Canadian Patents Database / Patent 2350453 Summary

Third-party information liability

Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.

Claims and Abstract availability

Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:

  • At the time the application is open to public inspection;
  • At the time of issue of the patent (grant).
(12) Patent: (11) CA 2350453
(54) English Title: METHOD AND APPARATUS FOR REMOVING WATER FROM WELL-BORE OF GAS WELLS TO PERMIT EFFICIENT PRODUCTION OF GAS
(54) French Title: METHODE ET APPAREIL POUR ENLEVER L'EAU D'UN PUITS DE FORAGE DE GAZ AFIN D'OBTENIR UNE PRODUCTION DE GAZ EFFICACE
(51) International Patent Classification (IPC):
  • E21B 43/38 (2006.01)
  • E21B 43/12 (2006.01)
(72) Inventors :
  • LIKNES, ALVIN C. (Canada)
(73) Owners :
  • NORTHERN PRESSURE SYSTEMS INC. (Canada)
(71) Applicants :
  • LIKNES, ALVIN C. (Canada)
(74) Agent: BORDEN LADNER GERVAIS LLP
(74) Associate agent:
(45) Issued: 2006-05-09
(22) Filed Date: 2001-06-13
(41) Open to Public Inspection: 2002-01-18
Examination requested: 2004-12-09
(30) Availability of licence: N/A
(30) Language of filing: English

(30) Application Priority Data:
Application No. Country/Territory Date
2,313,617 Canada 2000-07-18

English Abstract

Method and apparatus for removing water from a gas well to permit efficient production of gas while protecting formation from introduced pressures. The apparatus comprises a check valve that seals the casing from production zone when hydrostatic pressure of water from production accumulates in casing above production perforations and checkvalue exceeds formation pressure. When the casing is sealed, a compressor pressurizes gas into the casing but not an exhaust conduit, the top of the casing being sealed around the exhaust conduit, permitting communication between the conduit and a suitable destination, such as via liquid separators on into sale pipeline. Accumulated water is caused to flow into the bottom of the exhaust conduit and out at surface to collection. When pressure within the sealed casing to the top end of exhaust conduit is equalized, the checkvalve opens and regular production can resume.


French Abstract

Procédé et appareil d'élimination d'eau d'un puits de gaz pour permettre la production efficace de gaz tout en protégeant la formation provenant de pressions introduites. L'appareil comprend un clapet de non-retour qui scelle le carter de la zone de production lorsque la pression hydrostatique de l'eau provenant de la production s'accumule dans le carter au-dessus de perforations de production et la valeur de contrôle dépasse la pression de formation. Lorsque le carter est scellé, un compresseur pressurise du gaz dans le carter mais pas un conduit d'échappement, le dessus du carter étant scellé autour du conduit d'échappement, permettant la communication entre le conduit et une destination appropriée, telle que par le biais de séparateurs liquides sur le gazoduc de vente. L'eau accumulée est poussée à s'écouler dans le fond du conduit d'échappement et à sortir à la surface pour le recueil. Lorsque la pression au sein du carter scellé vers l'extrémité supérieure du conduit d'échappement est égalisée, le clapet de non-retour s'ouvre et la production normale peut reprendre.


Note: Claims are shown in the official language in which they were submitted.


WHAT IS CLAIMED IS:

1. An assembly for production of gas from a down-hole gas-producing
formation to surface through a well bore lined with casing having openings
through which gas can pass from the formation into the casing, the assembly
capable of being periodically cleared of accumulated liquids when the
pressure of produced gas is insufficient to overcome hydrostatic pressure of
the accumulated liquids, the assembly comprising:
a. a tubing string extending from surface through the casing and having
a lower open end positioned below a point at which the hyrdrostatic
pressure of the accumulated liquids exceeds the pressure of produced
gas, the tubing string having a bare sealed from fluid flow
communication with the casing except through the lower open end;
b. a check valve positioned and sealed to the casing above the openings
and below the lower open end of the tubing string, the check valve
permitting flow of fluids from the openings toward the lower open
end of the tubing string, but restricting reverse flow therethrough; and
c. a means for introducing pressurized gas from a source at surface to
either the casing or the tubing string to create a pressure in excess of
the hydrostatic pressure exerted by the column of accumulated liquids
above the accumulated liquids to push the accumulated liquids from
bottom hole up through the other of the casing or the tubing string to
surface and out of said well bore.
2 The assembly of claim 1 with a means of collecting fluids passing from the
tubing string to surface.



29




3 The assembly of claim 1 with a means for collecting fluids passing from the
casing at surface.
4 The assembly as in claim 1 wherein said tubing string is an existing tubing
string placed within said casing as part of a production program.
The assembly in claim 1 wherein said check valve is a ball-and-seat valve.
6 The assembly in claim 1 wherein said check valve is a sprung flapper valve.
7 The assembly in claim 1 wherein the source of pressurized gas is a
compressor.
8 The assembly in claim 1 wherein the pressurized gas is air from atmosphere
at surface.
9 The assembly in claim 1 wherein the pressurized gas is gas collected at
surface from the formation.
The assembly in claim 1 wherein the pressurized gas is collected gas from
another well.
11 The assembly in claim 1 wherein the means for collecting fluids passing
from
the casing at surface is a conduit including a valve for controlling fluid
flow
therethrough and connected to a gas collection system.
12 The assembly in claim 1 wherein the means for collecting fluids from the
tubing string at surface is a conduit leading to a gas collection system.



13 A method of unloading accumulated liquids from a well bore to a level
sufficient to permit gas to be produced from the well bore, the well bore
being lined with casing and having openings in the casing to permit
produced gas to pass from a formation into the casing, the method
comprising:
a. providing an assembly including a tubing string extending from
surface through the casing and having a lower open end positioned
below a point at which the hydrostatic pressure of the accumulated
liquids exceeds the pressure of produced gas and above a check valve,
the tubing string having a bore sealed from fluid flow communication
with the casing except through the lower open end; a check valve
sealed to the casing above the openings and below the lower open end
of the tubing string, the check valve permitting upward flow of fluids
from the openings to the lower open end of the tubing string, but
restricting reverse flow therethrough; and a means for introducing gas
from a source of pressurized gas at surface to either the casing or the
tubing string;
b. closing the check valve;
c. introducing gas from surface to either the casing or the tubing string to
create a pressure in excess of the hydrostatic pressure exerted by the
column of accumulated liquids above the accumulated liquids to push
the accumulated liquids from bottom-hole up through the other of the
casing or the tubing string to surface and out of said well bore; and
d. stopping introduction of gas from surface to permit the well bore to
return to production of gas from the formation.
31



14. The method in claim 13, further comprising the step of collecting fluids
passing from the casing at surface.
15. The method in claim 13, further comprising the step of collecting fluids
passing from the tubing string at surface.
16. The method in claim 13 wherein the step of closing the check valve is
accomplished when the pressure of the accumulated liquids above the check
valve is greater than the pressure exerted below the check valve by the
formation.
17. The method in claim 13 wherein the step of closing the check valve is
accomplished by introducing gas from surface such that the pressure above
the check valve is greater than the pressure exerted below the check valve by
the formation.
18. The method in claim 13 further comprising determining when the check
valve is closed by observing when the flow of produced gas has ceased.
19. The method in claim 13 wherein said accumulated liquids are forced to
surface through the tubing string and out through the means for collecting
fluids passing from the tubing string at surface, the means including an
apparatus providing for separation of liquids from gases.
32

Note: Descriptions are shown in the official language in which they were submitted.




