Abstract:
A device for employing sonic transmissions is utilized to determine fluid level in a well or a container. The device may be utilized while the well is operating. It is known that wells replenish fluid at different rates even in the same formation or well field. Increased well production at minimum pumping cost is achieved for a given well. The device generates a sonic event through the use of a compressed fluid that is obtained from within a well. A fluid level measurement system is obtained in a well in which gas is produced under vacuum.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to determining the level of a fluid in a well such as a gas well, an oil well, or water well. 
     2. Description of the Art Practices 
     It is known that wells replenish fluids at different rates even in the same formation or well field. The rate of fluid flow into the well bore is maximized because the hydrostatic head driving the fluid is at a maximum. See for example Burris, et al., U.S. Pat. No. 6,085,836 issued Jul. 11, 2000. The Burris, et al., patent is incorporated herein by reference. 
     The preceding observation suggests that the well pump should run constantly to keep the level in the well bore as low as possible thus maximizing production. Of course, this is often unsatisfactory for several reasons. 
     First, running the pump constantly or at too great a speed is inefficient since, some of the time, the well bore is completely empty and there is nothing to pump. Thus, energy conservation becomes a cost consideration. Second, the equipment is subject to wear and damage resulting in costly repairs when pumps are run dry. Third, paraffin build up is more pronounced when a well is allowed to pump dry. In the dry pump condition gases are drawn into the bore. The gases in the bore then expand and cool. As the gases cool, paraffin build up is promoted as these high melting hydrocarbons begin to plate out on the surfaces of the bore. However, a well may be pumped continuously provided that the liquid level of the well is high enough to ensue the well sump has liquid therein, e.g. avoid pumping gas into the tubing. 
     Given the above considerations, control strategies aimed at optimizing well production have emerged. Notably, timers have been used to control the pump duty cycle. A timer may be programmed to run the well nearly perfectly if the one could determine the duration of the on cycle and off cycle which keeps the fluid level in the bore low but which does not pump the bore dry. 
     The pump on cycle and off cycle can be determined for a group of wells or for an entire well field. Savings in energy may be maximized by knowing which wells fill at what rate and then optimizing pumping to reduce or maintain a constant electric load below the maximum peak available. 
     Given fluid level information, deciding when or how fast to run the pump is very straightforward and production can be optimized. Fluid level determinations, particularly for deep down hole (bore) systems, have been implemented. Unfortunately, these deep down hole systems have been costly and complex to install, unreliable in operation, and costly to repair or service. Although the implementation details will not be discussed here, it is worth noting that these systems, when operating correctly, have proven that significant gains in well production are available when control strategies using fluid level measurement are applied. 
     One system that has been attempted is the use of one-shot measurements. The one-shot measurement will use a sonic event such as a shotgun shell to generate the event. Another system is based on a nitrogen tank being utilized to generate a sonic event. In either of the foregoing systems the production of the well must be shut down to implement the sonic event and the corresponding data evaluations. By contrast the present invention will permit continuous operation of the well as the sonic events are generated, the data collected, the well conditions read out, and changes in pumping implemented. Moreover, the system of the present invention is conducted utilizing fluid from the well thus avoiding the cost of the nitrogen and does not require opening of the well to the atmosphere. 
     Clearly, what is needed is a control system with the advantages of fluid level measurement which is cost effective to install and operate and which is reliable. Basic features for fluid level measurement should include applicability to oil, water, or other wells and should be applicable to rod, screw (such as by a frequency drive), or other pump types. 
     A fluid level measurement system should be simple and inexpensive to install in the T-Head and useful for well depths to 10,000 feet. Such a fluid level measurement system should be self calibrating for each installation and accurate to 10 feet (3.1 meters). The system should be robust to harsh environments within and around the well. 
     A fluid level measurement system is desirably able to provide fluid level measurements in well in which gas is produced under vacuum. That is, some wells do not have sufficient pressure in the well to permit the gas to flow to the T-Head. In such cases, the well is often one in which methane is derived from a coal seam in which progressive cavity pumps are employed. 
