Note: Descriptions are shown in the official language in which they were submitted.
CA 02692562 2010-01-04
WELL JET DEVICE AND THE OPERATION METHOD THEREOF
Field of the Invention
This invention relates to the field of pump engineering and in particular to
well jet devices for
carrying out logging works.
Background of the Invention
A well jet device is known, which comprises a pipe string with a jet pump and
a packer and is
capable of pumping an operating fluid through the jet pump (see: RU Patent No.
2059891 Cl,
F04F 5/02, 10.05.1996).
The same patent teaches a method of operating a well jet device, which
includes: installing a jet
pump on a pipe string in a well, installing a geophysical instrument in a flow
string below the jet
pump, lowering the pipe string together with the jet pump, a packer and the
geophysical
instrument into the well and pumping an operating fluid through the jet pump.
The above method of operating a well jet device enables to pump a variety of
produced media,
e.g., oil, out of a well, while simultaneously treating a produced medium and
the formation near-
well area, but the possibility of carrying out works on well surveying is
limited, which in a
number of cases narrows the field of use of this device and the operation
method thereof.
In respect of the device, as a subject matter of the invention, the closest to
the invention as to the
technical essence and the achieved result is a well jet device comprising a
pipe string, a packer
and a jet pump, in the body of which an active nozzle with a mixing chamber
are installed and a
through channel with a seat for mounting a sealing unit having an axial
channel is made, the
output of the jet pump being connected to the pipe string above the sealing
unit, the inlet of the
jet pump channel for supplying a pumped out medium being connected to the pipe
string below
the sealing unit, and the inlet of the channel for supplying an operating
fluid to the active nozzle
is connected to the space surrounding the flow string, and several channels
for supplying a
pumped out medium being made in the jet pump body (see: RU Patent No. 2106540,
F04F 5/02,
10.03.1998).
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The same patent teaches an operation method as a subject matter of the
invention, the closest to
the invention as to the technical essence and the achieved result in respect
of the operation
method, which includes: arranging a packer and a jet pump on a pipe string in
a well, the packer
being installed over a producing formation, lowering a sealing unit and a
logging instrument
attached to a cable, and pumping an active operating fluid, e.g., water, into
the nozzle of the jet
pump through the pipe string annular space, thus reducing pressure in the
under-packer area and
creating pressure drawdown to the formation, monitoring parameters of the
fluid pumped out of
the formation during the jet pump operation, and equalizing pressures after
stopping the supply
of the active operating fluid by a fluid backflow along the jet pump flow-
through portion.
The above device and the operation method thereof enable to carry out various
process
operations in a well below the jet pump installation level, also by reducing a
pressure differential
above and below the sealing unit. But this device does not enable to use its
possibilities to the
fullest extent due to the impossibility of maintaining a differential pressure
drawdown when the
jet pump is not in operation, which does not enable to survey wells
completely.
Summary of the Invention
The objective of this invention is to prevent a spontaneous backflow of an
active operating fluid
after stopping the jet pump operation, while maintaining a differential
pressure drawdown on a
formation when the jet pump is not in operation.
The technical effect achieved by this invention consists in improving the
reliability and
productivity of a well jet device during well testing and optimizing the
operational procedure
during testing wells.
In respect of the device, as a subject matter of the invention, the stated
technical problem can be
solved due to the fact that the proposed well jet device comprises a jet pump
installed on a pipe
string and a packer with an axial passage opening, an active nozzle and a
mixing chamber with a
diffuser being arranged in alignment in the jet pump body, and the said body
also has a stepped
through channel with a mounting seat between steps, a channel for supplying a
medium pumped
out of a well, which communicates below the mounting seat through lateral
holes made in the jet
pump body to the stepped through channel, and a channel for supplying an
active operating fluid,
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which communicates to the active nozzle on its outlet end and to the pipe
string annular space on
its inlet end, the channel for supplying a pumped out medium communicating to
the pipe string
below the stepped through channel via a check valve, and the stepped through
channel providing
the possibility of installing a sealing unit which is made as a hollow stepped
cylindrical housing
which upper part comprises a sealing element and below, in the cavity, a
stepped piston is
arranged, which abuts against a shoulder made in the sealing unit housing and
is spring-loaded
against the sealing element; holes are made in the wall of the sealing unit
housing opposite to the
lateral holes made in the jet pump body, and the stepped piston in its lower
position closes the
holes in the wall of the sealing unit housing, and in the stepped piston upper
position the channel
for supplying a medium pumped out of a well is communicated to the pipe string
below the jet
pump body via the lateral holes in the jet pump body and the holes made in the
wall of the
sealing unit housing; axial channels, which are in alignment, are made in the
stepped piston and
the sealing element for the purpose of passing a logging cable therethrough
which serves for
suspending a logging instrument with the use of a cable head and below the jet
pump body; a
check valve is installed in the channel for supplying an active operating
fluid; and the diameter
of the stepped through channel below the mounting seat is not less than the
diameter of the axial
through opening of the packer.
