US4715470A
Expired / Lapsed
US
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Downhole electromagnetic seismic source
Assignee: Chevron USA Inc
•
Filing: 1986-03-18
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Granted: 1987-12-29
•
Expires: 2006-03-18
Abstract
Abstract The present invention is a downhole seismic source capable of generating seismic forces in excess of 1000 newtons. The source produces seismic waves for seismic applications, particularly cross borehole measurements and vertical seismic profiling. Coupled with motion sensing devices, the present invention also performs as a seismic logging tool. The source is comprised of an outer housing, a means for clamping the source securely to the wellbore, and a linear electromagnetic actuator which utilizes permanent magnetic material having remanent magnetic field exceeding about 0.9 T such as rare earth permanent magnetics. The source has a diameter of about 12.5 cm to fit within a typical wellbore and the actuator has a length of about 1 meter.
Inventors
- 👤 Bjorn N. P. Paulsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:22
CPC Classifications
G; G01; G01V; G01V11/00; G01V11/002; G01V11/005; E; E21; E21B; E21B23/00; E21B23/01; G01V1/00; G01V1/02; G01V1/143; G01V1/155
Claims Analysis
Total Claims: 83
Claim 1
Independent Claim
109 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing comprising; (a) a cylindrically shaped shell having an outer portion attached to said housing and an inner portion; (b) an armature winding attached to said inner portion of said shell; and (c) an inner core reaction mass slidably positioned inside said armature winding such that motion of said mass will impart substantially shear waves and presure waves on a surrounding formation, said reaction mass substantially constructed from a magnetically active material and moving along its lengthwise axis when said armature winding is energized.
Claim 2
Dependent Claim
109 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing comprising; (a) a cylindrically shaped shell having an outer portion attached to said housing and an inner portion; (b) an armature winding attached to said inner portion of said shell; and (c) an inner core reaction mass slidably positioned inside said armature winding such that motion of said mass will impart substantially shear waves and presure waves on a surrounding formation, said reaction mass substantially constructed from a magnetically active material and moving along its lengthwise axis when said armature winding is energized.
Claim 3
Dependent Claim
20 words
The downhole seismic source according to claim 1 wherein said actuator is capable of achieving forces exceeding about 1,000 newtons.
Claim 4
Dependent Claim
23 words
The downhole seismic source according to claim 1 wherein said actuator is capable of achieving forces of between about 12,000 and 18,000 newtons.
Claim 5
Dependent Claim
23 words
The downhole seismic source according to claim 1 wherein said actuator is capable of achieving forces of between about 1,000 and 18,000 newtons.
Claim 6
Dependent Claim
25 words
The downhole seismic source according to claim 1 wherein said magnetically active material is selected from: iron, iron alloys, permanent magnetic material, and mixtures thereof.
Claim 7
Dependent Claim
24 words
The downhole seismic source according to claim 5 wherein said permanent magnetic material has a remanent magnetic field of at least about 0.9 T.
Claim 8
Dependent Claim
20 words
The downhole seismic source according to claim 5 wherein said permanent magnetic material is a rare earth permanent magnetic material.
Claim 9
Dependent Claim
18 words
The downhole seismic source according to claim 7 wherein said rare earth permanent magnetic material is samarium cobalt.
Claim 10
Dependent Claim
17 words
The downhole seismic source according to claim 7 wherein said rare earth permanent magnetic material is Neodymium-Iron-Boron.
Claim 11
Dependent Claim
26 words
The downhole seismic source according to claim 1 wherein said inner core reaction mass is comprised of iron laminated with a rare earth permanent magnetic material.
Claim 12
Dependent Claim
22 words
The downhole seismic source according to claim 1 wherein said inner portion of said shell is substantially constructed from magnetically active material.
Claim 13
Dependent Claim
15 words
The downhole seismic source according to claim 1 further comprising: a second linear electromagnetic actuator.
Claim 14
Dependent Claim
29 words
The downhole seismic source according to claim 1 wherein said actuator is oriented in parallel with respect to the wellbore and said reaction mass vibrates along its lengthwise axis.