     SUMMARY OF THE INVENTION 
     The present invention describes a device for controlling pump conditions comprising:
     a T-Head connector;
       at least one microphone connected with said T-Head connector;   a gas compression chamber connected with said T-Head connector;   a first valve for controlling fluid communication between said gas compression chamber and a wellhead;   
       a computer controller;   said computer controller connected with said first valve to open and close said first valve to permit fluid communication between said gas compression chamber and the wellhead;   said computer controller to activate said gas compression chamber, for when in use, to compress gas from the wellhead to obtain a compressed gas at a greater pressure than that of the wellhead,   and,   said computer controller connected with said gas compression chamber, for when in use, to open a valve to release the compressed gas into the wellhead.   

     The present invention also describes a device for controlling pump comprising:
     a T-Head connector;   at least one microphone connected with said T-Head connector;   a piston chamber connected with said T-Head connector;   a piston located within said piston chamber;   a first valve for controlling fluid communication between said piston chamber and a wellhead;   a second valve for controlling fluid communication between said piston chamber and the wellhead;   said first valve and said second valve located on opposite sides of said piston;   a computer controller;   said computer controller connected with at least one of said first valve or said second valve to open and close said first valve or said second valve to permit fluid communication between said piston chamber and the wellhead; and,   said computer controller connected with said piston, for when in use, to drive said piston in said cylinder.   

     A further aspect of the present invention describes a method for comprising:
     at least partially opening a first valve to permit fluid communication between a gas compression chamber and a wellhead;   closing said first valve to prevent fluid communication between said gas compression chamber and the wellhead;   activating said gas compression chamber to compress fluid in said gas compression chamber thereby obtaining a compressed fluid in said gas compression chamber;   at least partially opening said first valve to release the compressed fluid into the wellhead thereby generating a sonic event;   obtaining data from the sonic event;   processing the data from the sonic event to determine the conditions for controlling the pump.   

     Yet another aspect of the present invention describes a method for controlling pump conditions for a well comprising:
     closing a first valve to prevent fluid communication between a piston chamber and a wellhead;   moving a piston in said piston chamber away from said valve;   opening said valve to permit fluid from the wellhead into the piston chamber thereby generating a sonic event;   obtaining data from the sonic event;   processing the data from the sonic event to determine the conditions for controlling the pump.   

     Yet another aspect of the present invention describes a method for compressing a method for controlling pump conditions for a well comprising:
     closing a first valve in a piston chamber to prevent fluid communication between said piston chamber and the wellhead;   simultaneously closing a second valve in said piston chamber to prevent fluid communication between said piston chamber and the wellhead;   moving a piston in said piston chamber away from said first valve so as to create a partial vacuum in the region between said first valve and said piston while compressing fluid in the region between said second valve and said piston;   simultaneously opening said first valve and said second valve to create a first sonic event in the wellhead and a second sonic event in the wellhead;   obtaining data from at least one of the sonic events; and,   processing the data from the sonic event to determine the conditions for controlling the pump.   

     The present invention also describes a device for receiving audio signals comprising a method for controlling pump conditions for a well comprising:
     at least partially opening a first valve to permit fluid communication between a piston chamber and a wellhead;   said piston chamber having therein a piston;   said piston having a front face and a rear face;   said piston chamber having a second valve;   closing said first valve to prevent fluid communication between said piston chamber and the wellhead;   driving said piston within said piston chamber in the direction of said first valve such that the first face of said piston compresses fluid in said piston chamber thereby obtaining a compressed fluid in said piston chamber;   at least partially opening said first valve to release the compressed fluid into the wellhead thereby generating a sonic event;   obtaining data from the sonic event;   processing the data from a sonic event to determine the conditions for controlling the pump   

     The present invention describes a device for receiving audio signals comprising a method for determining at least one of the amount of a liquid phase and/or a gaseous phase in a sealable container, for when in use the sealable container containing a liquid phase and a gaseous phase, the sealable container having located therein:
         at least one microphone;   a gas compression chamber;   a piston located within the gas compression chamber;   a first valve for controlling fluid communication between the gas compression chamber and said sealable container;   means to open and close the first valve to permit fluid communication between the gas compression chamber and the sealable container; and,   means to drive the piston in the gas compression chamber, closing the first valve to prevent fluid communication between the gas compression chamber and the sealable container;       

     then causing at least one of:
             moving the piston in the gas compression chamber away from the first valve to cause at least a partial vacuum in the gas compression chamber;   opening the first valve to permit fluid communication between the sealable container and the gas compression chamber thereby generating a sonic event by fluid from the sealable container moving into the gas compression chamber, or   compressing fluid within the gas compression chamber to obtain a compressed fluid with the first valve closed to prevent evacuation of the fluid from the gas compression chamber and opening the first valve to release the compressed fluid into the sealable container thereby generating a sonic event; and,
 
obtaining data from the generation of the sonic event with the microphone, correlating the data, and determining at least one of the amount of a liquid phase and/or a gaseous phase in the sealable container.