METHOD AND APPARATUS FOR REMOVING WATER FROM WELL-BORE
OF GAS WELLS TO PERMIT EFFICIENT PRODUCTION OF GAS
FIELD OF INVENTION
This invention relates to an improved method and apparatus for the removal
of water from the ~n~ell-bore of gas wells so as to reduce the hydro static
head
associated with the produced water and to thus unload the 'n~ell and permit
more
efficient production of gas.
BACKGROUND OF THE INVENTION
Numer ous gas wells in Alberta, Canada, and throughout the world, produce
a minimum of natural gas because of pr oblems associated ~~ith water produced
with
the gas, ~~hich accumulates at bottom-hole, and by vir tue of its ~~eight
provides a
hydrostatic back pressure which partially or entirely defeats the ability of
formation
gas pressure to move well gas to the surface for collection.
There are a number of methods in use to remove water from the well-bore of
a pr oducing gas well when the column height of water in the bore produces a
hydrostatic pressure greater than the pressure of the gas from formation
sufficient to
impair production.
The gas in those situations has typically been produced out of a smaller
2~ diameter tubing string inserted into the well because the smaller cross-
section of the
tubing produces higher velocities of gas floe at formation pressures ~n~hich
it is
hoped will carry the water out of the well-bore during production and thus
"unload" the well.
As a reference, the article "A Practical Approach to Removing Gas V~~ell
Liquids" ~-vritten by E.J. Hutlas and W.R. Cranberry (published August 197? in
CA 02350453 2001-06-13




