U.S. patent number RE45,268 [Application Number 13/952,135] was granted by the patent office on 2014-12-02 for apparatus for seismic data acquisition.
This patent grant is currently assigned to Fairfield Industries, Inc.. The grantee listed for this patent is Fairfield Industries, Inc.. Invention is credited to Glenn D. Fisseler, Hal B. Haygood, Clifford H. Ray.
United States Patent |
RE45,268 |
Ray , et al. |
December 2, 2014 |
**Please see images for:
( Certificate of Correction ) ** |
Apparatus for seismic data acquisition
Abstract
A seismic exploration method and unit comprised of continuous
recording, self-contained wireless seismometer units or pods. The
self-contained unit may include a tilt meter, a compass and a
mechanically gimbaled clock platform. Upon retrieval, seismic data
recorded by the unit can be extracted and the unit can be charged,
tested, re-synchronized, and operation can be re-initiated without
the need to open the unit's case. The unit may include an
additional geophone to mechanically vibrate the unit to gauge the
degree of coupling between the unit and the earth. The unit may
correct seismic data for the effects of crystal aging arising from
the clock. Deployment location of the unit may be determined
tracking linear and angular acceleration from an initial position.
The unit may utilize multiple geophones angularly oriented to one
another in order to redundantly measure seismic activity in a
particular plane.
Inventors: |
Ray; Clifford H. (Fulshear,
TX), Fisseler; Glenn D. (Houston, TX), Haygood; Hal
B. (Richmond, TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
Fairfield Industries, Inc. |
Sugar Land |
TX |
US |
|
|
Assignee: |
Fairfield Industries, Inc.
(Sugar Land, TX)
|
Family
ID: |
34837781 |
Appl.
No.: |
13/952,135 |
Filed: |
July 26, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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12220518 |
Jul 25, 2008 |
7668047 |
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10766253 |
Jan 28, 2004 |
7561493 |
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Reissue of: |
12547478 |
Aug 25, 2009 |
7986589 |
Jul 26, 2011 |
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Current U.S.
Class: |
367/76; 367/178;
367/77; 367/188 |
Current CPC
Class: |
G01V
1/16 (20130101); G01V 1/24 (20130101); G01V
2200/12 (20130101) |
Current International
Class: |
G01V
1/00 (20060101) |
Field of
Search: |
;367/38,188,76,79,178 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 275 337 |
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Aug 1994 |
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GB |
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2275337 |
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Aug 1994 |
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GB |
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9710461 |
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Sep 1996 |
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WO |
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WO-97/10461 |
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Mar 1997 |
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WO |
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WO-01/96672 |
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Dec 2001 |
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WO |
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WO-02/37140 |
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May 2002 |
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WO |
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Other References
Buttgenbach, Dr. Thomas, Schleisiek Klaus, "4-C System Goes
Ultradeep," Hart's E&P, Houston, Texas/United States of
America, Jan. 2002, 3 pages. cited by applicant .
Canadian Office Action DTD May 24, 2013 for Application No.
2581193, filed Mar. 20, 2007, 3 pages. cited by applicant .
Canadian Office Action DTD Aug. 1, 2012 for Application No.
2554788, filed Jul. 27, 2006, 3 pages. cited by applicant .
Geopro GmbH, "WARRP Offshore," GeoPro GmbH, Hamburg/Germany, Mar.
2002, 2 pages. cited by applicant .
Thales Underwater Systems, "Reservoir Monitoring Solutions,"
Thales, Jan. 2003, 18 pages. cited by applicant .
US Office Action DTD Jul. 12, 2013 for related U.S. Appl. No.
13/565,445, filed Aug. 2, 2012, 4 pages. cited by applicant .
Office Action in Chinese Application No. 201210243445.3 dated Jun.
17, 2014 (English translation included--10 pages). cited by
applicant .
Notice of Allowance in U.S. Appl. No. 13/565,445 dated Jul. 8, 2014
(5 pages). cited by applicant .
Final Office Action in corresponding U.S. Appl. No. 13/565,445,
filed Aug. 2, 2012, 11 pages. cited by applicant .
First Examination Report for European Patent Application No.
04809786.9 dated Sep. 9, 2013, 3 pages. cited by applicant .
Notification of the First Office Action in corresponding Chinese
Application No. 201110436777.9 dated Feb. 28, 2014, 7 pages. cited
by applicant .
Seabed Geophysical AS, "Case, CAble-less SEIsmic System," 8 pages,
SeaBed Geophysical AS, Trondheim/Norway. cited by
applicant.
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Primary Examiner: Hellner; Mark
Attorney, Agent or Firm: Foley & Lardner LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser.
No. 12/220,518, filed Jul. 25, 2008, now U.S. Pat. No. 7,668,047,
which is a divisional of U.S. patent application Ser. No.
10/766,253, filed Jan. 28, 2004, which claims priority to and the
benefit of U.S. Pat. No. 7,561,493, filed on May 30, 2003, all of
which are hereby incorporated by reference.
Claims
What is claimed is:
1. A seismic data collection unit comprising: a. a fully enclosed,
single case formed of a housing, said case having a wall defining
an internal compartment within said housing; b. at least one
geophone internally fixed within said housing; c. a clock disposed
within said housing; d. a power source disposed within said
housing; and e. a seismic data recorder disposed within said
housing; f. wherein each of said elements b-e include an electrical
connection and all electrical connections between any elements b-e
are contained within said housing; and g. wherein said geophone is
coupled to said seismic data recorder to permit seismic signals
detected by said geophones to be recorded on said seismic data
recorder, h. wherein the single case comprises a first plate having
a first periphery and a second plate having a second periphery,
wherein the plates are joined along their peripheries by a circular
wall.
