U.S. patent application number 12/935958 was filed with the patent office on 2011-03-10 for system and method for recompletion of old wells.
This patent application is currently assigned to STATOIL ASA. Invention is credited to Haavard Aakre, Vidar Mathiesen.
Application Number | 20110056700 12/935958 |
Document ID | / |
Family ID | 41136044 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110056700 |
Kind Code |
A1 |
Mathiesen; Vidar ; et
al. |
March 10, 2011 |
SYSTEM AND METHOD FOR RECOMPLETION OF OLD WELLS
Abstract
A system for recompletion of an old well in order to achieve an
increased oil recovery from a reservoir, said system comprising a
pipe inserted into the old well, at least two constrictors or swell
packers being arranged along the length of the recompleted well and
defining a well section between two successive constrictors or
swell packers, said system further comprising at least one
autonomous valve arranged in said well section defined between said
two successive swell packers or constrictors. Disclosed is also a
method for recompletion of an old well in order to achieve an
increased oil recovery from a reservoir.
Inventors: |
Mathiesen; Vidar;
(Porsgrunn, NO) ; Aakre; Haavard; (Skien,
NO) |
Assignee: |
STATOIL ASA
STAVANGER
NO
|
Family ID: |
41136044 |
Appl. No.: |
12/935958 |
Filed: |
April 1, 2009 |
PCT Filed: |
April 1, 2009 |
PCT NO: |
PCT/NO09/00124 |
371 Date: |
November 23, 2010 |
Current U.S.
Class: |
166/369 ;
166/130 |
Current CPC
Class: |
E21B 34/08 20130101;
E21B 43/12 20130101; E21B 43/14 20130101; E21B 33/1243 20130101;
E21B 43/32 20130101; E21B 43/08 20130101 |
Class at
Publication: |
166/369 ;
166/130 |
International
Class: |
E21B 43/00 20060101
E21B043/00; E21B 33/12 20060101 E21B033/12 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2008 |
NO |
20081657 |
Claims
1. A system for recompletion of an old well in order to achieve an
increased oil recovery from a reservoir, said system comprising: a
pipe inserted into the old well, at least two constrictors or swell
packers being arranged along the length of the recompleted well and
defining a well section between two successive constrictors or
swell packers; and at least one autonomous valve arranged in said
well section defined between said two successive swell packers or
constrictors.
2. A system according to claim 1, wherein a plurality of well
sections are defined along the length of the well and that at least
one autonomous valve is arranged within each well section.
3. The system according to claim 1, wherein the at least one
autonomous valve operates by the Bernoully principle and has a
substantially constant flow-through volume above a given
differential pressure.
4. The system according to claim 1, wherein the inserted pipe
covers substantially the whole length of the old well.
5. The system according to claim 1, wherein the well is a
horizontal well.
6. The system according to claim 1, wherein the well is a well of
any inclination from horizontal, including vertical.
7. A method for completion of an old well in order to achieve an
increased oil recovery from a reservoir, comprising the following
steps (not necessarily in said order): providing a pipe comprising
at least one autonomous valve arranged in the pipe, passing the
pipe into the old well for recompleting said old well, providing at
least two swell packers or constrictors along the well to seal
between the inserted pipe and the old well to define at least one
well section between said two successive constrictors or swell
packers in which at least one well section the at least one
autonomous valve is arranged.
8. A method according to claim 7, further comprising the step of
providing a plurality of well sections along the well in each of
which sections at least one autonomous valve is arranged.
9. The method according to claim 8, further comprising the step of
covering substantially the whole length of the old well with the
inserted pipe.
10. The method according to claim 7, wherein the at least one
autonomous valve operates by the Bernoully principle and has a
substantially constant flow-through volume above a given
differential pressure.
11. The system according to claim 2, wherein the at least one
autonomous valve operates by the Bernoully principle and has a
substantially constant flow-through volume above a given
differential pressure.