Jo1iT31Cil of Petroleum Technology) discusses the history of methods of
removing
un~n~anted accumulations of liquids from gas wells. 'the article states that
the best
methods for removing liquid from producing gas wells are pumping units, (for
shallow fields having very low pressure), liquid diverters, intermitters and
gas lifts
~ (for deeper higher-pressure fields), and inserted tubing strings for wells
where
severe formation damage could result from stopping operations (e.g. well
shock).
United States Patent No. 4,265,312 to Theirs, METHOD FOR DEVELOPING
WATER WELLS, issued May 5, 1981, per tams to a method of developing a water
~n>ell, but is instructive in that it deals ~n~ith the introduction of a gas-
lift eater pump
into a well-bore, the pump's action being provided by introduction from
surface of
high-pressure gas (air, in that case) in an inner tube deployed such that its
bottom
end is above the bottom end of an outer tube in ~~hich the inner tube is
centered,
and the bottom of both of which tubes are deploy>ed submersed in the ~n~ell-
bore's
accumulated water. The pressured gas escapes from the bottom of the inner tube
and is collected and exits the well-bore, r ising up through the annulus
between the
pressurized tubing and the second, outer tube, taking ~>ith it entrained
~~~ater from
the wellbore (within which the tubes were deployed).
In the Theirs patent, the purpose was to provide a gas-lift pumping means
with some agitation at the well-bore's bottom end to remove settled solids and
improve water flo«~ within a eater well. The apparatus is a good example of a
form
of gas-lift pump (concentrically deployed tubing strings, providing
pressurized gas
from surface to the inner tube, permitting gas and entrained liquids to exit
using the
2~ annulus between inner and outer tube as a discharge path).
There are two related prior art downhole pump systems, US Patent No.
3,894,583 and US Patent No. 3,894,814 to Morgan, both issued July 15, 1975,
titled
ARTIFICAL LIFT FOR OIL WELLS, ~1'111c11 describe a two-chamber do~~n-hole
CA 02350453 2001-06-13




pump apparatus to be removably inserted into an oil well's casing to pump oil
from
an oil well where production pressure is insufficient to provide lift to
surface.
Morgan's '583 patent describes an apparatus and system where the well's
casing is isolated by a packing from the production zone and from the pump at
bottom-hole to provide a storage tank for compressed air, an accumulator below
the
packing to collect oil from formation via a check valve which is vented to
surface,
said vent line being periodically pressurized by connecting tubing and valves
to the
casing's stored pressurized air to force the collected of from the accumulator
up a
secondary tubing string to surface. A piston, pig or s~neab is deployed below
the oil
in the production tubing string. The vent/pressure tubing is deployed
adjacent/concentrically to said production tubing. Crossover conduits between
production tubing/venting tubing are used to s~n~itch annulus mid-bore. An
electric
switch/ball float is deployed in the log-~~er well-bore to sense the
accumulator's state
1 ~ (full or not), and to energize an air pump top-hole and electrically
switched ~~al~~es to
pressurize the ~~ent tubing.
Morgan's '81=~ patent describes and claims the same system and apparatus,
absent the use of the upper casing as a pressure tank and requiring an
electrically
actuated 3-way ~~al~~e and dog-~~n-hole sensor.
Morgan's '583 patent also describes an embodiment ~n~here the accumulator
means is formed by a chamber comprised of the ~~ell's casing belo~~ the packer
isolating the upper casing's compressed air storage area from production, and
also
2~ belo~~ a second packer below the perforations in the casing to formation,
with a
check val~~e from the thereby isolated production zone of tile casing into the
accumulator chamber below said second packer, said production and vent tubing
extending in a sealed way through both packers and into the accumulator zone.
CA 02350453 2001-06-13




In US Patent No. 3,797,968 to Elfarr, issued March 19,1974 APPARATUS FOR
FLOWING LIQUID FROM A WELL, describes a downhole siphon pump apparatus
for producing oil from an oil well where formation pressure is insufficient to
move
oil from bottom-hole to surface, powered by compressed gas from surface. The
~ Elfarr system is comprised of two concentrically deployed tubing stings
inserted
within the well's casing. The inner tubing string for its length to near
bottom carries
compressed gas from surface. The annulus between the two tubing strings
carries
oil from the bottom-hole pump to surface. Near the bottom, the conduits cross-
over
via cross-over passages in a fitting. At various heights in the production
annulus,
check valves are deployed to permit upward-only flow of oil. At bottom, a
check
valve permits oil from the formation in the casing to enter the outer conduit
and
accumulate in the tubing string's outer annulus. A check valve in the bottom
of the
inner tubing string, below cross-over and above the lower check valve is
deployed
permitting oil to floe upward only into the production passage~n~ay for
pumping.
1 ~ The ilmer tubing at surface can be pressurized, causing the pressure
differential
across the check ~~al~~es at bottom to (a) close communication between the t~-
~~o
tubing strings and the casing; and (b) Open C0111II1unlCatlon between 11111er
and outer
conduits, permitting and causing the accumulated captured oil to flow up~n~ard
to~n~ard the surface. The formation is thus not exposed to higher than bottom-
hole
ambient pressure. The check ~~al~~es in the outer production annulus and the
system
can be cleared by removal of the inner tubing string, which is for most of its
length
(from surface to cross-over) used ol~ly to carry pressurized gas from the
surface.
There is thus formed a pump ~~ith two chambers deployed up-hole, formed
of concentric-tubing strings, cross-over fittings, and check val~~es, with the
removable inner str ing sitting on nipples and seats on tile inner surface of
the outer
tubing string, for pumping oil from wells using introduced pressurized gas
from
surface. The pump was designed to move oil to surface in an oil well to
enhance
production, but it is complex, small-diameter, and requires specialty
fittings, seats
and nipples, and it has a large number of complex and special-purpose
~~al~~es. It
a
CA 02350453 2001-06-13




would interfere significantly with free gas-flow, and while it operates on
pressure
differentials (a siphon-like function), it is for the speci:Eic purpose of
pumping oil to
surface.
United States Patent No. 4,509,599 to Chenoweth et al, GAS WELL LIQUID
REMOVAL SYSTEM AND PROCESS, issued April 9, 1985, describes a system and
apparatus for dewatering a gas well which, at the well-bore's bottom end has
collected sufficient fluid (water, for example) that the bottom-hole pressure
(adjacent
the production from formation to casing) is insufficient to independently
transport
gas from formation to surface (through, it is assumed, a conduit or tubing
string
secondary to the casing's cross-section).
Chenoweth's invention pro~~ides for the division of the casing's annulus into
1 ~ tmo independent conduits (typically, a tubing string and the casing/tubing
annulus), with a compressor at surface producing lo~n~er pressure ~~ithin one
of the
conduits sufficient that production pressure (from formation) at bottom-hole
propels
gas-fluid mixture to surface through that low-pressure conduit, permitting gas
alone
to flow through the other conduit (once the o~~er-pressure situation has been
remedied by remo~~al of sufficient fluid from the well's bottom). There is
also
provided a means of heating the top segment of the mixed fluid-gas-carr~~ing
conduit to a~~oid precipitation of paraffin.
It is a necessary part of the Chenoweth in~~ention that both conduits
2~ communicate with formation throughout the process claimed. It is also
provided
that a lowered pressure (partial ~~acuum) is applied, at surface, which Can be
difficult, and which might damage the well's production interface. It does not
contemplate any need to segregate production zones from the method or
apparatus
for dewatering the well. It is a "closed" systelll 111 that all matter
exhausted from the
s
CA 02350453 2001-06-13




~~ellbore is (once liquids are separated) inserted into the gas collection
system to the
sales line.
The discussion in the prior art cited in the Chenoweth specification discloses
the insertion of highly pressurized gas into a ~n~ell-bore to cause the
e~~acuation of
gas and liquid from well-bottom through a second "siphon tube" string to
"unload"
a gas well, as well as methods involving gas-lift valves, downhole mechanical
pumps, differential gas intermitter systems, and the like, and claims to
overcome the
difficulties inherent in those systems. Of particular interest here is the
mention of
insertion of high pressure gas to "blow" liquid-gas mixtures up a siphon tube
depended within the well's casing, as a variant to reduction of pressure from
collection system pressure ranges to lo~n~er, atmospheric pressure ranges, in
order to
exhaust gas through the SIphOI1 tube at hlgh ell0ugh ~'elOCltleS to unload the
problematic well.
1~
The cure in the objects of the Chenoweth '599 patent for damage potential
frOlll hlghh' pleSSUrIZIIIg the CaSlIlg (and production fl7rmatlOn) 1S to
significantl~~
reduce the pressure through the siphon tubing, thus permitting formation
pressures
to be the highest pressures in the system (and thus eliminating formation
damage
potentials caused by insertion of high pressure gas from surface into casing,
which
can "drive" entrapped liquids and solids at bottom-hole in the well-bore back
through the casing perforations into formation).
United States Patent No. 4,437,514 to Canalizo DEWATERING APPARATUS,
2~ issued March 20,1984, discloses a ~~al~~e-set comprised of two valves, one
permitting
liquid-only fluid flow from casing-tubing annulus into tubing, the other,
higher,
~~alve permitting communication from casing-tubing annulus of gas or liquid
into
the tubing. The valve-set is put at the lower end of a tubing string, and may
be
actuated automatically or from surface.
G
CA 02350453 2001-06-13




During operation, when the ~n~ell-bore begins to fill ~n~ith ~n~ater from
production, the water rises within the casing-tubing annulus, and when its
hydrostatic pressure is sufficient to open the lo~~er valve, water is made to
enter the
tubing string. When the tubing string is filled to a desired level, the
second, higher,
valve is opened, and the tubing, being open to atmosphere at surface, is over
pressured by pressure of produced gas and liquids, ~n~111c11 thus enter the
bottom of
the tubing string and cause a gas bubble to enter and to evacuate water and
gas to
surface, optionally ~~ith the use of a pig or plunger between the gas and
trapped
~n~ater. This may be referred to as a gas-lift intermitter.
When suitably evacuated, the pressure in the casing-tubing annulus ~~ill have
dropped, it being sealed at surface with collection tubing with a third check
(one-
way out) valve, which causes the second, higher valve to close, shutting off
produced pressure to the tubing.
1~
There is no need to insert additional pressure to the casing-tubing annulus,
nor is any method disclosed. There is no seal of the well-bore above
production, as
there is no intr oduced pressure to damage the pr oducing formation. A problem
which the'~1-1 system will encounter in deep wells is th~lt the longer length
tubing
introduces more chances of the equipment binding in the tubing string.
United States Patent No. x,226,28-1 to Evans, GAS WELL DEWATERING
METHOD AND SYSTEM, issued October 7, 1980, provides for a closed system of
pipes and valves operable via a timer, which permits casing pressure to den-
eater a
2~ gas well b5~ blowing produced gas d0~-1'11 aI1 lllSerted tubing string
using pipeline or
formation pressure, so that entrained water with produced gas is blo«~n back
up the
casing/tubing annulus directly 111t0 a COn~'elltlOnal pTOduCtlon COlleCtloll
S~'SteI21
(«~hich typically includes a normal gas flo~n~ line and liquid separator
means), in
order not to waste pr oduced gas in the dewater ing pr ocess.
JO
7
CA 02350453 2001-06-13




Other~~ise, the Evans invention shoes no increase in casing pressure, nor any
method of protecting the formation, the inventi~~e step being the closed
piping and
valve system with timer. Energy is provided again from pipeline or production
pressure to the lift mechanism.
Canadian Patent No. 848,766 to Kelley and Kelley, LIQUID CONTROL FOR
GAS WELLS, issued August 11, 1970, discloses an apparatus to control the
liquid
depth in gas and oil wells. This invention is comprised of a positive action
liquid/gas separator within a well-bore, a tubing string within the well-bore
connected to the separator, a gas lift ~~alve connected to the tubing string
and
responsi~~e to predetermined pressure (supplying gas under pressure from the
well-
bore to the tubing string so it lifts liquid through the tubing string to the
surface),
and a free piston member (or pig or swab) retained within the tubing string
for
movement between the gas lift val~~e and the surface belov,~ the column of
liquid (to
assist the gas lift in dri~~ing the column of liquid from the well b5~
segregating the
neater abo~~e the lift gas).
Canadian Patent No. 890,226 to KelleS~ and Kelley, APPARATUS FOR
REMOVING LIQUID GAS FROM AND OIL WELLS, issued January 11, 1972,
discloses an apparatus for the remo~~al of liquid from gas and oil ~~ells.
This
in~~ention is similar to Canadian Patent No 8-18,766 absent the liquid-gas
separator
but with the addition of a self-lubricating free piston member (to replace the
free
piston member). The in~~ention shows an intermitter gas lift ~n~ith a free
piston. The
free piston is disposed in the tubing string and retained by a bottom stop and
2~ catcher apparatus, and is lifted b5~ introduced gas from formation below
the column
of liquid to distribute the pressure of gas admitted to the tubing string b5~
the gas lift
de~~ice across the bottom of the column of liquid and to avoid the gas
dissolving in
the liquid as it is lifted to lo~n~er pressure regions. ThlS 111~'elltloll
pro~~ides
automatically regulated 111terI111ttellt flog-v through the tubing string
without manual
control or c~~cle timers. This in~~ention and Canadian Patent No. 848,766
require
s
CA 02350453 2001-06-13




relatively high inherent (not introduced) differential gas pressures to
operate
r eliably.
United States Patent No. 5,339,905 to Dowker, GAS INJECTION
DEWATERING PROCESS AND APPARATUS, filed November 1992, discloses a gas
injection dewatering process and apparatus. In this invention a conduit is
provided
in a watered-in well in the form of tubing of smaller diameter than the well-
bore or
cased bore to conduct ~n~ater from the bottom of said well-bore to the
surface, said
conduit including a check check-valve such that «Then water flows up~n~ard, it
cannot
then reflux backward.
Periodically, a volume of dried, pressurized natural gas is injected into the
lower end of the conduit from an adjacent gas line from surface and which
injected
gas is then allowed to expand, thereby forcing a slug or column of water
upward
1 ~ through the conduit to~n~ard the upper end. This is a typical "gas lift"
method.
This "pulse" of induced gas is repeated, being pumped periodically do«~n the
secondary conduit through the «~elI-bore or casing through that conduit, and
then
being alto«~ed to expand «~ithin the production tubing conduit in or der to
cause a
pulse of increased pressure within the production conduit «~111c11 1S Illeallt
t0 Cause
the ~s~ater into «~hich that conduit is depended to be forced to surface.
In one embodiment, there ar a t«~o conduits deployed essentially in parallel
down the ~n~ell-bore's length from surface to below water, with one being an
exhaust
2~ conduit and the other being a delivery system for the pressurized
dehydrated
natural gas, ~n~here the said dehydrated natural gas is injected into the body
of the
exhaust conduit, thus causing a "bubble" of expanding gas to flow upwardly
~n~lthlll
the said exhaust conduit, decreasing pressure within the exhaust conduit and
thus
pulling «~ater up the exhaust conduit coupled ~s~ith pulses of expanding gas.
9
CA 02350453 2001-06-13




There are a number of difficulties with this system, chief amongst them being
that by pressurizing the well-bore to force water up the conduit this method
also can
cause the pressure within the formation ~n~ith which it is in communication to
increase, and incidentally causing the eater (and any included matter)
accumulated
S lI1 the well-bore to be forced back into the formation, together ~~ith any
sand or
other substance in the well's bore at bottom-hole near the casing, and thus
"reloading" and potentially damaging the formation, rather than evacuating the
accumulated water at bottom hole.
Additionally, this invention requires special equipment to provide
dehydrated natural gas under pressure, and requires the deployment of
specialized
dual/parallel tubing and injector mechanisms, thus being more costly than
desired.
United States Patent No. 4,823,880 to Klatt, GASWELL DEHYDRATOR
1 ~ VALVE, filed September 1988, discloses a gas «~ell dehydrator valve. This
invention deals with the particular situation of t~vo contiguous producing gas
zones
within one well-bore, both being produced simultaneously, the tower one
through a
tubing dependent past a segregation packer in the «~ell-pore between the t«~o
zones.
Then the upper producing zone produces sufficient eater such that the
h~~drostatic
pressure caused by that eater's accumulation above the segregation packer
within
the «~ell-bore overloads the production from that upper zone, this invention's
sa~stem provides for a special valve within the packer to allow communication
of the
gas under higher pressure from the lower formation to be introduced to the
annulus
bet«~een the inner conduit and the well's casing, where the upper production
is
2~ done and ~n~here there is no~n~ ~n~ater accumulated, in order to use that
introduced gas
pressure to essentially "pump" or "blow" said accumulated water up that
annulus
to surface, reducing the hydrostatic pressure and unloading the upper
formation,
allo~~~ing production from the upper reservoir to resume under natural
pressure
(when the specialized packer-valve is reset).
JO
CA 02350453 2001-06-13




This invention has a number of particular deficiencies, notably: the
requirement for t~n~o contiguous production zones, the lo~~er zone not
accumulating
water from formation (i.e. maintaining its natural pressurization sufficient
to clear
the accumulated water in the upper zone); the requirement for specialized and
complex valve and actuation devices at the segregation packer and the packer
itself,
together with difficulties inherent in properly locating and sealing those
apparatus
properly in the well-bore.
United States Patent No. 4,171,016 to Kempton, WATER REMOVAL SYSTEM
FOR GAS WELLS, filed February 1978, discloses a water removal system for gas
wells. This invention involves a set of concentrically deposed tubes with a
specialized injector at the bOttOIl1 elld ~1'lthlll a 'fell-bOTe, depending
1I1t0 water at
the well-bore's bottom. Pressurized water is pumped do~n~n the annulus between
the
inner tube's outer ~,~all and the outer tube's inner «~a11, and is injected at
bOttOIn
1 ~ ups-vardly into the inner tube's annulus, causing said water to jet under
significant
pressure up the inner tube, ~n~hich in turn causes the pressure «~ithin the
inner tube
to drop somewhat from the pressure within the formation, and thus causing the
water within the well-bore to flo«~ or be thus pumped to surface. This is a
do«-n-
hole 1I11eCt10I1 Or jet pump.
There are a number of difficulties ~-~~ith this system and method, chief among
those being the requirement to pump Iarge volumes of water at relatively high
pressures into the well-bore near the formation in order to cause sufficient
jet-
pumping pressure differentials to evacuate the water from near to the
formation.
2~ Additionally, if the injector becomes damaged or clogged, this system will
result in
additional volumes of water being introduced to the production zone of the
«~ell
under high pressure, thus potentially seriously damaging that well's future
ability to
produce gas.
CA 02350453 2001-06-13




United States Patent No. 4,596,516 to Scott et al, GAS LIFT APPARATUS
HAVING CONDITION RESPONSIVE GAS INLET VALVE, issued June 24, 1986,
discloses a gas lift where a siphon tube is deployed ~~ithin the well's
casing, and
near the bottom end of the siphon tube is a valve, operable from surface (or
alternatively, responsive to the differential between hydrostatic pressure of
a
column of water within said annulus and the pressure within the siphon
tubing),
~~hich, ~~hen opened, permits communication from the casing's annulus outside
of
the siphon tubing with the inter for of the siphon tubing.
The valve structure is sealed to the casing (belo~n~ the communications
openings) by a set of two packings, situated above the perforations from
formation
to the casing's annulus. The seals or packings are provided with a pipe which
(full-
time) communicates from formation to the casing's annulus, said pipe extending
~~ithin said annulus upward from the packing to abo~=e the operative parts of
said
1 ~ valve.
~~l~hen the wellbore including the casing annulus and the tubing string
(siphon) are filled with produced water, and it seems desirable to evacuate
said
~-eater, the valve within the tubing is opened, permitting produced gas from
for oration to enter said valve above the packing seals, and to enter the
siphon
tubing, causing a bubble of produced gas to "burp" up the tubing, and evacuate
«~ater therefrom to surface (~1'lth the optional assistance of a piston-like
"pig" which
travels above the gas slug but belo~~ the moved liquid to surface, where the
liquid is
drained off and the pig is permitted to descend the tubing to bottom).
There is pr ovided no means of fully sealing the wellbore just above casing
perforation to protect the production formation during pressurizing of the
well.
Formation pressure, ~n~hen introduced through the novel valve/seal means, is
sufficient to provide gas-lift to evacuate water without adding or inserting
pressure
to casing.
CA 02350453 2001-06-13




This, then, is a typical downhole valve system of evacuating ~n~ater from a
producing gas well's bore using a second tubing string and production
pressures
and gases to provide necessary lift.
J
Objects of the Invention
It is an object of this invention to overcome or mitigate as many of the
difficulties apparent in the prior art as is workable.
SUMMARY OF THE INVENTION
This invention is a system and apparatus for the removal of water from a gas
«~ell.
1~
The present in~~ention o~~ercomes or mitigates some shortfalls in the prior
art,
chiefly those which concern potential damage to producing formation or to the
w~ell-
bore and casing from injected pressurized fluid or gas to power pump or lift
devices,
the insertion of pressure into the «~ell-bore which could communicate either
directl~~
or ~~ia pressure conve~~ed through fluid and gas in the ~;vell-bore to the
production
formation, or similar problems. As well, the present in~~ention provides an
efficient
system of ciewatering and thus unloading a watered-in gas ~~ell with locally
obtained pressurized gas using facilities, materials and equipment ~~hich are
conventionallST available and easy to operate either manually or
automaticall~~ in the
2~ field.
In accordance ~n~ith a broad aspect of the present invention, there is
provided an
assembly for pr oduction of gas from a do~~n-hole gas-producing formation to
surface through a well bore lined ~Vltll CdS111g lla~'lllg Ope11111gS thlOUgh
~1'hlcll gaS
.O0 CaI1 paSS frOIn the fOrlnat1011 IIltO the casing alld the assembly being
capable of
0
CA 02350453 2001-06-13


CA 02350453 2005-07-15
perivdicahy clearing of accumulated liquids whex< the pressure of produced gas
is
insufficient to overcome hydrostatic pressure of the accumulated liquids, the
assembly carnprising: a tubing stzix~g extending from surface through the
casing and
havixtg a lower open end positioned below a. point at which the hydrostatic
pressure
of accumulated liquids exceeds the formation pressure of produced gas, the
tubing
string having a bore sealed from fluid flow communication with the casing
except
through the lower open end; a check valve positioned and sealed to the casing
above
the openings and below the lower open end of the tubing string, the check
valve
permitting flow of fluids from formation through the openings to the lower end
of
the tubing string, but restricting reverse flow therethrough; and a means for
introducing gas from a source of pressurized gas at surface to either the
casing or
the tubing sizing to create a pressure in excess of the hydrostatic pressure
exerted by
the column of accumulated liquids above the accumulated liquids to push the
accumulated liquids from botta~an hole up through the other of the casing oz'
the
tubing string to surface and out of said well bore.
A, means for collecting fluids passing from the casing at surface; a means for
collecting fluids passing froxx< the tubing string at surface may be provided.
In accordance with another broad aspect of the present invention, there is
provided a method of unloading accumulated liquids from a well bore to a level
sufficient to permit gas to be produced from. the well bore, using formation
pressure,
the well bore being lined with casing and haviztg openings in the casing to
permit
produced gas to pass from a formation into the casing, the meEllod comprising:
providing an assembly including a tubing string extending from surface through
the
casing and having a lower open end positioned below a point at which the
hydrostatic pressure of the accuixlulated liquids exceeds the pressure of
produced
gas, the Tubing stnizlg having a bore sealed from fluid flow communicattioxt
with the
casing except through the lower open end; a check valve sealed to the casing
above
the openings and below the lower open end of the iubirlg string, the check
valve
permitting upward flow of fluids from the openings or perforations to the
lower
open end of the tubing string, but restricting the reverse flow therethrough;
and a
14


CA 02350453 2005-07-15
means for introducing gas ~rox~n a source of pressurized gas at surface to
either the
casing or the tubing string; closing the check valve; introdudng gas from
surface to
either the casing or the tubing string to create pressure in excess of the
hydrostatic
pressure excited by the column of accumulated liquids above the accumulated
liquids to push the accumulated liquids from bottom-hole up through the other
of
the casing or the tubing string to surface and out of said well bore; and
stopping
introduction of gas from surface to permit the well bore to return to
production of
gas frozxl the formation.
A means for collecting fluids passing from the casing at surface; a means for
collecting fluids passing frozx~ the tubing string at surface may be provided.
The casing lines the well bore, as is known and can be standard casing or any
other well bore liner. The well bore can be vertical or horizontal and can be
the main
well bore or laterals kicked off from a ~x~,n boxe hole. Where the well bore
services
more than one production zone, has a large internal volume or includes
numerous
lateral well bores, packers can be used to isolate areas into which gas is
introduced
to apply pressure above accumulated liquids.
In some situations, such as in a dangerous or sour gas well, or other
regulated
wells, or where the integrity of the casing is suspect, production may be
through an
internal conduit or tubing string depended or placed within the said well's
original
casing. The internal conduit extends downward from surface to a packer above
the
production formation perforations, the annulus between the casing and the
internal
conduit being filled with an essentially inert fluid or other substance to
protect the
adjacent environment from leaks in the well's casir5g. In such cases, the
internal
conduit would be considered for the purposes of this invention to be the
"casing" as
described in this disclosure.
The openings in the casing will generally be perforations formed through the
casing and cement behind the casing, but can also be other arrangements for




permitting gas to flow from the formation into the casing such as, for
example, a
slotted liner or screen or open hole.
The tubing string can be an existing production or production-enhancement
S tubing string or a string run in for the purpose of unloading accumulated
water
from the well. As such, the tubing can be of any desired diameter, provided
fluid
flow through the casing about the tubing string and through the tubing string
is
significantly restricted. The tubing used in the tubing string must be rigid
enough
so that it will not collapse due to the pressure differentials Which will be
present on
either side of its walls.
In conventional production wells, tubing string diameters can be of Various
sizes and still be used in this invention. Typical diameters are 1/2", 3/4",
1", 1 1/4",
1 1/2", etc. The only requirement to operate this invention is that the tubing
string's
1 ~ bore (if it is used as the exhaust conduit) has to be of a size that the
liquids being
removed do not flow down past the gas flowing up tile conduit (for example, 3
1/2" outside diameter tubing is too large if installed in a 4" inside diameter
casing,
as the compressed gas bubbles through the liquid, the liquid flows down past
the
gas, and in both instances the liquid is not produced to surface to unload the
well).
The pr eS211t 1I1~'elltlOn ~1'lll ~1'Or k ~1'lth 1 / ~" t0 2" tubing installed
lI1 a 4 1 / 2"
casing. Generally', it is preferred to use the tubing which is already present
in most
producing gas ~n'ells susceptible to becoming overloaded with ~n'ater. In
cases where
the tubing was too large, the present invention generally works if the roles
of the
2~ t~n'o conduits are reversed.
Since the level of accumulated liquids Fill be brought do~n'n onh' to the
level
of the lower open end of the tubing string, the lower open end of the tubing
string
must be positioned below a point at which the h~'drostatic pressure of the
accumulated liquids exceeds the pressure produced gas. Preferably, the lower
end
16
CA 02350453 2001-06-13




of the tubing string is positioned closely above the openings so that a
maximum
amount of accumulated liquids can be uWoaded in each operation.
The bore of the tubing string can be sealed from communication with the
casing by various configurations. One useful configuration is a seal
positioned in
the annulus bet~n~een the casing inner wall and the exterior surface of the
tubing
string at the well head.
The check valve can be mounted permanently or temporarily within the
casing. The check valve should be of type suitable for the nature of the ~~ell
bore
and casing. For example, in a vertical cased «~ell, a check valve can be a
ball-anc-1-
seat mechanism well known in the art, while in a horizontal well, the check
valve
can be a sprung flapper valve or similar mechanism.
1 ~ The check valve can be installed either by ~~~ireline or can be attached
to the
lo~n~er end of the introduced tubing string, depending upon «~hich conduit is
acting
as the 'casing'. If the tubing (which is acting as the casing, referred to as
the
"casing/ tubing") has a packer isolating the casing/ tubing from the «~ell's
annulus,
the check valve can be installed with conventional wire-line equipment and
techniques, and set at the lo~s~est point in the casing/ tubing (~n~hich is
the acting
casing) by setting the check valve at the to«~est connection or bottom end in
the
casing/tubing. The (typically, coiled) inserted second tubing string 'would
then be
"landed" as close to the check valve as practical, but above the check valve
which
had been previously installed by wire-line within the casing/tubing at its
to«~est
?J COI111eCt1o11, abo~Te its bottom, and below the inserted tubing string.
In s«~eet wells, it is generally IlOt necessary to pack-off or isolate the
annulus
from the casing/tubing by a packer, and in those «~ells, coiled tubing is used
to
conduct accumulated water from the well-bore to the surface, the coiled tubing
carrying with it as an installed piece at its bottom, an assemble COTISIStIIIg
of a
CA 02350453 2001-06-13




landing cone attached to the bottom of the check valve, ~n~hich in turn is
attached to
a slotted sleeve or similar fitting (to permit communication between the
interior of
the coiled tubing and the tubing-to-casing annulus through the slots, above
the
check valve) ~n~hich is in turn attached to the lower end of the coiled
tubing; a
conventional slip-stop removable packer/seal (ordinarily used to seal the
annulus
between a fitting on the coil tubing's bottom end's circumference and the
casing/tubing within which the coiled tubing is sought to be sealed) is first
installed
in the casing/tubing above the openings to the production formation, and the
coiled tubing with its bottom assembly is lo~~ered until the weight of the
coiled
tubing and its assembly rests, pressing its bottom-most landing cone into the
slip
stop, causing a secure seal of the casing/tubing annulus to the check valve,
isolating
(when the check valve is closed) the tv~~o conduits (coiled tubing's bore plus
casing/tubing-to-coil tubing annulus) from the production openings.
1 ~ The wire-line and coiled tubing installers are equipped ~~ith counters
which
indicate the length of wire or tubing inserted into any well, which indicates
the
depth t0 ~1'I11CI1 tile ~Nlre-I111e OT tubing has been lo~n~ered. Those
counters are
generally sufficiently accurate for placement of the check valve above the
openings
to formation. If the check valve is lowered belo~n~ those open lugs, the well-
bore will
llOt hold a test pressurization, in which case the check valve should be moved
up
(usually not more than a meter or so at a time), and retried.
If the seal of the check valve to the casing/tubing is effected by lowering
the
coiled tubing to rest on a slip stop packer, for example, care should be taken
in the
2~ temperature of the pressurized gas ~n~hich is inserted into the coiled
tubing's bore to
unload the well, because it has been found that insertion of chilled air (from
very
cold surface conditions, for example) may cause the coiled tubing to contract
longitudinally enough to lift the check valve and seat assembly at its bottom
off the
slip stop, and to thus permit communication bet«~een the Slph011 all
allgel11e11t
~s
CA 02350453 2001-06-13

07/24/01 TUE 10:49 FAX 4032857219 Bennett Jones f~]002
above the check valve and the openings below the check valve, thus defeating
the
purpose of the invention.
The means of collecting fluids passing from the casing and the tubing string
at surface can be a system of conduits, seals and valves and preferably
includes a gas
collection system including gas/liquid separators, compressors and/or
containment
vessels as is known in the art.
The seals between the two conduits (for example, coiled tubing inserted into
a cased well) are usually accomplished using conventional coiled tubing
hangers,
an example of which is produced by Select Energy Systems, Inc. of Calgary,
Alberta. Such hanger systems provide a composite bag through which the tubing
is
led, and which when compressed forms a very tight seal between the hanger s
body
and the tubing's exterior surface.
The means for introducing gas preferably includes conduits, seals and valves
from the source of pressurized gas. In one embodiment, the source of
pressurized
gas is a high pressure pr oducing gas well. Xn another embodiment, the source
of
pressurized gas is a compressor connected to the well head by a conduit. In
that
case, a valve is preferably provided to permit closing off the conduit to the
compressor ox other source of pressurized gas,. It will be apparent to those
skilled
in the art the compressor should preferably be automatically operable without
requiring attention or priming. It Xs desirable that the compressor be capable
of
extended unattended stop-and-start operation. One type of suitable compressor
is
very similar to the low to moderate volume but moderate to high pressure
output
requirements met by compressors used in filling scuba-diving tanks. The higher
the
volume capacity of the compressor the faster the water is evacuated. The
compressor can also be of a, type mounted on a truck ar large vehicle. Where
there
is a plurality of production wells closely positioned, there can be one
permanent or
19
CA 02350453 2001-06-13




semi-permanent compressor or source of high pressure gas placed to service all
of
these wells.
The pressurized gas should preferably remain in a gaseous state at the
S pressures to be used. As an example, the introduced gas should not be
something
like pure propane, which in most circumstances at the pressures required,
would be
compressed into its liquid, on-gaseous state. Suitable gases for introduction
are, for
example, surface air or compressed natural gas from the collection pipeline at
the
well head or produced at a nearby ~n~elI, or nitrogen or other inert gas
~~here
chemical reaction might be problematic.
Where the well is producing s~n~eet gas at low pressures, it has been
preferred
to use air from atmosphere through a compressor as the pressurized fluid in
the
present ln~'e11t10I1. ~-l~here a well is near a source of natural gas under
pressure
1 ~ higher than that requir ed to unload the «~ell and in sufficient volumes,
such as a
nearby producing «~ell or pipeline, those sources can be used as the surface
source
of pressurized gas for insertion. 'l~here a well is near to a source of
natural gas of
sufficient volume but insufficient pressure to be utilized «~ithout
compression,
compression may be used ~~ith such a gas source.
Ideally, the «~ater produced by the unloading process will be produced into
the collection system of separators and sales lines, and carried away from the
~~~ell-
site for proper disposal. The compressor used should be large enough to
provide
adequate volumes of pressurized gas in the required pressure ranges to pr
oduce the
2~ accumulated liquids within a reasonable period of time. 'Those types of
compressors
will be apparent to one skilled in the art. Generally, the less time spent
unloading,
the more time spent producing, the better.
It is to be understood that the pressure-containing capacity of ~s>ell
C0121p011entS SLICK as Well-heads, conduit, piping, joints, packers, fittings,
zo
CA 02350453 2001-06-13




