Abstract: Downhole magnetic measurement devices and methods are provided for estimation of magnetic fields during drilling. In certain embodiments, a triaxial vector magnetometer is provided and affixed to a drill string subassembly. While the drill string subassembly is rotating, as during drilling operations, an average total magnetic field value (BTwR) is determined as an average of the instantaneous vector magnitudes of the three measured orthogonal component magnetic fields. In this way, near-bit estimates of the downhole magnetic field may be obtained and used for a variety of functions. These downhole magnetic measurement devices may be useful determining magnetic fields, and estimating borehole inclination and azimuth of drill string subassemblies during drilling operations. Additionally, downhole magnetic measurement devices may be used for detecting the presence and distance to external ferromagnetic materials.

Abstract: Downhole magnetic measurement devices and methods are provided for estimation of magnetic fields during drilling. In certain embodiments, a triaxial vector magnetometer is provided and affixed to a drill string subassembly. While the drill string subassembly is rotating, as during drilling operations, an average total magnetic field value (BTwR) is determined as an average of the instantaneous vector magnitudes of the three measured orthogonal component magnetic fields. In this way, near-bit estimates of the downhole magnetic field may be obtained and used for a variety of functions. These downhole magnetic measurement devices may be useful determining magnetic fields, and estimating borehole inclination and azimuth of drill string subassemblies during drilling operations. Additionally, downhole magnetic measurement devices may be used for detecting the presence and distance to external ferromagnetic materials.

Abstract: A measurement apparatus for making magnetic and gravity component measurements in a borehole, including measurements made while the apparatus is rotating about the borehole axis, comprising a magnetic field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, a gravity field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, an inertial angular rotation sensing device having an axis of sensitivity along the borehole axis to sense inertial angular motion about the borehole axis, control, power and processing circuitry to operate said sensing devices and to process the outputs of said sensing devices to obtain stabilized component data in a coordinate system that does not rotate with the said measurement apparatus, communication circuitry to transmit output data to auxiliary equipment at the surface or in the borehole, and support structure to support the sensing devices.

Abstract: In the method of providing for well tubular member magnetization, the steps include providing a magnetizing structure comprising an electrical coil defining an axis, relatively displacing the member and the structure, with the coil positioned and guided in close, centered proximity to the member, while supplying electric current to flow in the coil, thereby creating magnetic flux passage through the member and core to magnetize the member, or a part of the member, and displacing the member in a wellbore.

Abstract: A measurement apparatus for making magnetic and gravity component measurements in a borehole, including measurements made while the apparatus is rotating about the borehole axis, comprising a magnetic field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, a gravity field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, an inertial angular rotation sensing device having an axis of sensitivity along the borehole axis to sense inertial angular motion about the borehole axis, control, power and processing circuitry to operate said sensing devices and to process the outputs of said sensing devices to obtain stabilized component data in a coordinate system that does not rotate with the said measurement apparatus, communication circuitry to transmit output data to auxiliary equipment at the surface or in the borehole, and support structure to support the sensing devices.

Abstract: A measurement apparatus for making magnetic and gravity component measurements in a borehole, including measurements made while the apparatus is rotating about the borehole axis, comprising a magnetic field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, a gravity field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, an inertial angular rotation sensing device having an axis of sensitivity along the borehole axis to sense inertial angular motion about the borehole axis, control, power and processing circuitry to operate said sensing devices and to process the outputs of said sensing devices to obtain stabilized component data in a coordinate system that does not rotate with the said measurement apparatus, communication circuitry to transmit output data to auxiliary equipment at the surface or in the borehole, and support structure to support the sensing devices.

Abstract: A method for drilling a wellbore to assure the avoidance of a substantially adjacent known magnetic source comprising the steps of obtaining survey data for the path or trajectory of a known magnetic source; preparing a wellplan comprising a path or trajectory for a second wellbore to be drilled, from the survey data and the wellplan, computing expected values of one or more parameters of the magnetic field to be encountered along a second wellbore during drilling operations, in association with drilling a second wellbore, measuring components of a magnetic field encountered and computing one or more magnetic field parameters at a series of survey points along the wellbore path or trajectory; and determining if measured values differ systematically from expected values, thereby indicating a deviation from the planned wellpath.

