U.S. patent application number 15/252412 was filed with the patent office on 2017-03-16 for sensing cavitation-related events in artificial lift systems.
The applicant listed for this patent is Weatherford Technology Holdings, LLC. Invention is credited to Manish AGARWAL, Michael C. KNOELLER, Ross E. MOFFETT, Bryan A. PAULET, Toby PUGH.
Application Number | 20170074089 15/252412 |
Document ID | / |
Family ID | 58236625 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170074089 |
Kind Code |
A1 |
AGARWAL; Manish ; et
al. |
March 16, 2017 |
SENSING CAVITATION-RELATED EVENTS IN ARTIFICIAL LIFT SYSTEMS
Abstract
Methods and apparatus are provided for sensing a
cavitation-related event in an artificial lift system for
hydrocarbon production and operating the system based on the sensed
event. One example method of operating an artificial lift system
for a wellbore generally includes monitoring the wellbore for an
indication (e.g., an acoustic or vibrational indication) of an
event associated with cavitation in the artificial lift system and
adjusting at least one parameter of the artificial lift system if
the event is detected. One example system for hydrocarbon
production generally includes an artificial lift system for a
wellbore and at least one sensor configured to detect an indication
of an event associated with cavitation in the artificial lift
system.
Inventors: |
AGARWAL; Manish; (Cypress,
TX) ; MOFFETT; Ross E.; (Kingwood, TX) ;
KNOELLER; Michael C.; (Humble, TX) ; PUGH; Toby;
(Arlington, TX) ; PAULET; Bryan A.; (Spring,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Weatherford Technology Holdings, LLC |
Houston |
TX |
US |
|
|
Family ID: |
58236625 |
Appl. No.: |
15/252412 |
Filed: |
August 31, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62216812 |
Sep 10, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/126 20130101;
E21B 47/12 20130101; E21B 43/124 20130101; E21B 47/008 20200501;
E21B 43/121 20130101 |
International
Class: |
E21B 47/12 20060101
E21B047/12; E21B 43/12 20060101 E21B043/12; E21B 47/00 20060101
E21B047/00 |
Claims
1. A method for operating an artificial lift system for a wellbore,
comprising: monitoring the wellbore for an indication of an event
associated with cavitation in the artificial lift system; and
adjusting at least one parameter of the artificial lift system if
the event is detected.
2. The method of claim 1, wherein the event comprises an onset of
the cavitation occurring.
3. The method of claim 1, wherein the event comprises the
cavitation occurring.
4. The method of claim 1, wherein the monitoring comprises using at
least one sensor to detect the indication.
5. The method of claim 1, wherein the adjusting comprises removing
a fluid pump of the artificial lift system from the wellbore.
6. The method of claim 5, wherein the adjusting further comprises:
inspecting the fluid pump for cavitation damage; and if the damage
is present, replacing the fluid pump or one or more components of
the fluid pump.
7. The method of claim 5, wherein the adjusting further comprises
replacing at least one component of the fluid pump with another
component to avoid cavitation damage in subsequent wellbore
operation.
8. The method of claim 7, wherein the fluid pump is a hydraulic jet
pump, the at least one component is a first throat, the other
component is a second throat, and the second throat has a different
size than the first throat.
9. The method of claim 1, wherein the adjusting is performed before
the cavitation occurs in the artificial lift system.
10. The method of claim 1, wherein the at least one parameter
comprises a production rate by the artificial lift system.
11. The method of claim 1, wherein the adjusting comprises stopping
production by the artificial lift system.
12. The method of claim 11, further comprising resuming production
after a sufficient time for fluid to settle in the wellbore.
13. The method of claim 1, wherein the adjusting comprises
outputting a signal.
14. A system for hydrocarbon production, comprising: an artificial
lift system for a wellbore; and at least one sensor configured to
detect an indication of an event associated with cavitation in the
artificial lift system.
15. The system of claim 14, wherein the at least one sensor is
configured to detect the event before the cavitation occurs in the
artificial lift system.
16. The system of claim 14, wherein the artificial lift system
comprises a downhole fluid pump disposed in the wellbore.
17. The system of claim 16, wherein the downhole fluid pump is a
hydraulic jet pump that comprises a nozzle and a throat, wherein
fluid is passed through the nozzle into the throat.