2. The unit of claim 1, wherein said unit is self contained and
requires no external communications or controls during
recording.
3. The unit of claim 1, wherein the case is watertight.
4. The unit of claim 1, wherein said at least one geophone is
disposed adjacent a plate.
5. A seismic data collection unit comprising: a. a fully enclosed,
single case formed of a housing, said single case having a first
plate having a first periphery and a second plate having a second
periphery, wherein the plates are joined along their peripheries by
a circular wall, said wall defining an internal compartment within
said housing; b. at least one geophone internally fixed within said
housing; c. a clock disposed within said housing; d. a power
source; and e. a seismic data recorder disposed within said
housing.
6. The unit of claim 5, wherein said unit is self contained and
requires no external communications or controls during
recording.
7. The unit of claim 5, wherein , wherein each of said elements b-c
include an electrical connection and all electrical connections
between any elements b-c are contained within said housing.
8. The unit of claim 5, wherein the power source includes a fuel
cell attached to the case.
9. The unit of claim 5, wherein the power source includes a solar
cell attached to the case.
10. The unit of claim 1, wherein the case defines an external
surface, and the external surface is provided with ridges to
enhance coupling of unit with the earth.
11. The unit of claim 1, wherein the case defines an external
surface, and the external surface is provided with at least one
spike to enhance coupling of unit with the earth.
12. The unit of claim 1, further comprising a. three geophones
disposed within said case; and b. a compass.
13. The unit of claim 1, wherein the geophone is a multi-component
geophone capable of measuring seismic signals in at least two
directions angularly oriented to one another.
14. The unit of claim 1, further comprising a GPS location
transducer.
15. The unit of claim 1, further comprising a radio unit.
16. The unit of claim 1, further comprising an external connector
in electrical communication with at least one of said geophone,
clock, power source and seismic recorder, said connector extending
through the wall of said case and disposed within said wall so as
to be set in from the external surface of said wall.
17. The unit of claim 16, further comprising a water tight,
pressure resistant cap disposed over said external connector.
18. The unit of claim 1, further comprising an internal control
mechanism for controlling all functions of the unit while
deployed.
19. The seismic data collection unit of claim 5, further
comprising: a. at least four seismic data geophones disposed within
said case, wherein at least three of said geophones are disposed
adjacent one another and at least one geophone is disposed in a
location within said case removed from said other geophones.
20. The seismic data collection unit of claim 5, further comprising
a case in which the at least four seismic data geophones are
disposed, wherein said at least three geophones are disposed in
said case to maximize detection of seismic energy and said at least
one geophone is disposed in said case to maximize vibration of said
case by said removed geophone.
21. A seismic data collection unit comprising: a. a fully enclosed,
single case formed of a housing, said single case having a first
plate having a first periphery and a second plate having a second
periphery, wherein the plates are joined along their peripheries by
a circular wall, said wall defining an internal compartment within
said housing; b. at least one geophone internally fixed within said
housing; c. a clock disposed within said housing; d. a power source
disposed within said housing; e. positional electronics disposed
within said housing; f. orientation electronics disposed within
said housing; and g. a seismic data recorder disposed within said
housing; h. wherein each of said elements b-g include an electrical
connection and all electrical connections between any elements b-g
are contained within said housing.
.Iadd.22. A seismic data collection unit comprising: a. a
non-spherical pod formed of a single housing, said pod comprising a
wall defining an internal compartment within said single housing;
b. at least one geophone internally fixed within said internal
compartment; c. a clock disposed within said internal compartment;
d. a power source disposed within said internal compartment; and e.
a seismic data recorder disposed within said internal compartment;
f. wherein each of said elements b-e include an electrical
connection and all electrical connections between any elements b-e
are contained within said internal compartment; and g. wherein the
at least one geophone is coupled to the seismic data recorder to
permit seismic signals detected by said geophones to be recorded on
said seismic data recorder. .Iaddend.
.Iadd.23. The seismic data collection unit of claim 22, wherein
said seismic data collection unit is self contained and requires no
external communications or controls during recording. .Iaddend.
.Iadd.24. The seismic data collection unit of claim 22, wherein
said pod is watertight. .Iaddend.
.Iadd.25. The seismic data collection unit of claim 22, wherein a
portion of an external surface of the pod comprises at least one
projection to enhance coupling of the seismic data collection unit
with the earth. .Iaddend.
.Iadd.26. The seismic data collection unit of claim 25, wherein the
at least one projection is at least one spike, at least one ridge,
or at least one groove. .Iaddend.
.Iadd.27. The seismic data collection unit of claim 22, further
comprising: a compass; and at least two additional geophones
disposed within said pod. .Iaddend.
.Iadd.28. The seismic data collection unit of claim 22, wherein the
at least one geophone is a multi-component geophone capable of
measuring seismic signals in at least two directions angularly
oriented to one another. .Iaddend.
.Iadd.29. The seismic data collection unit of claim 22, wherein a
portion of the pod has a circular shape. .Iaddend.
.Iadd.30. The seismic data collection unit of claim 22, wherein a
portion of the pod has a non-circular shape. .Iaddend.
.Iadd.31. The seismic data collection unit of claim 22, further
comprising a GPS location transducer. .Iaddend.
.Iadd.32. The seismic data collection unit of claim 22, further
comprising a radio unit. .Iaddend.
