Abstract:
The chemical stick storage and delivery system includes a chemical stick delivery tube in communication with a well which supports a rotatable chemical stick storage device on the uppermost end of the delivery tube. The delivery tube includes an upper opening and the chemical stick storage device rotates to position chemical sticks sequentially over the delivery tube opening. Within the delivery tube is a first valve positioned directly beneath the delivery tube opening and a second valve spaced below the first valve for a distance sufficient to form a chamber between the first and second valves to receive a chemical stick. A central processor unit controls the operation of the first and second valves so that the first valve is opened while the second valve is closed and the chamber is brought to well head pressure before the second valve is opened to drop the chemical stick from the chamber into the well.

Description:
This application is a continuation-in-part application of U.S. application Ser. No. 09/081,682 filed May 20, 1998, now U.S. Pat. No. 6,044,905, which claims priority to Provisional application Serial No. 60/047,355 filed May 21, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     In the production of natural gas from oil and gas wells, a problem develops when water comes into the well from the producing formation and begins to exert a back pressure (due to the hydrostatic head of the water column) against the producing formation. This back pressure rises in direct proportion to the height of the water and its density. 
     The most popular procedure to remove this water is to drop soap sticks into the well to foam the water. This foamed water begins to reduce back pressure on the formation as it is formed and this in turn allows more gas to enter the well and to create more foamed water. This eventually exits the well at the surface. Slowly this water begins to build up again and more sticks are dropped by hand into the well on a daily basis. Other applications include the regular insertion of corrosion Inhibitor sticks, Scale Removing sticks, Paraffin Inhibitor, etc. 
     SUMMARY OF THE INVENTION 
     The purpose of this invention is to allow the oil and gas company field people to load a launching device with one or more sticks and to drop these sticks under the control of a controller. This is a big advantage for the oil and gas company due to the following: 
     1. Less trips by field people to insert sticks in well. 
     2. More productive wells because the water is kept at a low level allowing greater gas production. 
     3. Some wells are not accessible in poor weather conditions. 
     4. More productive field personnel saving them many hours per month which can be devoted to other work. 
     This purpose is achieved by providing a chemical stick delivery tube in communication with a well which supports a rotatable chemical stick storage device on the uppermost end of the delivery tube. The delivery tube includes an upper opening which opens into the chemical stick storage device and the chemical stick storage device rotates to position specially designed chemical sticks sequentially over the delivery tube opening. Within the delivery tube is a first valve positioned directly beneath the delivery tube opening and a second valve spaced below the first valve for a distance sufficient to form a chamber between the first and second valves to receive a chemical stick. A controller, such as a central processing unit or a timing device controls the operation of the first and second valves so that after the first valve is opened while the second valve is closed to drop a chemical stick into the chamber, the first valve is then closed and a fill valve is opened to equalize the pressure between the well head and the chamber so that the chemical stick can drop from the chamber into the well. Once pressure is equalized, the fill valve is closed and the second valve is opened to drop the chemical stick into the well. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is diagrammatic illustration of the chemical stick storage and delivery system of the present invention; 
     FIG. 2 is a diagrammatic illustration of a second embodiment of the chemical stick storage and delivery system of the present invention; 
     FIG. 3 is a perspective view of a third embodiment of the chemical stick storage and delivery system of the present invention; 
     FIG. 4 is a perspective view of the stick delivery unit of FIG. 3; 
     FIG. 5 is a sectional view of a chemical stick used in the stick delivery unit of FIG. 4; and 
     FIG. 6 is a flow diagram showing the operation of the central processor unit of FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawing, the chemical stick storage and delivery system indicated generally at  10  is mounted on the well head of a well  12 . This chemical stick storage and delivery system includes a delivery tube  14  having one end opening into the well, and the opposite end supporting a chemical stick storage dome  16 . The delivery tube  14  opens into the bottom of the storage dome  16  to receive chemical sticks  18  which are stored in the storage dome. These sticks are loosely mounted in holes  17  and  19  formed in upper and lower rotatable plates  20  and  22  respectively which are joined to rotate on and with a central shaft  24  within the storage dome. The plates are designed to position each of the chemical sticks in sequence over the open end of the delivery tube  14  so that the sticks can drop into the delivery tube. Plates  20  and  22  are rotated in a step wise manner by a ratchet  26  formed on an upper valve operator  28 . This ratchet engages a gear  30  on the bottom of the lower plate  22  to rotate the upper and lower plates about the central shaft  24 . For each operation of the ratchet, a new chemical stick is positioned over the delivery tube  14 . 
