U.S. patent application number 11/755319 was filed with the patent office on 2007-11-29 for process and device for generating signals which can be transmitted in a well.
This patent application is currently assigned to PRECISION ENERGY SERVICES GMBH. Invention is credited to Hermann Jungerink.
Application Number | 20070274844 11/755319 |
Document ID | / |
Family ID | 33038989 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070274844 |
Kind Code |
A1 |
Jungerink; Hermann |
November 29, 2007 |
PROCESS AND DEVICE FOR GENERATING SIGNALS WHICH CAN BE TRANSMITTED
IN A WELL
Abstract
In a process for generating signals which can be transmitted
from above ground to a receiver located below ground in a well, the
volume flow of a fluid pump (1) arranged above ground, which
conveys fluid from a fluid tank (8) through the interior of a drill
string to the bottom of a well, is temporally changed. The temporal
change of the volume flow of the fluid pump (1) is caused by a
change of the drive speed of the fluid pump (1), with the drive
speed not falling below a minimum speed for maintaining a minimum
volume flow.
Inventors: |
Jungerink; Hermann;
(Isernhagen, DE) |
Correspondence
Address: |
WONG, CABELLO, LUTSCH, RUTHERFORD & BRUCCULERI,;L.L.P.
20333 SH 249
SUITE 600
HOUSTON
TX
77070
US
|
Assignee: |
PRECISION ENERGY SERVICES
GMBH
Eddesser Strasse 1
Edemissen
DE
D-31234
|
Family ID: |
33038989 |
Appl. No.: |
11/755319 |
Filed: |
May 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10818650 |
Apr 6, 2004 |
|
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|
11755319 |
May 30, 2007 |
|
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Current U.S.
Class: |
417/326 ;
417/364; 417/375; 417/410.1; 417/481 |
Current CPC
Class: |
E21B 47/18 20130101 |
Class at
Publication: |
417/326 ;
417/364; 417/375; 417/410.1; 417/481 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 2003 |
DE |
10316515.0 |
Claims
1. A method for transmitting signals from above ground to a
receiver located below: ground in a well, the method comprising:
temporarily changing the drive speed of an above-ground fluid pump
that conveys fluid to a bottom of a well through an interior
portion of a drill string, thereby changing the volume flow of the
fluid pump; wherein the change of volume flow comprises a signal
detectable by the receiver located below ground in the well; and
wherein the drive speed is maintained above a minimum speed so as
to maintain a minimum fluid flow.
2. The method of claim 1, wherein the temporary changes of the
drive speed of the fluid pump are synchronized to maintain a
constant average fluid flow.
3. The method of claim 1, wherein the temporary changes of the
drive speed of the fluid pump have a frequency of less than 1
Hertz.
4. The method of claim 1 wherein the pump is a reciprocating
pump.
5. The method of claim 1 wherein the pump is driven by an electric
motor.
6. The method of claim 1 wherein the pump is driven by a diesel
engine.
7. The method of claim 6 wherein the diesel engine speed is varied
to change the drive speed of the pump.
8. The method of claim 6 wherein a hydraulic converter is used to
change the drive speed of the pump.
9. A device for transmitting signals from above ground to a
receiver located below ground in a well, the device comprising: an
above-ground fluid pump that conveys fluid to a bottom of a well
through an interior portion of a drill string; a value transmitter
adapted to modulate a drive speed of the fluid pump, thereby
changing the volume flow of the fluid pump, in response to a signal
intended for transmission to the receiver located below ground in
the well; wherein the change of volume flow comprises a signal
detectable by the receiver located below ground in the well; and
wherein the drive speed is maintained above a minimum speed so as
to maintain a minimum fluid flow.
10. The device of claim 9, wherein the signal intended for
transmission to the receiver located below ground in the well is
generated by a manually operable voltage divider.
11. The device of claim 9, wherein the signal intended for
transmission to the receiver located below ground in the well is
generated by an analog curve shape generator.
12. The device of claim 9, wherein the signal intended for
transmission to the receiver located below ground in the well is
generated by a computer that generates the modulation via
software.
13. The device of claim 12 wherein the computer emits said
modulation as an analog signal.
