Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention generally relates to water well
treatment apparatuses and methods or procedures followed during
such treatment and more particularly relates to water well
treatment apparatuses and methods in which fluids produced from
the well are recycled through the well and aquifer with the
recirculated fluids being subjected selectively to variol~s
treatment techniques.to more effectively clean or otherwise
treat the well and aquifer. By using various modifications of
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the basic arrangement, shallow wells and deep wells may be
effectively treated and wells which use turbine pumps,
submersible pumps and the like may also be effectively
treated. The apparatus and method includes a structure for
heating the recirculated fluid to desired temperature levels,
adding various cleaning and treating solutions thereto, varying
the parameters of the treatment methods in accordance with the
conditions of the well and aquifer and purging the well when
desired.
INFORMATION DISCLOSURE STATEMENT
Prior U.S. Patent No. 3,899,027 issued August 12, 1975
discloses an apparatus and method of treating a water well in
which all or a portion of the fluid produced from the well can
be recycled through the well and aquifer. Other patents exist
which relate to treatment of wells for various purposes by
injecting various fluids into underground strata for enhancing
well production or for other purposes. However, the prior art
does not include apparatuses and methods equivalent to the
present invention. A separate information disclosure statement
will be filed including copies of the above-mentioned patent
and other patents known to applicants.
SUMMARY OF THE INVENTION
An object of the present invention is to provlde water
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well treatment apparatuses and methods in which a portion of or
all of the fluid produced by the well can be recirculated with
the recirculated fluid being treated by heating or by the use
of selected additives which distinguishes from prior art
systems in which heating has been accomplished but without a
recycle loop. The treated fluid is discharged directly into
the upper end portion of the annulus so that it will fall in an
unrestricted manner downwardly until it strikes the residual
water in the casing with the impact causing a turbulent action
that creates force waves within the residual water in the
casing.
Another object of the invention is to provide a water
well treatment apparatus and method that can be utilized with
various types of wells such as shallow wells and deep wells
provided with various types of pumps such as turbine pumps,
submersible pumps and with various types of well structures
including those drilled in confined aquifers and those in
unconfined aquifers and including wells with unperforated
casings with a well screen placed at the bottom of the well
hole to allow water to enter from a specific zone such as a
well in a confined aquifer and in a well having a perforated
casing extending from the water table level to the bottom of
the hole such as used in an unconfined aquifer.
A further object of the invention is to provide water
well treatment apparatuses and methods with various
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modifications for application to different types of wells
including the use of extension pipes extending downwardly from
a turbine pump to the top of a well screen and the use of a
turbine and inflatable packer when combined with a submersible
purnp and shroud.
Still another object of the invention is to provide
water well treatment apparatuses and methods in which the
apparatuses are relatively simple in construction and utilize
conventional components in a unique manner to perform efficient
treatment methods.
Still another object of the invention relates to a
well treating apparatus combined with a well having a casing
and column pipe therein with the casing and column pipe being
concentrically spaced to form an annulus and extending into
an underground strata for receiving fluids therefrom, a pump
in the casing and connected with the column pipe for pumping
fluids received from the underground strata upwardly through
the column pipe to a discharge pipe, a recycling pipe
selectively communicating the discharge pipe with the casing
for recirculating the pumped fluid back into the annulus
: between the casing and pipe for free-fall into residual fluid
in the casing, means communicating with the discharge pipe
upstream of the recycling pipe for selectively heating the
recirculating fluid and means communicating with the discharge
pipe upstream of the recyling pipe for selectively injecting
additives into the recirculating fluid, said well being a deep
well with an unperforated casing and a well screen forming an
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extension of the casing at the lower end thereof and extending
into the underground strata, said pump being a turbine pump
with an extension pipe connected thereto forming a suction
pipe extending to the lower one-third of the screen at the
lower end of the casing.
Still another object of the invention relates to the
method of treating a water well which includes an outer casing
extending downwardly into an aquifer and in fluid communication
with the aquifer, a pipe within the casing and spaced concen-
trically therefrom with a pump associated with the lower end
of the pipe and casing for pumping water from the aquifer to
above-ground surface into a discharge pipe, and a recycle pipe
interconnecting the discharge pipe and the annulus between the
casing and pipe therein consisting of the steps of controlling
flow of water for discharge from the discharge pipe and
recirculating water from the discharge pipe through the
recycle pipe into the annulus adjacent the upper end of the
casing for free-fall of water in the annulus for impacting
residual water in the annulus and heating the recirculated
water, determining the recovery rate of water level in the
annulus from the lowest pumping level when water is being
pumped and discharged from the discharge pipe to a static
water level when water is not being pumped and dividing the
distance between the lowest pumping level and the static water
level into multiple equal increments and recycling water with
free-fall at each of the increment levels above the lowest
pumping level thereby providing impact wave energy to each of
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the increment water levels of the aquifer between the lowest
pumping level and the static water level.