     The upper valve operator  28  is mounted on the housing of an upper valve  32  which opens and closes the upper end of the delivery tube  14 . A lower valve  34  also operates to open and close the delivery tube  14  and includes a valve operator  36 . When the upper valve  32  is closed, the lower valve  34  is opened and when the upper valve  32  is opened, the lower valve  34  is closed. The upper and lower valve operators are connected by a link  38 , which operates the two valves simultaneously and causes one to close as the other opens. This is accomplished by means of a hydraulic cylinder  40  which is connected to raise or lower the lower valve operator  36 . 
     A twelve volt battery  42  provides power to a timer  44  which operates a solenoid valve  46 . When the valve  46  opens, a small amount of gas from the well  12  or air or gas from another source is provided to operate the hydraulic cylinder  40 . In the field, the battery  42  is recharged by a solar panel  48 . 
     In the operation of the chemical stick storage and delivery system  10 , chemical sticks such as soap sticks, corrosion, inhibitor sticks, scale removing sticks or paraffin inhibitor sticks are inserted into the holes of the upper and lower plates  20  and  22  and rest against the bottom wall  50  of the circular dome  16 . The timer  44  is then set for the time to be expended between stick drops, and the timer cycle is initiated. When a drop time occurs, the timer  44  provides power to open the solenoid valve  46  so that gas or air is provided to the hydraulic cylinder  40 . This causes the cylinder to extend a piston  52  which moves the lower valve operator  36  upwardly to close the lower valve  34 . At the same time, the connecting link  38  moves the upper valve operator  28  upwardly to open the upper valve  32  and permit a chemical stick to drop into the delivery tube  14 . Subsequently, the timer  44  removes power from the solenoid valve  46  causing it to vent the cylinder  40  and lower the piston  52 . As the piston lowers, the lower valve actuator  36  opens the lower valve  34  to drop the stick into the well  12 , and as the upper valve actuator  28  is lowered to close the upper valve  32 , the ratchet  26  pivots the upper and lower plates  20  and  22  to position another chemical stick  18  over the end of the delivery tube  14 . The timer now begins a subsequent timing process. 
     A second embodiment of the stick storage and delivery system is illustrated at  54  in FIG. 2 where the same reference numerals used in FIG. 1 are used to designate elements having the same function and structure. Here, the shaft  24  is rotatably supported by the bottom wall  50  which is secured to the upper end of the delivery tube  14 . In FIG. 2, the opening into the delivery tube is illustrated at  56 . 
     A stepper motor  58  drives a gear  60  which engages a gear  62  formed on the edge of the plate  22  to rotate the plates  20  and  22  and the shaft  24 . As a chemical stick  18  is moved into position over the opening  56 , it engages the actuator  64  of a delay switch  66  to cause the delay switch to open so that power to the stepper motor  58  is cut off. Once the chemical stick drops into the delivery tube, the delay switch again closes after a delay period (i.e. 30 seconds) to again complete the power circuit from the battery  48  to the stepper motor. 
     A timer  68  controls the operation of the stick storage and delivery system. At preset timed intervals when a stick is to be delivered, the timer provides power from the battery  48  to an electrically operated flow purge valve  70  to shut down the well output line  71 . At the same time, the timer insures that a bottom valve  72  within the delivery tube is closed so that gas cannot escape through the delivery tube when a top valve  74  is opened. If the bottom valve is an electrically operated normally closed valve, the timer provides no power to open the valve so that it remains closed. If, however, the lower valve is operated by a hydraulic cylinder and piston  76 , the timer  68  provides power from the battery to open a solenoid valve  78  so that gas pressure from the well over a line  80  is fed to the hydraulic cylinder and piston  76  to insure closure of the lower valve  72 . A second solenoid valve  82  remains open to provide gas flow over the line  80  to a hydraulic cylinder and piston  84  which operates the top valve  74  to maintain this valve closed. When a delay period (i.e. 30 seconds) has elapsed after the closure of the valve  70 , the timer operates the valve  82  to close, blocking gas from the line  80  and to vent the hydraulic cylinder and piston  84  to cause it to open the top valve  74 . Now the chemical stick which was positioned over the opening  56  will drop into the delivery tube  14  and rest on the lower valve  72 . This releases the actuator  64  of the delay switch  66 , but the delay switch does not close the power circuit to the stepper motor  58  until a delay period has elapsed. 
     During the delay period determined by the delay switch  66 , the timer  68  opens the valve  82  causing the hydraulic cylinder and piston  84  to close the top valve  74 . With the top valve closed, the timer closes the valve  78  to block gas from the line  80  and to vent the hydraulic cylinder and piston  76  to open the lower valve  72 . Now gas pressure from the well will equalize in the delivery tube below the closed top valve  74  causing the chemical stick in the delivery tube to drop into the well. 