12. The system according to claim 2, wherein the inserted pipe
covers substantially the whole length of the old well.
13. The system according to claim 3, wherein the inserted pipe
covers substantially the whole length of the old well.
14. The system according to claim 2, wherein the well is a
horizontal well.
15. The system according to claim 3, wherein the well is a
horizontal well.
16. The system according to claim 4, wherein the well is a
horizontal well.
17. The system according to claim 2, wherein the well is a well of
any inclination from horizontal, including vertical.
18. The system according to claim 3, wherein the well is a well of
any inclination from horizontal, including vertical.
19. The system according to claim 4, wherein the well is a well of
any inclination from horizontal, including vertical.
20. The method according to claim 8, wherein the at least one
autonomous valve operates by the Bernoully principle and has a
substantially constant flow-through volume above a given
differential pressure.
Description
[0001] The present invention relates to a system and method for
recompletion of old wells. More specifically the invention relates
to a system and a method as disclosed in the preamble of claim 1
and 7, respectively.
[0002] In a preferred embodiment of the invention a plurality of
autonomous valves or flow control devices are substantially as
those described in WO 2008/0048745 A1, belonging to the applicant
of the present application.
[0003] Devices for recovering of oil and gas from long, horizontal
and vertical wells are known from US patent publications Nos.
4,821,801, 4,858,691, 4,577,691 and GB patent publication No.
2169018. These known devices comprise a perforated drainage pipe
with, for example, a filter for control of sand around the pipe. A
considerable disadvantage with the known devices for oil/and or gas
production in highly permeable geological formations is that the
pressure in the drainage pipe increases exponentially in the
upstream direction as a result of the flow friction in the pipe.
Because the differential pressure between the reservoir and the
drainage pipe will decrease upstream as a result, the quantity of
oil and/or gas flowing from the reservoir into the drainage pipe
will decrease correspondingly. The total oil and/or gas produced by
this means will therefore be low. With thin oil zones and highly
permeable geological formations, there is further a high risk that
of coning, i.e. flow of unwanted water or gas into the drainage
pipe downstream, where the velocity of the oil flow from the
reservoir to the pipe is the greatest.
[0004] From World Oil, vol. 212, N. 11 (11/91), pages 73-80, is
previously known to divide a drainage pipe into sections with one
or more inflow restriction devices such as sliding sleeves or
throttling devices. However, this reference is mainly dealing with
the use of inflow control to limit the inflow rate for up hole
zones and thereby avoid or reduce coning of water and or gas.
[0005] WO-A-9208875 describes a horizontal production pipe
comprising a plurality of production sections connected by mixing
chambers having a larger internal diameter than the production
sections. The production sections comprise an external slotted
liner which can be considered as performing a filtering action.
However, the sequence of sections, of different diameter creates
flow turbulence and prevent the running of work-over tools.
[0006] U.S. Pat. No. 5,435,393 describes a production pipe with a
lover drainage pipe divided into sections and with one or more
inflow restriction devices which controls the flow of oil or gas
from the reservoir into the drainage pipe based on the
precalculated loss of friction pressure along the drainage pipe,
the precalculated production profile of the reservoir and the
precalculated inflow of gas or water. This publication does thus
not relate to recompletion of old wells, nor to the use of
autonomous flow control devices in said recompletion.
[0007] When extracting oil and or gas from geological production
formations, fluids of different qualities, i.e. oil, gas, water
(and sand) is produced in different amounts and mixtures depending
on the property or quality of the formation. None of the
above-mentioned, known devices are able to distinguish between and
control the inflow of oil, gas or water on the basis of their
relative composition and/or quality.
[0008] With the autonomous valve as described in WO 2008/0048745 A1
is provided an inflow control device which is self adjusting or
autonomous and can easily be fitted in the wall of a production
pipe and which therefore provide for the use of work-over tools.
The device is designed to "distinguish" between the oil and/or gas
and/or water and is able to control the flow or inflow of oil or
gas, depending on which of these fluids such flow control is
required.
