Apparatus for determining the position and orientation of a remote object relative to a reference coordinate frame is disclosed. A plurality of radiating means having orthogonal components are centered about the origin of the reference coordinate frame. Means are provided for applying to the radiating means electrical signals which generate a plurality of electromagnetic fields. The electromagnetic fields are multiplexed and thus are distinguishable from one another. A plurality of receiving means are disposed on the remote object, the receiving means having orthogonal components for detecting and measuring components of the electromagnetic fields. The radiating means and receiving means are separated by a distance sufficiently large to insure that the far-field components of the electromagnetic fields are substantially greater in magnitude than the near-field components of the electro-magnetic fields. Analyzing means is provided for converting in a non-iterative manner the received components of the electromagnetic fields into remote object position and orientation relative to the reference coordinate frame with at most one ambiguous combinations of orientation and position. The processing speed and the complexity of either the receiver of transmitter is reduced by providing one of the radiating means and receiving means with only two orthogonal components and the other with three orthogonal components.

Remote object position and orientation locator

A method and apparatus is provided for determining remote object orientation and position with an electromagnetic coupling. A plurality of radiating antennas are provided for radiating electromagnetic energy. Each of the radiating antennas have independent components for defining a source reference coordinate frame. A transmitter is provided for applying electrical signals to the radiating antennas for generating a plurality of electromagnetic fields. The signals are multiplexed so that the fields are distinguishable from one another. A plurality of receiving antennas are disposed on a remote object for receiving the transmitted electromagnetic fields. The receiving antennas have a plurality of independent components for detecting the transmitted electromagnetic fields and defining a sensor reference coordinate frame. An analyzer is provided for receiving the output of the receiving antennas and converting the components of the transmitted electromagnetic fields into remote object position and orientation relative to the source reference coordinate frame. The analyzing means includes means for processing the components of the electromagnetic fields independently into remote object position in cartesian coordinates and remote object orientation using a quaternion processing strategy. The processing technique provides an uncoupled, noniterative, closed form solution for both position and orientation which is fast and continuous. Further, in the case where dipole antennas are used and the size of the antennas is significant relative to the separation distance between the radiating and receiving antennas, an aperture compensation technique is provided for compensating for distortion in the dipole fields. Still further, the processing technique provides an arrangement for smoothing or filtering the solution for position and orientation by blending previous solutions into the current solution.

Method and apparatus for determining remote object orientation and position

A drilling apparatus for forming a horizontal borehole substantially parallel to a first drilled horizontal borehole which has a signal generating apparatus inserted into the first borehole. A horizontal drill is inserted into the subterranean strata adjacent the first drilled borehole and operated until it is in the formation. A signal receiver contained in the horizontal drill apparatus will then receive a signal generated by the signal generating apparatus. The signal generating apparatus will always be maintained a fixed distance behind or in front of the horizontal drilling apparatus. The signal receiver in the horizontal drill will also include an antenna sensitive to direction which can orient itself with the signal generating apparatus. Knowing the angle between the horizontal drill and the signal generating apparatus, along with the distance along the first borehole between the horizontal drill and the signal generating apparatus, will provide sufficient data to calculate the distance between the first horizontal borehole and the drilling apparatus.

Guidance system for a horizontal drilling apparatus

A method for determining the distance and direction from a first borehole to a second borehole includes generating, by way of a rotating magnetic field source at a first location in a second borehole, and elliptically polarized magnetic field in the region of the first borehole. First and second sensors positioned at an observation point in the first borehole measure the amplitude and relative phase of respective first and second components of the polarized magnetic field and from these measurements, the direction, relative to the sensors, from the observation point to the first location is determined. The distance between these points is determined by measuring at plural observation points amplitude variations with depth of the rotating magnetic field in the first borehole, and computing theoretical variations in the amplitude for different assumed distances between the observation points and the location of the magnetic field source. The measured amplitude variations are compared with theoretical variations to determine the distance between the first and second boreholes.

Rotating magnet for distance and direction measurements from a first borehole to a second borehole

Logging apparatus for measuring alternating magnetic fields generated by electric current flow on a subterranean target near a borehole is disclosed. Electric current of a predetermined temporal form is made to flow on the target; the resulting magnetic field is measured by magnetometers in a downhole sonde. The orientation of the sonde is fixed by various combinations of gyroscope, accelerometer, magnetometer measurements, and borehole survey data.

Method for determining the location of a deep-well casing by magnetic field sensing

A subterranean missile is equipped with three mutually orthogonal coils in its body and a fourth suitably fixed in an articulatable steering member. The missile is guided along any desired underground trajectory defined with reference to a coordinate system including the plane of a dipole-quadrupole antenna system laid on the ground above. Voltages induced in the noncenterline body coils are used in a closed feedback loop to maintain the resultant magnetic field circularly polarized at the mole location. Heading errors are then revealed as a voltage phasor on the centerline coil. Rotation of the steering member sufficiently to bring the voltage induced in its coil into phase with the centerline coil voltage also aligns the steering member such that its articulation will reduce the heading error to zero. Any new trajectory may be defined as a suitable new voltage added to the centerline coil voltage.

James C Coyne

Papers

Mole guidance system