Abstract: A measurement apparatus for making magnetic and gravity component measurements in a borehole, including measurements made while the apparatus is rotating about the borehole axis, comprising a magnetic field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, a gravity field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, an inertial angular rotation sensing device having an axis of sensitivity along the borehole axis to sense inertial angular motion about the borehole axis, control, power and processing circuitry to operate said sensing devices and to process the outputs of said sensing devices to obtain stabilized component data in a coordinate system that does not rotate with the said measurement apparatus, communication circuitry to transmit output data to auxiliary equipment at the surface or in the borehole, and support structure to support the sensing devices.

Abstract: A method for drilling a wellbore to assure the avoidance of a substantially adjacent known magnetic source comprising the steps of obtaining survey data for the path or trajectory of a known magnetic source; preparing a wellplan comprising a path or trajectory for a second wellbore to be drilled, from the survey data and the wellplan, computing expected values of one or more parameters of the magnetic field to be encountered along a second wellbore during drilling operations, in association with drilling a second wellbore, measuring components of a magnetic field encountered and computing one or more magnetic field parameters at a series of survey points along the wellbore path or trajectory; and determining if measured values differ systematically from expected values, thereby indicating a deviation from the planned wellpath.

Abstract: In the method of providing for well tubular member magnetization, the steps include providing a magnetizing structure comprising an electrical coil defining an axis, relatively displacing the member and the structure, with the coil positioned and guided in close, centered proximity to the member, while supplying electric current to flow in the coil, thereby creating magnetic flux passage through the member and core to magnetize the member, or a part of the member, and displacing the member in a wellbore.

Abstract: An apparatus for borehole electric-field telemetry that comprises a source of modulated voltage or current, at least one axially non-conductive collar connected between pipe sections in a pipe string, and a system of insulated wireline components providing electrical connections, insulated from drilling fluids, between the ends of the one or more aforementioned insulated collars in the pipe string, to transmit the voltage to current.

Abstract: An apparatus for borehole electric field telemetry includes a source of modulated voltage or current, at least one axially extending collar collar connected between pipe sections in a pipe string, and a system of insulated wireline components providing electrical connections, insulated from drilling fluids, between the ends of the one or more aforementioned insulative collars in the pipe string, to transmit the voltage or current. The source of modulated voltage or current comprises an electrical pulse-producer for producing short duration pulse wave forms selected to obtain optimum transmission characteristics in the underground formation. The electrical connections are to the drillstring, and there are upper and lower instrument housings associated with the electrical connections, which are upper and lower connections. The housings are supported within the pipe string, the upper housing located above at least one of the insulative collars, and the lower housing projecting below the insulative collar.

Abstract: A method to determine the earth's magnetic field vector along a sub-surface wellpath having unknown and possibly changing azimuth, in the presence of a magnetic disturbance caused by a magnetic source external to the wellpath includes estimating the three components of the earth field along the three axes of a magnetic sensor package by a polynomial function of measured depth along the wellpath. Magnetic survey accuracy is thereby improved. Upon removal of the earth's magnetic field from the measurements, the resultant magnetic field of the disturbance is determined and can be used to determine the position and orientation of the source of the disturbance.

Abstract: An apparatus for borehole electric field telemetry includes a source of modulated voltage or current, at least one axially extending collar connected between pipe sections in a pipe string, and a system of insulated wireline components providing electrical connections, insulated from drilling fluids, between the ends of the one or more aforementioned insulative collars in the pipe string, to transmit the voltage or current. The source of modulated voltage or current comprises an electrical pulse-producer for producing short duration pulse wave forms selected to obtain optimum transmission characteristics in the underground formation. The electrical connections are to the drillstring, and there are upper and lower instrument housings associated with the electrical connections, which are upper and lower connections. The housings are supported within the pipe string, the upper housing located above at least one of the insulative collars, and the lower housing projecting below the insulative collar.

Abstract: An apparatus and method for display of biologically induced electrical activity is disclosed. The apparatus includes sensors for measuring EEG or MEG signals from a living body and using these signals to compute one or more dipoles representative of the measured electrical activity. Values of the electrical activity may also be computed for discrete locations in or on the body. The operator has the ability to input a variety of different computational specifications or criteria to facilitate dipole computation. The resulting computed data may be selectively displayed as a dipole within a three-dimensional representation of the body, as a movie-like series of dipoles, as a composite or tracing of dipoles or as various topographic maps. The operator also has the ability to change the display to provide different perspective views or to enlarge the displayed scene.