In respect of the method, as a subject matter of the invention, the stated
technical problem can be
solved due to the fact that the method of operating the proposed well jet
device includes:
assembling a pipe string by arranging a jet pump and a packer on the pipe
string, lowering the
whole assembly into a well, releasing the packer, supplying a pressurized
hydrofracturing fluid
or an acid solution via the pipe string into a producing formation, lowering a
sealing unit with the
use of a logging cable, together with a logging instrument attached to a
logging cable head,
installing the sealing unit onto the mounting seat in the stepped through
channel of the jet pump,
arranging the logging instrument in the producing formation area, registering
background values
of physical fields, in particular thermal fields, in rocks along the well hole
during the said
lowering operation, creating differential pressure drawdown onto the producing
formation by
supplying an active operating fluid to the active nozzle with the use of the
jet pump, pumping the
hydrofracturing fluid or products of chemical treatment out of the producing
formation, and
registering, while the jet pump is operated, current values of physical fields
in rocks and those of
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formation fluid coming into the well. During the said registration the logging
cable is moved
along the well hole, including the producing formation, with the use of the
logging cable, then
the jet pump is stopped, and the inner cavity of the pipe string above the jet
pump together with
the annular space above the packer is separated from the inner cavity of the
pipe string under the
jet pump together with the under-packer space with the use of the check valve
installed in the
channel for supplying a pumped out medium, thus maintaining a reduced
bottomhole pressure
and registering a formation pressure-restoration curve with the use of the
logging instrument.
Then, the logging instrument is lifted up with the use of the logging cable,
and the stepped piston
is pressed by the cable head from below for moving it up and communicating the
well under-
packer space to the pipe string inner cavity above the jet pump and the well
annular space above
the packer via the holes made in the sealing unit housing and the lateral
holes made in the jet
pump body, thus equalizing pressures above and under the packer, and then the
logging
instrument together with the sealing unit is moved out of the well.
An analysis of various designs shows that the operation reliability may be
improved by
increasing the functional capabilities of the proposed device used for testing
and developing
wells.
It has been found that the above-described set of the well jet device elements
enables to organize
an operational procedure most efficient for using equipment arranged on the
pipe string when
carrying out logging works on surveying, testing and developing producing
formations in rocks.
It also creates conditions both for obtaining full and reliable information on
producing
formations and for carrying out treatments of producing formations during a
survey. The
proposed well jet device enables to create several differential pressure
drawdown values at a
given differential pressure by using a jet pump in the under-packer area of a
well, and use a
logging instrument for registering pressure, temperature and other physical
parameters of a well
itself and a medium pumped out of it, surveying and testing a well, and
register a formation
pressure-restoration curve in the under-packer space of a well without using a
special functional
insert. However, in a number of cases where only a survey is conducted or a
producing formation
is treated with the use of a logging instrument, e.g., in a case of treating a
producing formation
with physical fields, in particular with ultrasound, it is insufficient for
intensifying an inflow
from a producing formation.
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Providing the well jet device with check valves in the channels for supplying
an active operating
fluid and a pumped out fluid, in combination with making the diameter of the
stepped through
channel below the mounting seat not less than the diameter of the axial
through opening of the
packer, enables to supply chemical reagents or a hydrofracturing fluid via the
pipe string without
using any additional tools or functional inserts on the pipe string and
improve the work
efficiency, wherein the check valves prevent media pumped into a producing
formation from
entering into the well annular space above the packer during pumping
operations. The above-said
relation between the diameters of the stepped through channel and the axial
through opening of
the packer is very important. Making the diameter of the stepped through
channel not less than
the diameter of the axial through opening of the packer is necessary for
obtaining the possibility
of lowering a logging instrument into the well under-packer area for the
purposes of treating a
formation with physical fields (treating with ultrasound or creating, e.g., a
thermal field) and
reducing hydraulic resistance both when pumping various media into a producing
formation and
for pumping a produced medium out of a producing formation after a
differential pressure
drawdown on such a producing formation is created. At the same time, it
becomes possible to
monitor a differential pressure drawdown value by controlling the rate of
supplying an active
operating fluid. During testing formations it is possible to adjust pumping
modes by changing the
pressure of an active operating fluid supplied to the active nozzle of the jet
pump. Also, a
spontaneous backflow of an operating fluid into the under-packer area is
precluded both when
the jet pump is operated and is not operated.
The result is intensification of works on surveying and developing wells,
which enables to carry
out surveying and testing wells after drilling and during overhauling with
good quality, and
prepare well for operation by comprehensively surveying and testing then in
different modes,
thus improving the reliability of well jet device operation.
Brief Description of the Drawings
Fig. I shows a longitudinal section of the proposed well jet device without a
sealing unit and a
logging instrument.