           

     Yet another aspect of the present invention describes a device for receiving audio signals comprising 
     a microphone having microphone leads; 
     said microphone and microphone leads encased in substantially hydrocarbon impervious flexible tubing; and, 
     said microphone capped with a latex cover. 
     A further aspect of the present invention describes a device for receiving for receiving audio signals comprising
         a microphone having microphone leads;   said microphone and microphone leads encased in substantially hydrocarbon impervious flexible tubing; and,
 
a heating element is located within said flexible tubing.
       

     A further aspect of the invention is a device for receiving audio signals comprising
         a microphone having microphone leads;   said microphone and microphone leads encased in substantially hydrocarbon impervious flexible tubing;
 
a heating element is located within said flexible tubing; and,
   said microphone capped with a latex cover.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from reading the following specification with reference to the accompanying drawings, in which: 
         FIG. 1  is a partial sectional view of an aspect of the invention; 
         FIG. 2  is a partial sectional view of a well head system; 
         FIG. 3  is a view of a microphone according to the invention; 
         FIG. 4  is a partial sectional view of a second embodiment of the present invention; and, 
         FIG. 5  is sectional view of a propane storage tank. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A pump controlling device  10  for controlling pump conditions in a well is shown in  FIG. 1 . The pump controlling device  10  is connected with well  12  as seen in  FIG. 2 . The pump controlling device  10  comprises a gas compression chamber shown herein as a piston chamber  14 . A piston  16  is located within the piston chamber  14 . The piston  16  has a piston front face  18  and a piston rear face  20 . The term compression chamber herein means any suitable means of compressing a gas. 
     The piston chamber  14  has a piston fore chamber  22  located on the side of the piston chamber  14  adjacent to the piston front face  18 . The piston  16  forms an airtight seal to prevent fluid communication between the piston front face  18  and the piston rear face  20 . The piston chamber  14  has a piston after chamber  24  located on the side of the piston chamber  14  adjacent to the piston rear face  20 . 
     The piston  16  has a piston stem  36 . The piston stem  36  extends axially in after chamber  24  and extends through an airtight opening  38 . The piston stem  36  is connected with a piston driver  40 . The piston driver  40  is conveniently operated by any source of power such as electricity or steam. The piston driver  40  may also be hydraulically operated. 
     The piston fore chamber  22  has an opening  48 . A conduit  52  forms an airtight seal at the opening  48  with the piston fore chamber  22 . The conduit  52  is thus in fluid communication with the piston fore chamber  22 . 
     The conduit  52  is connected with a pressure measuring device  58 . The pressure measuring device  58  is located so as to determine fluid pressure within the conduit  52 . The conduit  52  is also connected with a temperature measuring device  62 . The temperature measuring device  62  is located so as to determine fluid temperature within the conduit  52 . 
     A valve  68  provides for fluid flow and fluid shutoff to the conduit  52 . A second conduit  70  is connected to the valve  68 . The valve  68  controls fluid flow between the conduit  52  and the second conduit  70 . 
