Fluid Level Determination Apparatus and Method of Determining a Fluid Level in a Hydrocarbon Well

Abstract

A system for matching the hydrocarbon reservoir inflow with the outflow of an artificial lift system utilizes an apparatus which makes real time fluid level determinations based upon shock waves detected by a surface device and inputs the observed fluid levels into a processor which controls the speed of a motor which operates a subsurface pump, so as to increase hydrocarbon production. The apparatus which makes real time fluid determinations is installed such that a gas emission port and a pressure wave pressure wave receiving port are placed within the tubing-casing annulus.

What is claimed is: 
     
         1 . An apparatus for determining the depth of a column of fluid within a casing of a well, the well comprising a wellhead, a string of casing and a string of tubing concentrically disposed within the casing wherein an annulus is defined between the tubing and the casing, the apparatus comprising:
 a gas emitting tubing disposed in the annulus through which outlet a charge of compressed gas is released thereby creating a shock wave;   a signal receiving tube having an inlet disposed in the annulus through which inlet a pressure wave is detected;   a measurement device capable of detecting and measuring shock waves attached to the signal receiving tube, said measurement device producing an output signal upon detecting a pre-designated pressure wave amplitude; and   processing means which, upon receipt of the output signal, determines the depth to fluid in the annulus.   
     
     
         2 . The apparatus of  claim 1  wherein the outlet of the gas emitting tubing is disposed in substantially downhole facing direction over the annulus. 
     
     
         3 . The apparatus of  claim 1  wherein the inlet of the signal receiving tube is disposed in substantially downhole facing direction over the annulus. 
     
     
         4 . The apparatus of  claim 1  wherein the charge of compressed gas comprises a produced gas from the well. 
     
     
         5 . The apparatus of  claim 1  wherein the gas emitting tubing and the signal receiving tube are substantially disposed within a carrier tray. 
     
     
         6 . The system of  claim 5  wherein the carrier tray is substantially contained within a housing attached to the wellhead, the carrier tray comprising a first end and a second end. 
     
     
         7 . The system of  claim 6  wherein the carrier tray may be disposed within a plurality of positions within the housing ranging from an extended position wherein the first end is disposed immediately adjacent to the annulus to a retracted position wherein the first end is pulled back from the annulus. 
     
     
         8 . The system of  claim 7  wherein an insertion tool shaft may be removably attached to the carrier tray and utilized to either move the carrier tray from the retracted position to the extended position or from the extended position to the retracted position. 
     
     
         9 . In an oil well comprising a wellhead, a string of casing and a string of tubing concentrically disposed within the casing wherein an annulus is defined between the tubing and the casing, a system allowing the balancing of the reservoir inflow performance of a producing reservoir with the outflow performance of a subsurface pump while maintaining the fluid level within the annulus at a desired level comprises:
 a real time fluid level determination apparatus comprising a gas emitting tubing disposed in the annulus through which outlet a charge of compressed gas is released, a signal receiving tube having an inlet disposed in the annulus through which inlet a pressure wave is detected, a shock wave measurement device attached to the signal receiving tube, said shock wave measurement device producing an output signal upon detecting a pre-designated amplitude of the shock wave, and processing means which, upon receipt of the output signal, determines the depth to fluid in the annulus;   an electrical motor which operates the subsurface pump; and   means for controlling the rotational speed of the electrical motor, said means for controlling the rotational speed of the motor adjustable according to the desired fluid level.   
     
     
         10 . The system of  claim 9  wherein the outlet of the gas emitting tubing is disposed in substantially downhole facing direction over the annulus. 
     
     
         11 . The system of  claim 9  wherein the inlet of the receiving tubing is disposed in substantially downhole facing direction over the annulus. 
     
     
         12 . The system of  claim 9  wherein the charge of compressed gas comprises a produced gas from the well. 
     
     
         13 . The system of  claim 9  wherein the gas emitting tubing and the pressure wave receiving tube are substantially disposed within a carrier tray. 
     
     
         14 . The system of  claim 13  wherein the carrier tray is substantially contained within a housing attached to the wellhead, the carrier tray comprising a first end and a second end. 
     
     
         15 . The system of  claim 14  wherein the carrier tray may be disposed within a plurality of positions within the housing ranging from an extended position wherein the first end is disposed immediately adjacent to the annulus to a retracted position wherein the first end is pulled back from the annulus. 
     
     
         16 . The system of  claim 15  wherein an insertion tool shaft may be removably attached to the carrier tray and utilized to either move the carrier tray from the retracted position to the extended position or from the extended position to the retracted position. 
     
     
         17 . In an oil field comprising at least a first oil producing well and a second oil producing well producing from the same oil reservoir, each well comprising a wellhead, a string of casing and a string of tubing concentrically disposed within the casing wherein an annulus is defined between the tubing and the casing, a system provides real time fluid level determinations within the annulus of each well and allows the fluid level within each oil well to be maintained at a desired distance above a subsurface pump within each well, the system comprising:
 a real time fluid level determination apparatus comprising a gas emitting tubing disposed in the annulus through which outlet a charge of compressed gas is released, a signal receiving tube having an inlet disposed in the annulus through which inlet a pressure wave is detected, a shock wave measurement device attached to the signal receiving tube, said shock wave measurement device producing an output signal upon detecting a pre-designated amplitude of the shock wave, and processing means which, upon receipt of the output signal, determines the depth to fluid in the annulus.   an electrical motor which operates the subsurface pump in each oil producing well; and   means for controlling the rotational speed of each electrical motor, said means for controlling the rotational speed of each motor adjustable according to the desired fluid level in each well.   
     
     
         18 . A method for determining the depth of a column of fluid within a casing of a well, the well comprising a wellhead, a string of casing and a string of tubing concentrically disposed within the casing wherein an annulus is defined between the tubing and the casing, the method comprising:
 emitting a first charge of compressed gas into the annulus;   emitting a second charge of compressed gas into the annulus separated by a time period of a half second or less;   receiving a first reflected signal from the first charge of compressed gas with a pressure sensor;   receiving a second reflected signal from the second charge of compress gas with the pressure sensor; and   processing the first reflected signal and the second reflected signal to determine the depth to fluid in the annulus.