Fig. 2 shows a longitudinal section of the proposed well jet device with a
sealing unit and a
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logging instrument that are arranged in the area of a producing formation.
Fig. 3 shows a longitudinal section of the proposed well jet device during
preparing it for lifting
up a logging instrument and a sealing unit to the surface.
Description of the Preferred Embodiment
The proposed well jet device comprises a jet pump 2 and a packer 3, which are
arranged on a
pipe string 1, an active nozzle 5 and a mixing chamber 6 with a diffuser being
installed in
alignment in the body 4 of the jet pump 2, the said body also includes a
stepped through channel
7 with a mounting seat 8 between steps, a channel 9 for supplying a medium
pumped out of a
well, which is connected via lateral holes 10 made in the body 4 of the jet
pump 2 to the stepped
through channel 7 below the mounting seat 8, and a channel 11 for supplying an
active operating
fluid, which is connected on its outlet end to the active nozzle 5 and on its
inlet end to the
annular space around the pipe string 1. The channel 9 for supplying a pumped
out medium is
connected via a check valve 12 to the pipe string 1 below the stepped through
channel 7, the
latter providing the possibility of installing a sealing unit 13 made as a
hollow stepped
cylindrical housing 14 which upper part is used for arranging a sealing
element 15, and a stepped
piston 17, which is spring-loaded against the sealing element 15 by means of
spring 18, is
arranged below the sealing element 15 so as to rest against annular step 16
made in the housing
14 of the sealing unit 13. Holes 19 are made in the housing 14 of the sealing
unit 13 opposite to
the lateral holes made in the body 4 of the jet pump 2. The stepped piston 17
in its lower position
closes the holes 19 in the housing 14 of the sealing unit 13 and in its upper
position the channel 9
for supplying a pumped out medium is connected via the lateral holes 10 in the
housing 4 of the
jet pump 2 and the holes 19 in the housing 14 of the sealing unit 13 to the
pipe string I below the
body 4 of the jet pump 2. Aligned axial chambers for passing through them a
logging cable 20
are made in the stepped piston 17 and the sealing element 15, and a logging
instrument 22 is
suspended on the cable 20 below the body 4 of the jet pump 2 with the use of a
cable head 21 in
such a way that the instrument 22 may be moved along a well and be disposed in
the area of a
producing formation 23. A check valve 24 is installed in the channel 11 for
supplying an active
operating fluid; the packer 3 is provided with an axial through opening 25;
and the diameter d of
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the stepped through channel 7 below the mounting seat 8 is less than the
diameter D of the axial
through opening 25 in the packer 3.
The operation method of the proposed well jet device can be carried out as
follows. The pipe
string 1 is assembled by installing the jet pump 2 and the packer 3 on the
pipe string 1. The
assembly is lowered into a well, and the packer 3 is released. A
hydrofracturing fluid or an acid
solution is supplied under pressure via the pipe string 1 to the producing
formation 23, and the
sealing unit 13 is lowered into the well on the logging cable 20 with the
logging instrument 22
attached to the cable 20 through the cable head 21. The sealing unit 13 is
installed on the
mounting seat 8 in the stepped through channel 7 of the jet pump 2, and the
logging instrument
22 is arranged in the area of the producing formation 23. During the lowering
operation the
logging instrument 22 is used for registering background values of physical
fields, in particular
thermal fields, in rocks along the well hole. Then, the hydrofracturing fluid
or products of
chemical treatment of the producing formation are pumped out of the producing
formation 23 by
the jet pump 2 by supplying an active operating fluid through the annular
space around the pipe
string 1 and into the active nozzle 5. After that, when the jet pump 2 is
operated, current values
of physical fields in rocks and a formation fluid coming into the well are
registered, and during
such registration the logging instrument 22 is moved along the well hole,
including the
producing formation 23, with the use of the logging cable 20. Then, the jet
pump 2 is stopped,
and the inner cavity of the pipe string 1 above the jet pump 2 with the
annular space above the
packer 3 is separated from the inner cavity of the pipe string 1 below the jet
pump 2 with the
under-packer space by using the check valve 12 in the channel 9 for supplying
a pumped out
medium, thus maintaining a reduced bottomhole pressure and registering a
formation pressure
restoration curve under the packer 3 by using the logging instrument 22. Then,
the logging
instrument 22 is lifted up with the use of the logging cable 20, and the
stepped piston 17 is
pressed from below by the cable head 21 for moving the piston up, thus
communicating the well
under-packer space to the inner cavity of the pipe string 1 above the jet pump
2 and the well
annular space above the packer via the holes 19 in the housing 14 of the
sealing unit 13 and the
lateral holes 10 in the body 4 of the jet pump 2, thus equalizing pressures
above and under the jet
pump 2, and then the logging instrument 22 with the sealing unit 13 are moved
out of the well.
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Industrial Applicability
The proposed invention may be used in the oil and gas industry for developing
wells after
drilling or during logging operations in any types of wells.
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