Claim 15
Dependent Claim
37 words
The downhole seismic source according to claim 1 wherein said actuator is oriented in parallel with respect to the wellbore and said reaction mass is rotatable about its lengthwise axis and vibrates torsionally in a twisting motion.
Claim 16
Dependent Claim
31 words
The downhole seismic source of claim 1 wherein said actuator is oriented perpendicularly with respect to the wellbore and said reaction mass vibrates along a lengthwise axis of said reaction mass.
Claim 17
Dependent Claim
30 words
The downhole seismic sources according to claim 12 wherein said actuators are oriented perpendicularly with respect to the borehole and have reaction masses which vibrate perpendicularly along their lengthwise axes.
Claim 18
Dependent Claim
32 words
The downhole seismic source according to claim 1 wherein said seismic source is less than about 12.5 cm in diameter and said linear actuator is at least about 1 meter in length.
Claim 19
Dependent Claim
48 words
The downhole seismic source according to claim 1 further comprising at least one seismic sensing device, said motion sensing device being acoustically isolated from said actuator and capable of being independently coupled to the wellbore, said motion sensing device selected from the group consisting of: accelerometers and geophones.
Claim 20
Dependent Claim
26 words
The downhole seismic source according to claim 18 further comprising a non-isolated motion sensing device, said non-isolated motion sensing device being acoustically coupling to said actuator.
Claim 21
Dependent Claim
173 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass within said housing comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized such that substantially shear waves and pressure waves are imparted on a surrounding formation.
Claim 22
Dependent Claim
173 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass within said housing comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized such that substantially shear waves and pressure waves are imparted on a surrounding formation.
Claim 23
Dependent Claim
29 words
The downhole seismic source according to claim 20 wherein said first and said second magnetically active material are selected from: iron, iron alloys, permanent magnetic material, and mixtures thereof.
Claim 24
Dependent Claim
24 words
The downhole seismic source according to claim 21 wherein said permanent magnetic material has a remanent magnetic field of at least about 0.9 T.
Claim 25
Dependent Claim
41 words
The downhole seismic source according to claim 20 wherein said first magnetically active material is a permanent magnetic material having a remanent magnetic field of at least about 0.9 T and said second magnetically active material is a non-permanent magnetic material.
Claim 26
Dependent Claim
32 words
The downhole seismic source according to claim 20 wherein said first magnetically active material is a rare earth permanent magnetic material and said second magnetically active material is a non-permanent magnetic material.
Claim 27
Dependent Claim
19 words
The downhole seismic source according to claim 24 wherein said first rare earth permanent magnetic material is samarium cobalt.
Claim 28
Dependent Claim
18 words
The downhole seismic source according to claim 24 wherein said first rare earth permanent magnetic material is Neodymium-Iron-Boron.
Claim 29
Dependent Claim
55 words
The downhole seismic source according to claim 20 wherein said second magnetically active material is a non-permanent magnetic material and said inner core is comprised of: an inner portion constructed from non-permanent magnetic material and an outer portion constructed from a permanent magnetic material having a remanent magnetic field of at least about 0.9 T.
Claim 30
Dependent Claim
46 words
The downhole seismic source according to claim 20 wherein said said second magnetically active material is a non-permanent magnetic material and said inner core is comprised of: an inner portion constructed from non-permanent magnetic material and an outer portion constructed from rare earth permanent magnetic material.
Claim 31
Dependent Claim
35 words
The downhole seismic source according to claim 20 wherein said second magnetic material has a remanent magnetic field of at least about 0.9 T and said first magnetically active material is a non-permanent magnetic material.
Claim 32
Dependent Claim
32 words
The downhole seismic source according to claim 20 wherein said second magnetically active material is a rare earth permanent magnetic material and said first magnetically active material is a non-permanent magnetic material.
Claim 33
Dependent Claim
19 words
The downhole seismic source according to claim 30 wherein said second rare earth permanent magnetic material is samarium cobalt.
Claim 34
Dependent Claim
18 words
The downhole seismic source according to claim 30 wherein said second rare earth permanent magnetic material is Neodymium-Iron-Boron.