.Iadd.33. The seismic data collection unit of claim 22, further
comprising an external connector, wherein the external connector is
disposed in electrical communication with the at least one
geophone, the clock, the power source and the seismic data
recorder, and wherein the external connector extends through a
portion of the wall of the single case. .Iaddend.
.Iadd.34. The seismic data collection unit of claim 33, further
comprising a water tight, pressure resistant cap disposed over said
external connector. .Iaddend.
.Iadd.35. The seismic data collection unit of claim 22, wherein the
power source comprises a fuel cell or a solar cell. .Iaddend.
.Iadd.36. The seismic data collection unit of claim 22, wherein:
the at least one geophone comprises at least four seismic data
geophones disposed within said case, at least three seismic data
geophones of said at least four seismic data geophones are disposed
proximate to one another, and at least one seismic data geophone of
said at least four seismic data geophones is disposed at a location
within said internal compartment that is removed from the at least
three seismic data geophones that are disposed proximate to each
other. .Iaddend.
.Iadd.37. The seismic data collection unit of claim 36, wherein the
at least three seismic data geophones that are disposed proximate
to each other are configured to maximize detection of seismic
energy, and wherein the at least one seismic data geophone that is
removed from the at least three seismic data geophones is
configured to mechanically vibrate the pod. .Iaddend.
.Iadd.38. The seismic data collection unit of claim 22, further
comprising a tilt meter disposed in the internal compartment.
.Iaddend.
.Iadd.39. The seismic data collection unit of claim 22, wherein the
pod comprises at least one internal partition disposed within the
internal compartment. .Iaddend.
.Iadd.40. The seismic data collection unit of claim 39, wherein the
at least one partition is disposed proximate to the power source,
and wherein the at least one partition separates the power source
from other components in the pod. .Iaddend.
.Iadd.41. The seismic data collection unit of claim 39, wherein the
at least one partition is disposed proximate to the seismic data
recorder, and wherein the at least one partition separates the
seismic data recorder from other components in the pod.
.Iaddend.
.Iadd.42. The seismic data collection unit of claim 39, wherein the
at least one partition is disposed proximate to the seismic data
recorder, and wherein the at least one partition separates the
seismic data recorder from the at least one geophone. .Iaddend.
.Iadd.43. The seismic data collection unit of claim 39, wherein the
at least one internal partition divides the internal compartment
into multiple compartments. .Iaddend.
.Iadd.44. The unit of claim 1, wherein said geophone is configured
to vibrate said housing. .Iaddend.
.Iadd.45. The unit of claim 1, wherein said geophone is a first
geophone, further comprising: a second geophone configured to
vibrate the case. .Iaddend.
.Iadd.46. The unit of claim 5, wherein said geophone is configured
to vibrate said housing. .Iaddend.
.Iadd.47. The unit of claim 5, wherein said geophone is a first
geophone, further comprising: a second geophone configured to
vibrate the case. .Iaddend.
.Iadd.48. The unit of claim 21, wherein at least one of said at
least one geophone is configured to vibrate said housing.
.Iaddend.
.Iadd.49. The unit of claim 22, wherein at least one of said at
least one geophone is configured to vibrate said pod. .Iaddend.
Description
BACKGROUND
The present invention relates to the field of seismic exploration.
More particularly, the invention relates to a method and apparatus
for seismic exploration, and most particularly to a self-contained,
land based or marine deployable seismometer system.
Seismic exploration generally utilizes a seismic energy source to
generate an acoustic signal that propagates into the earth and is
partially reflected by subsurface seismic reflectors (i.e.,
interfaces between subsurface lithologic or fluid layers
characterized by different elastic properties). The reflected
signals (known as "seismic reflections") are detected and recorded
by seismic receivers located at or near the surface of the earth,
thereby generating a seismic survey of the subsurface. The recorded
signals, or seismic energy data, can then be processed to yield
information relating to the lithologic subsurface formations,
identifying such features, as, for example, lithologic subsurface
formation boundaries.
Typically, the seismic receivers are laid out in an array, wherein
the array consists of a line of stations each comprised of strings
of receivers laid out in order to record data from the seismic
cross-section below the line of receivers. For data over a larger
area and for three-dimensional representations of a formation,
multiple single-line arrays may be set out side-by-side, such that
a grid of receivers is formed. Often, the stations and their
receivers are remotely located or spread apart. In land seismic
surveys for example, hundreds to thousands of receivers, called
geophones, may be deployed in a spatially diverse manner, such as a
typical grid configuration where each line extends for 5000 meters
with receivers spaced every 25 meters and the successive lines are
spaced 500 meters apart.
Generally, several receivers are connected in a parallel-series
combination on a single twisted pair of wires to form a single
receiver group or channel for a station. During the data collection
process, the output from each channel is digitized and recorded for
subsequent analysis. In turn, the groups of receivers are usually
connected to cables used to communicate with the receivers and
transport the collected data to recorders located at a central
location, often called the "dog house." More specifically, when
such surveys are conducted on land, cable telemetry is used for
data transmission between the individual receivers, the stations
and the dog house. Other systems use wireless methods for data
transmission so that the individual receivers and stations are not
connected to each other. Still other systems temporarily store the
data at each station until the data is extracted.
