| Patent Number |
Title Of Patent |
Date Issued |
| 4325438 |
Lengthening drill string containing an instrument |
April 20, 1982 |
| A pipe section is added to a drill string while an instrument and a flexible line leading to the instrument remain in the string. The effective length of the flexible line is increased in corresponding with the increase in length of the drill string by connection of the flexible line |
| 4178567 |
Period-modulated voltage controlled oscillator |
December 11, 1979 |
| An oscillator for producing an output whose frequency varies in correspondence with changes in the level of an input voltage, and which includes a base or clock oscillator operating at a fixed frequency, a counter operable to count a predetermined number of oscillations of said base |
| 4157619 |
Inclination and direction responsive apparatus |
June 12, 1979 |
| An inclination responsive device including a coil energized to produce a magnetic field extending along a normally vertical axis of the device, and a flux gate assembly adapted to respond to a horizontal component of that field upon tilting movement of the axis to an inclined non-vertica |
| 4153120 |
Change in length of drill string while instrument remains therein |
May 8, 1979 |
| A hole in the earth is formed utilizing a drill string containing an instrument connected by a flexible conductive line to a unit at the surface of the earth. During intervals when the length of the drill string is being changed, as by addition of another pipe section to the outer end |
| 4143721 |
Change in length of drill string containing an instrument |
March 13, 1979 |
| Methods and apparatus are provided for enabling an instrument and a connected flexible line contained in a drill string to be left in the string while a pipe section is being added to or removed from the string, to thereby avoid the inconvenience and loss of time normally involved in |
| 4139950 |
Direction responsive flux gate unit |
February 20, 1979 |
| A flux gate unit for producing an output representing the directional orientation of the unit with respect to the horizontal component of the earth's magnetic field, and in which a saturable flux gate magnetic core structure is mounted for leveling movement relative to associated flux |