compressors, valves, and the like, will have to be sufficiently higher than
the
pressures encountered during the operation of the system. It is also to be
understood that all components of the assembly according to the present
invention,
must be suitable for use in ~nrell bore conditions, which may be corrosive,
etc.
The pressurized gas can be introduced to either the casing or to the tubing
string to act on the accumulated liquids. In a preferred embodiment, the gas
is
introduced into the casing causing liquids to be forced up through the tubing
string
to surface. This is preferred where the casing is large diameter and the
tubing is of
relatively small diameter. It is generall~~ preferred to produce pressured gas
into
the conduit with the smaller cross-section, and to exhaust the liquids from
the
conduit with the larger cross-section.
The check valve can be closed, in one embodiment, when hydrostatic
1~ pressure caused by the accumulation of water from the production zone in
the
bottom of the casing above the check valve exceeds the pressure from the
formation.
In another embodiment, the check ~~al~~e is forced to close by introducing gas
from
surface to increase the pressure abo~~e the check val~~e.
The introduction of gas from surface to force liquid out of the ~n~ell can be
initiated when it is determined that the check valve is closed, as will be
indicated by
observing the flo~n~ or produced gas from the well. When the floe of produced
gas
ceases, the check ~~alve is assumed to be closed. Alternatively, tile
llltrOduCtloll Of
gas from surface can be initiated on a regular basis by use, for example, of a
timer.
7J
Prior to introduction of gas, the casing will be sealed to prevent escape of
introduced gas and produced fluids, in order to utilize the pressure
differentials,
except through the conduit being used to exhaust the accumulated fluids.
CA 02350453 2001-06-13