14. The device of claim 12 wherein the computer emits said
modulation as a digital signal.
15. The device of claim 9 wherein the pump is a reciprocating
pump.
16. The device of claim 9 wherein the pump is driven by an electric
motor.
17. The device of claim 9 wherein the pump is driven by a diesel
engine.
18. The method of claim 17 wherein the diesel engine speed is
varied to change the drive speed of the pump.
19. The method of claim 17 wherein a hydraulic converter is used to
change the drive speed of the pump.
20. A device for transmitting signals from above ground to a
receiver located below ground in a well, the device comprising: an
above-ground fluid pump that conveys fluid to a bottom of a well
through an interior portion of a drill string; and means for
varying the speed of the fluid pump, thereby changing the volume
flow of the fluid pump, whereby the changing volume flow comprises
a signal to the receiver.
Description
[0001] The invention relates to a process for generating signals
which can be transmitted from above ground to a receiver located
below ground in a well, wherein the volume flow of a fluid pump
arranged above ground, which conveys fluid from a fluid tank
through the interior of a drill string to the bottom of a well, is
temporally changed. The invention furthermore relates to a device
for executing this process.
[0002] In a process of the aforementioned type known from U.S. Pat.
No. 5,332,048, the volume flow of the fluid generated by the fluid
pump is changed by successively switching the fluid pump on and
off. This process has, however, the disadvantage that it is
time-consuming and requires an interruption to the drilling
operation. There is also the risk that, during the interruption of
the fluid current, cuttings may be deposited as a result of which
the continuation of the drilling operation is impeded.
[0003] It is furthermore known from EP 0 744 527 B1, for
transmitting information present above ground to an information
receiver located below ground in a well during the drilling
operation, to change the volume flow of the fluid generated by the
fluid pump so that in a region downstream of the fluid pump a
partial flow is diverted from the principal flow of the fluid pump
and is returned into the fluid tank. This process is associated
with significant energy losses, as, owing to the conveying height
of the fluid pump, the diverted partial flow has a significant
energy content which cannot be recouped at reasonable cost.
[0004] A process for signal generation by changing the volume flow
of a fluid pump is known from U.S. Pat. No. 5,113,379, wherein a
diverted partial flow of the volume flow conveyed by the fluid pump
is received by a buffer reservoir and is then returned from this
into the principal flow with the aid of a second pump. This process
has the disadvantage that it requires significant equipment
costs.
[0005] Furthermore, owing to the limited holding capacity of the
buffer reservoir, only a very short volume flow change with limited
amplitude can be achieved with this known process.
[0006] The object of the invention is to disclose a process of the
aforementioned type which can be executed without interruption of
the drilling operation, which does not cause any high energy losses
and whose execution is possible with comparatively low equipment
costs.
[0007] The object is achieved according to the invention by the
process disclosed in claim 1 and by the device disclosed in claim
9. Advantageous embodiments of the process and of the device are
disclosed in the subclaims associated with these claims in each
case.
[0008] According to the process according to the invention, the
temporal change of the volume flow of the fluid pump is caused by a
change of the drive speed of the fluid pump which does not fall
below a minimum speed for maintaining a minimum fluid flow.
[0009] The process according to the invention is based on the
knowledge that the volume flow of fluid pumps is substantially
proportional to the pump speed. In order to achieve a temporal
change of the volume flow of the fluid pump, it is thus only
necessary to decrease or to increase the speed of the fluid pump in
proportion to the required volume flow change. So that a signal,
which is based on a change of the volume flow of the fluid pump,
can still be received without errors below ground, a change of the
volume flow is generally required, for instance, of 15% for a
period of, for instance, 10 seconds. To generate a signal of this
type it is thus sufficient to decrease the pump speed by 15% for
the said period and then to increase the pump speed to the original
value again. Speed changes of this type can be easily achieved with
the conventional fluid pumps by controlling their drive
accordingly. The required changes of the volume flow are also of a
magnitude which can be achieved without significant disruption of
the drilling operation.
[0010] The process according to the invention offers the
opportunity to temporarily increase the pump speed after a
reduction above the previously set normal value, in order to thus
compensate for the volume flow loss caused by the reduction and to
maintain on average a constant volume flow. A procedure of this
type can be important for practical drilling reasons in order to
prevent disruptions caused by inadequate transportation of the
cuttings.