[0009] The device as disclosed in WO 2008/0048745 A1 is robust, can
withstand large forces and high temperatures, needs no energy
supply, can withstand sand production, is reliable, but is still
simple and very cheap.
[0010] A problem with the prior art is that the well, with or
without inflow control devices, has to be abandoned since the well
is not able to produce anymore due to gas and/or water
breakthrough.
[0011] In existing wells large quantities of oil will remain along
the path of the well due to "short-circuit" effects, i.e. that only
parts of the well are producing oil. As shown in the enclosed FIG.
9 a section of the well path adjoins a high permeability zone in
which substantially all the inflow occurs. In such high
permeability zones gas and/or water will enter at a faster rate
than in other zones of the well. If gas experiences a break-through
in such high permeability zones the gas will flow even easier than
the oil (gas has a higher mobility than oil) such that this zone
will increase its proportion of the total inflow compared with a
situation in which oil was present there. If water experiences a
breakthrough, water will also flow easier that oil. The importance
of this will be increasing with a higher difference in viscosity
between oil and water. These effects reduce the drainage rate.
[0012] Short-circuit effects might also appear in low oil zones
with zones comprising gas and/or water above or below them.
[0013] The system and method according to the invention seeks to
reduce or eliminate the above and other problems or disadvantages
by inserting a pipe with a at least one, and preferably a plurality
of autonomous valves into an existing well, and thus increase oil
recovery with limited investments. The invention might thus be
regarded as an improvement of an existing stinger solution in which
an impervious pipe section having solid walls are arranged on a
location in the well in which gas breakthrough previously has been
experienced.
[0014] The system and method according to the invention are
characterized by the features as disclosed in the characterizing
clause of claim 1 and 7, respectively.
[0015] Advantageous embodiments are set forth in the dependent
claims.
[0016] The present invention will be further described in the
following by means of examples and with reference to the drawings,
where:
[0017] FIG. 1 shows a schematic view of a production pipe with a
control device according to WO 2008/0048745 A1,
[0018] FIG. 2 a) shows, in larger scale, a cross section of the
control device according to WO 2008/0048745 A1, b) shows the same
device in a top view.
[0019] FIG. 3 is a diagram showing the flow volume through a
control device according to the invention vs. the differential
pressure in comparison with a fixed inflow device,
[0020] FIG. 4 shows the device shown in FIG. 2, but with the
indication of different pressure zones influencing the design of
the device for different applications.
[0021] FIG. 5 shows a principal sketch of another embodiment of the
control device according to WO 2008/0048745 A1,
[0022] FIG. 6 shows a principal sketch of a third embodiment of the
control device according to WO 2008/0048745 A1,
[0023] FIG. 7 shows a principal sketch of a fourth embodiment of
the control device according to WO 2008/0048745 A1.
[0024] FIG. 8 shows a principal sketch of a fifth embodiment of WO
2008/0048745 A1 where the control device is an integral part of a
flow arrangement.
[0025] FIG. 9 shows a principal view of a prior art well
intersecting a high permeability zone of a reservoir.
[0026] FIG. 10 shows a principal view of the well in FIG. 9, which,
in accordance with the invention, is recompleted with a new pipe
with autonomous valves inserted into the well, causing a
substantially uniform inflow into the well.
[0027] FIG. 11a shows a principal view of a lateral well in
accordance with the invention, e.g. the well in FIG. 10, and
[0028] FIG. 11b shows an enlarged principal view of the part of
FIG. 11a constricted by a circle.
[0029] FIG. 1 shows, as stated above, a section of a production
pipe 1 in which a control device 2, according to WO 2008/0048745 A1
is provided. The control device 2 is preferably of circular,
relatively flat shape and may be provided with external threads 3
(see FIG. 2) to be screwed into a circular hole with corresponding
internal threads in the pipe or an injector. By controlling the
thickness, the device 2, may be adapted to the thickness of the
pipe or injector and fit within its outer and inner periphery.