Claim 35
Dependent Claim
55 words
The downhole seismic source according to claim 20 wherein said first magnetically active material is a non-permanent magnetic material and said outer core is comprised of: an outer portion constructed from non-permanent magnetic material and an inner portion constructed from a permanent magnetic material having a remanent magnetic field of at least about 0.9 T.
Claim 36
Dependent Claim
46 words
The downhole sei.smic source according to claim 20 wherein said said first magnetically active material is a non-permanent magnetic material and said outer core is comprised of: an outer portion constructed from non-permanent magnetic material and an inner portion constructed from rare earth permanent magnetic material.
Claim 37
Dependent Claim
22 words
The downhole seismic source according to claim 20 wherein said actuator is capable of achieving forces in excess of about 1000 newtons.
Claim 38
Dependent Claim
23 words
The downhole seismic source according to claim 20 wherein said actuator is capable of achieving forces of between about 3000 and 4000 newtons.
Claim 39
Dependent Claim
23 words
The downhole seismic source according to claim 20 wherein said actuator is capable of achieving forces of between about 1000 and 18,000 newtons.
Claim 40
Dependent Claim
16 words
The downhole seismic source according to claim 20 having at least a second linear electromagnetic actuator.
Claim 41
Dependent Claim
37 words
The downhole seismic source according to claim 20 wherein said actuator is oriented in parallel with respect to the wellbore and said reaction mass is rotatable about its lengthwise axis and vibrates torsionally in a twisting motion.
Claim 42
Dependent Claim
32 words
The downhole seismic source according to claim 20 wherein said actuator is oriented perpendicularly with respect to the wellbore and said reaction, mass vibrates along a lengthwise axis of said reaction mass.
Claim 43
Dependent Claim
30 words
The downhole seismic source according to claim 20 wherein said source is less than about 12.5 cm in diameter and said actuator is at least about 1 meter in length.
Claim 44
Dependent Claim
17 words
The downhole seismic source according to claim 20 wherein said actuator is about 2 meters in length.
Claim 45
Dependent Claim
35 words
The downhole seismic source according to calim 20 further comprising at least one motion sensing device, said motion sensing device being acoustically isolated from said actuator and capable of being independently coupled to the wellbore.
Claim 46
Dependent Claim
35 words
The downhole seismic source according to calim 20 further comprising at least one motion sensing device, said motion sensing device being acoustically isolated from said actuator and capable of being independently coupled to the wellbore.
Claim 47
Dependent Claim
29 words
The downhole seismic source according to claim 43 wherein said first and said second magnetically active material are selected from: iron, iron alloys, permanent magnetic material, and mixtures thereof.
Claim 48
Dependent Claim
24 words
The downhole seismic source according to claim 44 wherein said permanent magnetic material has a remanent magnetic field, of at least about 0.9 T.
Claim 49
Dependent Claim
20 words
The downhole seismic source according to claim 44 wherein said permanent magnetic material is a rare earth permanent magnetic material.
Claim 50
Dependent Claim
21 words
The downhole seismic source according to claim 43, wherein said motion sensing devices are comprised of: geophones, accelerometers, and mixtures thereof.
Claim 51
Dependent Claim
26 words
The downhole seismic source according to claim 42 further comprising a non-isolated motion sensing device, said non-isolated motion sensing device being acoustically coupled to said actuator.
Claim 52
Dependent Claim
22 words
The downhole seismic source according to claim 43 wherein said actuator is capable of achieving forces in excess of about 1000 newtons.
Claim 53
Dependent Claim
27 words
The downhole seismic source according to claim 43 wherein said actuator is capable of producing seismic waves in a frequency range of about 10 to 200 hz.
Claim 54
Dependent Claim
27 words
The downhole seismic source according to claim 43 wherein said actuator is capable of producing seismic waves in a frequency range of about 10 to 1500 hz.
Claim 55
Dependent Claim
45 words
A downhole seismic source comprising: a housing; a reaction mass within said housing; a clamping means for coupling said housing securely within a wellbore; and an electromagnetic actuator means within said housing for moving said reaction mass to create substantially pressure waves and shear waves.
Claim 56
Dependent Claim
45 words
A downhole seismic source comprising: a housing; a reaction mass within said housing; a clamping means for coupling said housing securely within a wellbore; and an electromagnetic actuator means within said housing for moving said reaction mass to create substantially pressure waves and shear waves.