18. The system of claim 16, wherein the at least one sensor is
coupled to the downhole fluid pump.
19. The system of claim 14, further comprising a wellhead, wherein
the at least one sensor is positioned at the wellhead.
20. The system of claim 14, wherein the at least one sensor is
positioned in the wellbore.
21. The system of claim 14, wherein the event comprises an onset of
the cavitation occurring.
22. The system of claim 14, wherein the at least one sensor
comprises at least one of a microphone, an accelerometer, or a
gyroscope.
23. A non-transitory computer-readable medium containing a program
which, when executed by a processing system, causes the processing
system to perform operations comprising: monitoring a wellbore for
an indication of an event associated with cavitation in an
artificial lift system; and adjusting at least one parameter of the
artificial lift system, if the event is detected.
24. The computer-readable medium of claim 23, wherein the event
comprises an onset of the cavitation occurring.
25. The computer-readable medium of claim 23, wherein the event
comprises the cavitation occurring.
26. The computer-readable medium of claim 23, wherein the program
causes the processing system to perform the adjusting before the
cavitation occurs in the artificial lift system.
27. The computer-readable medium of claim 23, wherein the at least
one parameter comprises a production rate by the artificial lift
system.
28. The computer-readable medium of claim 23, wherein the adjusting
comprises stopping production by the artificial lift system.
29. The computer-readable medium of claim 28, wherein the
operations further comprise: resuming production after a sufficient
time for fluid to settle in the wellbore.
30. The computer-readable medium of claim 23, wherein the adjusting
comprises outputting a signal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present Application for Patent claims priority to U.S.
Provisional Application No. 62/216,812, filed Sep. 10, 2015, which
is assigned to the assignee of the present application and hereby
expressly incorporated by reference herein in its entirety.
BACKGROUND
[0002] Field of the Disclosure
[0003] Certain aspects of the present disclosure generally relate
to hydrocarbon production using artificial lift and, more
particularly, to sensing an event associated with cavitation in an
artificial lift system.
[0004] Description of the Related Art
[0005] Several artificial lift techniques are currently available
to initiate and/or increase hydrocarbon production from drilled
wells. These artificial lift techniques include rod pumping,
plunger lift, gas lift, hydraulic lift, progressing cavity pumping,
and electric submersible pumping, for example.
[0006] Sensors are often used to monitor various aspects when
operating artificial lift systems. For example, U.S. Pat. No.
6,634,426 to McCoy et al., entitled "Determination of Plunger
Location and Well Performance Parameters in a Borehole Plunger Lift
System" and issued Oct. 21, 2003, describes monitoring acoustic
signals in the production tubing at the surface to determine depth
of a plunger based on sound made as the plunger passes by a tubing
collar recess.
SUMMARY
[0007] Certain aspects of the present disclosure provide a method
for operating an artificial lift system for a wellbore. The method
generally includes monitoring the wellbore for an indication of an
event associated with cavitation in the artificial lift system and
adjusting at least one parameter of the artificial lift system if
the event is detected.
[0008] Certain aspects of the present disclosure provide a system
for hydrocarbon production. The system generally includes an
artificial lift system for a wellbore and at least one sensor
configured to detect an indication of an event associated with
cavitation in the artificial lift system.
[0009] According to certain aspects, the sensor is configured to
detect the event before the cavitation occurs in the artificial
lift system.
[0010] [000s] According to certain aspects, the artificial lift
system includes a downhole fluid pump disposed in the wellbore. For
certain aspects, the fluid pump is a hydraulic jet pump. In this
case, the hydraulic jet pump may include a nozzle and a throat,
wherein fluid is passed through the nozzle into the throat.
Cavitation damage may occur to the throat. For certain aspects, the
sensor is coupled to the downhole fluid pump.
[0011] According to certain aspects, the artificial lift system
includes a power fluid pump.
[0012] According to certain aspects, the system further includes a
wellhead. For certain aspects, the sensor is positioned at the
wellhead.
[0013] According to certain aspects, the sensor is positioned in
the wellbore.
[0014] According to certain aspects, the event comprises an onset
of cavitation occurring or actual cavitation occurring.