CA 02350453 2005-07-15
The introduction of gas fxoxn surface cax~ be continued until the introduced
gas beo ns to be expelled after the accumulated liquids are exhausted, or for
a
selected period of time, regardless of whether water continues to be
evacuated.
There are other situatxoxis and well configuxatlons which those skilled in
fine
art would consider to be equivalent to "casiz~gs" or "conduits" or "tubing
strings",
or to "bores' or "surface" or "collection systems" or "gas", "fluid", "valve",
and the
like, and such terms are to be read expansively zather than restrictively, the
description here being made to inform those skilled izt the art of the concept
of the
invention and some of its embodiments, but not so as to restrict the claims
set out
herein.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a schematic view of the apparatus and method, illustrating one
embodiment of the invention.
Figure IA is a schematic view of the apparatus and xz~ethod, illustrating a
second embodiment of the invention.
DETAILED DESCIZIFTION OF THE INVENTION
The following description relates to one embodiment of the invention, and is
made with reference to Figure l, which is a stylized schematic drawing of an
exemplary gas producing well, including the apparatus of the present
invention. A
well bore 5 containing the apparatus extends from surface 10 ax<d passed into
or
through a gas-producing reservoir 12. Well bore 5 is lined with casing 16. As
is
knawn, perforations X8 are farmed through ~sir~g x6 adjacez~t reservoir 12 to
permit
reservoir fluids to enter the bore of the casvzg. 'f'he azunulus about casing
16 is filled
with cement or other sealants such that migration of fluids therethrough is
avoided
and instead fluids pass through perforations into the casing.
zz




