U.S. patent application number 10/106840 was filed with the patent office on 2002-10-31 for method and packer for processing a productive formation in bottom-hole zone of a well, and method for fixing a packer inside a well.
Invention is credited to Kurlenya, Mikhail Vladimirovich, Serdjukov, Sergei Vladimirovich, Tkach, Khaim Berkovich.
Application Number | 20020157831 10/106840 |
Document ID | / |
Family ID | 27354205 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020157831 |
Kind Code |
A1 |
Kurlenya, Mikhail Vladimirovich ;
et al. |
October 31, 2002 |
Method and packer for processing a productive formation in
bottom-hole zone of a well, and method for fixing a packer inside a
well
Abstract
The proposed method for processing the productive formation in a
bottom-hole zone of a well (1) comprises heating the liquid in the
bottom-hole zone of a well (1) and removing clogging products
therefrom. In accordance with the technical solution, the upper
part of the bottom-hole zone of the well (1) is sealed before
heating the liquid, thus forming a bottom-hole chamber (6), and
after the heating, the liquid within the volume of the bottom-hole
chamber (6) is cooled and then this chamber (6) is unsealed before
removing the clogging products therefrom. In the proposed packer
(4) for processing the productive formation in the bottom-hole zone
of a well (1), comprising a body (10) with a means for radial
compaction in the form of sliding cheeks, a cup-type seal (15) and
a drive, and a suspension means (2), in accordance with the
technical solution, the lower end face (5) is made in the form of a
concave surface of the second order. A method for fixing a packer
(4) in a well (1), comprising lowering it into the well (1) to a
required depth, increasing the diametral size of the packer (4) and
deforming its cup-type seal (15) in a radial direction, wherein in
accordance with the technical solution, the packer (4) is subjected
to temperature action different from the temperature of the well
liquid at the point of its installation. 19 dependent claims, 15
drawings.
Inventors: |
Kurlenya, Mikhail
Vladimirovich; (Novosibirsk, RU) ; Serdjukov, Sergei
Vladimirovich; (Novosibirsk, RU) ; Tkach, Khaim
Berkovich; (Novosibirsk, RU) |
Correspondence
Address: |
JACOBSON HOLMAN
PROFESSIONAL LIMITED LIABILITY COMPANY
400 SEVENTH STREET, N. W.
WASHINGTON
DC
20004
US
|
Family ID: |
27354205 |
Appl. No.: |
10/106840 |
Filed: |
March 27, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10106840 |
Mar 27, 2002 |
|
|
|
PCT/RU00/00402 |
Sep 29, 2000 |
|
|
|
Current U.S.
Class: |
166/302 ;
166/118; 166/387 |
Current CPC
Class: |
E21B 36/00 20130101;
E21B 33/126 20130101; E21B 43/25 20130101; E21B 33/12 20130101 |
Class at
Publication: |
166/302 ;
166/387; 166/118 |
International
Class: |
E21B 043/24; E21B
049/00; E21B 023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 1999 |
RU |
99120960 |
Nov 16, 1999 |
RU |
99124243 |
Mar 13, 2000 |
RU |
2000106277 |
Claims
1. A method for processing a productive formation in a bottom-hole
zone of a well (1), comprising heating liquid in the bottom-hole
zone and removing clogging products from the bottom-hole zone,
characterized in that a temperature-action element (14) for heating
the liquid to a temperature above the boiling point of its
components is lowered into the bottom-hole zone with use of a
suspension means (2), a bottom-hole chamber (6) is formed in the
bottom-hole zone of the well (1), an upper portion of the chamber
higher than the positioning of the temperature-action element (14)
is sealed by a packer (4), after being heated the liquid is cooled,
wherein heating the liquid and cooling it is carried out within the
volume of the bottom-hole chamber (6), then the bottom-hole chamber
(6) is unsealed by removal of the packer (4), after which the
clogging products together with oil products are removed from the
bottom-hole zone.
2. A method according to claim 1, characterized in that the liquid
in the bottom-hole chamber (6) is heated to a temperature above the
boiling point of one of the light oil fractions, e.g.,
gasoline.
3. A method according to claim 1, characterized in that the liquid
in the bottom-hole chamber (6) is heated to a temperature above the
boiling point of water.
4. A method according to claim 1, characterized in that the liquid
in the bottom-hole chamber (6) is heated to a temperature above the
boiling point of one of the heavy oil fractions, e.g., oils.
5. A method according to any one of claims 1-4, characterized in
that the liquid in the bottom-hole chamber (6) is heated instantly,
e.g., by an explosion.
6. A method according to any one of claims 1-5, characterized in
that cooling the liquid within the volume of the bottom-hole
chamber (6) is carried out in a forced manner with the use of, for
example, thermocouples.
7. A method according to any one of claims 1-5, characterized in
that cooling the liquid within the volume of the bottom-hole
chamber (6) is carried out in a forced manner, feeding cold water
from the surface.
8. A method according to any one of claims 1-7, characterized in
that a column of well liquid in the bottom-hole chamber (6) is
divided into two parts by the packer (4) with at least one channel
(12) connecting its end faces and with a back-pressure valve (13),
wherein one of the parts of the column of well liquid is directed
toward the bottom-hole zone of the well (1) for hydraulic
fracturing, the other part is removed through the channel (12) of
the packer (4), and movement of the well liquid through that
channel (12) toward the bottom-hole chamber (6) from the
above-packer space of the well is closed.
9. A method according to claim 8, characterized in that after
removal of a part of the column of well liquid from the bottom-hole
chamber (6) through the packer (4), the pressure in the upper part
thereof is reduced and simultaneously the bottom-hole chamber (6)
is filled with formation liquid.
10. A packer (4) for processing a productive formation in a
bottom-hole zone of a well (1), comprising a body (10) with a means
for radial compaction in the form of sliding cheeks, a cup-type
seal (15) and a drive, and a suspension means (2), characterized in
that its lower end face (5) is made in the form of a concave
surface of the second order.
11. A packer (4) according to claim 10, characterized in that the
concave surface of the second order is made hemispherical.
12. A packer (4) according to claim 10, characterized in that the
concave surface of the second order is made paraboloidal.
13. A packer (4) according to any one of claims 10-12,
characterized in that in the case where a pressure generator (8) is
used in the well (1), including with an explosive, the packer (4)
has at least one channel (12) connecting its end faces, and a
back-pressure valve (13) is mounted with the possibility for
passage of a flow of well liquid from a bottom-hole chamber (6)
through the channel (12) of the packer (4) into above-packer space
due to the action of pressure generator (8) gases, and for
elimination of movement of the well liquid from the above-packer
space into the bottom-hole chamber (6) with closure of the channel
(12) under the action of a column of liquid in the above-packer
space and depression in the bottom-hole chamber (6).
14. A packer (4) according to claim 13, characterized in that the
back-pressure valve (13) is made in the form of an elastic plate
secured in its central part to the body of the packer (4).
15. A packer (4) according to claim 13 or claim 14, characterized
in that the back-pressure valve (13) is mounted in its channel
(12).
16. A packer (4) according to claim 15, characterized in that the
channel (12) connecting its end faces is made in the body of the
packer (4), and the back-pressure valve (13) is mounted from the
side of its upper end face.
17. A packer (4) according to any one of claims 10-16,
characterized in that its sliding cheeks are made in the form of a
cylinder (19) with longitudinal slots (21), ending with openings
(27), wherein longitudinal parts of the cylinder ( 19) between tie
slots (21 ) are made in the form of lobes (20) of a material with
shape memory.
18. A packer (4) according to claim 17, characterized in that it
has a temperature-action element (14) in the form of a cooler to
reduce the temperature of packer (4) elements when electric power
is applied to the cooler.
19. A packer (4) according to claim 18 characterized in that it is
additionally provided with a heater, for example, a pyrotechnic
cartridge or an electric spiral.
20. A method for fixing a packer (4) in a well (1), comprising
lowering the packer (4) into the well (1) to a required depth
increasing diametral size of the packer (4) by changing the shape
of sliding cheeks during reverse martensite conversion of material
with shape memory, deforming its cup-type seal (15) in a radial
direction, subjecting the packer (4) to temperature action,
different from the temperature of the well liquid at the point of
its installation, characterized in that the temperature action on
the packer (4) is carried out by reducing the temperature to a
temperature below the temperature of the well liquid at the point
of installation of the packer (4) prior to lowering the packer (4)
to the required depth.
