Abstract: The present invention provides a new and unique method, sensor, and apparatus for performing a seismic survey of an earth formation in relation to a borehole. The method includes arranging at least one strain seismic sensor in conjunction with a borehole structure, and mechanically coupling the borehole structure to the borehole to allow seismic data to be accurately transferred to the sensor. The sensor is preferably a fiber optic sensor, including a Fiber Bragg Grating which may be coupled to a relevant borehole structure in a number of ways.

Abstract: An electromagnetic wave propagation resistivity borehole logging system comprising multiple groups of electromagnetic transmitter-receiver arrays operating at three frequencies. The borehole logging tool component of the system employs eight transmitters and four receivers. The transmitters and receivers are disposed axially and symmetrically along the major axis of the tool to form four group pairs. Each group pair consists of a transmitter-receiver groups axially and symmetrically on opposing sides of a reference point on the tool. Each, transmitter-receiver group consists of one transmitter assembly and two receiver assemblies. Each transmitter-receiver group is operated at two of three operating frequencies which are 100 kHz, 400 kHz and 2 MHz. The transmitter and receiver assemblies are fabricated to yield azimuthally symmetrical resistivity measurements in a plane essentially perpendicular to the axis of the tool.

Abstract: A drilling tool has a bent sub or a defined “High Side”. An instrument housing which includes a magnetometer is secured to the directional drilling tool. The magnetometer measures the magnetic field vector in the plane perpendicular to the tool axis. Prior to running the directional drilling tool and the instrument housing into the well, a magnetic source is positioned next to the instrument housing at a position near the magnetometer. The magnetic source is made and positioned such that its magnetic field at the magnetometer points to the chalk line of the high side of a bent sub. The net magnetic field generated from the source is obtained by the difference in magnetic field measurements before and while the magnetic source is applied The azimuthal angle between the net magnetic field vector and the x-axis of the magnetometer or other direction sensor reference point used for tool face calculation is obtained by a computer.

Abstract: An electromagnetic wave propagation resistivity borehole logging system comprising multiple groups of electromagnetic transmitter-receiver arrays operating at three frequencies. The borehole logging tool component of the system employs eight transmitters and four receivers. The transmitters and receivers are disposed axially and symmetrically along the major axis of the tool to form four group pairs. Each group pair consists of a transmitter-receiver groups axially and symmetrically on opposing sides of a reference point on the tool. Each, transmitter-receiver group consists of one transmitter assembly and two receiver assemblies. Each transmitter-receiver group is operated at two of three operating frequencies which are 100 kHz, 400 kHz and 2 MHz. Some of the transmitter and receiver assemblies are fabricated to yield azimuthally focused resistivity measurements, and to yield vertical and horizontal resistivity in anisotropic dipping beds.

Abstract: A drilling tool has a bent sub or a defined “High Side”. An instrument housing which includes a magnetometer is secured to the directional drilling tool. The magnetometer measures the magnetic field vector in the plane perpendicular to the tool axis. Prior to running the directional drilling tool and the instrument housing into the well, a magnetic source is positioned next to the instrument housing at a position near the magnetometer. The magnetic source is made and positioned such that its magnetic field at the magnetometer points to the chalk line of the high side of a bent sub. The net magnetic field generated from the source is obtained by the difference in magnetic field measurements before and while the magnetic source is applied The azimuthal angle between the net magnetic field vector and the x-axis of the magnetometer or other direction sensor reference point used for tool face calculation is obtained by a computer.

Abstract: The present invention is directed to a method and apparatus for determining the dip angle and horizontal and vertical conductivities of a wellbore during drilling operations. If the dip angle is not known, the present invention allows for the use of multifrequency measurements and a model which maps dielectric permitivities to conductivities to calculate the horizontal conductivity, the vertical conductivity, the horizontal dielectric permitivity, the dielectric permitivity, and the dip angle. If the dip angle is known, the present invention allows a multifrequency tool to be utilized alone to calculate the horizontal conductivity, the vertical conductivity, the horizontal dielectric permitivity, and the vertical dielectric permitivity.

Abstract: A quartz sensing system includes a quartz sensor, an electromechanical converter, an optical source, an optical fiber and a signal processor. The quartz sensor responds to a pressure, and further responds to an electrical power signal, for providing a quartz sensor electrical signal containing information about the pressure. The electromechanical converter responds to the quartz sensor signal, for providing an electromechanical converter force containing information about the sensed voltage or current signal. The optical source for provides an optical source signal. The optical fiber responds to the electromechanical converter force, for changing an optical parameter or characteristic of the optical source signal depending on the change in length of the optical fiber and providing an electromechanical converter optical signal containing information about the electromechanical converter force.

Abstract: The present invention provides a seismic sensing system having at least one sensor, transducer, optical source and detection unit, optical fiber and measurement unit. The sensor responds to a seismic disturbance, for providing a sensor signal containing information about the seismic disturbance. The sensor may be a geophone that detects vibrations passing though rocks, soil etc, and provides an electrical voltage sensor signal. The transducer responds to the sensor signal, for providing a transducer force containing information about the sensor signal. The transducer may be a piezoelectric, magnetostrictive or electrostrictive transducer. The optical source provides an optical signal through the fiber. The optical fiber responds to the transducer force, changes an optical parameter or characteristic of the optical signal depending on the change in length of the optical fiber, for providing a transduced optical signal containing information about the transducer force.

Abstract: The invention provides a select trigger or detonation system featuring an optical source, an optical fiber, one or more optical couplers and one or more light trigger or detonation devices. The an optical source provides an optical signal containing information about triggering or detonating a respective device. The optical fiber has one or more fiber Bragg Gratings for providing one or more fiber Bragg Grating optical trigger or detonation signals, each having a respective optical trigger or detonation wavelength. The one or more optical couplers each respond to the one or more fiber Bragg Grating optical trigger or detonation signals depending on the respective optical trigger or detonation wavelength, for providing a respective coupled fiber Bragg Grating optical trigger or detonation signal.