[0030] FIG. 2 a) and b) shows the prior control device 2 of WO
2008/0048745 A1 in larger scale. The device consists of a first
disc-shaped housing body 4 with an outer cylindrical segment 5 and
inner cylindrical segment 6 and with a central hole or aperture 10,
and a second disc-shaped holder body 7 with an outer cylindrical
segment 8, as well as a preferably flat disc or freely movable body
9 provided in an open space 14 formed between the first 4 and
second 7 disc-shaped housing and holder bodies. The body 9 may for
particular applications and adjustments depart from the flat shape
and have a partly conical or semicircular shape (for instance
towards the aperture 10.) As can be seen from the figure, the
cylindrical segment 8 of the second disc-shaped holder body 7 fits
within and protrudes in the opposite direction of the outer
cylindrical segment 5 of the first disc-shaped housing body 4
thereby forming a flow path as shown by the arrows 11, where the
fluid enters the control device through the central hole or
aperture (inlet) 10 and flows towards and radially along the disc 9
before flowing through the annular opening 12 formed between the
cylindrical segments 8 and 6 and further out through the annular
opening 13 formed between the cylindrical segments 8 and 5. The two
disc-shaped housing and holder bodies 4, 7 are attached to one
another by a screw connection, welding or other means (not further
shown in the figures) at a connection area 15 as shown in FIG.
2b).
[0031] The present invention exploits the effect of Bernoulli
teaching that the sum of static pressure, dynamic pressure and
friction is constant along a flow line:
p static + 1 2 .rho. v 2 + .DELTA. p friction ##EQU00001##
[0032] When subjecting the disc 9 to a fluid flow, which is the
case with the present invention, the pressure difference over the
disc 9 can be expressed as follows:
.DELTA. p over = [ p over ( P 4 ) - p under ( f ( p 1 , p 2 , p 3 )
] = 1 2 .rho. v 2 ##EQU00002##
[0033] Due to lower viscosity, a fluid such as gas will "make the
turn later" and follow further along the disc towards its outer end
(indicated by reference number 14). This makes a higher stagnation
pressure in the area 16 at the end of the disc 9, which in turn
makes a higher pressure over the disc. And the disc 9, which is
freely movable within the space between the disc-shaped bodies 4,
7, will move downwards and thereby narrow the flow path between the
disc 9 and inner cylindrical segment 6. Thus, the disc 9 moves
dawn-wards or up-wards depending on the viscosity of the fluid
flowing through, whereby this principle can be used to control
(close/open) the flow of fluid through of the device.
[0034] Further, the pressure drop through a traditional inflow
control device (ICD) with fixed geometry will be proportional to
the dynamic pressure:
.DELTA. p = K 1 2 .rho. v 2 ##EQU00003##
[0035] where the constant, K is mainly a function of the geometry
and less dependent on the Reynolds number. In the control device
according to the present invention the flow area will decrease when
the differential pressure increases, such that the volume flow
through the control device will not, or nearly not, increase when
the pressure drop increases. A comparison between a control device
according to the present invention with movable disc and a control
device with fixed flow-through opening is shown in FIG. 3, and as
can be seen from the figure, the flow-through volume for the
present invention is constant above a given differential
pressure.
[0036] This represents a major advantage with the present invention
as it can be used to ensure the same volume flowing through each
section for the entire horizontal well, which is not possible with
fixed inflow control devices.
[0037] When producing oil and gas the control device according to
the invention may have two different applications: Using it as
inflow control device to reduce inflow of water, or using it to
reduce inflow of gas at gas break through situations. When
designing the control device according to the invention for the
different application such as water or gas, as mentioned above, the
different areas and pressure zones, as shown in FIG. 4, will have
impact on the efficiency and flow though properties of the device.