     A T-Head connector  80  is a generally cylindrical barrel having an air tight closure cap  82  at one end. The T-Head connector  80  has an opening  84  at the opposite end from the closure cap  82 . The second conduit  70  extends through the opening  84  into the T-Head connector  80 . The second conduit  70  makes an airtight connection with the T-Head connector  80 . 
     The second conduit  70  has a right angle bend  86  within the T-Head connector  80 . The right angle bend  86  provides a second segment  88  of the second conduit  70 . 
     The second segment  88  of the second conduit  70  has an opening  90  to provide fluid communication to the T-Head connector  80  of a well  12 . The opening  90  is at the opposite end from the closure cap  82 . Thus, when the valve  68  is in the open position there is fluid communication from the opening  90  to the piston fore chamber  22 . 
     A tube  92  extends between the piston after chamber  24  and the T-Head connector  80 . The tube  92  makes an airtight seal with the piston after chamber  24  at an opening  94  in the piston after chamber  24 . The opening  94  is located in the piston after chamber  24  such that the maximum stroke of the piston  16  by the piston stem  36  does not permit the piston front face  18  to be positioned such that there is fluid communication between the piston fore chamber  22  and the tube  92 . 
     An opening  96  is located in the T-Head connector  80 . The tube  92  makes an airtight seal with the T-Head connector  80  at the opening  96 . The tube  92  provides fluid communication between the piston after chamber  24  and the T-Head connector  80 . 
     A microphone opening  98  is located in the T-Head connector  80 . A microphone conduit  100  is adapted to form an airtight seal in the T-Head connector  80  at the microphone opening  98 . The microphone conduit  100  has an open end  102  in fluid communication the T-Head connector  80 . 
     The microphone  110  is preferably a condenser microphone. The microphone  110  is preferably unidirectional. The microphone  110  is connected with a computer  120 . The computer  120  is capable of processing the reception of sonic events by the microphone  110 . For convenience, the various leads to the computer  120  are not shown and labeled in the Figs. The computer  120  is also capable of providing a signal to drive the piston  16  in the piston chamber  14 . 
     The microphone is best seen in  FIG. 3 . The microphone  110  is enclosed by a microphone sleeve  112 . The microphone sleeve  112  has a threaded screw  114  at one end. A microphone cap  116  fits over the microphone sleeve  112  to protect the microphone  110  from dust. A microphone heating element  118  is placed in the microphone sleeve  112  to protect the microphone  110  from condensation. The microphone sleeve  112  is conveniently bent at a 45 degree angle to permit easy insertion into the T-Head connector  80  at the microphone opening  98 . 
     As best seen in  FIG. 2 , the well  12  comprises in part a wellhead  138 . A well casing  140  is located within the wellhead  138  and extends downward into the well  12 . The wellhead  138  may also be utilized for the underground storage of propane or other liquefied gas. In the later case there is no annulus but rather tubing in which the pump controlling device  10  is conveniently mounted. 
     Well tubing  142  is located within the well casing  140 . The well tubing  142  extends downward in the well casing  140  forming an annulus  146  between the outer surface of the well tubing  142  and the inner surface of the well casing  140 . 
     The well casing  140  and the well tubing  142  are fastened to a standard T-Head connection  150 . The well casing  140  and the well tubing  142  are not in fluid communication at the T-Head connection  150 . 
     The T-Head connection  150  has two pipes  152  and  154 . A T-head valve  158  and a T-head valve  160  respectively terminate the pipes  152  and  154  of the T-Head connection  150 . 
     The pipe  152  in the T-Head connection  150  is utilized to remove, in the case of an oil and gas well, the gas. The second pipe  154  is utilized as a backup. In the present invention the T-Head connector  80  is connected to the opposite side of the T-head valve  160  from the pipe  154 . The T-Head connector  80  is in fluid communication with the annulus  146  of the well when the T-head valve  160  is open. 
     In operation, the valve  68  is placed in the closed position to prevent fluid communication between the T-Head connector  80  and the piston fore chamber  22 . The T-head valve  160  is open such that the T-Head connector  80  is in fluid communication with the T-Head connection  150 . The T-Head connection  150  is then in fluid communication with the annulus  146  of a well as shown in  FIG. 2 . 