These together with other objects and advantages
which will become subsequently apparent reside in the details
of construction and operation as more fully hereinafter
described and claimed, reference being had to the accompanying
drawings forming a part hereof, wherein like numerals refer to
like parts throu~hout.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates a shallow well having a
perforated casing and turbine pump.
Figure 2 is a schematic view illustrating a
modification of Fig. 1 for use in deep wells utilizing a
packer, unperforated casing and well screen.
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Figure 3 is a schematic view illustrating a well
treating apparatus and method utilizing a packer, submersible
pump with shroud and a well screen at the bottom of an
unperforated casing.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now specifically to Fig. 1, well 10 includes
a casing 12 provided with perforations 14 in the upper and
lower end thereof for association with an aquifer. The well
casing includes a production tube or column pipe 16 spaced
concentrically inwardly from the casing 12 with an annulus 18
provided between the casing and production tube. A multiple
stage turbine pump assembly 20 is located at the lower end of
the production tube or column pipe 16 with the upper end
thereof communicating with a discharge pipe 22 having a valve
24 therein and a chemical injection and sampling nipple 26
incorporated therein. The upper end of the production tube may
extend through a motor housing 28 which also houses the motor
that drives the down hole pump 20.
Adjacent the upper end of the casing 12, a
recirculating pipe 29 is provided which is in communication
with the upper end portion of the annulus 18 at its lower end
and is in communication with the discharge pipe 22 at its upper
end. Also, a purge pipe or line 30 is communicated with the
upper end portion of the recirculation pipe. The purge pipe 30
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and the recirculating pipe 29 include fast acting valves with
the fast acting valve 82 in the recirculation pipe being
oriented below the connection between the purge pipe and the
upper end of the recirculation pipe 29 which also communicates
with the discharge pipe 22 inwardly of the valve 24 and on the
discharge side of the injection or sampling nipple 26. A heat
exchanger 34 is mounted adjacent the motor housing and adjacent
the well head and includes an inlet pipe 36 communicated with
the discharge pipe 22 upstream of the injection and sample
nipple 26 with a valve 38 being incorporated into the inlet
pipe 36. An outlet pipe 40 connects the heat exchanger 34 with
the recirculation pipe 29 with a valve 42 incorporated into the
outlet pipe 40. The heat exchanger is associated with a
heating device generally designated by the numeral 44 to heat
the fluid circulating through the heat exchanger to whatever
temperature desired.
Figure 2 discloses a deep well application of the
present invention in which the production tube or column pipe
16 is extended down below the bowls of the pump 20 with the
extension pipe being designated by numeral 46 and is actually a
suction pipe and may be constructed of rigid plastic material
or the like. The suction pipe 46 terminates in the middle of a
well screen 48 which forms an extension of an unperforated
casing S0. The lower end portion of the suction pipe 46 is
provided with a packer 52 which may be an inflatable packer or
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the like and is installed just above the well screen 4~
although the position of installation may vary as long as it is
below the pumpinq level.
Figure 3 discloses a modification of the invention in
which a submersible pump with shroud is utilized as indicated
by numeral 54 which is positioned centrally in the casing 56
with a packer 58 being provided above the pump 54 and mounted
at any position on the production tube or column pipe 60. A
pipe extension 62 extends from the lower end of the pump 54
through an unperforated ca~ing 6~ and terminates in a lower
inlet or suction end 66 at the upper end of a well screen 68.
With the modifications of the invention. various
installational requirements can be met including installation
in a shallow well, a deep well and with various types of
casings, perforations, well screens, pumps and aquifers. The
recirculated fluid may be heated and chemical additives
incorporated therein with the various parameters of materials,
times and temperatures being varied depending upon conditions
encountered.
The cleaning operation of a well may be divided into
several phases. In an initial phase, sodium hypochlorite may
be circulated at a concentration of from 500 to 1000 PPM for
two to four hours after which the well is purged. A second
phase may include circulation of a solution of sodium
hexametaphosphate of between 100 to 500 PPM which is
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recirculated for 15 to 24 hours after which the well is again
purged~ A third phase of the cleaning operation involves
injection of hydrochloric acid which may be a 15% solution
circulated for a period of several hours. It is pointed out
that the various concentrations and time parameters can vary.
A significant novel feature of the apparatus and method is to
provide the heat exchanger and heater so that the recirculated
fluid can be heated either continuously or intermittently.
Heating the fluid tends to expand the casing to remove and
slough-off incrustations and provide some degree of movement
between the exterior of the casing and the surrounding gravel
pack which more effectively cleans the casing. The cleaning
action is substantially enhanced by the water that is being
recirculated and free-falling or dropping from approximately
ground level to the static water level or pumping level which
may be a distance of several hundred feet or more. The energy
provided by the falling water when it impacts with the residual
water in the annulus will create energy waves that will travel
through the casing and aquifer for enhancing cleaning action.