     The timer  68  now completes the cycle by opening the valve  70  and the valve  78  to again close the lower valve  72 . The stepper motor  58  will be energized through the delay switch  66  to move another chemical stick over the opening  56  and into contact with the actuator  64  to open the delay switch. Then, after a preset time interval has elapsed, the timer  68  will again initiate the cycle to drop a chemical stick into the well. 
     It is obvious that the line  80  can be connected to a liquid or gas source other than the well gas to operate the hydraulic cylinders and pistons  76  and  84 . Also, the upper and lower valves  74  and  72  can be normally closed electrically operated solenoid valves which are energized to open and deenergized to close in the described manner by the timer  68 . 
     For many applications, it may not be desirable to have the chemical stick storage and delivery system operate in response to a preset timed schedule, as variable well conditions may require the application of a chemical stick at different intervals. Often, a central processor unit connected to well sensors receives data indicative of well conditions. Many oil field systems now include a plurality of wells controlled by a central computer which receives well data and transmits control signals by radio transmission or telemetry. The chemical stick storage and delivery system  86  of FIGS. 3 and 4 is designed to operate under the control of a central processor unit  88  connected to receive well condition data from well sensors represented by the sensor  90 . The central processor unit  88  can constitute a stand alone microprocessor directly connected to control elements of the chemical stick storage and delivery system, as illustrated in FIG. 3, and for this application, the microprocessor would be powered by a battery  42  and solar panel  48  of the type shown in FIG.  1 . The microprocessor can be connected to transmit data to a remote well logging unit. 
     Alternatively, the control processor unit can be a remote computer operative to control a plurality of wells. In this case, instead of the direct connections shown in FIG. 3, the central processor unit sends control signals and receives input data by radio transmission or telemetry to control components of the chemical stick storage and delivery system  86  in the field, which components are battery powered. However, for purposes of description only, the operation of the chemical stick storage and delivery system  86  will be described as being under the control of a directly connected central processor unit  88  with the understanding that these direct connections can be replaced by wireless connections to a remote processor unit. 
     The chemical stick storage and delivery system  86  includes an elongate delivery tube  92  mounted on a well head  94 . The delivery tube  94  is formed by interconnected tubular sections  96 ,  98 ,  100 ,  102  and  104 , and a lower valve  106  is connected between the tubular sections  98  and  100  while an upper valve  108  is connected between the tubular sections  102  and  104 . A normally open one way check valve  110  is connected between tubular sections  100  and  102 , and a hammer union disconnect  112  joins tubular sections  96  and  98 . A second hammer union disconnect  114  mounts an enclosed turret housing unit  116  and drive motor  118  on the tubular section  104  over the open end  120  of the delivery tube  94 . 
     A double action air cylinder and piston  122  is connected to a valve actuator  124  to selectively open or close the upper valve  108 , while a second double action air cylinder and piston  126  is connected to a valve actuator  128  to open or close the lower valve  106 . The double action air cylinder and pistons  122  and  126  are mounted on the tubular section  100  and receive air by means of solenoid valves  130  and  132  respectively from a compressed air source  134 . Alternatively, the double action air cylinders and pistons can receive pressurized gas from the well head as shown in FIG. 1. A sensor switch  136  senses whether the upper valve  108  is open or closed and transmits this data to the central processor unit  88 , and a sensor switch  138  operates to sense whether the lower valve  106  is open or closed and to transmit this data to the central processor unit. 
     The central processor unit is connected to control a fill valve  140  which controls the passage of gas from the well head through a line  142 , a filter  144 , a line  146  and a filter  148  to the tubular section  102 . Similarly, the central processor unit is connected to control a bypass valve  150  connected between the line  146  and atmosphere. 
     A hinge  152  is connected to the tubular sections  96  and  100  and permits pivotal movement therebetween when the hammer union disconnect  112  is manipulated to disconnect the tubular sections  96  and  98 . This permits the delivery tube to be pivoted from the vertical position of FIG. 3 to a horizontal position to facilitate loading of chemical sticks into the stick storage unit  116 . A hinge switch  154  connected to the central processor unit  88  indicates when the delivery tube is in the vertical position for operation or is in the horizontal position where operation should be discontinued. 
     Referring now to FIG. 4, a stationary plate  156  having a low friction upper surface  158  forms the bottom of the turret housing unit  116 . A stick receiving opening  160  extends through the plate  156  and aligns with the open end  120  of the delivery tube  92 . Spaced above the stationary plate and mounted on a rotatably mounted shaft  162 , is a lower plate  164 , and spaced above the lower plate  164  on the shaft  162  is a second upper plate  166 . The upper plate  166  may be vertically adjusted along the shaft  162  to vary the spacing between the plates  166  and  164 , and the shaft is driven by the drive motor  118  which is connected to the central processor unit by a control line  168 . 