Claim 57
Dependent Claim
58 words
The downhole seismic source of claim 52 wherein said electromagnetic actuator means is a linear electromagnetic actuator comprising: (a) an armature winding capable of producing a magnetic field; and (b) a cylindrically shaped shell constructed substantially from magnetically active material, said shell reacting with the magnetic field generated by said armature winding when said armature winding is energized.
Claim 58
Dependent Claim
25 words
The downhole seismic source according to claim 53 wherein said magnetically active material is selected from: iron, iron alloys, permanent magnetic material, and mixtures thereof.
Claim 59
Dependent Claim
19 words
The downhole seismic source according to claim 54 wherein said permanent magnetic material includes rare earth permanent magnetic material.
Claim 60
Dependent Claim
22 words
The downhole seismic source according to claim 52, wherein said actuator is capable of achieving forces in excess of about 1000 newtons.
Claim 61
Dependent Claim
56 words
A downhole seismic source comprising: (a) a housing; (b) a clamping means for coupling said housing securely within a wellbore; (c) a linear eletromagnetic actuator within said housing; and (d) a reaction mass slidably positioned in said actuator such that motion of said mass will impart substantially shear waves and pressure waves on a surrounding formation.
Claim 62
Dependent Claim
56 words
A downhole seismic source comprising: (a) a housing; (b) a clamping means for coupling said housing securely within a wellbore; (c) a linear eletromagnetic actuator within said housing; and (d) a reaction mass slidably positioned in said actuator such that motion of said mass will impart substantially shear waves and pressure waves on a surrounding formation.
Claim 63
Dependent Claim
51 words
The downhole seismic source according to claim 57, whrein said linear electromagnetic actuator further comprises: (a) a shell having an outer portion attached to said housing and an inner portion; (b) an armature winding attached to said inner portion of said shell; and (c) a magnetically active inner core reaction mass.
Claim 64
Dependent Claim
26 words
A downhole seismic source according to claim 58 wherein said armature winding is constructed to move linearly along its lengthwise axis when said armature is energized.
Claim 65
Independent Claim
72 words
A method of generating seismic waves comprising: lowering a seismic source into a borehole in an earthen formation said seismic source comprising a housing, a linear electromagnetic liner actuator a reaction mass slidably positioned within said actuator, and a clamping means; securing said seismic source in the formation with said clamping means; energizing said electromagnetic liner actuator to move said mass to generate substantially pressure waves and shear on said earthen formation.
Claim 66
Independent Claim
72 words
A method of generating seismic waves comprising: lowering a seismic source into a borehole in an earthen formation said seismic source comprising a housing, a linear electromagnetic liner actuator a reaction mass slidably positioned within said actuator, and a clamping means; securing said seismic source in the formation with said clamping means; energizing said electromagnetic liner actuator to move said mass to generate substantially pressure waves and shear on said earthen formation.
Claim 67
Dependent Claim
23 words
The method as recitd in claim 60 wherein the step of energizing said electromagnetic liner actuator generates vibrational forces exceeding about 1,000 newtons.
Claim 68
Dependent Claim
26 words
The method as recited in claim 60 wherein the step of enregizing said electromagnetic linear actuator generates vibrational forces exceeding between about 12,000 and 18,00 newtons.
Claim 69
Dependent Claim
26 words
The method as recited in claim 60 wherein the step of energizing said electromagnetic linear actuator generates vibrational forces exceeding between about 1,000 and 18,000 newtons.
Claim 70
Dependent Claim
20 words
The method as recited in claim 60 wherein said vibrational forces are generated along a lengthwise axis of said borehole.
Claim 71
Dependent Claim
21 words
The method as recited in claim 60 wherein said vibrational forces are generated perpendicularly to a lengthwise axis of said borehole.
Claim 72
Dependent Claim
17 words
The method as recited in claim 60 wherein said vibrational forces are generated torsionally in said borehole.
Claim 73
Dependent Claim
20 words
The method as recited in claim 60 further comprising the step of sensing the motion of said electromagnetic linear actuator.