A check valve 20 is installed in casing 16 above perforations 18. Valve 20
permits passage of fluids upwardly therethrough but seals against passage of
fluids
downwardly towards reservoir 12. The valve can be a permanent installation or
can
be more tempos ary in nature. Valve 20 can be any of ~~arious check valves
such as,
for example, a ball valve or a sprung flapper valve.
A tubing string 26 extends within casing 16 from surface 10 and has a lo~~er,
open end 28 positioned above check ~~alve 20. With tubing string 26, two
conduits
are provided for passage of fluids from reser~~oir to surface. The first
conduit is the
annulus 30 between casing 16 and tubing 26 and the second conduit it through
the
inner bore of tubing string 26. Val~~e 20 contr ols the passage of fluids from
the
reser~~oir to the two conduits.
1 ~ The tubing string can be a string pre~~iously r un into the well for
production
or production-enhancement purposes or can be run in for the purpose of
unloading
the ~n~ell bore of water. While tubing string 26 is preferably formed of
standard
production tubing, other tubing materials can be used.. In any e~~ent, the
tubing
skiing must be able to withstand pressure differentials across its walls and
must be
able to support its own weight in the length required to extend from its
hanger at or
near surface to just abo~~e the check ~~al~~e. It should be of inside diameter
sufficient
to efficiently move water in the required ~~olumes ~n~ithin reasonable amounts
of
time ~~ith reasonable energy expenditures. In addition, the tubing string
should
have an outer diameter selected with consideration as to the casing's inside
2~ diameter to permit efficient mo~~ement of gas past the tubing string over
its length.
In conventional production ~~ells, tubing string diameters can be of various
sizes
and still be used in this invention. Typical diameters are 1/2", 3/4", 1", 1
1/4", 1
1/2", etc. The only requirement to operate this invention is that the tubing
string's
bore (if it is used as the exhaust conduit) has to be of a size that the
liquids being
remo~~ed do not flow down past the gas flowing up the conduit (for example, 3
23
CA 02350453 2001-06-13