21. A method according to claim 20. characterized in that
temperature relief of the packer (4) is carried out after
temperature action on the packer (4) at the point of its
installation in the well (1) at the required depth.
Description
FIELD OF THE INVENTION
[0001] The proposed invention relates to the oil producing industry
and has the purpose of increasing the productivity of a well by
intensifying the flow of oil and increasing the oil recovery
factor, and also serves for major repair of wells, for cutting-off
water-encroached formations, etc.
BACKGROUND ART
[0002] A method is known for electrically heating a bottom-hole
zone (see, e.g., A.A. Popov. Impact action on bottom-hole zone.
Moscow, "Nedra,"1990, pp. 36-38). This method consists in that the
liquid in the bottom-hole zone is heated to about 100.degree. C.,
which ensures a reduction of the viscosity of paraffin-base and
high-viscosity crude oils of, for example, the Usinsky and
Kharyachinslky fields. As a result the oil recovery from the wells
is increased.
[0003] The main drawback of the foregoing method is that it is only
possible to use it in a narrow field - during the production of
high-viscosity and paraffin-base crude oils, when paraffins resins
and asphaltenes precipitate into the bottom-hole zone. Furthermore,
the described method is complex in the practical realization
thereof, since the electric heaters often break down because of the
poor quality of the cable and the heating elements, which work in
an aggressive medium.
[0004] A method for thermal treatment of the bottom-hole zone of an
oil formation is also known according to USSR Inventor's
Certificate No. 467173, class E 21 B 43/24,published in BI No. 14,
1975. This method consists in providing thermal treatment to the
bottom-hole zone by pumping a heat carrier with high thermal
conductivity into the formation. Granulated material, for example,
metal powder, is used as the heat carrier. The granulometric
composition of the metal powders is selected on the basis of
considerations relating to their being pumped in and also to their
capability of penetrating into cracks of the formation. A source of
thermal-gas or thermal-gas-chemical action, the plane of the start
of combustion of which is positioned below the lower perforations
of the interval being processed by 5-15% of its length, is used as
the slowly-burning source of thermal action, and after accumulating
heat in the processed interval, movement of the downhole
technological equipment with the source of thermal-gas or
thermal-gas-chemical action is carried out along the interval being
processed, after which a technological delay is carried out to
substitute the gaseous combustion products in the interval being
processed with well liquid. The prepared suspensions do not
penetrate into pore channels, but fill the formation cracks in the
bottom-hole zone, which are present and open up in the process of
pumping. After a system of cracks, filled with granulated metal
powder, is created in the formation, an electrical heating device
is lowered into the well and the bottom-hole zone is heated.
[0005] The method is also complex in realization, since actually it
is a two-step method, i.e. at first hydraulic fracturing is
effected, and then metal powders are pumped into the cracks. Its
relatively low effectiveness is predetermined by the fact that in
order for the metal powder to penetrate into the formed cracks,
small forces, occurring as a result of the volumetric expansion
during the heating of the bottom-hole liquid, are used, and
therefore the heating spreads into the depth of the formation to
only a small distance.
[0006] A method of fracturing a formation is known, the method
comprising creating cracks by fracturing the formation with
explosive gases and fixing the cracks by pumping a liquid with a
solid agent, for example, silica sand, into the formation with a
pump (see, for example, Yu.M. Zheltov. Deformation of rocks.
Moscow, "Nedra," 1966).
[0007] A drawback of this method is the high amount of labor
consumed and the cost, which is related to the use of pumps.
[0008] A method of fracturing a formation with explosive gases is
also known from U.S. Pat. No. 3,422,760, class 102-21.6. This
method comprises creating cracks by the pressure of gases which are
produced during the combustion in the well of an explosive charge
positioned opposite the productive formation. A drawback of this
method is that the explosive gases are only partially used to
create cracks in the bottom-hole zone, a part thereof (about 50%)
goes up through the well, wherewith the cable to which the charge
is suspended twists, and this predetermines the necessity for its
subsequent extraction. This last step is rather complex, is often
related to the necessity of cutting the cable and extracting
separate pieces thereof with catchers. Sometimes, it is not
possible to extract all the pieces of the cut cable and the well
has to be abandoned.
[0009] A method of processing the zone of a productive formation in
the region of the bottom with the use of implosion is also known
(see, for example. A.A. Popov. Impact actions on bottom-hole zone.
Moscow, "Nedra," 1990, pp. 35-36). The substance of this method is
that a hollow vessel with a membrane is arranged on a tubing string
opposite the interval of the formation being processed. Then this
membrane is fractured, as a result of which rarefaction is created
in the bottom hole. Due to the occurrence of depression of the
pressure, the formation liquid enters the well at high speed. The
intensive movement of the formation liquid into the well promotes
the cleansing of the part of the formation being filtered of
deposits.
[0010] An analysis of the available results of processing
bottom-hole zones with the use of implosions at the
Zapadno-Tebuksk, Nizhneomrinsky and lzhma-Omrinsky oil fields has
shown that this method has limited use in respect to mining and
geological conditions. It is of low effectiveness at high
permeability of the bottom-hole zone, since the speed of the flow
of formation liquid from the productive formation into the well is
low because of the large size of the pores and cracks in the
bottom-hole zone.
[0011] Furthermore, there were cases where the use of implosions
did not provide the desired result because the membranes, produced
from grey iron SSH15-32, fractured before they were supposed to.
This reduces the range of use of the method with implosions and its
effectiveness, and wherewith, a positive result is not achieved in
all cases when this method is used.
[0012] The analog most similar to the proposed method in respect to
technical essence and attained effect is the method for processing
the bottom-hole zone according to patent RF No. 2087693, class E21
B 43/25, published in BI No. 23, 1997. This latter method comprises
lowering downhole technological equipment with a charge of a slowly
burning source of thermal action, burning the latter in an interval
being processed, carrying out a technological delay to accumulate
heat in the interval being processed, providing depression action
and removing a part of the well liquid with clogging elements which
entered it from the bottom-hole zone during the depression action.
Wherein, a slowly-burning source of thermal action is used, the
plane of the beginning of combustion of which is positioned below
the lower perforations of the internal being processed by 5-10% of
its length, and after accumulating heat in the interval being
processed, the downhole technological equipment with the source of
thermal-gas-chemical action is moved along the interval being
processed, after which there is a technological delay to substitute
gaseous combustion products in the interval being processed with
well liquid.
[0013] Drawbacks of this method are: a) the difficulty of
implementation, related to movement of the equipment along the
interval being processed; b) the length of the process, related to
movement of the equipment and the technological delays in order to
replace the gaseous combustion products in the interval being
processed with well liquid; c) small distances from the well walls
on which the high-temperature zone acts (it is because of this
reason in particular that it is necessary to move the equipment
with the source of thermal action along the well). All these
drawbacks reduce the effectiveness of use of this method.
[0014] A packer is known in accordance with USSR Inventor's
Certificate No. 1099047, class E21 B 33/12, published in BI No. 23,
1984. This packer comprises a hollow body with radial channels, on
which body a seal element with a cavity for its drive is mounted, a
shaft arranged in the body with the possibility for axial movement
and coupled to a string, the shaft being hollow, sealed in the
lower part, with two rows of radial channels to couple the
intratube space accordingly with the annulus above-packer space and
the cavity of the seal element drive. Wherein the packer is
provided with a housing with radial channels, which is mounted
above the seal element and forms with the body a chamber in which a
spring-loaded choke bean is mounted, and the annulus above-packer
space is coupled to the intratube space via the channel of the
choke bean.
[0015] Drawbacks of the known packer are the complexity of its
structure and, in view of this, low operational reliability, since
clogging of the channel "A" of the hydraulic resistance and the
openings, communicating its inner cavity with the upper, and the
upper and lower chambers, with particles found in the well liquid,
is not eliminated. The packer under consideration seals the cross
section of the well, preventing movement of the flow in any
direction. A packer of such a construction cannot be used in the
case where it is necessary to provide for flow of the well liquid
in one direction only.
