Abstract: A method is provided for computing the differential azimuth between two sets of spaced-apart gravity component measurement devices in a borehole, employing multiple rotation angles. The method includes modeling relationships of axes as defined; forming equations relating rotation angles to outputs of gravity measuring devices; solving such equations to derive the values representative of all of the rotation angles, using measured values of the outputs from the first and second sets of gravity component measuring devices, and computing from the values of the rotation angles the differential azimuth angle between the first set and the second set of gravity measuring devices.

Abstract: A method for determining the orientation of the axis of a borehole with respect to an Earth-fixed reference coordinate system at a selected series of locations in the borehole, the borehole having a trajectory, and adapted to receive a drill string, comprising defining a model for the influence of magnetic interference from elements of the drill string on the measurement of components of the Earth's magnetic field in the borehole in terms of an unknown vector, a measurement vector, and a measurement matrix relating the unknown vector and the measurement vector; measuring at two or more selected locations along the borehole trajectory at least one of two cross-borehole components of the Earth's gravity field at the selected locations in the borehole, and two cross-borehole components and an along-borehole component of the Earth's gravity field at the selected locations in the borehole; two cross-borehole components and an along-borehole component of the Earth's magnetic field at the selected locations; computi

Abstract: A borehole mapping apparatus which employs a ring laser gyroscope. The path of the laser is defined by looping paths of laser beam travel having long and short stretches of travel. The ratio of the stretches being substantially greater than two.

Abstract: The invention relates generally to mapping or survey apparatus and methods, and more particularly concerns efficient transmission of survey signals or data from depth level in a borehole or well to the well surface, for analysis, display or recordation; further it concerns efficient transmission of command data from a surface computer unit to the survey tool at depth level in a borehole or well for control of instrumentation operating modes, operating characteristics, or diagnostic purposes; and further it concerns supply of DC power downwardly to the instrumentation via a wireline by which such command signal and survey data or signals may be transmitted upwardly or downwardly respectively.

Abstract: This invention relates to mapping or survey apparatus and methods, and more particularly concerns derivation of the azimuth output indications for such apparatus in a borehole from the outputs or output indications of either an inertial angular rate vector sensor (or sensors) and an acceleration vector sensor (or sensors), or a magnetic field vector sensor (or sensors), and from the outputs of an acceleration vector sensor (or sensors). At least one of such sensors in any instrument may be canted relative to the borehole axis. Borehole tilt is also derived.

Abstract: A well mapping apparatus comprises:(a) a magnetic field sensing device whose output is proportional to a local magnetic field vector,(b) an acceleration sensing device whose output is proportional to a local gravity vector,(c) the devices supported for rotation about a common axis, in a borehole,(d) the outputs being usable in the determination of azimuth and inclination of the borehole.

Abstract: This invention relates to mapping or survey apparatus and methods, and more particularly concerns derivation of the azimuth output indications for such apparatus in a borehole from the outputs or output indications of either an inertial angular rate vector sensor (or sensors) and an acceleration vector sensor (or sensors), or a magnetic field vector sensor (or sensors), and from the outputs of an acceleration vector sensor (or sensors). Borehole tilt is also derived.