Claim 74
Dependent Claim
105 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing comprising; (a) a cylindrically shaped shell having an outer portion attached to said housing and an inner portion; (b) an armature winding attached to said inner portion of said shell; and (c) an inner core reaction mass slidably positioned inside said armature winding, said reaction mass substantially constructed from a magnetically active material and moving linearly along its lengthwise axis when said armature winding is energized, said mass comprised of iron laminated with a rare earth permanent magnetic material.
Claim 75
Dependent Claim
105 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing comprising; (a) a cylindrically shaped shell having an outer portion attached to said housing and an inner portion; (b) an armature winding attached to said inner portion of said shell; and (c) an inner core reaction mass slidably positioned inside said armature winding, said reaction mass substantially constructed from a magnetically active material and moving linearly along its lengthwise axis when said armature winding is energized, said mass comprised of iron laminated with a rare earth permanent magnetic material.
Claim 76
Dependent Claim
201 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (iii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material, said second magnetically active material being a non-permanent magnetic material and said inner core comprised of: an inner portion constructed from non-permanent magnetic material and an outer portion constructed from a permanent magnetic material having a remanent magnetic field of at least about 0.9 T; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized.
Claim 77
Dependent Claim
201 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (iii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material, said second magnetically active material being a non-permanent magnetic material and said inner core comprised of: an inner portion constructed from non-permanent magnetic material and an outer portion constructed from a permanent magnetic material having a remanent magnetic field of at least about 0.9 T; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized.
Claim 78
Dependent Claim
191 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material, said second magnetically active material being a non-permanent magnetic material and said inner core comprised of: an inner portion constructed from non-permanent magnetic material and an outer portion contructed from rare earth permanent magnetic material; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized.
Claim 79
Dependent Claim
191 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material, said second magnetically active material being a non-permanent magnetic material and said inner core comprised of: an inner portion constructed from non-permanent magnetic material and an outer portion contructed from rare earth permanent magnetic material; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized.
Claim 80
Dependent Claim
201 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material, said first magnetically active material being a non-permanent magnetic material and said outer core comprised of: an outer portion constructed from non-permanent magnetic material and an inner portion constructed from a permanent magnetic material having a remanent magnetic field of at least about 0.9 T; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material; said reaction mass moving reiteratively from a first position to a said position when said armature winding is energized.
Claim 81
Dependent Claim
201 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylindrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material, said first magnetically active material being a non-permanent magnetic material and said outer core comprised of: an outer portion constructed from non-permanent magnetic material and an inner portion constructed from a permanent magnetic material having a remanent magnetic field of at least about 0.9 T; and (iii) a cylindrically shaped outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material; said reaction mass moving reiteratively from a first position to a said position when said armature winding is energized.
Claim 82
Dependent Claim
191 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylinddrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material, said first magnetically active material being a non-permanent magnetic material and said outer core comprised of: an outer portion constructed from non-permanent magnetic material and an inner portion constructed from rare earth permanent magnetic material; and (iii) a cylindrically shpaed outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized.
Claim 83
Dependent Claim
191 words
A downhole seismic source comprising: a housing; a clamping means for coupling said housing securely within a wellbore; and a linear electromagnetic actuator within said housing, comprising; (a) an armature winding attached to said housing, said armature winding having a cylinddrical shape around a center axis; and (b) a reaction mass comprising: (i) a center shaft coaxially positioned inside said armature winding and adapted to be slidably movable along its lengthwise axis; (ii) a cylindrically shaped inner core attached to said center shaft and coaxially positioned between said center shaft and said armature winding, said inner core being substantially constructed from a first magnetically active material, said first magnetically active material being a non-permanent magnetic material and said outer core comprised of: an outer portion constructed from non-permanent magnetic material and an inner portion constructed from rare earth permanent magnetic material; and (iii) a cylindrically shpaed outer core attached to said center shaft and coaxially positioned outside said armature winding, said outer core being substantially constructed from a second magnetically active material; said reaction mass moving reiteratively from a first position to a second position when said armature winding is energized.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-28 | 1991-06-29 | 1991-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-28 | 1995-06-29 | 1995-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-28 | 1999-06-29 | 1999-12-29 | $7700.00 | Window Closed / Lapsed |