Sand detection
AssigneeShell Oil Company
InventorsHarm Mast, Jan W. Kraayeveld, Peter B. Vriezen, Gerrit J. Wunnink
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Abstract
A method and apparatus for detecting sand particles in a flowing fluid, for example, the production from a gas or oil well. An acoustic transducer is used to detect the sand particles and the resulting signal is filtered to pass a frequency band of 50 to 500 kiloherz. A pulse height discriminating means and pulse counter is provided for counting the number of pulses that exceed a pre-set amplitude.
Claims9
A method of detecting solid sand particles in a fluid flowing from a well through a conduit, comprising:
- an acoustic transducer means having a housing with a piezoelectric element disposed therein, said piezoelectric element being biased into contact with one wall of said housing, said piezoelectric element in addition being coupled to a preamplifier disposed in said housing;
- generating an electric signal by allowing the particles to impinge against the housing of said acoustic transducer means;
- filtering said signal to pass frequency components thereof in a pulse train ranging within the frequency band of about 50 kHz to about 500 kHz;
- comparing the values of the amplitudes of each said pulse train in the filtered signal with at least one predetermined range of amplitude values;
- generating for each pulse train an electric standard pulse having a predetermined time period and amplitude when the maximum amplitude of said pulse train has a value that is above said one of predetermined range of amplitude values;
- and,
- counting the number of standard pulses generated by said pulse train within each set predetermined period.
Means for detecting solid sand particles in a fluid flowing from a well through a conduit, comprising:
- an acoustic transducer means having a housing with a piezoelectric element disposed therein, said piezoelectric element being biased into contact with one wall of said housing, said piesoelectric element in addition being coupled to a preamplifier disposed in said housing;
- indicating means for indicating the number of impacts made by particles on the acoustic transducer means;
- and,
- circuitry means interconnecting said transducer means and said indicating means, said circuitry means comprising filter means for processing the electric signals generated by the transducer means to pass frequency components thereof in a pulse train ranging within the frequency band of about 50 kHz to about 500 kHz, a pulse height discriminating means and a pulse shaper means, said two latter means being adapted to form for each pulse train a standard pulse having a predetermined time period and amplitude, said standard pulse being passed on to the indicating means each time the value of the maximum amplitude of a pulse train is above a preset range of values in the filtered signal.
Dependencies are inferred from the claim text.