As used throughout this description, "land-based seismic systems"
shall include seismic systems utilized in costal transition zones
such as shallow water or marshes. With respect to operation of most
land-based seismic systems, the prior art generally requires some
externally generated control command in order to initiate and
acquire data for each shot, cause stored seismic data to be
transmitted back to the dog house and cause any other data, such as
quality control data, to be transmitted back to the dog house. Thus
the seismic receiver units must be either physically connected to
the central control recording station or "connectable" by wireless
techniques. As mentioned above, those skilled in the art will
understand that certain environments can present extreme challenges
for conventional methods of connecting and controlling seismic,
such as congested or marine environments, rugged mountain
environments and jungles or remote desert locations. Difficulties
may also arise in instances where the interconnected, hard-wired
receiver array must be periodically moved to cover a larger
area.
Whatever the case, each type of connection, whether via a physical
cable or through wireless techniques, has its own drawbacks. In
cable telemetry systems, large arrays may result in large
quantities of electrically conductive cabling that are expensive
and difficult to handle, deploy or otherwise manipulate, as well as
repair and maintain. In hostile environments characterized by
extreme or corrosive conditions, such as salt water, hot, sandy
deserts or overgrown, damp jungles, costly cable armoring may be
required. Furthermore, conventional cabling also requires a
physical connection between the cable and the sensor unit. Since it
is generally not practical to hard wire strings of receivers to a
cable, the more conventional technique is to use external cabling
and connectors between strings of receivers and the telemetry
cable. This point of the connection between the cable and the
sensor is particularly vulnerable to damage, especially in extreme
or corrosive environments. Of course, with systems that are
physically cabled together, it is much easier to provide power to
the stations/units, to synchronize data acquisition with the shot
time, to perform quality control checks and to otherwise control
the units.
It should be noted that whether for cabled or wireless systems, the
seismic recording systems of the prior art separate the receiver
package, i.e., the geophones, from the radio control package and/or
the recording package of the units to the extent the units provide
any on-board recording. It has heretofore been conventional
thinking in the prior art that geophone coupling with the earth can
be maximized in this way. External cabling is required in these
prior art systems to connect the geophone package of a unit with
the recording and/or radio telemetry packages of the unit. As such,
many of the aforementioned drawbacks that arise from cabling system
units together also exist when cabling various package components
of an individual unit to one another.
In cases where either wireless technology is utilized or operation
of units and their sensors is through pre-programming, control and
monitoring of the units and sensors becomes more difficult. For
example, ensuring that recording is synchronized with the shot
timing is crucial since the individual sensor units are not wired
together as described above. Hence the need for accurate on-board
clocks as mentioned above. In this regard, activating each unit for
sensing and recording at the appropriate time must coincide with
the shot. One common prior art technique in this regard is to
utilize a command signal sent from the control station to power up
the system, initiate transmission of data stored from the previous
shot and initiate collection of data for the current shot which is
temporarily written into memory until transmitted back to the
control station at the time of the next shot.
Ensuring that the units are sufficiently powered has also
heretofore been a concern. Many prior art patents have focused on
techniques and mechanisms for powering up sensors during data
acquisition/recording and powering down the sensors during dormant
periods.
A land-based system representative of the prior art is taught in
U.S. Pat. No. 6,070,129, which pertains to the compression and
distribution of seismic data from a plurality of acquisition units,
each unit being suited to acquire, to temporarily store and to
compress the data for distributed transmission to a central control
and recording station. Each acquisition unit is hard wired to a
plurality of distributed seismic geophones/receivers from which the
acquisition unit receives data. Each acquisition unit is also
disposed to receive operation instructions from the central control
and recording station. In one embodiment of the invention, during
acquisition of data from a particular shot, partial data from the
previous shot is transmitted to the central control and recording
station to permit a quality control check and to ensure that the
acquisition units are properly working. Data from any given shot
may be distributed and transmitted over multiple transmission
channels and during successive transmission windows to lessen
variation in data flow.
Each of the referenced prior art devices embodies one or more of
the drawbacks of the prior art. One drawback to these prior art
systems is the need to activate and deactivate the units for
recording and operation, including data and quality control
transmission. For land-based systems, this generally requires a
control signal transmitted via a cable or radio signal from the dog
house. However, external control may be undesirable since it
requires signal transmission and additional components in the
system. Of course, any type of control signal cabling for
transmission of electrical signals is undesirable because it adds a
level of complexity to the handling and control of the unit and
requires external connectors or couplings. Such cabling and
connectors are particularly susceptible to leakage and failure in
extreme environments, whether the corrosive environment of
transition zone water or the high temperature, corrosive
environments of the desert.
A similar problem exists with units that utilize external
electrical wiring to interconnect distributed elements of the unit,
such as is taught in U.S. Pat. No. 5,189,642 and similar devices
where the geophone package is separate from the electronics
package. Furthermore, to the extent the electronics of a system are
distributed, the likelihood of malfunction of the system
increases.
Many of the prior art systems also use radio telemetry rather than
recording data on-board the unit, to collect the data. Such
systems, of course, have limitations imposed by the characteristics
of radio transmission, such as radio spectrum license restrictions,
range limitations, line-of-sight obstructions, antenna limitations,
data rate limitations, power restrictions, etc.
Thus, it would be desirable to provide a land-based seismic data
collection system that does not require external
communication/power cabling, either from the control station or on
the seismic data collection unit itself between unit components.
Likewise, the unit should record and otherwise operate without any
type of external control signal. In other words, the unit should
operate on a "drop and forget" basis. Likewise, the device should
be easily serviced without the need to open the device to perform
activities such as data extraction, quality control and power
replenishment. The device should also be designed to withstand the
corrosive, extreme environments which are often encountered in
seismic exploration. The device should also permit quality control
data sent back by radio to determine if the remote units of the
system are operating properly without the need for control signals
or tying the quality control data transmission to a shot cycle.