Referring to FIG. 4, the different area/pressure zones may be
divided into: [0038] A.sub.1, P.sub.1 is the inflow area and
pressure respectively. The force (P.sub.1A.sub.1) generated by this
pressure will strive to open the control device (move the disc or
body 9 upwards). [0039] A.sub.2, P.sub.2 is the area and pressure
in the zone where the velocity will be largest and hence to
represents a dynamic pressure source. The resulting force of the
dynamic pressure will strive to close the control device (move the
disc or body 9 downwards as the flow velocity increases). [0040]
A.sub.3, P.sub.3 is the area and pressure at the outlet. This
should be the same as the well pressure (inlet pressure). [0041]
A.sub.4, P.sub.4 is the area and pressure (stagnation pressure)
behind the movable disc or body 9. The stagnation pressure, at
position 16 (FIG. 2), creates the pressure and the force behind the
body. This will strive to close the control device (move the body
downwards).
[0042] Fluids with different viscosities will provide different
forces in each zone depending on the design of these zones. In
order to optimize the efficiency and flow through properties of the
control device, the design of the areas will be different for
different applications, e.g. gas/oil or oil/water flow. Hence, for
each application the areas needs to be carefully balanced and
optimally designed taking into account the properties and physical
conditions (viscosity, temperature, pressure etc.) for each design
situation.
[0043] FIG. 5 shows a principal sketch of another embodiment of the
control device according to WO 2008/0048745 A1, which is of a more
simple design than the version shown in FIG. 2. The control device
2 consists, as with the version shown in FIG. 2, of a first
disc-shaped housing body 4 with an outer cylindrical segment 5 and
with a central hole or aperture 10, and a second disc-shaped holder
body 17 attached to the segment 5 of the housing body 4, as well as
a preferably flat disc 9 provided in an open space 14 formed
between the first and second disc-shaped housing and holder bodies
4, 17. However, since the second disc-shaped holder body 17 is
inwardly open (through a hole or holes 23, etc.) and is now only
holding the disc in place, and since the cylindrical segment 5 is
shorter with a different flow path than what is shown in FIG. 2,
there is no build up of stagnation pressure (P.sub.4) on the back
side of the disc 9 as explained above in conjunction with FIG. 4.
With this solution without stagnation pressure the building
thickness for the device is lower and may withstand a larger amount
of particles contained in the fluid.
[0044] FIG. 6 shows a third embodiment according to WO 2008/0048745
A1 where the design is the same as with the example shown in FIG.
2, but where a spring element 18, in the form of a spiral or other
suitable spring device, is provided on either side of the disc and
connects the disc with the holder 7, 22, recess 21 or housing
4.
[0045] The spring element 18 is used to balance and control the
inflow area between the disc 9 and the inlet 10, or rather the
surrounding edge or seat 19 of the inlet 10. Thus, depending on the
spring constant and thereby the spring force, the opening between
the disc 9 and edge 19 will be larger or smaller, and with a
suitable selected spring constant, depending on the inflow and
pressure conditions at the selected place where the control device
is provided, constant mass flow through the device may be
obtained.
[0046] FIG. 7 shows a fourth embodiment according to WO
2008/0048745 A1, where the design is the same as with the example
in FIG. 6 above, but where the disc 9 is, on the side facing the
inlet opening 10, provided with a thermally responsive device such
as bi-metallic element 20.
[0047] When producing oil and/or gas the conditions may rapidly
change from a situation where only or mostly oil is produced to a
situation where only or mostly gas is produced (gas breakthrough or
gas coning). With for instance a pressure drop of 16 bar from 100
bar the temperature drop would correspond to approximately
20.degree. C. By providing the disc 9 with a thermally responsive
element such as a bi-metallic element as shown in FIG. 7, the disc
will bend upwards or be moved upwards by the element 20 abutting
the holder shaped body 7 and thereby narrowing the opening between
the disc and the inlet 10 or fully closing said inlet.