CA 02350453 2005-07-15
1 /2" outside diameter tubing is too large if installed in a ~" inside
diazxtete~r casing,
as the compressed gas bubbles through the liquid, the liquid flows down past
the
gas, and in both instances the liquid is not produced to surface to unload the
well).
Lower open end 2$ of the tubing string represents the lowest level to which
water can be unloaded from the well. Thus the tubing string must be extended
down to a level selected with consideration as to the column of water that
will be
left in the well and the pressure of the gas in the formation. In particular,
the tubing
must be low enough such that the reservoir gas pressure exceeds the
hydrostatic
pressure of a water column extending to lower open end 2$. In one embodiment,
end 28 is 0.01 - 3.0 meters above the check valve and the check valve is
located just
above, for example, 0.5 - 3.0 ~metexs, the highest perforation in the casing.
A casing valve 31 is provided at well head 32 which permits closure of either
or both of tubing string 26 or annulus 30. Casing valve 31 permits various of
the
wellhead rnrnponents 32 above it to be rexmoved, while the well is shut down.
At the well head, a seal 3~ is positioned in annulus 30 to seal against the
passage of fluids. 'This may be in the form of a coiled tubing hangez~, for
example.
Above seal 34, tubiaxg string 2b opens into a conduit 40 leading to a gas
collection
system (not shown) including gas/liquid separators, and communication to
pipelines, etc. Thus, any fluids, such as gas or produced water, Flowing
through
tubing string 26, as will be discussed hereinafter, can be passed to the
collection
system.
Below seal 34, a conduit ~2 opens through casing 16 into annulus 30. Conduit
42 opens into tyro further coxiduits 44 and 46. Conduit ~, which can be closed
by a
valve ~S, pexznits flow of gas produced tluough the casizig azululus 30 to a
gas
collection system 55 including gas/liduid separators, storage facilities,
compressors,
access to pipelines, ete. Conduit 46 is in communication
24




with a source 49 of pressurized gas, controlled by valve 51, and permits floe
of
pressurized gas therethrough to annulus 30. The sour ce of pressurized gas can
be
air or produced gas from a compressor or gas from a high-pressure source such
as a
nearby high pressure well bore. Where a gas produced by a high pressure gas
well
S is used, no compressor will be needed. However, when using either a hlgh
pressure gas well or a compressor, various control systems must be used to
ensure
that gas is introduced to the well only at selected times and for selected
duration's
or until desired results are achieved.
Seal 34 provided for separate handling of fluids from annulus 30 and fluids
from tubing string 26. As will be appreciated, other means can be used in
place of
the seal to maintain separate fluids from these two conduits. It will also be
appreciated that other conduit arrangements can be used for effectively
permitting
introduction and removal of gases and liquids from the well bore.
1~
The apparatus as described IllaS' be used in the follo~~ing Illethod to
de~n~ater
a gas well. When the reservoir 12 produces gas, it passed through perforations
18
and into casing 16. After passing through the check valve 20, the gas passes
through annulus 30 and is collected through conduits 42 and 44. Alternatel~~,
produced gas can pass up both annulus 30 and tubing string 26 and be collected
at
surface therefrom. In another embodiment, tubing string can be removed during
regular production and only run in for unloading of produced water, when
necessary.
2~ In some wells, eater 52 is produced and may collect at the well's bottom.
Eventually the ~n~ater level in the ~n~ell bore ~n~ill attain a height such
that its
h~~drostatic pressure impairs the production of gas from reservoir 12 using
the
reservoir's inherent pressure. This causes a decline or even cessation of gas
flow
from reservoir 12 to surface 10 for collection. In those circumstances, the
apparatus
described can be actuated to remove that accumulated w=ater and other liquids.
~s
CA 02350453 2001-06-13