     The pressure of the gas in the annulus  146  is determined by the pressure measuring device  58  with the valve  68  open. The pressure determined by the pressure measuring device  58  is reported to the computer  120 . 
     The temperature measuring device  62  may be used to measure the fluid temperature in the annulus  146  at this time. As the operation of the invention may be conducted in a dynamic manner the temperature of the fluid drawn through the T-Head connector  80  is effectively the temperature of the fluid in annulus  146 . The fluid temperature determined by temperature measuring device  62  is reported to the computer  120 . 
     The valve  68  is then placed in the closed position preventing further fluid communication between the annulus  146  and the piston fore chamber  22 . The piston  16  is moved away from the closed valve  68  causing an effective axial expansion of the piston fore chamber  22  with the result being a partial vacuum in the piston fore chamber  22 . There is no practical resistance to the movement of the piston  16  as the tube  92  is in fluid communication with the after chamber  24 . 
     The piston  16  is then driven toward the closed valve  68 . Driving of the piston  16  compresses the fluid in the piston fore chamber  22  thereby forming a compressed fluid having a greater pressure and temperature than the fluid in the annulus  146 . Typically, it is desirable that the pressure of the compressed fluid in the piston fore chamber  22  be at least 30 psi greater than the pressure of the fluid in the annulus  146 . 
     The pressure and the temperature of the compressed fluid in the piston fore chamber  22  may be measured by the pressure measuring device  58  temperature measuring device  62  and reported to the computer  120 . 
     The valve  68  is then opened releasing the compressed fluid through the second conduit  70  around the right angle bend  86 . The expanding compressed fluid moves around the right angle bend  86  through the second segment  88  exiting the opening  90  into the T-Head connector  80 . 
     The T-Head connector  80  volume is much greater than the regions that the compressed fluid has passed. The result of the larger volume is that the compressed fluid rapidly decompresses releasing mechanical energy in the form of a sonic event. 
     The sonic event is transmitted through the fluid in the T-Head connector  80  into the annulus  146 . The measurement of the level of liquid in annulus  146  is determined by the Doppler effect as received by the microphone  110 . The signal from the microphone is transmitted to the computer  120 . 
     When the computer  120  has correlated the data from the sonic events the computer  120  determines the amount of liquid  180  in the wellhead  138 . The computer then generates a signal to the pump (not shown) to order the pump to begin operation to remove liquid  180  from the wellhead  138 . Similarly, the computer  120  may generate a signal to the pump to discontinue the pumping operation to prevent an excess of liquid  180  from being removed from the well. 
     For continuous operation of a well, such as with a screw pump, the operating conditions may be varied to maximize production while minimizing electric consumption. That is, every time a well starts pumping a large voltage is required to overcome the pump inertia. If the pump is operated on a continuous basis electrical consumption may be minimized. Similarly, where it is desired to stop to start pumping, the optimum conditions for removing liquid  180  from the tubing  142  may be determined. 
     A second embodiment of the present invention is shown in  FIG. 4 . The tube  92  is replaced with the following components. 
     The piston after chamber  24  has an opening  94 . A conduit  252  forms an airtight seal at the opening  94  with the piston after chamber  24 . The conduit  252  is thus in fluid communication with the piston after chamber  24 . 
     The conduit  252  is connected with a pressure measuring device  258 . The pressure measuring device  258  is located so as to determine fluid pressure within the conduit  252 . The conduit  252  is also connected with a temperature measuring device  262 . The temperature measuring device  262  is located so as to determine fluid temperature within the conduit  252 . 
     A valve  268  provides for fluid flow and fluid shutoff to the conduit  252 . A second conduit  270  is connected to the valve  268 . The valve  268  controls fluid flow between the conduit  252  and the second conduit  270 . 
     An opening  96  is located in the T-Head connector  80 . The second conduit  270  makes an airtight seal with the T-Head connector  80  at the opening  96 . The second conduit  270  provides fluid communication between the piston after chamber  24  and the T-Head connector  80 . 