[0011] According to a further embodiment of the process according
to the invention, the temporal changes of the pump speed and thus
of its principal flow lie in frequency ranges below 1 hertz. This
has the advantage that higher frequency telemetric signals are not
distorted, so that transmission of signals of this kind via the
drilling fluid in the drill string in the opposing direction, that
is, from below ground to above ground is simultaneously possible.
Furthermore, low frequency current changes with respect to the
transmission ratios in the drill string are attenuated less
strongly. The changes of the volume flow required to generate a
signal which can be received without errors can thus be of less
intensity.
[0012] Significant energy losses do not occur in the process
according to the invention. The efficiency of conventional fluid
pumps changes only slightly in the event of changes of the drive
speed of a magnitude of up to 30%. The acceleration and
deceleration of the moving masses also does not lead to significant
losses, as the deceleration work helps to convey the fluid and
relieves the drive of the fluid pump accordingly.
[0013] The invention will be described in more detail hereinafter
with reference to the embodiments shown in the drawings, in
which:
[0014] FIG. 1 shows a typical drilling rig,
[0015] FIG. 2 shows the general integration of a device for
directly influencing the speed of the fluid pump,
[0016] FIG. 3 shows a version of a pump drive with a direct current
motor with integration of the device for influencing the speed,
[0017] FIG. 4 shows a version of a pump drive with a three-phase
alternating current motor with integration of the device for
influencing the speed,
[0018] FIG. 5 shows a version of a pump drive with a diesel motor
and a hydraulic torque converter with integration of the device for
influencing the speed,
[0019] FIG. 6a to 6d show possible signal shapes of the generated
telemetric signal and
[0020] FIG. 7 shows a possible electric embodiment of the
integration of the signal for changing the speed.
[0021] FIG. 1 shows a typical rig for deep drilling. A fluid pump 1
is driven by an appropriate drive 2. This can be electric or other
motors, for example, diesel motors, with appropriate transmission
devices. Accordingly, the required drive energy 3 can be supplied
electrically or deriving from a combustible fuel. In order to
generate the pumping rate required for drilling, that is, the
required volume flow of fluid, the pump speed can be controlled via
a desired value transmitter 4 acting electrically, hydraulically or
pneumatically on the control unit of the drive 2.
[0022] The fluid flow is pumped via the interior of the drill
string 5 to the drill head 6 and flows into the annular chamber 7
back to the surface and from there into the reservoir tank 8. For
drilling, the drill string 5 is rotated by a rotary table 30 of a
rotary drive, which is driven by a motor 31 via a coupling 32.
Alternatively, a fluid-driven well motor can also be provided at
the drill head to drive the drill bit.
[0023] At the lower end of the drill string 5 there is a receiver 9
of a measuring and/or control device which is supposed to receive
data from the surface and possibly transmits data to the surface
itself, these signals being generated, for example via modulation
of the fluid flow, as is known from many examples of deep drilling
measuring devices with wireless data transmission.
[0024] FIG. 2 shows the fluid pump 1 with its drive 2 which, via a
rotational movement with a defined speed, ensures that the pumping
rate for the well required for drilling is generated. The required
speed is adjusted via the desired value transmitter 4. A signal
generator 10 for generating signals, which can be transmitted to
the below ground receiver 9, changes the desired value 11 required
for drilling with a control signal 12 in an interface 13 in such a
way that desired value change 14 transmitted to the drive 2
controls the drive speed 15 of the fluid pump 1 in such a way that
the temporal changes of the volume flow 16 of the fluid pump 1
required by the signal generator 10 result. The reciprocating pumps
which are predominantly used with fluid pumps directly convert a
speed change into a linearly proportional change of the volume
flow, this volume flow change being accompanied by a pressure
change acting in the same direction owing to the constant flow
resistance of the overall system. The signal generator 10 can be,
for example, a manually operable voltage divider, an analog curve
shape generator or a computer, which generates the required
modulation via software and emits said modulation via
digital/analog conversion as electric analog voltage or directly as
a digital signal.
