzed in analyzer 50 in
order to determine the best way to re-establish the ratios of
ingredients, a desired crystallization temperature, a desired
density, or other property. If needed according to the results of
the analysis, or if desired for any reason, additives may be
introduced from feeder 51. Where the steam or vapor is simply
vented from the SPR, concentrated fluid from the SPR 30 may bypass
the flash tank as in line 36, and some or all of this may be
recycled through line 37 to the SPR according to a predetermined
desired efficiency for the system, balancing flow rates, heat
input, and concentrations. Another option is to combine the two
blowdowns of concentrated fluid in lines 35 and 36, and work with
them thereafter either to reuse them directly or to adjust the
concentration of one or more constituents for a desired purpose. In
yet another option, line 38 may recycle at least some of the fluid
from the SPR for additional heat input from the Diesel Exhaust Heat
Exchanger (or waste heat from the alternative power source where a
Diesel engine is not used). Optional filters 40, 41, 43, 44, 45,
46, and 47 may be installed at various points in the system for
various purposes; filter 40 on incoming line 32 may comprise a
screen for larger solids. Filter 43 and filter 47 are of special
interest because, contrary to practice with a distillation unit,
the SPR passes all solids through it while removing water. In the
case of a used brine which may have incurred some crystallization
in spite of dilution, because of an imbalance in its constituents,
the valuable crystallized components may be re-dissolved in the
higher temperatures of the SPR and passed through, yet other solids
are removed by the filter. Supplemental pumps and valves, not
shown, may be deployed throughout the system to assure the desired
flow rates and pressures, and to direct the fluids in the system to
and through the various options described; automatic or manual
controls for the valves and pumps may also be installed.
[0041] The following tables demonstrate the monetary savings
available through the use of our invention. Table 1 shows the costs
making a brine from beginning calcium bromide brines having
densities ranging from 14.2 pounds per gallon to 15.1 pounds per
gallon, by adding more calcium bromide (CaBr.sub.2). The number of
pounds of dry calcium bromide (salt) to be added is shown for each
level together with an estimated cost of the calcium bromide. Table
2 shows the cost of the Diesel fuel required to achieve brines of
the same densities by evaporation in the SPR without any additions
to the brines at all. Savings are achieved not only in the cost of
making up the denser brines but also, significantly, in the cost of
inventory of the calcium bromide, which can be greatly minimized.
Similar results are seen with cesium-containing fluids.
TABLE-US-00001 TABLE 1 DRY SALT ADDITION ESTIMATES Starting
Original Final Final Dry Salt Cost Gravity Volume Gravity Volume
Added of Salt Lbs/Gal Bbls Lbs/Gal Bbls Lbs $ 14.2 1,000 15.2 1074
89,806 $134,709 14.3 1,000 15.2 1064 79,143 $118,115 14.4 1,000
15.2 1057 70,352 $105,528 14.5 1,000 15.2 1050 61,695 $92,542 14.6
1,000 15.2 1044 53,589 $80,384 14.7 1,000 15.2 1036 44,280 $66,421
14.8 1,000 15.2 1028 35,366 $53,048 14.9 1,000 15.2 1022 26,569
$39,853 15.0 1,000 15.2 1014 17,733 $26,599 15.1 1,000 15.2 1007
8,857 $13,286 Note 1: 14.2 ppg Starting Cost $447.30/Bbl Note 2:
CaBr.sub.2 Dry $1.50/Lb
TABLE-US-00002 TABLE 2 CONCENTRATOR PERFORMANCE ESTIMATES Final
Diesel Starting Lb H.sub.2O to Volume of Time to Fuel Diesel
Gravity Evaporate 15.2 ppg Concentrate Required Cost Lbs/Gal Lbs
Fluid Bbls Hrs Gal $2/Gal 14.2 56,000 846 56.0 1,848 $3,696.00 14.3
49,700 863 50.0 1,650 $3,300.00 14.4 43,000 877 43.0 1,419
$2,838.00 14.5 38,000 893 38.0 1,254 $2,508.00 14.6 34,700 900 35.0
1,155 $2,310.00 14.7 27,200 920 27.0 891 $1,782.00 14.8 19,000 940
21.0 693 $1,386.00 14.9 16,000 954 16.0 528 $1,056.00 15.0 9,500
970 9.5 314 $628.00 15.1 5,500 980 3.5 181 $362.00 Note 1: Original
Volume 1,000 bbls. Note 2: Does not include use of heat
exchanger.
