Abstract: A gravity sensor is disclosed which includes a first mass adapted to free fall when selectively released from an initial position. The mass has optical elements adapted to change a length of an optical path in response to movement of the mass. The sensor output is coupled to a beam splitter. One output of the splitter is coupled substantially optically directly to an interferometer. Another output of the splitter is coupled to the interferometer through an optical delay line. A frequency of the interference pattern is directly related to gravity at the mass. A second such mass having similar optics, optically coupled in series to the first mass and adapted to change the path length in opposed sign, when selectively dropped to cause time coincident movement of the two masses, generates an interference pattern having frequency related to gravity difference.

Abstract: A gravity sensor is disclosed which includes a first mass adapted to free fall when selectively released from an initial position. The mass has optical elements adapted to change a length of an optical path in response to movement of the mass. The sensor output is coupled to a beam splitter. One output of the splitter is coupled substantially optically directly to an interferometer. Another output of the splitter is coupled to the interferometer through an optical delay line. A frequency of the interference pattern is directly related to gravity at the mass. A second such mass having similar optics, optically coupled in series to the first mass and adapted to change the path length in opposed sign, when selectively dropped to cause time coincident movement of the two masses, generates an interference pattern having frequency related to gravity difference.

Abstract: A new induction logging tool has a toolstring length that is shorter than the toolstring length of the induction logging tool of the prior art. The new induction logging tool includes a new induction array which appears to be folded about an axis that coincides with the transmitter of the induction array of the prior art induction logging tool. The new folded induction array including a transmitter coil, located at an end of the new folded induction array, and a plurality of "cowound" receiver coils and bucking coils, a further plurality of individual receiver coils, and at least one further bucking coil located adjacent to and on one side of the transmitter coil of the new folded induction array.

Abstract: A new induction logging tool has a toolstring length that is shorter than the toolstring length of the induction logging tool of the prior art. The new induction logging tool includes a new induction array which appears to be folded about an axis that coincides with the transmitter of the induction array of the prior art induction logging tool. The new folded induction array including a transmitter coil, located at an end of the new folded induction array, and a plurality of "cowound" receiver coils and bucking coils, a further plurality of individual receiver coils, and at least one further bucking coil located adjacent to and on one side of the transmitter coil of the new folded induction array.

Abstract: A logging apparatus is adapted to be disposed in a mud filled wellbore, and a measurement probe is connected to a bottom of a tool string of the logging apparatus. The measurement probe is adapted for measuring a resistivity of a mud in the mud filled wellbore. The measurement probe includes a bottom electrode disposed on a bottom of the probe when the logging apparatus is disposed in the wellbore, a second electrode, and at least one measurement electrode disposed adjacent the bottom electrode for measuring a voltage potential drop in a region of the mud which is disposed directly below the bottom electrode of the measurement probe when the probe is disposed in the wellbore. When the measurement probe is energized, a current flows in the mud between the bottom electrode and the second electrode.

Abstract: An improved method and apparatus is disclosed for use in a return line system of a drilling rig to determine a volumetric fluid flow rate and, therefore, to aid in detecting a kick in a well. The apparatus comprises an ultrasonic level sensor, an ultrasonic Doppler velocity sensor and a digital computer electrically coupled to the level sensor and the Doppler velocity sensor to determine the fluid flow regime in the return line system. The flow regime is determined by the programmed computer to accurately determine the volumetric fluid flow rate in the return line system in real time, during drilling operations.