[0016] An interval packer is known according to USSR Inventor's
Certificate No. 643625, class E21 B 33/12, published in BI No. 3,
1979. This packer comprises upper and lower packers with shafts
made with radial channels, a body with windows, an anchor, a valve
device, case and catch, wherein the shaft of the lower packer is
rigidly connected to the case, and the catch is mounted at the end
of the shaft of the upper packer with the possibility for
interaction with the case, wherein in the lower part of the shaft
of the lower packer a branch pipe is rigidly connected thereto, the
branch pipe forming with the shaft an annular cavity, and a piston
is mounted under a sealing element, the piston forming with the
shaft a chamber communicating with the annular cavity, and during
packing - with the intrapacker space. The construction of the
packer is designed to cut off the flow of liquid and it cannot be
used to provide passage of the flow of well liquid in one direction
only.
[0017] A packer according to USSR Inventor's Certificate No.
304345, class E 21 B 33/12, published in BI No. 17, 1971, is also
known. This packer comprises a body with radial channels, sealing
elements with slips, a housing and fixing unit with spring-loaded
slips interacting with pushers and a toothed surface of a branch
pipe. A piston, rigidly connected to pushers, is positioned
concentrically between the body and the housing, and the
under-piston cavity communicates with an intrapipe space.
[0018] A drawback of the known packer is the low reliability of its
operation because of the possible clogging of channels "a" and "b"
and cavities "A" and "B" with particles which are in the well
liquid. Furthermore, the cross section of the central channel of
the packer is sharply reduced because of the concentrically
positioned body, annular piston and housing.
[0019] A well fixing apparatus according to USSR Inventor's
Certificate No. 1122817, class E21 B 47/00, published in BI No. 41,
1984, is also known. This apparatus comprises a body, a cable, a
bushing, a stopping device, a tightening mechanism coupled to a
spacer element provided with a parachute of elastic material
stretched on a frame of levers hinge-connected to the bushing, and
a resilient element, an additional spring, additional supports, a
stopping bushing with inner supports and with a ring-catch, lower
levers, wherein the additional spring is arranged inside the
stopping bushing mounted in the lower part of the body,
spring-loading the bushing relative to the body, and interacts with
the tightening mechanism, and the additional supports are mounted
on the lower levers, hinge connected to the resilient element. The
lower end face thereof is made in the form of a cone.
[0020] A drawback of the fixing apparatus being considered is the
ineffectiveness of its use during an explosion, since the gases
produced thereby will promote unsealing of the well.
[0021] The analog most similar in respect to technical essence and
attained effect is the hydraulic packer for a formation tester
according to USSR Inventor's Certificate No. 571581, class E21 B
33/12, published in BI No. 33, 1977. This packer comprises a rod, a
hydraulic pump and an elastic cup with a springy support made of
inner and outer rows of plates shifted relative to one another.
Wherewith, the inner plates are provided with end pieces which are
placed in the elastic cup and rigidly connected to the plates of
the outer row. The lower surface of the packer is made flat,
passing into a conical surface, then again into a flat and conical,
which form with the wall of the well a wedge "pocket."
[0022] A drawback of the packer under consideration is that its use
is not possible in order to provide flow of the well liquid in one
direction only, since it completely seals the flow cross section of
the well. Furthermore, a drawback of the packer is its low
reliability, this being related to the possibility of channel "a"
and the inner cavity of the elastic cup being clogged with
particles which are in the well liquid.
[0023] A method for fixing a packer in a well is known, this method
being realized in the construction of the packer according to USSR
Inventor's Certificate No. 252244, class E21 B, published in BI No.
29, 1969, and consisting in that the sealing elements of the packer
are unwedged, moving one part thereof relative to another, wherein
the tapered elements of the packer, which have tapered surfaces,
are moved (in the longitudinal section two neighboring elements
have an inclined surface, and each element is made in the form a
triangle, wherein one of the bases of neighboring elements faces
the wall of the well, the other faces the longitudinal axis
thereof). In order to extract the packer it is pulled upwards,
thereby cutting off the pins and thus reducing its cross
section.
[0024] A drawback of this method is the difficulty of extracting a
packer of such a construction because of the large diametrical
dimensions, since tapered sections are used which move one on top
of another, as a result of which the packer occupies greater space
in the cross section. During the unwedging it is not possible to
substantially reduce its cross section in order to reliably extract
it from the well.
[0025] A method for fixing a packer in a well is also known, this
method being realized in the hydraulic packer according to USSR
Inventor's Certificate No. 571581, class E21 B 33/12, published in
BI No. 33, 1977, and consisting in that an elastic cup is spread
apart in a radial direction by applying drilling fluid under
pressure into the inner cavity of the elastic cup. A piston and
hydraulic pump are used to create pressure. In order to extract the
packer, the pressure is turned off and by moving the piston to the
upper position the elastic cup is returned to its initial position
by springs especially serving this purpose.
[0026] A drawback of the described method is the necessity of using
two drives to fix the packer to the wall of the well and to
separate it therefrom, and this makes the construction of the
packer and control of its operation more complex.
[0027] A method for fixing a packer, realized in a packing device
according to USSR Inventor's Certificate No. 898043, class E21 B
{fraction (33/12)}, published in BI No. 2, 1982, is known. This
method comprises changing the radial dimension of a sealing element
of the packing device by mechanical axial action on it, wherewith
this action is carried out in two steps, in particular: at first
the lower part of the packing device is set in the bottom hole of
the well, moving one of its parts relative to another in an axial
direction, and then contraction is created by hydraulic
pressure.
[0028] A drawback of the known method is that it is not possible to
mount the packing device high above the well bottom. Furthermore,
the use of two drives for fixing and separating predetermines
complexity of the construction of the packing device and complexity
of its control.
[0029] The analog most similar in respect to technical essence and
attained effect is the method for fixing a packer in a well, which
is realized in the packer according to USSR Inventor's Certificate
No. 304345, class E21 B {fraction (33/12)}, published in BI No. 17,
1971, and consists in radial deformation of an annular packer seal
as a result of its axial compression by the hydraulic pressure of
liquid pumped into the well.
[0030] A drawback of the known method is that it does not ensure
reliability of operation of the packer, this being related to the
necessity for a constant supply of well liquid under pressure,
which finally results in clogging of the working chamber of the
packer, which via the moving piston supplies the hydraulic pressure
of the liquid to the sealing elements of the packer.
Disclosure Of The Invention
[0031] The technical object of the proposed invention is to enhance
the effectiveness of oil inflow, and consequently, enhance the
productivity of the well by removing the clogging products from the
bottom-hole zone, and to simplify the technology of processing the
bottom-hole zone by removing the clogging products from the
bottom-hole zone of the well in one step and to eliminate
destruction of the packer suspension means. Furthermore, the
construction of the packer is simplified and the reliability of its
fixation in the well is enhanced by temperature action and
additional tightness between the surfaces of the packer and the
well.
[0032] This object is achieved in a method for processing the
productive formation in a bottom-hole zone of a well, comprising
heating liquid in the bottom-hole zone and removing clogging
products from the bottom-hole zone, in that in accordance with the
technical solution, prior to heating the liquid, the bottom-hole
zone of the well is sealed in the upper part, forming thereby a
bottom-hole chamber, and after heating, the liquid is cooled in the
volume of the bottom-hole chamber and then this chamber is unsealed
prior to removing the clogging products therefrom.
[0033] These steps and their sequence ensure a liquid flow at first
in the direction of the formation due to volumetric expansion of
the liquid in the bottom-hole chamber, and then in the reverse
direction from the formation due to depression, which ensures the
simultaneous expansion of cracks in the bottom-hole zone as a
result of the produced flow, and consequently, pressure of the
liquid, and also reduction of the viscosity of the oil and removal
of asphalt-resin-paraffin deposits by temperature action (the known
effect of temperature action). The reverse flow of liquid from the
formation into the bottom-hole chamber promotes purification of the
filtered part of the formation of deposits and in certain cases
results in breakage of the rock in the bottom-hole zone of the well
and the formation of additional cracks there. This, finally,
enhances the productivity of the well and simplifies technology,
since cases of twisting the cable in the well because of the
presence of the parker are eliminated, and this means that steps in
respect to cutting it and extracting separate pieces of the cable
with catchers are eliminated.
