Method for distinguishing between single-phase gas and single-phase liquid leaks in well casings
AssigneeMobil Oil Corporation
InventorEdwin E. Glenn, Jr.
Life of this patent
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Abstract
An acoustic detector is moved through a well to detect sound at various levels within the well. An electrical signal indicative of the detected sound is applied from the acoustic detector by way of a conductor cable to uphole recording equipment including an amplifier, spectrum analyzer, and recorder. The spectrum analyzer provides a frequency spectrum of the amplified signal from the acoustic detector. This frequency spectrum is recorded for use in the identification of flow leaks through or behind the casing of the well in accordance with predetermined spectrum analysis characteristics of single-phase gas and single-phase liquid leaks.
Claims15
A method of distinguishing between single-phase gas and single-phase liquid leaks through or behind the casing of a well, comprising the steps of:
- a. monitoring acoustic noise generated by a casing leak within a well,
- b. producing an electrical signal representative of said monitored acoustic noise,
- c. measuring the frequency spectrum of said electrical signal,
- d. selecting a reference frequency within said measured frequency spectrum above which a single-phase gas leak exhibits at first select frequencies noise peaks having a decrease in amplitude from the amplitude of the noise peak at said reference frequency and a single-phase liquid leak exhibits at second select frequencies noise peaks having no change or an increase in amplitude from the amplitude of the noise peak at said reference frequency,
- e. comparing the amplitudes of the noise peaks of said acoustic noise at said reference frequency and at said first and second select frequencies above said reference frequency,
- f. identifying said casing leak as a single-phase gas leak if the amplitude of the noise peaks at said first select frequencies are decreased from the amplitude of the noise peak at said reference frequency, and
- g. identifying said casing leak as a single-phase liquid leak if the amplitude of the noise peaks at said second select frequencies is the same or is increased from the amplitude of the noise peak at said reference frequency.
Dependencies are inferred from the claim text.