     The second conduit  270  extends through the opening  96  into the T-Head connector  80 . The T-Head connector  80  has an opening  84 . The second conduit  270  makes an airtight connection with the T-Head connector  80 . 
     The second conduit  270  has a right angle bend  286  within the T-Head connector  80 . The right angle bend  286  provides a second segment  288  of the second conduit  270 . 
     The second segment  288  of the second conduit  270  has an opening  290  to provide fluid communication to the T-Head connector  80  of a well  12 . The opening  290  is at the opposite end from the closure cap  82 . Thus, when the valve  268  is in the open position there is fluid communication from the opening  290  to the piston after chamber  24 . 
     A microphone opening  298  is located in the T-Head connector  80 . A microphone conduit  300  is adapted to form an airtight seal in the T-Head connector  80  at the microphone opening  298 . The microphone conduit  300  has an open end  302  in fluid communication the T-Head connector  80 . 
     The microphone  310  is preferably a condenser microphone. The microphone  310  is preferably unidirectional. The microphone  310  is essentially the same as the microphone  110  seen in  FIG. 3 . The microphone  310  is connected to the computer  120 . The computer  120  is capable of processing the reception of sonic events by the microphone  310 . 
     The second mode of operation is generally the same as the first mode of operation. In the second mode of operation, the valve  68  is placed in the closed position to prevent fluid communication between the T-Head connector  80  and the piston fore chamber  22 . The T-head valve  160  is open such that the T-Head connector  80  is in fluid communication with the T-Head connection  150 . The T-Head connection  150  is then in fluid communication with the annulus  146  of a well as shown in  FIG. 2 . 
     The pressure of the gas in the annulus  146  is determined by the pressure measuring device  58  with the valve  68  open. The pressure determined by the pressure measuring device  58  is reported to the computer  120 . 
     The temperature measuring device  62  may be used to measure the fluid temperature in the annulus  146  at this time. As the operation of the invention may be conducted in a dynamic manner the temperature of the fluid drawn through the T-Head connector  80  is effectively the temperature of the fluid in annulus  146 . The fluid temperature determined by temperature measuring device  62  is reported to the computer  120 . 
     The valve  68  is then placed in the closed position preventing further fluid communication between the annulus  146  and the piston fore chamber  22 . The valve  268  is placed in the open position to reduce the effort needed to draw the piston  16  away from the valve  68 . 
     The piston  16  is moved away from the closed valve  68  causing an effective axial expansion of the piston fore chamber  22  with the result being a partial vacuum in the piston fore chamber  22 . The valve  68  is rapidly opened resulting in a sonic event (an implosion) as the fluid from the annulus  146  moving into the piston fore chamber  22 . The return echo from the sonic event is received by the microphone  110  and the data therefrom transmitted to the computer  120 . 
     The piston  16  is then driven toward the closed valve  68 . Simultaneously, the valve  268  is closed. The driving of the piston  16  compresses the fluid in the piston fore chamber  22  thereby forming a compressed fluid having a greater pressure and temperature than the fluid in the annulus  146 . Typically, it is desirable that the pressure of the compressed fluid in the piston fore chamber  22  be at least 30 psi greater than the pressure of the fluid in the annulus  146 . 
     The pressure and the temperature of the compressed fluid in the piston fore chamber  22  may be measured by the pressure measuring device  58  temperature measuring device  62  and reported to the computer  120 . 
     The valve  68  is then opened releasing the compressed fluid through the second conduit  70  around the right angle bend  86 . The expanding compressed fluid moves around the right angle bend  86  through the second segment  88  exiting the opening  90  into the T-Head connector  80 . 
     The T-Head connector  80  volume is much greater than the regions that the compressed fluid has passed. The result of the larger volume is that the compressed fluid rapidly decompresses releasing mechanical energy in the form of a sonic event. 
     The sonic event is transmitted through the fluid in the T-Head connector  80  into the annulus  146 . The measurement of the level of liquid in annulus  146  is determined by the Doppler effect as received by the microphone  110 . The signal from the microphone is transmitted to the computer  120 . 