SUMMARY
The present invention provides a land-based system for collecting
seismic data by deploying multiple, continuous operating,
autonomous, wireless, self-contained seismic recording units or
pods Seismic data previously recorded by the pod can be retrieved
and the pod can be charged, tested, re-synchronized, and operation
can be re-initiated without the need to open the pod.
More specifically, the unit is self-contained such that all of the
electronics are disposed within or on the case, including a
geophone package, a seismic data recording device and a clock. A
power source is either contained within the case, or may be
attached externally to the case. The clock may be attached to a
gimbaled platform having multiple degrees of freedom to minimize
the effects of gravity on the clock.
In one embodiment of the invention, the clock is a rubidium clock.
The rubidium clock is much less susceptible to temperature or
gravitational effects or orientation of the unit.
In another embodiment, the unit includes a crystal clock and the
crystal clock is corrected for the effects of aging on the
crystals.
The power source is preferably rechargeable batteries disposed
within the unit's case that can operate in a sealed environment,
such as lithium ion batteries. Alternatively, the power source may
incorporate a fuel cell or solar cell attached to the unit's
case.
The self-contained seismic units may include a tilt meter within
the unit's case. While tilt meter data is utilized by the invention
for several different inventive functions, such as the
above-mentioned crystal clock correction procedure, none of the
prior art seismic units have incorporated a tilt meter within a
seismic unit comprising a single, self-contained package. Rather,
such prior art units have separate attached packages housing the
separate components. For example, a prior art unit may have one
package that houses a tilt meter while a separate package houses a
geophone.
Of course, a tilt meter may also be used to determine the vertical
orientation of a unit so that corresponding seismic data can be
correct accordingly. One aspect of the invention is to obtain and
utilize tilt meter data in a time continuous fashion. Prior art
units typically determine a unit's vertical orientation using means
external to said case and orientation data are generated therefrom
only once at the beginning of seismic recording. To the extent
orientation corrections have been made to seismic data acquired
with such prior art units, the corrections are based only on the
initial orientation of the unit. Yet it has been observed that the
orientation of a seismic unit may change over the course of
deployment as the unit is subject to external forces which have
been known to range from water currents to kicking by cows. Thus,
in the invention, vertical orientation data is measured by the tilt
meter as a function of time so that seismic data can be
correspondingly corrected.
With respect to corrections for tilt, timing or similar data that
could effect the accuracy of the collected seismic data, all of the
prior art devices make such corrections at a processing center.
None of the prior art devices make such corrections on-board the
unit while it is deployed. Thus, one method of the invention is to
make such corrections on-board the unit while it is deployed.
The self-contained seismic units of the invention may also include
a compass. Compass data may be used to provide directional frame of
reference data for each individual unit relative to the frame of
reference for the overall survey. Much like a tilt meter, the prior
art has not incorporated a compass into a single, self-contained
package housing all the components of the seismic acquisition unit.
To the extent a compass has been incorporated in prior art seismic
units, the compass has been housed in a separate package from other
components, such as the geophones. Of course, many prior art units
do not determine a unit's directional orientation at all and thus
do not incorporate a compass. Rather, only vertical orientation
data is acquired using a tilt meter. When the self-contained
multidirectional sensor unit of the invention incorporates both a
compass used in conjunction with a tilt meter, the specific three
dimensional orientation of the unit can be determined. None of the
prior art devices incorporate the combination of both a compass and
a tilt meter on board a single, self-contained unit package,
particularly for this function.
In another aspect of the invention, the unit is activated prior to
transportation out to the field and deactivated once retrieved,
such that it is continuously acquiring data from before the time of
deployment to after the time of retrieval. Likewise in one
embodiment, the unit begins recording data prior to deployment.
Systems that are activated and begin recording before deployment
are thereby stabilized prior to the time when signal detection is
desired. This minimizes the likelihood that an altered state in
electronics operation will disrupt signal detection and recording
or effect clock synchronization.
In another aspect of the invention, the seismic data recording
device includes wrap around memory and continuously records, even
when not in use. This obviates the need for initiation or start
instructions, ensures that the unit is stabilized at the desired
recording times, and serves to back-up data from prior recordings
until such time as the prior data is written over. As long as the
clock is synchronized, such a recording device is ready for
deployment at any time. Furthermore, routine operations such as
data collection, quality control tests and battery charging can
take place without interrupting recording.
Continuous operation is also desirable as an element of an inertial
navigation system incorporated in the seismic unit and used to
measure the unit's x, y and z position information as the unit is
transported from an initial position, such as a storage location,
to a deployment position out in the field. An inertial navigation
system may include sensors, such as accelerometers to track x, y
and z position information, as well as a compass and tilt meter to
determine orientations. Such a system can be used to determine the
deployment location of a unit in the field.
Each unit may include a communications portal to permit the unit to
interface with a master control station via the communications
portal, typically after the unit has been retrieved from
deployment. Through the portal, information recorded on the unit
can be downloaded, the unit batteries can be recharged, quality
control checks on the unit can be conducted, recording can be
re-initiated and the unit can be reactivated without the need to
open or disassemble the unit.