During normal operation of the pump, the water level
is drawn down from the static water level into a draw down cone
as illustrated by the draw down curve in the drawings. During
the recycling operation, the water reintroduced into the
annulus will provide an elevated cone thus providing additional
outward pressure into the aquifer to enhance the cleaning
action of the recirculated fluid in the aquifer.
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The procedure consists of recycling the water from the
discharge pipe 22 through the recirculation pipe 29 so that the
recycled water will fall downward in the annulus without
restriction until it strikes the residual water in the casing.
The impacting water causes a turbulent action that creates
force waves within the casing. When the recycle mode
commences, the water level in the casing is at its lowest point
and, upon impacting, the water level elevates and the pressures
increase and decrease with the fluctuations caused by the
energy`wave thus providing sequential pressure variations in
and out through the perforations. When the system is in a
recycle mode, no water is being discharged which causes the
pumping level to rise to near the static level and this level
will be maintained during the recycle mode. The time period
from first impact of the falling water at the pumping level to
when it reaches the static level is referred to as the recovery
rate. The recovery rate should be divided into ten equal time
parts so that the impact zone of the water fall travels upward
from the pumping level a distance equal to 10% of the total
distance and after this 10% travel has been obtained, the
system should be purged which will again drop the pumping level
back down to its lowest level so that a second cycle can then
be started with the same procedure being used but the impact
zone is allowed to rise to 20% of the total distance and this
procedure i~ repeated through ten cycles. By this action, the
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entire wetted depth of the well has been bombarded by the
impact ~one of the water fall and the deepest part of the well
has received the most energy since it is at the bottom of the
cone of depression. This cycle will be used after each phase
of the treatment process to insure a thorough cleaning of the
casing, gravel pack and outside of the bore hole.
Various incrustations may be removed by the addition
of acid. The acid most widely used for this purpose is
hydrochloric although others can be used since calcium
carbonate is the primary ingredient of incrustations. After
the desired concentration of acid and type of acid has been
determined, it is added to the recycle system and after
complete mixing has occurred, the pump should continue to
operate as necessary and the well should be purged before the
action of the acid has been completed and the above described
energy cycle should be used whenever the well is purged.
In order to remove silts and clays, the same procedure
can be used as for incrustations except that the chemicals to
be used may be various types of phosphates which take longer to
act. In view of this, the system may be operated in the
recycle mode for a period of one hour and the pump continued in
operation for a period of four hours with purging done when
necessary.
In order to sterilize a well, the recycling fluid
should be heated to a temperature from 100F. to 150F. with
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120 to 130F. being preferred and calcium hypochlorite is used
at a concentration of 100 to 500 PPM.
The above-described process will produce an increase
. in the porosity of most water wells thus increasing the
specific capacity and yield. When used on a preventive
maintenance program, high yields will be maintained. Since it
is not necessary to remove the pumping unit from the well and
down time is minimized, the treatment and cleaning process can
be economically more feasible.
In the acid treatment process, the packer is used
where the screens or perforatlons are below the pump bowls.
When the system is in the recycle mode and the recirculating
water has been heated, the pump is shut down and the packer is
inflated. Since the screen is at the bottom of the hole, it
becomes necessary to get the acid down to this region as
undiluted as possible which is accomplished by pouring the acid
down the column pipe followed by enough water to force all of
the acid out of the column pipe. With all of the valves
closed, the reaction gasses produced by the acid will cause
pressures to develop which will force the acid further out into
the aquifer wlth this pressure being monitored by a gauge 27 on
the purge line. If the pressure becomes excessive, it can be
reduced by venting out of the purge valve 32. When the
reaction diminishes, the well can be purged until clean water
is being pumped and then the packer can be d~flated to check
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the specific capacity. The acid treatment can be repeated
until no further increase is noted.
In removing silts and clays or sterilizing the well,
the packer is not used as it remains deflated. As before, the
recirculated water is heated so that superior action from the
chemicals will take place. The heating unit is shut down and
phosphates added to the recycling stream of water. Since it
takes several hours for phosphates to function, the system can
be operated on a recycling basis for one hour and then shut
down for three hours after which the system and well is purged.
In sterilization, the recycling water is heated and
calcium hypochlorite is added and the recycling mode is
continued for one-half hour or longer and the system is then
purged. Also, it is necessary to make some modifications
depending upon the type of pump used. When a turbine pump is
used, a down hole extension or suction pipe 46 is necessary
which is e~tended into the bottom screen area and a packer is
also necessary which is used to plug the annulus of the well.
The packer can be inflated with air or liquid and can be
controlled at the surface with the packer being fitted on the
column pipe in the vicinity of the pumping water level and
above the bowls.
