Geospace Technologies Corporation

Shaw Industries, Inc.

Weatherford/lamb, Inc.

Daniel M Woo

James R Dunphy

Arne Berg

Sverre Knudsen

James C Woodall, Jr

A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Micro-geophone

A geophone in which a coil bobbin assembly ideally includes a provision for receiving a third coil winding between the upper and lower coils. A third mass-tuning coil is wound around the bobbin whose purpose is to adjust the overall mass of the bobbin assembly with greater accuracy and precision than can be achieved by machining techniques alone. Mass is adjusted by adding or subtracting one or more turns of wire in the tuning coil. The tuning coil is preferably electrically shorted for increasing geophone damping.

Geophone having improved damping control

A geophone utilizing an Alnico-9 magnet and having an improved sensitivity over Alnico-9 geophones of prior art through the lengthening of the parasitic air gap between the upper and lower pole pieces which, results in less magnetic flux leakage. The flux concentration through the geophone coils is increased and shifted towards the ends of the magnet. The increase of sensitivity of geophone of the present invention over prior art geophones may exceed 3 dB. The axial length of the coil bobbin is increased, and the positions of the electrical coils are moved towards the ends of the magnet to align with the shifted magnetic flux.

Geophone having improved sensitivity

A vertical geophone that includes a lower frequency spring, which forms part of the geophone electrical circuit, that is positioned directly on the lower end cap This arrangement eliminates the 'spring supported by a spring' arrangement of prior art geophones to minimize geophone distortion and simplify tuning of the frequency springs. A contact spring is positioned between the lower frequency spring and the lower pole piece for forming part of the geophone electrical circuit. One surface of contact spring includes a plurality of wiper surfaces that ensure consistent sliding electrical contact against either the bottom surface of the lower pole piece or the upper surface of the lower frequency spring. The obverse surface of the contact spring is preferably spot welded to the other adjacent member.

Vertical geophone having improved distortion characteristics

A highly sensitive accelerometer for determining the acceleration of a structure includes a mass within a housing suspended by opposing support members. The support members are alternately wound around a pair of fixed mandrels and the mass in a push pull arrangement. At least a portion of one of the support members comprises a transducer capable measuring the displacement of the mass within the housing. An embodiment of the invention employs optical fiber coils as the support members for use in interferometric sensing processes. Arrays of such interferometer based accelerometers may be multiplexed using known techniques.

Highly sensitive accelerometer

An improved reduced distortion spring spider for geophones is disclosed that has the desired ratio of spurious resonant frequency to the natural frequency of the geophone and can absorb the sharp lateral forces imposed on the geophone during destructive testing and field usage.

Low distortion geophone spring

A geophone is disclosed that has a cylindrical housing closed at one end by a bottom and the other end by a top. A magnet assembly of a rare earth magnet with pole pieces at each end of the magnet is centrally mounted in the housing providing an annular space between the magnet assembly and the housing. A coil form is located in the annular space. Springs support the coil form for axial movement relative to the magnet assembly along the longitudinal axis of the housing. The rare earth magnet produces a magnetic field sufficiently strong that the pole pieces can be made longer than the coils on the coil form thereby provided a uniform magnetic field in which the coils move thereby reducing the amount of harmonic distortion produced by the geophone.

High resolution geophone

A geophone is disclosed that has a cylindrical housing closed at one end by a bottom and the other end by a top. A magnet assembly with pole pieces at each end of the magnet is centrally mounted in the housing providing an annular space between the magnet assembly and the housing. A coil form is located in the annular space. Springs support the coil form for axial movement relative to the magnet assembly along the longitudinal axis of the housing. Washers are included on the upper and lower sides of each of the springs to enhance the life span of the springs by reducing the damage caused by torsional forces experienced by the springs during normal operation and rough handling. Also incorporated in the geophone are resilient members mounted between the coil form and the housing to prevent the coil form from directly hitting the housing and thereby reduce the amount of frequency shift experienced by the geophone over its life span.

Geophone shock absorber

An improved spring spider for geophones is disclosed that has the desired ratio of spurious resonant frequency to the natural frequency of the geophone and can absorb the sharp lateral forces imposed on the geophone during destructive testing and hand usage.

Geophone spring

A geophone is disclosed that has a cylindrical housing closed at one end by a bottom and at the other end by a top. A magnet assembly and a coil-mass are located in the housing. Springs support the coil-mass for axial movement relative to the magnet assembly along the longitudinal axis of the housing. A pair of coil terminals are mounted in the upper end of the coil-mass adjacent the top of the housing. A pair of eyelets extend through the top of the housing and outside geophone terminals are attached to and extend through the eyelets into the housing. A pair of pigtails connect the geophone terminals to the coil terminals.

Growing community of inventors

Missouri City, TX, United States of America

Daniel M Woo