Abstract: The present invention is directed to a method and apparatus for determining the dip angle and horizontal and vertical conductivities of a wellbore during drilling operations. If the dip angle is not known, the present invention allows for the use of multifrequency measurements and a model which maps dielectric permitivities to conductivities to calculate the horizontal conductivity, the vertical conductivity, the horizontal dielectric permitivity, the dielectric permitivity, and the dip angle. If the dip angle is known, the present invention allows a multifrequency tool to be utilized alone to calculate the horizontal conductivity, the vertical conductivity, the horizontal dielectric permitivity, and the vertical dielectric permitivity.

Abstract: The present invention relates to an acoustic logging system having a sonde for arranging in a borehole of a well such as an oil well. The sonde has at least one transmitter for providing at least one transmitter acoustic signal, and has receivers for responding to the at least one transmitter acoustic signal, for providing receiver signals containing information about properties of earth formations in the borehole. The acoustic logging system features one or more transducers, a light source, an optical fiber and a detection and management unit. The one or more transducers responds to the receiver signals from the receiver of the sonde, for providing one or more mechanical transducer forces containing information about the receiver signals. At least one transducer may be a piezoelectric or magnetostrictive transducer. The light source provides an optical signal.

Abstract: An apparatus and a method for determining the conductivity and dielectric constants of an anisotropic formation uses a redundant set of electromagnetic measurements in combination with anisotropic formation models that relate the anisotropic conductivity and dielectric constant of the formation to measurements of a propagating electromagnetic wave in the formation. A conjugate gradient scheme or a Newton-Raphson algorithm is used to obtain solutions to the nonlinear equations of propagation. The solutions to the equations are usually non-unique and are also susceptible to measurement errors. Use of redundant measurements makes it possible to resolve the non-uniqueness. The redundancy is obtained by using multiple frequency and/or multiple spacing tools. The use of redundant measurements also makes it possible to reduce the error in the solution of the wave propagation equation.

Abstract: The present invention provides a nuclear magnetic resonance ("NMR") tool for determining geological properties of formations surrounding a borehole when said tool is traversed in the borehole. One embodiment of the NMR tool includes at least one permanent magnet that is disposed substantially parallel to a longitudinal axis of the tool to generate a static magnetic field at a known distance in the formation. Radio frequency magnetic field in the zone of interest is generated by passing current at a radio frequency through a linear electrical conduction path along the longitudinal axis of the tool. The frequency may be swept during operation of the tool. The return path for the RF current is through the formation. A receiver detects signals from the formation responsive to the induced radio frequency magnetic field, which are processed to provide information about a formation parameter such as the formation porosity, hydrocarbon saturation and permeability of the zone of interest.

Abstract: A fiber optic sensor includes a sensor element responsive to a property or condition of a material, such a resistivity, capacitance, inductance, frequency, etc., for providing an output voltage signal that is dependent upon the property or condition of the material. The sensor further includes an optical-to-electrical conversion element, such as a photo detector or a solar cell, that converts an optical signal (photo detector driving optical signal) carried by an optical fiber into an electrical signal. The electrical signal is applied to the sensor element, and in response, the sensor element provides the output electrical signal. The output electrical signal is applied to a measurement device, such as a piezoelectric element, having at least one dimension that varies with changes in the output electrical signal.

Abstract: An arrangement of two closely spaced transmitters and two spaced apart receivers symmetrically disposed about the transmitters in a measurement while drilling tool avoids the effects of mutual coupling between the receivers. In one method of operation of the transmitters, each transmitter is sequentially activated while the other transmitter is decoupled to eliminate mutual coupling, and the recorded signals processed to take advantage of reciprocity relations. In another method of operation, both transmitters are operated simultaneously with one relative polarity and then with another relative polarity, to eliminate the effects of mutual coupling and to take advantage of reciprocity relations.

Abstract: An electromagnetic propagation tool using magnetic dipole antennas comprising small current loops having characteristics of a point dipole is presented. The electromagnetic tool comprises a drill collar segment having at least one dipole antenna for each transmitter and/or receiver antenna. The dipole antennas are disposed within pockets formed in the drill collar segment.

Abstract: The invention is directed toward the elimination of the effects of electromagnetic coupling between pairs of receivers. The preferred embodiment encompasses the measurement of resistivity and other electromagnetic properties of earth formation in a borehole environment. The invention also incorporates techniques for eliminating the effects of receiver antenna drift and the effects of power variations of two or more transmitters.

Abstract: An electromagnetic propagation tool using magnetic dipole antennas comprising small current loops having characteristics of a point dipole is presented. The electromagnetic tool comprises a drill collar segment having at least one dipole antenna for each transmitter and receiver antenna. The dipole antennas are disposed within pockets formed in the drill collar segment.

Abstract: A method for detecting and sensing boundaries between strata in a formation during directional drilling so that the drilling operation can be adjusted to maintain the drillstring within a selected stratum is presented. The method comprises the initial drilling of an offset well from which resistivity of the formation with depth is determined. This resistivity information is then modeled to provide a modeled log indicative of the response of a resistivity tool within a selected stratum in a substantially horizontal direction. A directional (e.g., horizontal) well is thereafter drilled wherein resistivity is logged in real time and compared to that of the modeled horizontal resistivity to determine the location of the drill string and thereby the borehole in the substantially horizontal stratum. From this, the direction of drilling can be corrected or adjusted so that the borehole is maintained within the desired stratum.