[0048] The above examples of a control device as shown in FIGS. 1
and 2 and 4-7 are all related to solutions where the control device
as such is a separate unit or device to be provided in conjunction
with a fluid flow situation or arrangement such as the wall of a
production pipe in connection with the production of oil and gas.
However, the control device may, as shown in FIG. 8, be an integral
part of the fluid flow arrangement, whereby the movable body 9 may
be provided in a recess 21 facing the outlet of an aperture or hole
10 of for instance a wall of a pipe 1 as shown in FIG. 1 instead of
being provided in a separate housing body 4. Further, the movable
body 9 may be held in place in the recess by means of a holder
device such as inwardly protruding spikes, a circular ring 22 or
the like being connected to the outer opening of the recess by
means of screwing, welding or the like.
[0049] FIG. 9 shows a principal view of a well 24 intersecting a
high permeability zone 25 of a reservoir 26. As indicated by the
size of the arrows the inflow into the well 24 is non-uniform, and
with a breakthrough in the zone 25 in which substantially all of
the inflow occurs.
[0050] FIG. 10 shows a principal view of the well in FIG. 9, which,
in accordance with the invention, is recompleted with a new pipe 27
with autonomous valves (not shown in this figure) inserted into the
well, causing a substantially uniform inflow into the well. A
plurality of constrictors or swell packers 29 are arranged along
the well to seal between the inserted pipe 27 and the existing well
24.
[0051] FIGS. 11a and 11b respectively show a principal view of a
lateral well in accordance with the invention, e.g. the well shown
in FIG. 10, and an enlarged principal view of the part of FIG. 11a
constricted by a circle. In FIG. 11b the existing or old well 24 is
indicated by dotted lines and the new pipe 27 with autonomous
valves 2 (of which only one is shown for clarity) is indicated by
solid lines. Preferably a plurality of autonomous valves 2 are
arranged along the length of the inserted pipe 27, and preferably
at least one valve 2 in each pipe section defined between two
successive constrictors or swell packers 29, in order to create a
substantially uniform inflow into the recompleted well 24, 27 and
thus an increased oil recovery.
[0052] An embodiment of a method according to the invention
preferably comprises the following steps (not necessarily in said
order): [0053] Providing an old well 24, [0054] Providing a new
pipe 27 comprising a plurality of autonomous valves 2 arranged
along the length of the pipe 27, [0055] passing said pipe 27 into
said old well 24 for recompleting the old well 24, [0056] providing
a plurality of swell packers or constrictors 29 along the well to
seal between the inserted pipe 27 and the old well 24 and to define
a plurality of well sections between two successive constrictors or
swell packers 29 in each of which sections at least one autonomous
valve 2 is to be located, [0057] in order to create a substantially
uniform inflow into the recompleted well 24, 27 and thus an
increased oil recovery.
[0058] Further, the inserted pipe 27 preferably covers
substantially the whole length of the old well 24.
[0059] In a most basic embodiment according to the invention, the
pipe 27 just covers a limited length to be arranged at a very
distinct location in the well 24 in which breakthrough is to be
prevented, i.e. a distinct fraction in the formation or reservoir
26 intersected by the well 24. This location will then be isolated
by providing one constrictor or swell packer 29 on each side of
said fraction, and with just one autonomous valve 2 arranged in
such a single isolated section of the well.
[0060] With the valve or control device described in WO
2008/0048745 A1, due to the constant volume rate, a much better
drainage of the reservoir is thus achieved. This result in
significant larger production of that reservoir.
[0061] Even though the well 24 shown in FIGS. 9-11 is a horizontal
or lateral well, it should be emphasized that wells of any
inclination, including vertical wells, are within the scope of the
present invention as stated in the appended claims.
[0062] As also mentioned in the introductionary part of the
description, the autonomous valves 2 preferably are those described
in WO 2008/0048745 A1 and above, but any type of autonomous valve
(e.g. electronically operated) is conceivable within the context of
the invention.
* * * * *