[0034] It is advisable that the liquid in the bottom-hole chamber
be heated to a temperature above the boiling point of one of the
light oil fractions, e.g. gasoline.
[0035] Such a step ensures the transition of light oil fractions
into vapors. (The boiling point is 80-96.degree. C. Here and below
consideration is given to normal pressure in view of the fact that
the pressure in the liquid in the bottom-hole zone depends on the
depth of the well. In view of this, the boiling point of water and
the fractions increases, remaining however different one from the
other, i.e. for a concrete well, their boiling points should be
calculated in accordance with the weight of the column of liquid in
the well.) The liquid in the bottom-hole chamber increases its
volume to a greater degree and this is promoted by the vapor into
which one of the components of the light fractions of oil has
passed. As a result, the pressure in the bottom-hole chamber is
sharply increased and, as a consequence thereof, the effectiveness
of the oil inflow is increased, since at higher pressure its action
is effected at a greater distance from the well and the depression
effect will also be large.
[0036] It is advisable that the liquid in the bottom-hole chamber
be heated to a temperature above the boiling point of water.
[0037] Such a step makes it possible to enhance the effectiveness
of the process of processing the bottom-hole zone of the well,
since the boiling point of water is above the boiling point of the
light oil fractions (respectively 100.degree. C. and 80-96.degree.
C. at normal pressure). Therefore, there is a transition of water
and the light oil fractions into vapor, and, consequently, the
partial pressure of the liquid components in the bottom-hole
chamber which pass into vapor will be added up and the resultant
pressure becomes greater than the partial pressure of one of the
liquid components which have passed into vapor.
[0038] It is advisable that the liquid in the bottom-hole zone be
heated to a temperature above the boiling point of one of the heavy
oil fractions, e.g., oils. This step even more enhances the
effectiveness of the proposed method, since a large number of the
liquid components in the bottom-hole chamber pass into vapor (the
boiling point of oils is 460-500.degree. C. at normal pressure),
consequently, the total pressure in the bottom-hole chamber
increases in accordance with the Dalton Law. The effectiveness of
the action of pressure in the bottom-hole chamber also increases,
that is it will act on the particles deposited in the pores of the
bottom-hole zone at a greater distance from the walls of the well.
The permeability of the bottom-hole zone of the productive
formation is enhanced by the simultaneous action of the pressure
and temperature created in the bottom-hole chamber.
[0039] It is advisable that the liquid in the bottom-hole chamber
be heated instantly, e.g., by an explosion. The effects described
above will be manifested to an even greater degree, since the
produced vapors which are in the bottom-hole chamber do not have
time to partially fall into the liquid and into the productive
formation, which is observed during slow heating, as a result of
which increased pressure will be in the bottom-hole chamber, and
consequently, the action of pressure will occur at a greater
distance from the well.
[0040] It is advisable that cooling the liquid within the volume of
the bottom-hole zone of the well be carried out in a forced manner
with the use of special means, for example, thermocouples.
[0041] Such an operation intensifies the flow of liquid from the
productive formation into the well, which makes it possible to
first remove the clogging products from the bottom-hole zone of the
well and then to increase the oil production rate.
[0042] It is advisable that after the formation of the bottom-hole
chamber, the column of well liquid therein be divided into two
parts, one of which directed to the bottom-hole zone of the well,
the other removed through the packer, and that movement of the well
liquid through the packer in the opposite direction be closed.
[0043] These operations and their sequence make it possible to
carry out hydraulic fracturing in the bottom-hole zone of the well
and simultaneously to create depression of the pressure in the
bottom-hole chamber by removing well liquid from that chamber,
which ensures a back flow of liquid from the formation into the
well after the hydraulic fracturing, and this makes it possible to
wash the cracks and pores in the bottom-hole zone of the well,
thereby removing the clogging products. Finally, these operations
make it possible to increase the inflow of formation liquid, which
increases the effectiveness of oil inflow, and consequently to
increase the productivity of operating the well.
[0044] It is advisable after removal of a part of the column of
well liquid from the bottom-hole chamber through the packer to
reduce the pressure in the upper part thereof and simultaneously to
fill the bottom-hole chamber with formation liquid.
[0045] This makes it possible to increase the intensity of the
inflow of formation liquid into the well, which enhances the
washing of the cracks and pores in the bottom-hole zone of the
well, and, consequently, improves the removal of clogging
products.
[0046] In a packer for processing the productive formation in the
bottom-hole zone of a well, comprising a body with a means for
radial compaction in the form of sliding cheeks, a cup-type seal
and a drive, and a suspension means, in accordance with the
technical solution, the lower end face is made in the form of a
concave surface of the second order.
[0047] Such a construction of the packer is less subject to the
negative actions of an explosion, in particular, the absence of
"pockets" eliminates unsealing of the packer (moreover, improves
the sealing), and, being a reflector, directs the explosive wave
along the axis of the well in the direction of the productive
formation, which improves the effectiveness of processing the
productive formation in the bottom-hole zone of the well.
[0048] It is advisable that the concave surface of the second order
in the packer be made hemispherical.
[0049] Such a construction of the packer is the simplest in
production and during an explosion, by directing the explosive wave
along the longitudinal axis of the well, ensures its
self-compaction.
[0050] It is advisable that the concave surface of the second order
in the packer be made paraboloidal.
[0051] Such a construction of the packer enhances the effectiveness
of its self-compaction and the directivity of the explosive wave
along the longitudinal axis of the well, since the lower end face
surface of the packer at the wall of the well has great length and
more gradually passes into a cylindrical surface.
[0052] It is advisable in these cases that the packer be made with
at least one channel connecting its end faces and be provided with
a back-pressure valve, eliminating movement of the well liquid in
the direction to the bottom-hole chamber from the above-packer
space of the well.
[0053] Such a construction of the packer provides for realization
of the proposed method for processing the productive formation in
the bottom-hole zone of a well, i.e., the effective removal of a
part of the well liquid from the bottom-hole chamber with
subsequent depression of the pressure therein by removal of the
clogging products.
[0054] It is advisable that the packer be provided with a
temperature-action element. Such a construction of the packer
provides for temperature action (heating or cooling) on its
elements, which makes it possible to increase or reduce the
diametral size of the packer cup-type seal, ensuring fixation of
the packer to the wall of the well (or its separation
therefrom).
[0055] It is advisable that the temperature-action element of the
packer be made in the form of a pyrotechnic cartridge. Such a
construction of the packer provides one-time heating of its
structural elements, which predetermines the possibility for
minimization of the energy necessary to heat them.
[0056] It is advisable that the temperature-action element of the
packer be made in the form of an electric spiral connected to a
power supply. Such a construction of the packer is as simple to
produce as possible and makes it possible to heat the elements of
the packer construction a multiple number of times.
[0057] It is advisable that the temperature-action element of the
packer be made in the form of a cooling thermocouple. Such a
construction of the packer eliminates the necessity for a constant
supply of energy during its fixation to the wall of the well (the
energy is used only during its extraction from the well or during
its installation in the well).
[0058] It is also advisable that the sliding cheeks of the packer
be made of a material with shape memory. Such a construction
increases the reliability of packer operation, since it ensures
reliability of its fixation, independent of the diameter of the
well and the cup-shaped packer seal, which is made with a certain
exactness and may change its size under the effect of wear.
Furthermore, the diameter of the well has a different magnitude at
different points of the depth.
[0059] In this case it is advisable that the sliding cheeks of the
packer be made in the form of a cylinder with longitudinal slots,
ending with openings, wherewith the longitudinal parts of the
cylinder between the slots be made in the form of lobes. Such a
packer, having a simple construction, provides reliable fixation to
the wall of a well and separation therefrom, and also free
extraction from the well.
[0060] In a method for fixing the packer in a well, comprising
lowering it into the well to the required depth, increasing the
diametral size of the packer and deforming its cup-type seal in the
radial direction, in accordance with the technical solution, the
packer is subjected to temperature action, different from the
temperature of the well liquid at the point of installation of the
packer. Such a combination of steps enhances the reliability of
fixing the packer to the wall of the well and simultaneously makes
it possible to simplify its construction, since the movable parts
are removed therefrom and there is one drive to fix the packer to
the wall of the well and to separate it therefrom.