[0015] According to certain aspects, the indication is an acoustic
or vibrational indication having a frequency of about 5.6 kHz.
[0016] According to certain aspects, the sensor comprises at least
one of a microphone, an accelerometer, or a gyroscope.
[0017] Certain aspects of the present disclosure provide a sensor
configured to detect an indication of an event associated with
cavitation in an artificial lift system.
[0018] According to certain aspects, the sensor is configured for
coupling to a wellhead of the wellbore. For other aspects, the
sensor is configured for positioning in the wellbore. For example,
the sensor may be configured for coupling to a fluid pump of the
artificial lift system.
[0019] According to certain aspects, the sensor comprises a
microphone, an accelerometer, or a gyroscope.
[0020] Certain aspects of the present disclosure provide an
apparatus for operating an artificial lift system for a wellbore.
The apparatus generally includes means for monitoring the wellbore
for an indication of an event associated with cavitation in the
artificial lift system; and means for adjusting at least one
parameter of the artificial lift system, if the event is
detected.
[0021] Certain aspects of the present disclosure provide a
non-transitory computer-readable medium containing a program. The
program, when executed by a processing system, causes the
processing system to perform operations generally including
monitoring a wellbore for an indication of an event associated with
cavitation in an artificial lift system and adjusting at least one
parameter of the artificial lift system, if the event is
detected.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] So that the manner in which the above-recited features of
the present disclosure can be understood in detail, a more
particular description, briefly summarized above, may be had by
reference to certain aspects, some of which are illustrated in the
appended drawings. It is to be noted, however, that the appended
drawings illustrate only certain typical aspects of this disclosure
and are therefore not to be considered limiting of its scope, for
the description may admit to other equally effective aspects.
[0023] FIG. 1 is a conceptual illustration of an example artificial
lift system with a cavitation sensor, in accordance with certain
aspects of the present disclosure.
[0024] FIG. 2 depicts an example downhole portion of an artificial
lift system with a cavitation sensor, in accordance with certain
aspects of the present disclosure.
[0025] FIG. 3 illustrates an example cavitation sensor connected
with a processing system, in accordance with certain aspects of the
present disclosure.
[0026] FIG. 4 is a conceptual illustration of an example fluid pump
for an artificial lift system, in accordance with certain aspects
of the present disclosure.
[0027] FIG. 5 is a flow diagram of example operations for
controlling an artificial lift system, in accordance with certain
aspects of the present disclosure.
DETAILED DESCRIPTION
[0028] Certain aspects of the disclosure provide techniques and
apparatus for monitoring a wellbore for an indication of an event
associated with cavitation in an artificial lift system and
adjusting at least one parameter of the artificial lift system if
the event is detected.
[0029] FIG. 1 is a conceptual illustration of an example artificial
lift system 100. The artificial lift system 100 includes a wellhead
102 coupled to production tubing 104 disposed downhole in a
wellbore 114 and surface machinery 106, generally located at the
surface of the wellbore. A downhole fluid pump 110 may be disposed
in the production tubing 104 in a downhole portion 116 of the
artificial lift system 100, while at the surface, a surface
controller 107 and a power fluid pump 112 may be coupled to the
wellhead 102. The power fluid pump 112 may force power fluid down
the production tubing 104, and, in response, the downhole fluid
pump 110 may force hydrocarbons back up the tubing 104 towards the
surface.
[0030] Artificial lift systems (e.g., system 100) may suffer from
production problems associated with cavitation. Cavitation occurs
when negative gage pressure vapor filled bubbles form in wellbore
fluid and higher pressure in the fluid surrounding the bubbles
causes the bubbles to implode violently. Bubbles can form, for
example, when a pump intake is starved for fluid or when localized
fluid pressure drops below the vapor pressure of the solution.
Micro-jets that may be due to the bubble implosions can cause
severe damage to artificial lift system components. In some cases,
incorrect pump selection (e.g., selecting a pump that generates
enough suction at the pump intake to lower pressure below the vapor
pressure of the solution) can lead to cavitation. In other cases,
altered well conditions (e.g., a change in the fluid entering the
pump intake) can lead to cavitation. Cavitation may damage or even
destroy pumps, thereby reducing artificial lift system efficiency
and sometimes completely disabling an artificial lift system.
