초록 ▼

A method and apparatus for measuring the depth of fluid in a well and for controlling the speed of a pump which pumps fluid out of the well according to the measured depth is disclosed. The depth of fluid in a well is measured by sending an acoustic pulse into an annulus between the well casing and

A method and apparatus for measuring the depth of fluid in a well and for controlling the speed of a pump which pumps fluid out of the well according to the measured depth is disclosed. The depth of fluid in a well is measured by sending an acoustic pulse into an annulus between the well casing and the production tubing and sensing reflections of the acoustic pulse from collars on the tubing and a reflection from the fluid surface. Since the collar spacing on the production tubing is known, the distance from the top of the well to the surface of the fluid can be obtained by accumulating the distance associated with the collars detected in the reflection signal. The collar reflections are sensed by converting the reflected acoustic wave into electrical signals and then amplitude demodulating the broadband electrical signals. Once the distance from the top of the well to the surface of the fluid is determined, the height of the fluid above the pump inlet can be obtained by subtracting the distance from the top of the well to the surface of the fluid from the known distance from the top of the well to the pump inlet. The speed of the pump, and therefore its pumping capacity, is controlled according to the height of the fluid above the pump inlet.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method of determining the depth to fluid in a well where a downhole pump is attached to a string of production tubing that is connected together with collars and the production tubing is disposed inside a well casing so as to form an annulus between the casing and the

[ What is claimed is:] [1.]1. A method of determining the depth to fluid in a well where a downhole pump is attached to a string of production tubing that is connected together with collars and the production tubing is disposed inside a well casing so as to form an annulus between the casing and the production tubing and the annulus is partially filled with fluid to be pumped and the annulus above a fluid surface is filled with gasses, the method comprising:generating and transmitting an acoustic pulse into the annulus inside the well casing;detecting reflections of the acoustic pulse from collars on the production tubing and from the fluid surface to obtain a digital reflection signal;analyzing the digital reflection signal using amplitude demodulation to determine the location of the start of the acoustic pulse within the reflection signal;analyzing the digital reflection signal using amplitude demodulation to determine the location of the reflection from the fluid surface within the reflection signal;analyzing the digital reflection signal using amplitude demodulation to detect reflections from collars within the reflection signal; andapplying a known distance to each collar reflection detected between the start of the acoustic pulse and the refection from the fluid surface to provide the distance from the top of the well to the fluid surface.