[0061] It is advisable that the temperature action on the packer be
carried out by increasing the temperature to a temperature above
the temperature of the well liquid in the place where the packer is
installed after it has been lowered to the required depth. This
makes it possible to control the process of fixing the packer in
the well independent of its depth (the temperature of the well
liquid depends on the depth of the well). Furthermore, the
possibility appears for enhancing the reliability of operation of
the packers of known constructions by use of additional tightness
created on the contacting surfaces of the cup-type seal and the
well when the packer is equipped with a heating element.
[0062] It is advisable that the temperature action on the packer be
carried by reducing the temperature to a temperature below the
temperature of the well liquid at the place where the packer is
installed prior to its being lowered to the required depth. The
introduction of such a step makes it possible to provide fixation
of the packer for a lengthy period of time without consumption of
additional energy, since the fixation is accomplished by the
temperature of the well liquid.
[0063] It is advisable after the temperature action on the packer
at the place of its installation in the well at the required depth
to carry out its temperature relief. The introduction of such a
step enhances the reliability of extracting the packer from the
well, since its diametral size is reduced, which ensures its free
extraction from the well.
BRIEF DESCRIPTION OF THE DRAWING
[0064] The substance of the proposed method for processing a
productive formation in the bottom-hole zone of a well, a packer
for carrying out the method and a method for fixing the packer in
the well is explained by an example of their use and by
drawings.
[0065] The presented drawings show the following.
[0066] FIG. 1 shows the steps for installing a heating element in a
well;
[0067] FIG. 2 shows sealing of the upper part of the bottom-hole
zone of a well;
[0068] FIG. 3 shows heating the liquid in the bottom-hole chamber
and creating a flow of liquid moving toward the formation;
[0069] FIG. 4 shows an explosion in the bottom-hole chamber;
[0070] FIG. 5 shows the step of cooling the liquid in the
bottom-hole chamber and forming a reverse flow of liquid as a
result of depression;
[0071] FIG. 6 shows unsealing of the well;
[0072] FIG. 7 shows a packer arranged in the well;
[0073] FIG. 8 shows the installation of a packer in the well and
the formation of a bottom-hole chamber;
[0074] FIG. 9 shows the division of a column of well liquid in the
bottom-hole chamber and the removal of well liquid therefrom
towards the productive formation and through the packer;
[0075] FIG. 10 shows the bottom-hole chamber purified of well
liquid and depression of the pressure created;
[0076] FIG. 11 shows the filling of the bottom-hole chamber with
formation liquid;
[0077] FIG. 12 shows the step of installing the packer in a
casing;
[0078] FIG. 13 shows the step of thermal action on the packer
(heating) and its fixation in the casing;
[0079] FIG. 14 shows a packer made of a material with a shape
memory and with a cooling thermocouple installed in the well;
[0080] FIG. 15 shows a packer made of a material with a shape
memory, fixed in a well.
BEST VARIANT OF CARRYING OUT THE INVENTION
[0081] Realization of the proposed methods and packer is carried
out in the following sequence.
[0082] Using a suspension means (cable or pipe) 2, a heating
element 3 (FIG. 1) is lowered into the bottom-hole zone of a well
(casing) 1. The heating element 3 may be of any construction and
its principle of action may be based on any physical or chemical
effect. Thus, for example, a slowly burning source of
thermal-gas-chemical action in the form of a EPIU-98-850
pyrotechnic charge with the following characteristics may be used:
length 850 mm, diameter - 98 mm, weight - 7.5 kg; components - fuel
54%, oxidant 40%, technological additives 6%; density - 1.83
g/cm.sup.3; combustion heat - 2000-2200 kcal/kg; combustion speed -
20 mm/s; time of burning - 42.5 s; volume of gaseous products - 600
l/kg; composition of combustion products: Cl.sub.2, H.sub.2O,
H.sub.2, MeO: combustion temperature - 2500.degree. C.: ignition
temperature - 500-700.degree. C.; current for ignition of
pyrotechnic charge - 3-4 A. When such a source is used, all the
components of the well liquid pass into a vapor state as a result
of heating. The further from the heating element, the lower the
temperature, and consequently, there will be a zone where water and
light fractions pass into vapor, then there will be a zone where
only the light fractions of oil pass into vapor, and finally, there
will be a zone where all the liquid in the well 1 is heated and its
volumetric expansion takes place.
[0083] An example is provided wherein the liquid is heated to a
temperature higher than the boiling point of the heavy fractions.
However, the heating temperature may be reduced to, for example,
100.degree. C. In this case, there will not be a zone in which the
heavy oil fractions pass into a vapor state. However, the other
zones remain.
[0084] The next step is sealing the well 1 in the upper part above
the point where the heating element 3 is positioned. In order to do
this a packer 4 of any construction is used (FIGS. 2-5, 7). In the
case of instant heating (during an explosion) of the liquid in the
bottom-hole zone of the well 1, it is advisable that the lower end
face 5 of the packer 4 (FIG. 7) be made in the form of a concave
surface of the second order. Thus, a bottom-hole chamber 6 is
formed in the bottom-hole zone of the well 1, the upper part of
chamber 6 being sealed.
[0085] Then heating the liquid in the bottom-hole chamber 6 is
begun. Volumetric expansion of the liquid in the bottom-hole
chamber 6 takes place as a result of an increase of the
temperature, and this predetermines the formation of a flow of
liquid towards the bottom hole of the well 1, and consequently,
toward the productive formation (FIG. 3). The higher the
temperature to which the liquid in the bottom-hole chamber 6 is
heated, the more intensive will be its flow in the direction toward
the productive formation. After heating the liquid in the
bottom-hole chamber 6 stops, it is cooled in that chamber 6, which
reduces its volume (FIG. 5), as a result of which a reverse flow of
liquid is formed from the productive formation to the chamber 6.
The intensity of the reverse flow will depend on the speed of
cooling the liquid in the bottom-hole chamber 6.
[0086] The speed of the reverse flow of liquid will be minimum in
the case where cooling is carried out in a natural manner, this
making the step simple to perform, since no equipment is needed.
However, this step may be accomplished faster by carrying out
forced cooling of the liquid in the bottom-hole chamber 6. In order
to do this a special means, for example a cooler 7, is
preliminarily placed in the bottom-hole chamber 6 below the packer
4 (FIG. 5). It is advisable that the cooler 7 and the heating
element 3 be secured to the packer 4 from below and lowered
simultaneously into the well 1. The cooler 7 may operate in
accordance with any principle of action: mechanical, when cold
water is fed from the surface of the well 1; electrical, when
thermocouples are used for cooling; or chemical, using expanding
gases. The more intense the cooling, the more intense the reverse
flow of the liquid, and, consequently, the better the purification
of the cracks and pores in the bottom-hole zone (filtration is
improved). As a result, the inflow of oil from the productive
formation into the well 1 is increased. The selection of the
principle of cooling and corresponding special means will be
determined by an economical approach and by the degree of
perfection of one or another method or set of equipment.
[0087] If the first step--heating the liquid in the bottom-hole
chamber 6--results in an improvement of the permeability of the
bottom-hole zone, since clogging the pores and cracks of the
bottom-hole zone is reduced in view of the heating and melting of
the paraffin, resin and asphaltenes deposited in the cracks and
pores, the step relating to cooling the liquid in the bottom-hole
chamber 6 creates rarefaction in the bottom-hole zone, as a result
of which intensive movement of the liquid from the productive
formation to the well 1 is observed, which promotes purification of
the part of the productive formation being filtered of deposits of
particles, paraffins, resins, etc., and in some cases results in
destruction of the rock of the bottom-hole zone of the productive
formation and formation of new cracks there. Cases are known when
after processing the bottom-hole zone with a reverse flow of
liquid, using implosion, the inflow of oil in oil producing wells 1
increases several times. Sometimes wells 1, operated according to a
mechanized method, turn into spouting wells.
[0088] The next step is unsealing the bottom-hole zone of the well
1 (FIG. 6), that is removal of the packer 4, after which the oil
producing well 1 may be exploited. The clogging products are
removed from the bottom-hole zone of the well 1 after the latter is
unsealed. This step is carried out simultaneously with the oil
production.