[0025] FIG. 3 shows a concrete embodiment of a pump drive with a
direct current motor 17 as can be found on many drilling rigs. The
direct current motor 17 is fed via a direct current converter 18
which converts the drive energy 3 in the form of an electric
alternating voltage 19 (typically, three-phase) into a direct
voltage 20 with a controllable amplitude. The speed of the motor 17
is controlled by changing the direct voltage amplitude, which
causes a linearly proportional regulation of the volume flow 16 of
the fluid pump 1. With the desired value transmitter 4, typically
for achieving the volume flow 16 required for drilling, an electric
control signal is set as a desired value 11 (voltage e.g. 0 to 10
volts or current e.g. 4 to 20 mA or a digital desired value), said
electric control signal controlling the output voltage of the
direct current converter 18 (SCR=silicon controlled rectifier). For
signal generation, the signal generator 10 changes the electric
desired value 11 with a control signal 12 in the interface 13 in
its percentage range in such a way that, owing to the desired value
change 14, the direct current converter 18 undertakes a change of
the drive direct voltage for the motor 17 during the time of the
required volume flow change, as a result of which the motor speed
15 and thus the volume flow 16 is synchronously modulated with the
influenced desired value voltage 14.
[0026] FIG. 4 shows a different conventional embodiment of a pump
drive. A three-phase alternating current motor 21 is fed via a
frequency converter 22 which converts the electric alternating
current of a fixed frequency 23 (typically, three-phase) into an
alternating current (typically, three-phase) with a controllable
frequency 24. The speed of the motor 21 is controlled by changing
the frequency 24 of this alternating current, which causes a
linearly proportional regulation of the volume flow 16 of the fluid
pump 1. With the desired value transmitter 4, again for achieving
the pumping rate required for drilling, the desired value 11 of an
electric control signal is set (voltage e.g. 0 to 10 volts or
current e.g. 4 to 20 mA or a digital desired value), said electric
control signal controlling the frequency 24 of the supply voltage
for the three-phase alternating current motor 21. The signal
generator 10 now changes this electric desired value 11 in the
interface 13 in its percentage range in such a way that the
frequency converter 22 undertakes a change of the frequency 24 of
the motor supply voltage during the time of the required volume
flow change, as a result of which the motor speed 15 and thus the
volume flow 16 is synchronously modulated with the influenced
desired value voltage.
[0027] FIG. 5 shows a further drive configuration for a fluid pump
1 to be found on drilling rigs. In this instance, a diesel motor 25
directly drives the pump 1 via an appropriate coupling 26 and a
hydraulic converter 27 for speed regulation, without intermediate
conversion of the mechanical energy into electric energy. Here, the
speed 15 at the drive shaft of the pump required to achieve the
volume flow required for drilling is achieved by controlling the
speed of the diesel motor 25 or by controlling the hydraulic
converter 27. Regulation of the desired values 11 and 11a by the
desired value transmitter 4 on the drilling platform is generally
caused in this instance not electrically, but hydraulically or
pneumatically. Accordingly, the interface 13 must convert the
electric control signals 12 generated by the signal generator 10
into corresponding hydraulic or pneumatic signal changes. This is
possible, for example, with the aid of electrically controlled
proportional valves. The speed of the diesel motor and/or, if
required, the hydraulic torque converter is now controlled with the
desired values 14, 14a influenced by the interface 13.
[0028] FIGS. 6a to 6d show as examples different signal shapes
which can be generated with the disclosed process and the disclosed
devices. In the examples shown, a pulse code modulation is always
shown as a modulation process. Here, the position of a "pulse",
that is, a change of the volume flow V of the fluid pump 1 in the
time t, defines the data content relative to a fixed reference
time. However, analogously to the examples shown, any other
modulation process can also be used, for example, amplitude
modulation or a combination of a plurality of modulation
processes.
[0029] The choice of which of the signal shapes shown as examples
is used is defined inter alia by the transmission characteristics
of the signal transmission path, the well with the drill string and
by the reception properties of the receiver.
[0030] FIG. 6a shows a trapezoidal signal shape as a simple basic
pattern. The pump speed n is decreased incrementally by several per
cent, remains for some time at this reduced speed and then
increases at the end of the signal back to the original desired
value required for drilling.