[0031] At least two events can be associated with cavitation: onset
of cavitation (also referred to as "incipient cavitation") and
cavitation. Onset of cavitation occurs before cavitation and may be
accompanied by an acoustic indication, such as a loud, high-pitched
noise or a vibrational indication. As an example, the acoustic
indication may have a frequency of about 5.6 kHz, where "about" as
used herein generally refers to a range within .+-.20% of the
nominal value. During onset of cavitation, fluid conditions are
nearly ripe for cavitation to begin occurring, but no
cavitation-related pump damage has occurred. However, once
cavitation occurs, pump damage may be certain and nearly
instantaneous, resulting in a substantial reduction in hydrocarbon
production efficiency.
[0032] Under current artificial lift system operating procedures,
cavitation is only detected post hoc (i.e., after cavitation has
already occurred); there is no procedure for detecting onset of
cavitation. The only indication of a cavitation event is a drop in
production efficiency, and the system production rate may fall
significantly, sometimes to zero. In any case, the system may have
to be shut down or set to a maintenance mode to allow for repairs,
e.g., to a pump or other artificial lift equipment. Before
production at full capacity can be resumed, the downhole fluid pump
may be drawn out of the wellbore, and damaged pump components may
be replaced by other components (or the entire pump may be
replaced). This typically involves waiting for the replacement
components to be shipped, which can result in significant system
downtime and production loss.
[0033] Losses due to cavitation can be reduced if system operating
parameters can be adjusted to prevent cavitation before the
cavitation occurs. Accordingly, techniques and apparatus for
detecting cavitation or an onset of cavitation in an artificial
lift system and adjusting one or more parameters of the artificial
lift system to avoid cavitation damage and production losses are
desired.
[0034] According to aspects of the present disclosure, to help
prevent production loss associated with cavitation, the artificial
lift system 100 may include at least one sensor 108, which may be
positioned at and acoustically, mechanically, and/or otherwise
coupled to the wellhead 102, for example. The sensor 108 is
configured to detect an indication of an event associated with
cavitation (e.g., that actual cavitation is occurring or an onset
of cavitation). For example, the sensor 108 may be a microphone, an
accelerometer or other vibrational sensor, or a gyroscope
configured to detect vibrations or other indications of cavitation.
The sensor 108 may be capable of detecting an indication associated
with actual cavitation and/or an indication associated with the
onset of cavitation and sending a signal (e.g., to the surface
controller 107 or another control system of the artificial lift
system 100). The signal may be an electrical signal conveyed via a
wire or wirelessly and/or an optical signal (e.g., a light pulse)
conveyed via an optical waveguide (e.g., an optical fiber). In
cases where the sensor 108 detects an indication associated with
the onset of cavitation, the sensor 108 may be instrumental in
helping prevent cavitation in the artificial lift system 100. For
example, a control system and/or an operator of the artificial lift
system 100 may adjust a parameter (e.g., decrease a flow rate), to
prevent cavitation in the artificial lift system 100, in response
to a signal from the sensor 108. Alternatively, in cases where the
sensor 108 detects an indication associated with actual cavitation,
the sensor 108 may be useful in helping prevent further damage to
the system 100. For example, a control system and/or an operator of
the artificial lift system 100 may adjust a parameter (e.g.,
inspect a pump for damage, replace a pump component, etc.), to
prevent further cavitation in the artificial lift system 100, in
response to a signal from the sensor 108.
[0035] FIG. 2 depicts an example downhole portion 202, such as the
downhole portion 116, of an artificial lift system, such as the
artificial lift system 100. However, instead of or in addition to
at least one sensor positioned at the wellhead 102, at least one
sensor 204 may be coupled to the downhole portion 202 such that the
sensor 204 is positioned downhole in the wellbore. The sensor 204
may be coupled to the downhole portion using any of various
suitable mechanisms, such as one or more clamps, a bolted-on
arrangement (as shown in FIG. 2), one or more tie-wraps, and the
like. In some aspects, the downhole portion 202 may be a downhole
fluid pump, such as the downhole fluid pump 110 shown in FIG. 1,
and at least one sensor 204 may be positioned at, above, and/or
below the downhole fluid pump.