Each unit may include a unique identification means, such as a
radio frequency identification (RFID) tag or similar identification
indicia to permit tracking of the individual units as they are
handled. Likewise, each unit may include a Global Positioning
System ("GPS"). Since the individual units are self-contained, the
location information, in association with the identification
indicia allows the units to be randomly handled and stored, but
permits data from multiple units to be retrieved and sequentially
ordered according to the location of the unit during a shot cycle.
Thus, the need to keep units in sequential order is obviated. Units
that might have been adjacent one another on a receiver line need
not be retrieved in order or stored next to one another.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cut-away top view of the seismic recorder unit of the
current invention.
FIG. 2 is a front side view of the unit of FIG. 1.
FIG. 3 is a back side view of the unit of FIG. 1.
FIG. 4 is a top view of the unit of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the detailed description of the invention, like numerals are
employed to designate like parts throughout. Various items of
equipment, such as fasteners, fittings, etc., may be omitted to
simplify the description. However, those skilled in the art will
realize that such conventional equipment can be employed as
desired.
With reference to FIG. 1, there is shown a seismic data collection
system or pod 10 of the invention. Pod 10 is comprised of a case 12
having a wall 14 defining an internal, compartment 16. Preferably,
case 12 is sealed to prevent water, dust or other debris from
migrating into compartment 16. Disposed within compartment 16 is at
least one geophone 18, a clock 20, a power source 22, a control
mechanism 23 and a seismic data recorder 24. In the embodiment, pod
10 is self-contained such that power source 22 meets all of the
power requirements of pod 10. Likewise, control mechanism 23
provides all control functions for pod 10 eliminating the need for
external control communications. In an alternative embodiment,
power source 22 may be attached externally to case 12 as described
below.
Those skilled in the art will appreciate that pod 10 is a
self-contained seismic data collection system which requires no
external communication or control in order to record seismic
signals. It will be further noted that geophone 18 is internally
mounted within pod 10 and thus requires no external wiring or
connection. It has been determined that utilizing a compact case
and positioning geophone 18 adjacent the casing wall, geophone 18
can be effectively coupled to the earth such that seismic data
transmitted through pod 10 to geophone 18 is not corrupted by
interference. Unless specifically indicated, all references to
geophones utilized in the invention include conventional geophones
as well as other known devices for detecting seismic wave activity
or directional sensors, including without limitation,
accelerometers, and references to accelerometers likewise include
other directional sensors, including, without limitation,
geophones.
In another embodiment of the invention, it has been found
advantageous to utilize four geophones 18a, 18b, 18c, 18d
positioned in a tetrahedral configuration such that each geophone
measures data in multiple planes. In a standard three dimensions
configuration, three geophones are positioned 90.degree. apart from
each other and each geophone measures signal in a single x, y or z
plane. In a four geophone configuration, the geophones are oriented
perpendicular to the plane of the tetrahedral faces so that each
geophone measures portions of multiple planes in the x, y, z
coordinate system. For example, one geophone may measure seismic
data in the x-plane and z-plane. Geophone configurations of four or
more geophones are desirable because they provide for redundancy in
the seismic unit in the event of failure of a geophone in a
particular plane.
Another embodiment of the invention utilizes a geophone 19 disposed
within pod 10 as a driven power source to gauge the degree of
coupling of pod 10 with the earth. Those skilled in the art will
understand that the physical coupling between a seismic unit and
the earth has become one of the primary concerns in the seismic
data collection industry. The invention incorporates a driven
geophone to test this coupling. Specifically, rather than simply
utilizing a geophone to detect energy, it has been found that a
geophone can be utilized as a power source to introduce energy,
i.e., vibrations, into pod 10. In other words, a geophone within
pod 10 can be driven thereby causing pod 10 to shake. Such a driven
geophone used in conjunction with the other geophones on board can
be used to determine the degree of physical coupling between pod 10
and the earth. If pod 10 is well coupled with the earth, the
vibrational energy generated by the geophone will be transmitted
through the pod's coupling structure, such as spike 52, and
dispersed within the earth. In such case, the other on-board
geophones used for detecting vibrational energy would detect energy
at a first low level. On the other hand, if there is not good
coupling between pod 10 and the earth, the generated vibrational
energy will not be transmitted into the earth. In such case, the
other on-board geophones used for detecting vibrational energy
would detect energy at a second level much higher than the first
level.
None of the prior art seismic units teach an on-board system to
test the degree of coupling between the unit and the earth. This is
true in part because none of the prior art devices comprise a
self-contained seismic recording unit as described herein. Rather,
the prior art units separate the geophone package from the
electronics of the rest of the unit. In such case, it would be
impractical to include a power source, along with the electronics
to control the power source, in a distributed, separate geophone
package. The above described system is desirable because it can be
utilized in a system with as few as two geophones, where one
geophone functions as an energy source and the other geophone
functions as an energy receiver. Further, such a system permits the
use of at least one geophone for a dual purpose, i.e., the geophone
can be used to generate energy during coupling tests but can
otherwise be used in a detection mode to detect seismic during
seismic exploration. Of course, to the extent a geophone is
dedicated only for use as an energy source, it need not be
positioned with the other seismic detection geophones in the unit.
Thus, for example, a three geophone package to measure seismic
energy in the x, y and z planes might be positioned within pod 10
to maximize their ability to detect seismic energy, such as
adjacent the base of pod 10, while a forth geophone dedicated as an
energy source might be positioned within pod 10 to maximize
distributions of vibrational energy within pod 10, such as near the
top of pod 10.
