Determing fluid levels in wells with flow induced pressure pulses
First Claim
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1. A method for measuring the speed of sound in a gaseous medium existing in the annulus between the casing and production tubing in a producing well said method comprising:
- filling a section of small tubing with a representative sample of gas obtained from the annulus;
measuring the temperature and pressure of said sample of gas;
creating a pressure wave in said sample of gas by quickly venting a small portion of the gas from one end of the tubing;
measuring the time of origination of said pressure wave at the emitting end;
measuring the time of arrival of the reflected pressure wave after it has traveled the length of the small tubing and has returned to the point of origination;
determining the round trip travel time of the pressure wave by subtracting the time of origination from the time of arrival of the reflected wave;
calculating the speed of sound within the gaseous medium by dividing twice the linear length of the small tubing by the round trip time so measured; and
storing the measured speed of sound for later use in determining the fluid level in the well.
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Abstract
An acoustic method is disclosed for measuring fluid level in producing wells and other inaccessible cavities. The method uses flow induced pressure phenomena to locate the fluid level. Simplified equipment is involved and acoustic velocities can be measured externally from the well. The method applies to known uses for fluid levels such as well productivity, lift equipment design, and reservoir studies.
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Citations
6 Claims
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1. A method for measuring the speed of sound in a gaseous medium existing in the annulus between the casing and production tubing in a producing well said method comprising:
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filling a section of small tubing with a representative sample of gas obtained from the annulus; measuring the temperature and pressure of said sample of gas; creating a pressure wave in said sample of gas by quickly venting a small portion of the gas from one end of the tubing; measuring the time of origination of said pressure wave at the emitting end; measuring the time of arrival of the reflected pressure wave after it has traveled the length of the small tubing and has returned to the point of origination; determining the round trip travel time of the pressure wave by subtracting the time of origination from the time of arrival of the reflected wave; calculating the speed of sound within the gaseous medium by dividing twice the linear length of the small tubing by the round trip time so measured; and storing the measured speed of sound for later use in determining the fluid level in the well. - View Dependent Claims (2, 3, 4, 5)
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6. A method for measuring the speed of sound in a gaseous medium existing in the annulus between the casing and production tubing in a producing well, said method comprising:
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filling a section of small tubing with a representative sample of gas obtained from the annulus; measuring the temperature and pressure of said sample of gas; creating a pressure wave in said sample of gas at one end of said tubing; measuring the time of origination of said pressure wave at the one end of said tubing; measuring the time of arrival of the reflected pressure wave after it has traveled the length of the small tubing and has returned to the one end of said tubing; determining the round trip travel time of the pressure wave by subtracting the time of origination from the time of arrival of the reflected wave; calculating the speed of sound within the gaseous medium by dividing twice the linear length of the small tubing by the round trip time so measured; and storing the measured speed of sound for later use in determining the fluid level in the well.
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Specification