[0089] When the liquid in the bottom-hole chamber 6 is heated to a
temperature of 80-96.degree. C. (here and below consideration is
given to temperature at normal pressure, since the pressure of the
liquid in the bottom-hole zones in wells 1 is different and depends
on the depth of the well 1, which changes from 800 to 4000 mn
depending on the deposit), the light fractions of oil (gasoline,
benzene, etc.) boil, water boils at a temperature of 100.degree.
C., the heavy oil fractions boil at temperatures of 460-500.degree.
C. In the bottom-hole zone, the boiling point of water and
intermediate oil fractions increases depending on the pressure of
the vertical column of the liquid in the well 1, remaining
different from each other.
[0090] If the light fractions of oil are heated to the boiling
point, the partial pressure in the bottom-hole chamber 6 is created
only by vapors of the light fractions of oil. If the temperature is
increased, partial pressure occurs from the vapors of light
fractions, water and heavy fractions of oil. Accordingly, the total
pressure of the gases, which do not interact chemically with each
other, is equal to the sum of the partial pressures of these gases
(Dalton Law).
[0091] In order to determine the optimum temperature for heating
the liquid in the bottom-hole chamber 6 it is necessary to know the
composition of the liquid in the well 1. If the water encroachment
of the latter is strong, then the heating may be limited to
100.degree. C., taking into account the pressure of the liquid in
the well 1 (taking the depth of the well into account). If there
are many light fractions in the oil, the heating temperature may be
reduced, and to the contrary, where there are a large number of
heavy (viscous) fractions in the oil, it is advisable that the
temperature be raised to the boiling point of those latter
fractions. At any heating temperature, the liquid, which has not
passed into vapor will increase in volume and thus promote the
creation of a flow from the bottom-hole chamber 6 toward the
productive formation. However, this component will be less than the
action of the pressure of the vapors of those or other fractions of
oil and water. There will be a complex interaction of the vapors
and expanding liquid in the bottom-hole zone. When pyrotechnic
charges are used, zonal heating will be observed where, as the
distance from the charge is increased, the temperature will fall,
and, consequently, a transition of all the components of the well
liquid together or separately to a vaporous state will be
observed.
[0092] The lower the temperature to which the liquid in the
bottom-hole chamber 6 is heated, the less the consumption of energy
to perform this operation, but the effectiveness of the inflow of
oil will be lower. If heating to high temperatures is used (when
oils boil), then the temperature near the source of heat will be
maximum, i.e., boiling of the heavy and other fractions of oil near
the heating source will be observed, and at some distance the
temperature will fall and only water and light fractions of oil
will boil.
[0093] It is most effective to use an explosion for realization of
the proposed method for processing the bottom-hole zone (FIG. 4).
In this case an increase of the pressure in the bottom-hole chamber
6 is ensured and the liquid therein is heated to the maximum
temperatures, i.e. there is simultaneous action of the pressure on
the pores in the bottom-hole zone of the productive formation and
temperature, reducing the viscosity of the oil. Taking into account
that the upper part of the bottom-hole zone of the well 1 is
sealed, the effectiveness of the explosion in that case is at least
two time more than the effectiveness of the methods for processing
the bottom-hole zone of a well which are used at present, since all
the combustion products are directed only downwards (a directed
explosion takes place).
[0094] On the other hand the proposed method for processing a
productive formation in the bottom-hole zone of the well 1 includes
the simultaneous action of an explosive wave, a hydraulic fracture
and temperature, which result in the formation of additional cracks
in the bottom-hole zone of the well 1, reduction of the viscosity
of oil fractions and especially deposits, and also the reverse flow
of liquid from the productive formation to the well 1, which
promotes the removal of the deposits from the pores and cracks. In
other words, the proposed method for processing the bottom-hole
zone of the well 1 provides the positive effects of known methods
for processing a bottom-hole zone. Moreover, by sealing the upper
part of the well 1, it is more effective than known methods, since
direction of the explosion is ensured, and this is at least two
times more effective than a simple explosion in the well 1.
[0095] Another advantage of the proposed method is the possibility
of controlling the degree to which the liquid in the bottom-hole
zone is heated, this being dependent on the composition of the oil
and the percentage content of light and heavy fractions therein,
and also the amount of water, which to a certain degree makes it
possible to reduce the power consumed during this operation.
[0096] And finally, the proposed method provides for the
preservation of geophysical cables and wire, arranged above the
bottom-hole zone (above the packer 4).
[0097] Greater effectiveness may be achieved if a pressure
generator 8 is mounted at some distance from the bottom hole of the
well (casing) 1 (FIG. 8). In order to achieve this, a packer 4 is
lowered into the well (casing) 1 (FIG. 8), using the suspension
means (cable or pipe) 2. The packer 4 is fixed to the wall of the
well 1 at some distance from the bottom, forming a bottom-hole
chamber 6. Any method for fixing the packer 4 to the wall of the
well 1, like any construction of the packer 4, may be used. The
pressure generator 8 is secured in the lower part of the packer 4
on a hanger 9 at some distance from the bottom of the well 1 and
the end face of the packer 4. The pressure generator 8 may be made
in the form of a tank with compressed gas or in the form of a
packet of explosive.
[0098] Then the column of well liquid is divided by the gas fed
from the tank or formed during an explosion of the explosive into
two parts, one of which (the lower) is directed toward the
bottom-hole zone of the well 1, the other (upper) through the
packer 4-to the above-packer space of the well 1 (FIG. 9). The well
liquid directed toward the bottom-hole zone of the well 1 effects
hydraulic fracturing in the bottom-hole zone of the well 1, which
predetermines expansion of the pores and cracks in the zone of the
productive formation surrounding the well 1, and also results in
the formation of new cracks. This, finally, will promote an
increase of the filtration of the formation liquid into the well 1,
which results in an increase of the inflow of oil.
[0099] After the bottom-hole chamber 6 has been cleansed of the
well liquid (FIG. 10), the pressure of the gases therein, fed from
the tank or formed as a result of an explosion, will fall, i.e.
depression of the pressure will occur as a result of reduction of
the temperature of the gases (heat through the wall of the well 1
as a result of the thermal conductivity of its walls will pass into
the surrounding medium).
[0100] The next step is the step of filling the bottom-hole chamber
6 with the formation liquid. Simultaneously with this, movement of
the flow of well liquid positioned above the packer 4 into the
bottom-hole chamber 6 is closed (FIG. 11). In view of this the
pressure of the gases in the bottom-hole chamber 6 will be reduced,
i.e. depression of the pressure will occur, and formation liquid
will enter the bottom-hole chamber 6. Wherewith, it will wash out
the clogging products which are in the pores and cracks. Particles
of earth, also to be found in the cracks and pores and hindering
filtration of the formation liquid, will also be washed out with
the flow of well liquid.
[0101] The proposed complex action on the bottom-hole zone of the
well 1 (at first hydraulic fracturing, and then the action of
pressure depression) enhances the effectiveness of filtration of
the formation liquid of the productive formation, which, finally,
increases the production rate of oil in the well 1.
[0102] In order to realize the proposed method with use of an
explosion as a step for the instantaneous increase of the
temperature in the bottom-hole chamber 6, it is advisable to use a
packer 4 with any construction of the means for radial compaction,
but in which the lower end face 5 is made in the form of a concave
surface of the second order. In other respects, the packer 4 units
may be of any construction. Such a concave surface may be made
hemispheric or paraboloidal. These forms of the lower end face 5 of
the packer 4 provide for direction of the explosive wave along the
longitudinal axis of the well 1 and simultaneously ensure
self-compaction of the packer 4 over the surface of the well 1,
without creating stress concentrators in the packer 4. In the first
case, production of the packer 4 is simplified, in the second - the
effectiveness is enhanced, since the lower end face 5 of the packer
4 at the wall of the well 1 has greater length and more gradually
passes to cylindrical.