In one important aspect of the invention, clock 20 is a rubidium
clock. Heretofore, rubidium clocks have not been used in seismic
exploration due in part to the expense when compared to traditional
crystal driven clocks. However, because the pod 10 of the invention
is intended to operate effectively independent of its orientation,
it is necessary to utilize a clock that in not susceptible to
orientation effects which can inhibit operation of traditional
prior art crystal clocks. Furthermore, rubidium clocks are less
susceptible to temperature and gravitational effects that can
inhibit operation of prior art clocks.
Gravitational effects on clock 20 can also be minimized through use
of a mechanically gimbaled platform 21 that rotates to maintain
clock 20 in a more optimal orientation for performance. Preferably,
gimbaled platform 21 can rotate in at least three degrees of
freedom, although gimbaled platform 21 may have fewer degrees of
freedom and still be utilized for the desired purpose. This is an
improvement over prior art seismic units which have not utilized
gimbaled clock platforms at all.
Unit 10 may also include tilt meter 25. Tilt meter 25 and the data
generated therefrom may serve several different purposes, including
without limitation, correction of clock data or for vertical
orientation determination. Furthermore, such tilt meter data is
measured as a function of time. Thus, preferably, the tilt meter
data is associated with a data set in a time continuous fashion
such that a data set generated at a particular time is associated
with tilt meter data generated at that same time. While prior art
seismic units have not incorporated tilt meters in a single,
self-contained multidirectional sensor unit, to the extent
orientation corrections have been made to seismic data generated
from prior art units, such corrections have been made from
orientation data generated at the beginning of a shot cycle to
correct all of the seismic data generated during the shot cycle.
This can result in inaccuracies to the extent the orientation of
the seismic unit is altered during a shot cycle or deployment
period. In one embodiment, all such tilt meter corrections are made
on-board the unit, preferably in real time.
In this same vein, unit 10 may include a compass 27, which,
heretofore has not been utilized in a single, self-contained
multidirectional sensor unit. Compass 27 and the data generated
therefrom may be used to provide directional frame of reference
data for each individual unit relative to the frame of reference
for the overall survey. Furthermore, when used in conjunction with
tilt meter data, the specific three-dimensional orientation of a
unit can be determined such that seismic data accuracy can be
further improved.
Power source 22 is preferably a lithium ion battery. To the extent
prior art seismometer systems have utilized on-board batteries, as
opposed to external cabling to supply power, the prior art
batteries have been lead-acid, alkaline or non-rechargeable
batteries. None of the prior art systems have utilized lithium ion
batteries. Furthermore, because of the sealed, self-contained
nature of the pod of the invention, it is desirable to utilize a
battery that does not vent fumes, such as a lithium ion type
battery. In an alternative embodiment, power source 22 may
incorporate a fuel cell or solar cell attached externally to case
12. Of course, while such power source components are not contained
within case 12, for purposes of the invention, pod 10 is still
self-contained in the sense that it operates as a stand alone unit
without communication, control signals or power from a source
removed from the pod.
In FIGS. 2, 3, and 4, the exterior of pod 10 is shown. Wall 14
defining case 12 may include a first plate 26 and a second plate 28
jointed together along their peripheries by a portion of wall 14.
Each plate defines an external surface 50. While plates 26 and 28
are disk shaped in the illustrated embodiment such that pod 10 has
an overall wheel shape, pod 10 can be of any shape so long as it
functions in accordance herewith. The external surface 50 may be
provided with projections 51, such as ridges or grooves, to enhance
coupling between pod 10 and the earth. In the embodiment shown in
FIG. 4, the projections 51 form a chevron pattern on surface 50.
More pronounced projections, such as spikes 52, may be provided to
prevent movement of pod 10 once it is deployed and improve
coupling.
Each unit may include a unique identification means, such as a
radio frequency identification (RFID) tag 40 or similar
identification indicia to permit tracking of the individual units
as they are handled during deployment and retrieval. Likewise, each
unit may include a GPS transducer 42 which permits the unit's
location to be determined (to the extent a unit is deployed in a
location in which GPS is effective).
FIG. 1 also shows a radio antennae 44 which is communication with a
radio unit 45 disposed within case 12.
A connector 46 for permitting communication with pod 10 may also be
disposed on case 12. Such communication may occur when pod 10 is in
storage at a central command unit or even to the extent data is
simply retrieved by an operator who travels out to the pod's
deployment location. Connector 46 may be a standard pin connector
or may be an infrared or similar connector that requires no hard
wiring in order to communicate with pod 10. Via connector 46, pod
10 may be serviced without removing one of plates 26, 28 or
otherwise opening case 12. Specifically, connector 46 permits
quality control tests to be run, recorded seismic data to be
extracted, clock 20 to be synchronized and power source 22 to be
recharged. A sealing connector cap 47 may also be provided to
protect connector 46. For under water uses or other wet
environments, connector cap 47 is preferably water tight. Utilizing
such a connector cap 47, connector 46 may be any standard connector
that satisfies the desired functions of the pod and need not be of
the type normally required of external connectors subjected to
extreme or corrosive environments.
One function of the seismic data recording unit of the invention is
the continuous operation of the unit. In this aspect of the
invention, data acquisition is initiated prior to positioning of
the unit on the earth's surface, i.e., prior to deployment. For
example, units may be activated at a central location prior to
trucking them out to the field. Systems that are activated and
begin acquiring data prior to deployment are thereby stabilized
prior to the time synchronization and seismic data recording are
desired. This minimizes the likelihood that an altered state in
electronics operation will have an effect of data integrity.