[0036] Similar to sensor 108, sensor 204 is configured to detect an
indication of an event associated with cavitation in the artificial
lift system. For example, the sensor 204 may be a microphone, an
accelerometer, or a gyroscope configured to detect sound or
vibration. The sensor 204 may detect an indication associated with
onset of cavitation, and/or an indication associated with
cavitation. In cases where the sensor 204 detects an indication
associated with onset of cavitation, the sensor 204 may help
prevent cavitation in the system by detecting onset of cavitation
and sending a signal (e.g., to a control system of an artificial
lift system) indicating the onset of cavitation before cavitation
occurs. The signal may be an electrical signal conveyed via a wire
or wirelessly and/or an optical signal (e.g., a light pulse)
conveyed via an optical waveguide (e.g., an optical fiber). A
control system and/or an operator of the artificial lift system may
respond to the signal by adjusting a parameter of the artificial
lift system to prevent cavitation from occurring. Alternatively, in
cases where the sensor 204 detects an indication associated with
cavitation, the sensor 204 may help prevent further damage to the
artificial lift system by sending a signal indicating that
cavitation is occurring. The signal may be an electrical signal
conveyed via a wire or wirelessly and/or an optical signal (e.g., a
light pulse) conveyed via an optical waveguide (e.g., an optical
fiber). A control system and/or an operator of the artificial lift
system may respond to the signal by adjusting a parameter of the
artificial lift system to prevent further cavitation from
occurring.
[0037] FIG. 3 depicts a sensor 300 for transducing properties of an
environment (e.g., vibrational or acoustic energy) into electrical
or optical signals. The sensor 300 includes communication lines
302, 304 for conveying information from the sensor 300. For
example, communication line 302 may transmit the electrical or
optical signals to a processing system 306 (e.g., with signal
processing, analog-to-digital converting, memory storing, and data
manipulating capabilities), such as the surface controller 107.
Communication line 304 may be used to receive signals from another
sensor in some aspects, while in other aspects, communication line
304 may be omitted. Furthermore, the sensor 300 is configured to be
positioned to detect an indication of an event associated with
cavitation in an artificial lift system of a wellbore. For example,
the sensor 300 may be configured for coupling to a wellhead.
Alternatively, the sensor 300 may be configured for positioning in
the wellbore. In this case, the sensor 300 may be configured for
coupling to a fluid pump of the artificial lift system, as
described above.
[0038] FIG. 4 is a conceptual illustration of an example fluid pump
for an artificial lift system, in accordance with certain aspects
of the disclosure. The fluid pump may be any of a variety of fluid
pumps including a hydraulic jet pump 402 as depicted. The hydraulic
jet pump 402 includes a nozzle 404, a throat 406, and one or more
production inlet chambers 408.
[0039] As an example operation of the fluid pump, the hydraulic jet
pump 402 may be disposed in a wellbore, and power fluid may be
pumped down the wellbore towards the hydraulic jet pump 402.
Initially, the fluid may have a high pressure and low velocity.
However, the nozzle 404 may constrict the flow of the power fluid,
drastically increasing the power fluid's velocity and decreasing
its pressure. This power fluid may then jet through the nozzle 404
into the throat 406. In some cases, the power fluid jetted from the
nozzle 404 is at a lower pressure than production fluid in the
production inlet chambers 408. The pressure gradient between the
production inlet chambers 408 and the throat 406 can result in
production fluid flowing into the throat. This may result in
production fluids intersecting and mixing with power fluid.
[0040] The intersecting and mixing of fluids in the throat 406 may
result in conditions that can lead to cavitation, as described
above regarding cavitation-associated events. For example, fluid
conditions and/or the nozzle-throat size combination may lead to
cavitation-associated events, which may damage the throat 406.
[0041] As described above, an event associated with cavitation may
be accompanied by an indication. For example, a
cavitation-associated event at the throat 406 of the hydraulic jet
pump 402 may lead to vibration of the fluid pump. In turn, the
fluid pump vibration may lead to an indication 410 (e.g., an
acoustic or vibrational indication). The indication 410 may have a
frequency of about 5.6 kHz, for example. The indication 410 may be
conveyed to a sensor, such as sensor 108, 202, or 300. In some
aspects, the indication 410 travels up the wellbore to the sensor
at the wellhead, where the sensor detects the indication 410. In
other aspects, the sensor is disposed in the wellbore, and the
indication 410 travels along the wellbore to the sensor.