[0103] In order to realize the proposed method with the use of an
explosion for cleansing the bottom-hole chamber 6 with division of
the column of well liquid, which is in this chamber 6, into two
parts and their displacement to the productive formation and the
above-packer space of the well 1, it is necessary to use a special
construction of the packer, which ensures the passage therethrough
of a flow of well liquid from the bottom-hole chamber 6 to the
above-packer space of the well 1 and prevents movement of the well
liquid in the opposite direction. A packer 4 with a flat lower end
face is shown in FIGS. 8, 9; with a concave surface of the second
order in FIGS. 10, 11. Both constructions satisfy the required
conditions for passage of the well liquid through the packer 4.
[0104] The packer 4 comprises a body 10 (FIGS. 8, 9) with a means
11 for radial compaction (a rubber bushing is shown in the FIG.,
which when heated expands and creates tightness between the body 10
and the wall of the well [casing] 1). The packer 4 is lowered to
the required depth by a suspension means 2 (FIG. 8), which may be a
cable or pipe. The packer 4 is made with channels (a channel) 12
(FIGS. 8-11) which connect its end faces.
[0105] The channels 12 may be made parallel to the longitudinal
axis of the packer 4 (FIGS. 8, 9) or inclined (FIGS. 10, 11), A
back-pressure valve 13, secured to the body 10 of the packer 4, is
mounted in the channels 12 or outside them as shown in FIGS. 8-11.
The back-pressure valve 13 is shown in the drawings in the form of
a flat elastic plate, secured in the central part to the body 10 of
the packer 4.
[0106] The principle of operation of the packer is as follows.
[0107] The packer 4 is lowered to the required depth and by any
known method is secured to the walls of the well 1 (FIG. 8). Well
liquid is on both sides of the end faces of the packer 4. A
pressure generator 8 may be suspended on a hanger 9 from the lower
part of the packer 4. A tank with compressed gas or a packet of
explosive may be used as the pressure generator 8. The pressure
generator 8 may be suspended on a special cable passed through the
packer 4. After the explosion (FIG. 9), under the action of the
explosion gases formed after the explosion of the explosive or the
gas in the tank, the upper part of the column of well liquid in the
bottom-hole chamber 6 will be displaced through the channels 12 of
the packer 4 into the above-chamber space of the well 1 (FIG. 9).
Wherein, the back-pressure valve 13 in the form of an elastic
plate, deforming, passes the well liquid into the above-packer
space. The lower part of the column of well liquid, which is in the
bottom-hole chamber 6, will be pressed toward the productive
formation. After the bottom-hole chamber 6 is freed of the well
liquid, the temperature of the gases in that chamber 6 will fall as
a result of the transmission of heat into the surrounding medium,
and this will results in a reduction of the pressure of the gases
in the bottom-hole chamber 6 - to depression of the pressure. Under
the action of the column of well liquid which is in the
above-packer space of the well 1, the channels 12 of the packer 4
are closed by the elastic force of the material of the elastic
plate of the back-pressure valve 13. Reduction of the pressure of
the gas will continue in the bottom-hole chamber 6, and after it
has fallen below the formation pressure, formation liquid will
begin to go from the formation into the bottom-hole zone. The
greater the depression of the pressure in the bottom-hole zone, the
more intensive will be the inflow of formation liquid into the
bottom-hole chamber 6. Wherein, the clogging products and separate
particles of earth, clogging the pores and cracks in the
bottom-hole zone of the well 1, will be washed out.
[0108] It is advisable to use packers 4 in which control of
fixation to the walls of the well (casing) 1 is carried out by
temperature action. Packers of such a construction are shown in
FIGS. 12-15.
[0109] The packer 4, secured to the suspension means 2 in the form
of a cable (FIGS. 12, 13) or a pipe (FIGS. 14, 15), is installed in
a well 1 (FIGS. 14-15) or casing 1 (FIGS. 12-13). The packer 4 may
be of any construction. However, it, in accordance with the
technical solution, should be provided with a temperature-action
element 14 (this may be either a heating element, for example, an
electric spiral, or a cooling element, for example, a
thermocouple).
[0110] A packer with a structural element made of a material with
shape memory is shown in FIG. 14. in this case, a diametral size
increase is effected by volumetric expansion of the material of the
structural elements (as described above) and by changing the shape
of the structural element of the packer 4, made of material with
shape memory. Wherewith, the second factor by tens, and sometimes
even hundreds, of times exceeds the first.
[0111] The packer 4 comprises an elastic cup-type seal 15 with a
thrust washer 16, clamps 17, 18 mounted above and below the
cup-type seal 15, a cylinder 19 with lobes 20 formed by slots 21,
in the lower part of which the slots 21 pass into an opening 22.
The cylinder 19 with lobes 20 is made of material with shape
memory, and therefore they serve as a drive (when moved apart), and
together with the elastic cup-type seal 15 - as sliding cheeks, a
part of which closes the gap between the packer 4 and the wall of
the well (casing) 1. The cylinder 19 with lobes 20 and slots 21 may
be whole or consist of several sectors mounted in a circle. The
temperature-action element 14 made in the form of a thermocouple
should desirably be mounted near the lobes 20 in order to cool them
more effectively. Power to the temperature-action element 14 -
thermocouple may be effected from the surface along wires 23. The
cylinder 19 is made of a material with shape memory, for example,
of a nickel-titanium alloy (for example, titanium nickelide NiTi
with a content of 50% nickel and 50% titanium). The specificity of
these alloys is that if a sample made from them is given a certain
shape by plastic deformation at a temperature higher than the
temperature A.sub.E, and then cooled to a temperature below the
temperature M.sub.E and again deformed, destroying the former
shape, then after heating the sample to a temperature above the
temperature A.sub.B, it will "remember" its original shape. The
temperatures M.sub.B and M.sub.E are the beginning and end
temperatures of forward martensite conversion, white A.sub.B and
A.sub.E are respectively the beginning and end temperatures of
reverse martensite conversion. In respect to a titanium nickelide
NiTi alloy, the temperatures M.sub.B =63.degree. C.,
A.sub.B=75.degree. C. Addition of the alloying additions Fe and Co
to titanium nickelide NiTi of a stoichiometric composition reduces
the temperature at which the shape is restored. The effect of the
alloying additions on the shape restoration temperature is set
forth, for example, in the work by A.S. Tikhonov, A.P. Gerasimov,
I.I. Prokhorov. Use of the shape memory effect in modem mechanical
engineering, "Mashinostroenie," Moscow, 1981, p. 80. Different
alloys having the shape memory effect have their own
physicomechanical parameters. Some of them are presented herebelow:
the degree of restoration of the original shape reaches 100%; the
degree of reverse deformation reaches 10-20%; the pressure produced
during heating reaches 500-700 MPa; the stress necessary for
preliminary deformation should not be more than 50-100 MPa The
temperature at which shape memory is manifested in alloys may
change from -250.degree. to 500.degree. C., and the width of the
temperature interval for restoration of the shape - from 5 to
100.degree. C., hysteresis from 2 to 80.degree. C.
[0112] Here material on the base of titanium nickelide NiTi is
indicated as an example, this material having high mechanical
strength and stability against lengthy temperature cycling,
generating significant mechanical stresses when heated, having a
significant specific working capacity.
[0113] The principle of operation of the packer and the method for
fixing it in a well is as follows.
[0114] A packer 4 is lowered into a well (or casing) 1 on a
suspension means 2 in the form of a cable (FIGS. 12, 13) or pipe
(FIGS. 14-15) to the depth at which it should be fixed. Taking into
account that as the depth increases the temperature of the well
liquid (this may be drilling mud or a mixture of oil and water)
increases, the diametral size of the packer 4 is selected so that
at the temperature of the well liquid at the depth of fixation, the
diametral size of the packer 4 would be less than the diameter of
the well 1. This may be achieved constructively, that is the parts
of the packer 4 made with corresponding diameter, or the packer 4
may be cooled, artificially reducing its diametral size. Then the
packer 4 is subjected to temperature action (in this case heating),
which results in an increase of its diametral size (FIG. 13). If
the packer 4 is made constructively with a diametral size less than
the diameter of the well 1, the heating may be carried out with a
temperature-action element 14, for example, an electric spiral, or
by using a pyrotechnic cartridge (not shown in the drawings). When
a pyrotechnic cartridge is used, the heating will be one-time, and
then this temperature will be maintained by the temperature of the
well liquid. When an electric spiral is used, the packer 4 may be
heated a multiple number of times and the maximum or optimum
temperature maintained. This is especially important when the
temperature of the well liquid is less than the temperature of the
martensite conversion of the shape memory alloy used. Wherewith,
the heating is carried out from a power source mounted on the
surface (not shown in the drawings). As a result of the heating, a
tightness is created between the surface of the cup-type seal 15 of
the packer 4 and the surface of the wall of the well (casing) 1. In
order to remove the packer 4 from the well 1, the temperature load
should be reduced (the packer 4 cooled), after which a reduction of
the volume of its structural elements occurs, the diametral size of
the packer 1 falls, and it may be extracted from the well 1. The
cooling may be natural (when the temperature of the well liquid is
low) or artificial by using, for example, a thermocouple. In the
latter case, the process may be controlled better, since it hardly
depends at all on the temperature of the well liquid.