In a similar embodiment, data recording is initiated prior to
positioning along a receiver line. Again, this permits units to
stabilize prior to the time synchronization and seismic data
recording are desired. To this end, one component of system
stabilization is clock stabilization. Of the various components of
the system, it is well known that clocks typically take a long time
to stabilize. Thus, in one embodiment of the invention, whether the
unit is continuously detecting data or continuously recording data,
the clock always remains on.
In either of the preceding two methods, the unit can be utilized in
several cycles of deployment and retrieval without interrupting the
continuous operation of the unit. Thus, for example, prior to
deployment, recording is initiated. The device is deployed,
retrieved and redeployed, all while recording is continued. As long
as memory is sufficient, this continuous recording during multiple
cycles of deployment and redeployment can be maintained.
In this regard, to the extent the seismic data unit includes wrap
around memory, it can continuously record even when not in use in
seismic detection. Thus, in addition to the advantages described
above, initiation or start instructions become unnecessary.
Further, continuous recording utilizing wrap around memory
functions as a back-up for data acquired from prior recordings
until such time as the prior data is written over. An additional
advantage is that the device is ready for deployment at any time as
long as the clock is synchronized.
To the extent recording is continued after a unit has been
retrieved, routine operations such as data retrieval, quality
control tests and battery charging can take place without
interrupting recording. One benefit of such a system is that the
device can be utilized to record quality control test data rather
than seismic data when conducting quality control tests. In other
words, the data input changes from seismic data to quality control
data. Once quality control is complete, the device may resume
recording seismic data or other desired data, such as data related
to position and timing.
While "continuous" unit operation has been described temporally in
one embodiment as setting operation parameters to initiate
operation prior to deployment of the unit, for purposes of the
meaning of "continuous" as used herein, the time period of unit
operation may simply be initiated prior to a shot and continue
through a series of shots or shot cycles and may also include
continued recording of a unit through a series of shots or shot
cycles. In another embodiment, while continuously operating,
parameters may be set to intermittently record at pre-set,
specified times.
The above described continuous operation of the seismic units of
the invention is particularly suited for use with a unique position
determination method of the invention. Specifically, a unit's x, y
and z position information is recorded as the unit is transported
from an initial position, such as a storage location, to a
deployment position out in the field. The positional information
may be determined using an inertial navigation system that measures
movement in each of the x, y and z dimensions as well as angular
movement around each x, y and z axis. In other words, the system
measures the six degrees of freedom of the unit as it travels from
the initial location to the deployment position, and utilizes such
measurement information to determine the location of the deployment
position. In the preferred embodiment, such x, y and z dimensional
information can be determined utilizing accelerometers. Angular
orientation, i.e., tilt and direction, information can be
determined utilizing a tilt meter and a compass or other
orientation devices, such as gyroscopes. In one embodiment of the
invention, three accelerometers and three gyroscopes are utilized
to generate the inertial navigation data used to determine the
unit's deployment position.
In any event, by combining accelerometer and the tilt and direction
orientation information as a function of time with the unit's
initial position and velocity at the time of initial deployment,
the travel path of the unit and hence the deployment location of
the unit, can be determined. Time sampling will occur at
appropriate intervals to yield the accuracy needed. Time sampling
between various measurement components may vary. For example, data
from the compass, used to measure direction, and the tilt meter,
used to measure tilt, may be sampled more slowly than data from the
accelerometers. Heretofore, no other seismic unit has utilized one
or more accelerometers to determine location in this way. In this
regard, the method and system replaces the need to determine
location utilizing other techniques, such as through GPS or the
like.
Because a unit is already recording data at the time of its
transportation to and deployment in the field, x, y and z
positional information is easily recorded on the unit and becomes
part of the unit's complete data record.
To the extent clock 20 is a crystal clock, one method of the
invention is to make clock corrections to compensate for aging of
the clock's crystals. Specifically, it has been determined that
seismic data can be effected by the aging of crystals within a
unit's crystal clock.
Typically, the aging curve for a given crystal will be logarithmic
for an initial period of time and gradually transition into a more
linear curve over an extended period of time. As such, the curve
has a significant slope at the beginning of the aging process and a
more linear, flat slope at as the aging process continues over
time. In this regard, a seismic unit will tend to have more crystal
aging at the beginning of a deployment period. In any event, prior
to deployment, a characterization curve for a clock's crystal can
be determined by plotting crystal aging vs. time over an extended
period of days, such as fifteen to twenty days. In operation, the
crystal frequency can be measured at the time of deployment and at
the end of deployment. Utilizing this information, the applicable
portion of the aging curve can be identified and the seismic data
collected over the period can be adjusted accordingly.
Of course, one process to minimize the effects of crystal aging is
to preage a clock's crystals prior to deployment of the unit. This
is somewhat equivalent to initiating operation of the unit prior to
deployment in order to permit the unit to stabilize as described
above. By preaging crystals, the exponential portion of the
characterization curve can be avoided such that the correction
information is simply linear in nature. In other words, presaging
stabilizes the aging slope and simplifies
In this regard, each time a seismic unit is powered off and back
on, the clock's crystals must be re-characterized. However, over
multiple cycles of operation, the linear portion of the aging
curve, i.e., crystal aging stabilization, is reached more quickly.
Notwithstanding the foregoing, whether crystals are preaged or not,
none of the prior art devices or seismic data processing techniques
correct for crystal aging as described herein.
While certain features and embodiments of the invention have been
described in detail herein, it will be readily understood that the
invention encompasses all modifications and enhancements within the
scope and spirit of the following claims.
* * * * *