     When the valve  68  is opened to release the compressed fluid the valve  268  is also opened causing a sonic event by the implosion of fluid into the piston after chamber  24 . The implosion caused by the valve  268  opening is received by the microphone  310 . 
     The operation of generating sonic events continues with valve  68  being closed while the piston  16  is withdrawn away from valve  68 . Simultaneously, the valve  268  is closed and the piston rear face  20  begins to compress fluid in the piston after chamber  24 . The compressed fluid in the piston after chamber  24  is then released when the valve  268  is opened thus generating another sonic event. 
     Four sonic events are generated by each piston cycle. By varying the degree that each of valve  68  and valve  268  are open as well as by varying the size of the piston fore chamber and the piston after chamber the tone of each sonic event may be varied to differentiate the echo received by the microphone  110  and microphone  310 . 
     When the computer  120  has correlated the data from the various sonic events the computer  120  determines the amount of liquid  180  in the wellhead  138 . The computer then generates a signal to the pump (not shown) to order the pump to begin operation to remove liquid  180  from the tubing  142 . Similarly, the computer  120  may generate a signal to the pump to discontinue the pumping operation to prevent an excess of liquid  180  from being removed from the well. 
     The device  10  may also be operated in a wellhead  138  to aid in pumping propane or other liquefied gas. The definition of pumping includes maintaining the static state of not removing any propane or other liquefied gas from underground storage but rather measuring the volume by determining the depth of the well to the point where the liquefied gas begins. In this manner not only can inventory of the propane or other liquefied gas in the well be determined but also the amount of propane or other liquefied gas that may be pumped into the well. 
     As best seen in  FIG. 5  is a liquefiable gas storage tank  400 . The liquefiable gas storage tank  400  is an enclosed vessel having a liquefiable gas storage tank bottom  402 . The liquefiable gas storage tank  400  has a liquefiable gas storage tank top  404 . The liquefiable gas storage tank  400  is generally cylindrical in shape having a liquefiable gas storage tank sidewall  406 . 
     The liquefiable gas storage tank  400  has a gas withdrawal conduit  410  extending through the liquefiable gas storage tank top  404 . A gas flow control valve  412  controls fluid communication between the liquefiable gas storage tank  400  and the gas take off conduit  414 . 
     A microphone assembly  420  extends through the liquefiable gas storage tank top  404  of the liquefiable gas storage tank  400 . The microphone assembly  420  is sealed to the liquefiable gas storage tank top  404  to prevent leakage of gas from the liquefiable gas storage tank  400 . 
     A piston assembly  430  extends through the liquefiable gas storage tank top  404  of the liquefiable gas storage tank  400 . The piston assembly  430  is sealed to the liquefiable gas storage tank top  404  to prevent leakage of gas from the liquefiable gas storage tank  400 . The piston assembly  430  is similar in design and function to the components of the pump controlling device  10 . 
     In use, the piston assembly  430  has components corresponding to the piston chamber  14  and the piston  16 . A valve (not shown) is alternately opened and closed to provide fluid communication between the piston chamber  14  and gas  432  within the liquefiable gas storage tank  400 . The piston is driven forward against the closed valve to compress the gas within the piston chamber  14 . When the gas has been sufficiently compressed within the piston chamber  14  the valve is opened. As the compressed gas is under a greater pressure than the gas  432  within the liquefiable gas storage tank  400  the compressed gas decompresses and releases mechanical energy thereby generating a sonic event. 
     The sonic event (acoustic waves) travel through the gas  432  within the liquefiable gas storage tank  400 . The acoustic waves eventually reach the surface of the liquefied gas  434  that is gravitationally positioned at a level below the level of gas  432 . The acoustic waves are reflected from the surface of the liquefied gas  434  toward the microphone assembly  420 . The microphone assembly  420  receives the reflected acoustic wave. By knowing the shape and volume of the liquefiable gas storage tank  400  the Doppler effect may be utilized to the determine the amount of liquefied gas and gas within the liquefiable gas storage tank  400 . 
     The inventions embodied herein are merely exemplary and the suggested feature should be utilized to unduly limit the scope of the invention.