[0115] The sequence of these operations is advisable when
volumetric expansion of the cup-type seal 15 of the packer 4 is
used or it is made of a material with a shape memory in which the
temperature of forward martensite conversion is higher than the
temperature of the well liquid at the depth of fixation of the
packer 4. When executed in this manner, it is necessary to
constantly consume power in order to ensure fixation of the packer
4 to the wall of a well (casing) 1.
[0116] It is advisable to cool the packer 4 prior to its
installation in the well 1 at the required depth (on the surface at
the moment when it is to be lowered). Different means may be used
on the surface in order to accomplish this (for example, cover the
packer with ice), in the well 1 it is most advisable to use a
thermocouple for this purpose. While the packer 4 is cooling, its
diametral size decreases and it becomes significantly less than the
diameter of the well 1, this simplifying the process of lowering
the packer 4 into the well 1. Due to the action of the temperature
of the well liquid, the packer 4 heats up, which results in an
increase of its diametral size. If the temperature of the well
liquid at the depth at which the packer 4 is installed is known, it
is possible to calculate the initial diameter so that at the
temperature of the well liquid, a tightness will appear between the
side surface of the packer 4 and the wall of the well 1. The force
which appears during the tightening provides fixation of the packer
4 against the wall of the well 1. In order to remove the packer 4
from the well 1, it is necessary to cool it again (to carry out
temperature relief). Wherewith, its diametral size becomes less
than the diameter of the well 1, after which it will be possible to
extract the packer 4 from the well 1.
[0117] The constructions of a packer 4, which is heated, are shown
in FIGS. 12 and 13, wherewith their fixation to the wall of the
well 1 is achieved as a result of the volumetric expansion of the
material during heating. Using this principle, a packer 4 of any
known construction may be used, providing it with a heating
element. In this case the reliability of fixation increases, since,
in addition to the mechanical change of the diametral size of the
packer 4 (for example, by displacing the tapered surfaces in the
packer according to USSR Inventor's Certificate No. 252244), an
additional tightness occurs as a result of the volumetric expansion
of the material from which the elements of the packer 4 are
made.
[0118] A packer 4 is shown in FIGS. 14 and 15, in which material
with shape memory is used. In this case, a diametral size increase
is effected as a result of the volumetric expansion of the material
(as described above) and a change of the shape of the packer 4.
[0119] The lobes 20 prior to being mounted in the packer 4 and
after being heated to a temperature exceeding temperature A.sub.E
are given the shape shown in FIG. 15, that is the lobes 20 are
opened. Then they are cooled and deforming they together form the
shape of a cylinder (FIG. 14), i.e. the packer 4 is gathered when
the lobes 20 have a flat shape in the longitudinal section, forming
together a cylindrical surface. The cylinder 19 together with the
lobes 20 is positioned in an elastic cup-type seal 15, wherewith
their contact surfaces may be glued. The production of the elastic
cup-type seal 15 together with the cylinder 19 and its lobes 20 is
possible, wherefore the rubber from which the cup-type seal 15 is
made is boiled, the cylinder 19 and lobes 20 will serve as if
armature. The problem of producing the elastic cup-type seal 15
together with the cylinder 19 and its lobes 20 is solved concretely
during the selection of the materials (what is meant is the
temperature to which the rubber of the cup-type seal 15 is heated
and the temperature A.sub.B). An opening 22 is made in the cylinder
19 to eliminate the formation of cracks in the whole part of the
cylinder 19. The cylinder 19 with lobes 20 and the cup-type seal 15
serve as the sliding cheeks.
[0120] Prior to the packer 4 being lowered, power is fed into the
well 1 along wires 23 to the temperature-action element 14 in the
form of a thermocouple serving as a cooler. The latter lowers the
temperature of the structural elements of the packer 4, and
therefore its diametral dimensions are somewhat reduced, while the
lobes 20 retain a cylindrical shape (FIG. 14). The packer 4 is
lowered into the well 1 to the required depth. Then the power to
the thermocouple is turned off. The structural elements of the
packer 4 are heated under the effect of the temperature of the well
liquid. When the temperature rises above A.sub.B, the lobes 20 take
on the shape shown in FIG. 15, which will be maintained as long as
the temperature will have an effect. If a more rapid rise of the
temperature is necessary, the packer 4 may be additionally provided
with a pyrotechnic cartridge or electric spiral, which may be
placed between the suspension means (pipe) 2 and the cup-type seal
15 (not shown in the FIG.). The use of an additional supply of
heat, for example, the heat of an electric spiral, is justified in
the case where the temperature of the well liquid is below the
temperature A.sub.E, which occurs when the wells are not deep and
in the case of use of material with shape memory, which has the
values A.sub.B, A.sub.E, M.sub.B and M.sub.E greater than the
temperature of the well liquid. This, in turn, is advisable when
universal packers 4 are used which operate at all depths, wherewith
at large depths, the temperature of the well liquid is sufficient
for fixation, and when used at small depths - an additional supply
of heat is necessary.
[0121] The open lobes 20 (FIG. 15) press the cup-type seal 15
against the surface of the wall of the well 1. Volumetric expansion
of the structural elements of the packer 4 as a result of the
temperature will promote tightness between the surfaces of the
elastic cup-type seal 15 and the wall of the well 1.
[0122] In order to extract the packer 4 from the well 1, it is
necessary to cool the lobes 20, feeding power to the thermocouple
and providing temperature relief to the packer 4. The lobes 20
converge in a radial direction, the tightness between the surfaces
of the elastic cup-type seal 15 and the wall of the well 1
disappears, after which the packer 4 may be extracted from the well
1, since its diametral size will be small, less than the diametral
size of the well 1.
[0123] The described operations, inherent to the method for fixing
the packer 4 to the wall of a well (casing) 1, in
particular-temperature action on the packer 4, do not depend on its
construction. Existing packers 4 may be used, providing them with
temperature-action elements 14 (heaters and coolers of different
principles of operation). In that case the reliability of their
fixation is enhanced. It is advisable to use packers 4, the
principle of action of which is based only on the action of
temperature. In that case a greater effect will be achieved, in
particular: the construction is simplified; the reliability of
operation is enhanced; control of the process of fixation is
significantly simplified, since it is provided by a special signal
sent from the surface, which does not depend on the pressure of the
well liquid, the packer 4 may be fixed at any depth and its
extraction from the well 1 is ensured.
Industrial Applicability
[0124] The proposed technical solution may be used most effectively
in the oil production industry: in order to increase the
productivity of a well 1 by intensifying the flows of oil; to
increase the oil recovery factor; during repair of wells; to cut
off water-encroached formations, etc. The method for processing the
productive formation in a bottom-hole zone of a well, in accordance
with the technical solution, is highly effective, relatively simple
and convenient in use, since it is a single-step method. The packer
4 for realization of the proposed method is simple in production,
ensures high reliability of fixation at any depth of the well 1 and
at different distances from its bottom-hole. As compared with known
method for processing the productive formation it is at least two
times more effective because the used explosion (heating) energy is
directed to the bottom hole of the well 1, while in known methods
more than 50% of the energy of an explosion goes upwards and does
not act on the productive formation. The construction of the packer
and the method for fixing it provide convenience of control due to
the use of a special signal consisting of heating and cooling
packer elements to temperatures which are not present near the
packer 4 in the well liquid at the necessary depth of its
fixation.
* * * * *