When using a submersible pump, the packer will be
placed in the same area as with a turbine pipe and a shroud is
used around the submersible pump to insure that the water being
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pumped passes over the pump for temperature control. The
shroud is merely a cover that is open on the bottom and is
closed on the top that compels the water to flow around the
pump and into the intake located at the top of the submersible
pump. The suction line is attached onto the shroud and extends
into the screened area. Inasmuch as the submersible pump has a
check valve, the chemicals cannot flow down the discharge line
to the screen area. Thus, a 1" acid injection line is needed
and extends from the surface down through the packer and around
the pump and enters a suction line by means of a fitting below
the pump. This allows the chemicals to be pumped down this
line entering the suction pipe so that they can travel to the
screened area. This injection line is schematically
illustrated in Fig. 3 and is designated by reference numeral 55.
When using the process in a confined aquifer the total
volume of water being pumped is returned to the annulus during
the recycle mode. The energy waves produced due to free fall
of the water in the annulus is confined in the unperforated
casing and is transmitted downward from the impact zone to the
bottom of the hole. When the recycle mode is first started,
the water level in the casing is at its lowest point and upon
impacting, the water level elevates and the pressures increase
and decrease with these fluctuations giving pressure variations
at the screened area. As in the previous system, there is no
water being discharged when in the recycle mode which forces
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the pumping level to rise to near the static level and
maintained during the recycle mode of operation. During the
recycle mode, water is falling or flowing downwardly in the
annulus at high velocities and some of this water in its
downward flow will bypass the end of the suction pipe and will
result in a turbulent action at the screen area which also
creates outward pressures at the screen area. Thus, by
adjusting the valves at the surface, the resulting increased
and decreased flows will create an inward and outward pressure
sequence which will be significantly beneficial in cleaning the
screen area. After treatment, the well will be purged until
the water is clean
One benefit from heating the recycled water is the
resultant expansion of the well screen and casing for aiding in
its cleaning. Also, heating will increase the efficiency of
any chemicals that are added and once the water in the well has
been heated, the energy cycle will be used to further clean the
well. The recycling of cool water at the beginning of the
cycle will contract the screen causing the completion of the
expansion and contraction cycle.
In acidizing in a confined aquifer, the system is
placed in the recycle mode and heated to a desired temperature
with the pump being stopped and the packer inflated with all
valves in the closed position. After determining the amount of
acid needed, it is injected into the system through the
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injection nipple 26 and will travel down the column pipe or
production tube 16 and since it is heavier than water, it will
displace the water and flow downward to the bottom portion of
thle well. A sufficient amount of water should then be poured
down the column pipe to displace all of the acid therein. A
chemical reaction will start to occur since the acid comes into
contact with the incrustating material and this reaction will
cause gasses to form which will increase the down hole
pressure. With the packer inflated, the only venting that can
occur will be through the column pipe and the screens. Thus,
this pressure can be monitored by the pressure gauge mounted on
the discharge pipe of the pump and if this pressure becomes
excessivej it can be vented through the purge line valve. A
beneficial action of the pressure increasing is that it will
force the acid outward through the screens into the aquifer.
Any debris loosened by the acid action can be removed by using
a sequestering agent in conjunction with the acid. Once the
pressure drops in the well, the packer is deflated and the
system is placed in the recycle mode and after the pH of the
solution as well as the amount of the solids being carried in
the recycle stream is determined, the system may be purged and
the specific capacity checked to determined if another acid
treatment is necessary.
In removing silts and clays in a confined aquifer, the
recycle mode lS used and the recycle fluid is heated to a
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desired temperature and conditioner is slowly added to the system
and the recycle mode is continued for one out of every four
hours, or the like, for a total of 16 hours after which the
system is purged and the specific capacity checked and the
treatment cycle repeated if necessary.
When "working-over" a well that has submersible pump
with a large surface area when compared to the cross-sectional
area of the casing rather than a downhole pump, the pump should
be removed and a submersible pump connected to a flexible hose is
lowered into the well and positioned near the bottom of the well
at any screen level which enables the cleaning process to be
carried out without restrictions due to a large surface area pump
being in the well. The inserted smaller pu~p enables the energy
from the free-fall of water to pass downwardly to the bottom of
the well. The chemicals and heat inserted into the recycle
stream will be assured of reaching the bottom of the well to
provide excellent cleaning from the top to the bottom of the
well. After cleaning, the inserted submersible pump and flexible
discharge hose are removed and the original production pump
lowered back into operating position. The process of cleaning as
described previously with respect to free falling water at each
increment level remains the same.
The foregoing is considered as illustrative only of the
principles of the invention. Further since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
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construction and operation shown and described, and, accordingly,
all suitable modifications and equivalents may be resorted to,
falling within the scope of the invention.
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