Alternatively, the sensor may be strapped to the fluid pump (as
shown in FIG. 2) and directly detect the indication 410.
Operating an Artificial Lift System
[0042] FIG. 5 is a flow diagram of example operations 500 for
controlling an artificial lift system for a wellbore, in accordance
with certain aspects of the disclosure. Performing the operations
500 may prevent cavitation damage from occurring to a fluid pump,
such as the fluid pumps described above. In some cases, performing
the operations 500 can prevent cavitation damage from occurring to
a throat of a hydraulic jet pump, such as the throat 406.
[0043] The operations 500 may begin, at block 502, by monitoring a
wellbore for an indication of an event associated with cavitation
in an artificial lift system. At block 504, at least one parameter
of the artificial lift system may be adjusted if the event is
detected. The event may, for example, be onset of cavitation, or
the event may be cavitation. Additionally, the indication may have
a frequency of about 5.6 kHz, for example.
[0044] Monitoring at block 502 may include using one or more
sensors to detect the indication. For example, the sensor(s) may be
sensor 108, 204, or 300, as described above. Thus, the sensor(s)
may include a microphone, an accelerometer, and/or a gyroscope.
Additionally, similar to aspects described above, the sensor(s) may
be positioned at a wellhead for the wellbore and/or in the
wellbore. As described regarding FIG. 2, the sensor(s) may be
coupled to a fluid pump of the artificial lift system.
[0045] Adjusting at block 504 may include changing any of various
suitable parameters of the artificial lift system, such as
replacing or repairing equipment or components; modifying,
introducing, or removing control signals; storing and/or reporting
the indication; setting a flag and/or outputting a signal based on
the indication; and the like. Outputting a signal may include, for
example, generating an analog or digital signal and transmitting
the signal via a wire, wirelessly (e.g., via a radio transmission),
and/or as one or more light pulses conveyed via an optical
waveguide (e.g., an optical fiber). Other examples of outputting a
signal include generating an audible sound, turning on a light,
and/or causing a message to appear on a display screen.
[0046] For certain aspects, at least one parameter can be adjusted
to avoid cavitation damage. These adjustments can be made before
cavitation occurs in the artificial lift system, such as during
onset of cavitation, or after cavitation occurs. For example, the
parameter may be a production rate by the artificial lift system.
In such aspects, adjusting may include increasing production,
reducing production, or stopping production of the artificial lift
system. If production is stopped, it may be helpful in certain
situations to wait a sufficient time before resuming production for
fluid to settle in the wellbore.
[0047] In some circumstances, such stop-and-go operation may not be
sufficient to resolve the event. For example, the event may be
occurring due to improper throat sizing and/or cavitation damage to
the fluid pump. In any case, adjusting the parameter may include
removing the fluid pump of the artificial lift system from the
wellbore. The fluid pump can then be inspected for cavitation
damage. If the damage is present, the fluid pump or one or more
components thereof can be replaced. Alternatively, the adjusting
may include replacing at least one component of the fluid pump with
another component to avoid cavitation damage in subsequent wellbore
operation. For example, the fluid pump may be a hydraulic jet pump,
as depicted in FIG. 4. In such cases, the throat installed in the
fluid pump may be replaced with a new throat that has a different
size than the installed throat. The different size throat may cause
flow (e.g., of a power fluid and production fluid mixture) through
the hydraulic jet pump to be altered from flow through the original
throat in such a manner that cavitation does not occur.
[0048] Any of the operations described above, such as the
operations 500, may be included as instructions in a
computer-readable medium for execution by the surface controller
107 or any suitable processing system. The computer-readable medium
may comprise any suitable memory or other storage device for
storing instructions, such as read-only memory (ROM), random access
memory (RAM), flash memory, an electrically erasable programmable
ROM (EEPROM), a compact disc ROM (CD-ROM), or a floppy disk.
[0049] While the foregoing is directed to certain aspects of the
present disclosure, other and further aspects may be devised
without departing from the basic scope thereof, and the scope
thereof is determined by the claims that follow.
* * * * *