[0042] Our system can separate drilling fluid components from oil
mud emulsions ranging from 1-95% oil and 99-5% water. Preferably
the oil is a heating oil or other oil chosen for a high boiling
temperature; these are commonly used for oil mud emulsions. A
typical used oil mud emulsion comprising 80% oil and 20% brine
(including the dissolved components and including solids) is
readily treated in our system since temperatures in the SPR can be
regulated to achieve evaporation of the water in the flash tank
downstream from the SPR while the oil, having a higher boiling
temperature, passes through without difficulty even though it may
be subjected to locally violent cavitation effects in the SPR. A
mixture of oil and water exiting the SPR in line 33 will separate
on entering the flash tank held at an appropriate temperature, the
steam being flashed off through conduit 34, which may be a vent,
and/or remaining in the upper space of the flash tank while liquid
water including dissolved salts is held in the bottom of the tank
and/or drains into line 35 or 39 or both. Since the emulsion is
substantially broken, the liquid water in the flash tank is covered
by oil which may be continuously or intermittently tapped through a
drain not shown and used or stored elsewhere. Any of the
non-vaporized water may also be drawn off of the flash tank in a
different drain line not shown, augmenting the water vaporization
process to remove water from the system Oil mud emulsions typically
include significant amounts of solids--5% or 10% to 45% or more by
weight of the overall composition--and our invention can handle
such compositions without problems.
EXAMPLE
Oil Mud Emulsion
[0043] Using a 15'' by 2'' cavitation device, ten gallons of oil
mud emulsion were treated to remove water. Initially the oil mud
emulsion contained 18% water by volume, the balance being oil and
solids typical of an oil well mud. The oil mud emulsion was sent
through the cavitation device operating at 3600 RPM and recycled
through the tank, which rapidly increased the temperature of the
oil mud emulsion from room temperature to 240.degree. F. Once that
temperature was reached, the RPM of the cavitation device was
controlled automatically in order to maintain an outlet temperature
240.degree. F. At equilibrium, while recirculating the material and
continuing to recycle through the tank, the speed was maintained at
1700 RPM, requiring about 13.5 HP. At 15 minutes, the material
contained 13% water; at 30 minutes, it contained 10% water, and at
45 minutes the water was reduced to 5% by volume. Essentially none
of the oil was evaporated
[0044] Thus our invention is seen to include a method of reducing
the water content of a used oil mud emulsion comprising heating the
oil mud emulsion in a cavitation device, removing vapor or steam
from the oil mud emulsion, and reusing at least a portion of the
solids in the resulting concentrated oil mud emulsion in a new oil
mud emulsion. The oil in the oil mud emulsion will have a boiling
point higher than water, generally higher than 250.degree. F. and
frequently at least 280.degree. F. Our process is quite capable of
removing all the water from an oil mud emulsion of virtually any
composition, leaving only the oil and solids components, both of
which may be reused in a new oil mud emulsion.
[0045] Our invention also includes a method of conserving
components of a used oil well fluid containing oil well fluid
components comprising (a) concentrating the oil well fluid by
passing the oil well fluid through a cavitation device to obtain a
concentrated oil well fluid containing oil well fluid components in
concentrations higher than the used oil well fluid, and (b) using
the concentrated oil well fluid as a source of oil well fluid
components for a new oil well fluid. The method may be repeated any
number of times--that is, the ingredients of the oil well fluids
may be recycled more or less indefinitely--and the used oil well
fluid may comprise a workover fluid, a completion fluid, a drilling
fluid, an oil mud emulsion, or any other oil well fluid including
components of value or interest for recycling or reuse. The
compositions may be adjusted by the addition of increments of their
ingredients prior to reuse; also the fluid may be filtered prior to
passing through the cavitation device, and the solids retained on
the filter either reused or discarded, or both.
[0046] Our invention also includes a method of processing a used
oil well fluid containing cesium comprising (a) optionally
filtering the used oil well fluid (for example to remove cuttings
from a drilling fluid), (b) passing the used oil well fluid through
a heat exchanger to increase its temperature utilizing waste heat
from an engine, (c) powering a cavitation device with the engine,
(d) passing the oil well fluid through the cavitation device to
further increase the temperature thereof, (e) passing the used oil
well fluid into a flash tank to separate steam and vapor from the
used oil well fluid and to obtain a concentrated fluid, (f)
removing at least a portion of the concentrated fluid from the
flash tank, and reusing the at least a portion of the concentrated
fluid in an oil well. The fluid from step (d) or from the flash
tank can be recycled to the cavitation device to increase its
temperature.
[0047] Water which is vented from the SPR or recovered as vapor or
otherwise from the flash tank may be condensed and used for fresh
makeup of various solutions and new oil well fluids, as a source of
fresh water for living quarters or otherwise on an offshore
platform, and for any other use for which fresh or distilled water
is conveniently used. In the form of steam or vapor, the moisture's
heat energy may be used in a turbine or boiler for conversion to
other types of energy, such as electrical energy.
[0048] Our invention also includes a method of treating a
hydrocarbon producing formation comprising introducing into said
formation through a well an oil well fluid containing at least 2.5%
by weight cesium, whereby said fluid becomes diluted in said
formation so that it contains less than 2.5% cesium by weight,
circulating said fluid from said well, and passing at least a
portion of said fluid through a cavitation device to remove
moisture therefrom and produce a regenerated fluid containing at
least 2.5% cesium by weight of said fluid.
* * * * *