[0031] In FIG. 6b, the signal shape of 6a is refined in such a way
that the speed n or volume flow V reduced for some time is followed
by a speed slightly above the desired speed for some time, so that
on average volume flow V remains constant, which may be
advantageous or necessary for drilling.
[0032] In FIG. 6c, the signal shape is further refined: it now has
a sinusoidal shape. This signal shape has less harmonic distortion,
as a result of which a possible telemetric connection in the
opposing direction which operates on a higher frequency band is
less distorted.
[0033] FIG. 6d shows a further signal shape with low harmonic
distortion; it follows the time function sinus(x)/x, a function
frequently used in signalling technology.
[0034] The signal shapes shown are to be understood as examples
only. Virtually any signal shapes can be generated with the
disclosed process and the disclosed device, so that the optimal
shape can be selected depending on the given marginal
conditions.
[0035] FIG. 7 shows as an example the concrete embodiment of an
interface 13 with which the desired value 11 from the desired value
transmitter 4 from FIG. 3 or 4 is modulated by a signal 12 of the
signal generator 10. In this instance, the desired value 11
required for drilling is an electric voltage between, for example,
0 and 10 volts, corresponding to the desired speeds 0 and n-max and
the pumping rates 0 and Vmax. In this example, the modulation
signal 12, which is also present as electric voltage, should also
be able to assume values between 0 and 10 volts, wherein at 5 volts
the speed required by the desired value 11 should be transmitted
without change, at 0 volts, the speed should be decreased by 20%
and at 10 volts increased by 20%. With the elements shown, this
function can be achieved by conventional electronics components,
the modulation signal first being decreased by the factor 2.5 with
a simple voltage divider 28 and then added to a fixed offset
voltage U0, in this instance, 8V. This occurs, for example, with a
simple operational amplifier stage.
[0036] The voltage Ub thus achieved is now linked to the original
desired value voltage Ua according to the function (UaxUb)/10 in an
analog multiplier stage, comprising, for example, the integrated
switching circuit RC4200 with corresponding resistance wiring. The
modulated output signal thus achieved then passes as a changed
desired value 14 to the control unit of the pump drive, which
generates the required speed from it. If, for example, the desired
value 11 has a voltage of 7 volts corresponding to a required speed
of 70% of n-max, the modulation signal 12 has a voltage of 10
volts, corresponding to a required increase of the speed of 20%,
then the signal Ub is 10V/2.5+8V=12V. The multiplier stage
generates 7V.times.12V/10V=8.4V from this, corresponding to 84% of
n-max, that is, a 20% increase of the required speed of 70% of
n-max. Here, the disclosed interface 13 is obviously shown in a
simplified form; the concrete embodiment is, however, generally
known from the prior art of semiconductor technology.
[0037] Analogously to this example, the interface 13 can, however,
also be configured with control currents instead of with control
voltages, with digital signals or with other physical (e.g.
hydraulic or pneumatic) signals.
[0038] Instead of the multiplicative influence shown, an additive
influence or a non-linear influence can also be produced if this is
advantageous for operational reasons.
[0039] According to a further embodiment of the invention, an
analog process for generating signals which can be transmitted from
above ground to a receiver located below ground in a well comprises
the temporal change of the speed of the drill string during rotary
drilling. In the same way as disclosed above with respect to the
modulation of the fluid flow for data transmission, a modulation of
the rotational speed of the drill string during rotary drilling to
generate signals which can be transmitted can also occur. In this
instance, drive embodiments as disclosed above for pump drives can
be developed analogously for rotary drives also. In many cases, the
drive techniques for drill string rotary drives are identical to
those of pump drives, it also being possible to use direct current
motors, three-phase alternating current motors and diesel motors
with corresponding traction elements. As a result, with the devices
disclosed above, for example, with the deep drilling rig shown in
FIG. 1, the speed of the motor 31 and thus the angular velocity of
the drill string 5 driven by the rotary table 30 can be temporally
changed in such a way that the change is received below ground in
the receiver by appropriate speed sensors. Single or multiple axis
magnetometers or accelerometers, for example, are suitable as
sensors of this kind.
* * * * *