Abstract: Apparatus for collecting a plurality of samples of fluids in earth formations traversed by a wellbore includes a pressure sensor for deriving a pressure measurement and a temperature sensor for simultaneously deriving a temperature measurement. The pressure measurement signals and the temperature measurement signal are transmitted to processing circuitry using a narrow band frequency modulated scheme. The temperature measurement is used to provide a real time temperature compensated pressure measurement.

Abstract: In apparatus for investigating earth formations traversed by a borehole, improved methods and apparatus are provided for performing inductive type formation measurements. A transmitter coil of a well logging tool moving through a borehole emits an alternating field into the adjacent earth formation thus inducing eddy currents therein. A voltage in a receiver coil in the tool is sampled at discrete elevations as the tool traverses the borehole and amplified. This voltage is phase detected with respect to the transmitter coil voltage to insure that the measured receiver voltage corresponds to the currents induced in the formation. An average of these voltage measurements is formed. Variations in the magnitude of the average phase-detected voltage are used to discretely control the amplitude of the alternating current induced into the formation.

Abstract: In apparatus for investigating earth formations traversed by a borehole, improved methods and apparatus are provided for achieving dynamic range control of formation measurements. In one embodiment adapted to formation resistivity measurements, a well logging tool moving through a borehole emits a current into the adjacent earth formation, and a corresponding measurement voltage correlative to the resistivity is sampled at discrete elevations as the tool traverses the borehole. An average of these voltage measurements is formed. When the magnitude of this average exceeds or drops below a predetermined range, the magnitude of the survey voltage is decreased or increased respectively by a discrete amount.

Abstract: In the representative embodiment of the present invention disclosed herein, new and improved pipe-inspection apparatus for examining oilfield piping includes, along with other flaw-inspection devices, a flux-leakage inspection device uniquely arranged for detecting minute magnetic-flux anomalies which are indicative of metal defects such as cracks, pits, holes and the like. In contrast, however, to the prior-art high-intensity electromagnetizers typically having cores of minimum magnetic reluctance, the unique pipe-inspection apparatus of the present invention instead employs an electromagnetizer having a core of a substantial length and minimum cross-sectional area to specifically make its reluctance relatively large in relation to the combined magnetic reluctances of the magnetized piping wall and the annular clearances between the piping wall and the magnetizer pole pieces.