CA 02350453 2005-07-15
When the appaxatus is used to remove water 52, check valve 20 must be
dosed. The check valve can be closed by the hydrostatic pressure of water
above
the check valve exceeding the pressure ~~co~an reservoir 12 below the check
valve.
Alternately, check valve 20 is closed by introduction at wellhead 32 of
pressurized
gas from source 49 (i.e. by c~osuz~e of valve 48 and introduction of gas
through
rnnduits 46, 42). A combination of those forces can also be used to close the
check
valve.
ice check valve 20 is closed, pz~essurized gas is introduced into the casing
14 annulus 30 from source 49, as indicated by the azxows G, which causes a
pressure
increase above accumulated liquid at the well's bottom. Seal 34 prevents any
introduced gas from passing to conduit 40, thus all gas passes down through
axunulu5 30. Eventually, the pressure of the introduced gas exceeds the
hydrostatic
pressure of the accumulated liquid 52 and the pressure of the fluid in tubiz~g
string
26 above the liquid. This causes the tubing string to behave as a siphon and
the
accumulated liquid 52 to be thus forced to flow, as indicated by arrows W, to
surface 10 and out through conduit 40 to a collection system 65.
It will be appreciated by those skilled in the art that the source of
pressurized gas
will be required to provide sufficient gas to fill and pressurize the sealed
casing. The
volume of casing to be filled is easily calculated by reference to the
casing's inside
diameter and its length. Preferably, sufficient gas should be available to
also fill the
tubing siring within the casing. The gas must be eventually at a pressure
greater
than the hydrostatic pressure of the accumulated water, which pressure can be
easily calculated by the accumulated water. Thus the pressures and volumes of
gas
required can be quite easily calculated using known information. For example,
in a
typical test well, equipped with 4 12/" casing and 1 1 /2" coiled tubing, and
with
reservoir pressure approximating 130 psi az~d well depth of 530 meters (1740
feet),
the hydrostatic pressure of a column of water within the casing of
z6




approximately 280 feet overcame the formation production pressures, at which
stage the ~n~ell ceased production (280 feet of salt-laden water equates to
approximately 130 psi at bottom of the column). Gas was introduced to the
~n~ell
into the casing and reached a pressure of up to 750 psi at its maximum (since
that is
the pressure induced by a 1 1/2" diameter column of salt-laden eater 1740 feet
high, being the exhaust tubing during the time when it is filled during the
unloading exercise). The above numbers are annr~ximat;r",~ fnr Aaco ~F
description, and ~~ould vary with the salinity of the produced water and the
depth
of the well and its formation pressure. From this example, ho~n~ever, it is
apparent
that the pressure ranges for the introduced gas can be readily calculated from
known or easily obtained information at the ~n~ell-site.
Gas can continue to be introduced until all of the accumulated liquid do~~n
to the level of end 28, as indicated b~~ introduced gas exiting through
conduit 40, or
1 ~ for a selected period of time. When a selected amount of accumulated
liquid is thus
evacuated to surface and out of the well, the flow of pressurized gas is
stopped.
The valve 48 is opened, and the pressurized gas ~~ithin tubing string 26 and
annulus 30 is aIlo«~ed to dissipate through conduits 40 and 42 to collection
systems,
~1'I11CI1 typically include separators, compressors and pipelines, etc. Once
the
pressure of introduced gas is sufficiently dissipated and provided a
sufficient
amount of introduced gas is sufficiently dissipated and provided a sufficient
amount of water has been removed, the check valve 20 opens and permits passage
of produced gas from reservoir 12. Produced gas then continues to flo~n~ up
through the casing to surface until produced «~ater accumulates such that the
check
2~ valve is again closed for ~n~ater removal.
While the described route of water removal is up through the tubing str ing,
it is to be understood that the reverse operation could be used (by altering
the valve
seal and pipe configuration at surface) ~s~herein compressed gas is introduced
CA 02350453 2001-06-13




through the tubing string to force accumulated water up through the casing
annulus.
It will be apparent that the introduction of pressured gas can be initiated
automatically or manually, and may be responsive to a timer, a pressure
differential
sensor system, a drop in production volumes which indicates an increase in
accumulated liquids at bottom-hole, or other suitable indications.
A person skilled in the art will understand that when the liquid is exhausted
from the casing annulus 30 above lower open end 28 of the tubing string 26,
there
will then be a large volume of introduced gas passing up through tubing string
26
to the collection system. In addition, there ~~ill be large volumes of
introduced gas
to be handled when the introduced gas is allo~~ed to depressurize. Thus,
flo~.v
control means and perhaps chemical injection means would profitably be
utilized to
1 ~ r educe such deer essurization and the commensurate temperature drops and
consequent hydr ate formation and other mechanical problems associated with
such
events.
It «~ill be understood that various changes in the details, materials,
ar r angements of parts, and operating C011d1t1onS ~-1'111c11 have beeI1
described and
illustrated here in or der to explain the nature of the invention may be made
b5~ those
skilled in the art ~n~ithin the principles and scope of the invention, and
will not
derogate from or limit the scope of the claims.
~s
CA 02350453 2001-06-13

A single figure which represents the drawing illustrating the invention.

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Admin Status

Title Date
Forecasted Issue Date 2006-05-09
(22) Filed 2001-06-13
(41) Open to Public Inspection 2002-01-18
Examination Requested 2004-12-09
(45) Issued 2006-05-09
Lapsed 2016-06-13

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Filing $150.00 2001-06-13
Registration of Documents $100.00 2002-12-23
Maintenance Fee - Application - New Act 2 2003-06-13 $100.00 2003-01-22
Maintenance Fee - Application - New Act 3 2004-06-14 $100.00 2004-02-09
Special Order $500.00 2004-12-09
Request for Examination $800.00 2004-12-09
Maintenance Fee - Application - New Act 4 2005-06-13 $100.00 2005-06-07
Final Fee $300.00 2006-02-24
Maintenance Fee - Patent - New Act 5 2006-06-13 $200.00 2006-06-06
Maintenance Fee - Patent - New Act 6 2007-06-13 $200.00 2007-02-08
Maintenance Fee - Patent - New Act 7 2008-06-13 $200.00 2008-02-29
Maintenance Fee - Patent - New Act 8 2009-06-15 $200.00 2009-06-08
Maintenance Fee - Patent - New Act 9 2010-06-14 $200.00 2010-02-17
Maintenance Fee - Patent - New Act 10 2011-06-13 $250.00 2011-03-03
Maintenance Fee - Patent - New Act 11 2012-06-13 $250.00 2012-05-30
Maintenance Fee - Patent - New Act 12 2013-06-13 $250.00 2013-03-26
Maintenance Fee - Patent - New Act 13 2014-06-13 $250.00 2014-03-11
Current owners on record shown in alphabetical order.
Current Owners on Record
NORTHERN PRESSURE SYSTEMS INC.
Past owners on record shown in alphabetical order.
Past Owners on Record
LIKNES, ALVIN C.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

To view selected files, please enter reCAPTCHA code :




Filter Download Selected in PDF format (Zip Archive)
Document
Description
Date
(yyyy-mm-dd)
Number of pages Size of Image (KB)
Representative Drawing 2001-12-21 1 6
Description 2001-06-13 28 1,353
Cover Page 2002-01-11 2 43
Abstract 2001-06-13 1 25
Claims 2001-06-13 4 130
Drawings 2001-06-13 1 13
Description 2005-07-15 28 1,321
Claims 2005-07-15 4 114
Drawings 2005-07-15 2 23
Representative Drawing 2006-04-07 1 8
Cover Page 2006-04-07 2 46
Assignment 2001-06-13 2 67
Correspondence 2002-12-23 2 54
Correspondence 2003-01-16 1 17
Assignment 2002-12-23 4 156
Correspondence 2003-02-05 1 19
Correspondence 2003-02-11 1 17
Correspondence 2003-03-11 1 16
Correspondence 2003-03-11 1 23
Correspondence 2003-01-16 1 23
Correspondence 2003-02-05 1 25
Prosecution-Amendment 2004-12-09 1 32
Prosecution-Amendment 2004-12-22 1 13
Prosecution-Amendment 2005-01-17 2 62
Prosecution-Amendment 2005-07-15 15 493
Correspondence 2006-02-24 1 34