Mobil Oil Corporation

Lucien Masse

William L Medlin

James H Sexton

W L Medlin

A simple harmonic oscillator for use in measuring dynamic elastic constants of rock material samples includes a pair of masses vertically suspended from a support position by a pair of wires. At least one mass is driven by a permanent magnet with the driving coil positioned in the air gap to the magnet. The rock sample is horizontally positioned between the pair of masses such that the rock sample acts as a spring element connecting the masses, thereby forming the simple harmonic oscillator. Resonance measurements are determined for various pore fluid contents by introducing various ratios of gas/water/oil into the rock sample.

Method for measuring the resonance of rock material

Circumferential and longitudinal strain measurements are carried out on a rock material under oscillatory loading conditions at seismic frequencies. The phase angle between each of these strains and the oscillatory driving force is determined by synchronous and quadrature detection.

Strain and phase detection for rock materials under oscillatory loading

A confining pressure system includes a pressure cell containing a mechanical oscillator and a gas supply for carrying out resonance measurements of rock material under confining pressure at seismic frequencies. An appropriate gas is used to avoid significant damping of oscillations under confining pressures of various ranges.

System for conducting resonance measurements of rock materials under

A harmonic oscillator and motion detection system for use in measuring dynamic elastic constants of rock material samples includes a pair of masses vertically suspended from a support position by a pair of wires. At least one mass is driven by a permanent magnet with the driving coil positioned in the air gap to the magnet. The rock sample is horizontally positioned between the pair of masses such that the rock sample acts as a spring element connecting the masses, thereby forming the simple harmonic oscillator. The motion detection system includes a pair of coil-magnets mounted to each mass for use in determining the amplitude and phase of the motion of the pair of masses.

Amplitude and phase detector in a harmonic oscillator system

A novel method is disclosed for using the resonance behavior of reservoir sand to distinguish between oil-rich, gas-rich and water-rich zones. A wellbore is logged, as for example with a long spaced acoustic logging tool, to obtain data which are then interpreted to determine the damping of the acoustic signal in one sand versus another, or in that sand versus a reference sand having similar resonance characteristics.

Sonic attenuating method for distinguishing between oil, water and gas

A method of logging a wellbore to identify oil, gas and water zones in a hydrocarbon-bearing formation that is characterized by acoustic velocities which are maximum when saturated with oil, minimum when saturated with water and intermediate when saturated with gas. The formation is logged with a sonic logging system utilizing a frequency within the range of 0.1 to 10 KHz and logged with a lithologic logging system to account for variations in lithology on the sonic log. Thereafter the sonic log is compared with the known acoustic velocity characteristic of the hydrocarbon-bearing formation to identify the oil, gas and water zones therein.

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Dallas, TX, United States of America

Lucien Masse