     The upper and lower plates  166  and  164  respectively are provided with aligned, spaced holes  170  and  172  which form sequential hole pairs each of which loosely receives a chemical stick  18 . Each hole pair is rotatable into alignment over the opening  160  as the shaft  162  rotates, and the lower plate  164  is provided with a plurality of index slots  174  with one index slot being provided in alignment with each of the holes  172 . A limit switch  176  mounted below the plate  164  engages the index slots as they pass by the limit switch to provide a position feedback signed to the central processor unit via a line  178 . The limit switch may be aligned with the opening  160 . 
     As a chemical stick  18  is moved into alignment over the opening  160 , it contacts the switch actuator  180  for a switch  182  mounted on the stationary plate  156  and causes a signal to be sent by the switch  182  over a line  184  to the central processor unit. 
     A manual winch  186  is supported on a mounting unit  188  connected to the tubular section  96  opposite the hinge  152 . The winch includes a cable  100  connected to the tubular section  190  and may be operated to move the chemical stick storage and delivery system between the vertical and horizontal positions. 
     The configuration of the sticks  18  which are loaded into the turret housing unit  116  is important, as these sticks are configured to operate effectively in combination with the rotating plates  164  and  166  to move over the stationary plate  156  and into the opening  160 . With reference to FIG. 5, each chemical stick  18  includes an elongate, tubular body  192  having a diameter D which is slightly less than the diameter of the holes  170  and  172 . The tubular body is formed with an outer layer  196  of water soluable polymer material or other water soluable material, and is filled with soap or various chemicals  198  which are in solid or gel form at ambient temperatures. The open bottom end of each chemical stick is closed by an arcuately shaped, domed closure  200  formed of plastic, water soluable polymer, water soluable paper, or other low friction material. This domed closure provides minimal contact with the low friction surface  158  of the stationary plate  156  and permits the chemical stick to move with minimum friction over the surface  158 . Also the domed closure guides the lower end of the chemical stick into the opening  160 . The use of the outer layer of soluable polymer material permits the chemical stick storage and delivery system to be used effectively all year round, for this outer layer stops problems caused by heat and humidity. soluable material, and is filled with soap or various chemicals  198  which are in solid or gel form at ambient temperatures. The open bottom end of each chemical stick is closed by an arcuately shaped, domed closure  200  formed of plastic, water soluable polymer, water soluable paper, or other low friction material. This domed closure provides minimal contact with the low friction surface  158  of the stationary plate  156  and permits the chemical stick to move with minimum friction over the surface  158 . Also the domed closure guides the lower end of the chemical stick into the opening  160 . The use of the outer layer of soluable polymer material permits the chemical stick storage and delivery system to be used effectively all year round, for this outer layer stops problems caused by heat and humidity. 
     Turning now to FIG. 6, the central processor unit  88  initiates a cycle of operation at  202  and then, by means of the hinge switch  154 , checks at  204  to make sure that the chemical stick storage and delivery system is in the vertical position. With the chemical stick storage and delivery system in the vertical position, the central processor unit then checks at  206  by means of the sensor switches  136  and  138  to make certain that the upper valve  108  and lower valve  106  are both closed. If one or both upper and lower valves are found to be open, the central processor unit operates at  208  to activate one or both of the solenoid valves  130  and  132  to cause one or both of the air cylinders and pistons  122  and  126  to close their respective valve. 
     With the lower and upper valves  106  and  108  closed, the central processor unit checks at  210  by means of the switch  182  to determine if a chemical stick  18  is positioned in the opening  160 . If the presence of a chemical stick is not sensed, the central processor unit activates the drive motor  118  at  212  to rotate the shaft  162  and plates  164  and  166 , and as soon as a stick in position is sensed by the switch  182 , the drive motor is deactivated at  214 . The drive motor will remain active either until a stick is properly positioned in the opening  160 , or until the central processor unit senses at  216  by means of the limit switch  176  and index slots  174  that a predetermined maximum number of hole pairs have passed over the opening  160 . Generally this maximum number is one less than the total number of hole pairs in the plates  164  and  166 , so if there are 34 hole pairs, the central processor unit will operate to deactivate the drive motor at  214  when it senses at  216  that  33  hole pairs have rotated over the opening  160 . 
     With a chemical stick positioned in the opening  160 , the central processor unit will make sure that the drive motor is deactivated at  214  and will open and close the top valve  108  at  218  by means of the solenoid valve  130  and air cylinder and piston  122  to drop the stick into the delivery tube section  100 . The stick will pass through the normally open check valve  110  which operates to close as a safety valve in response to the resultant upward flow of gas through the delivery tube  92  if the lower and upper valves  106  and  108  should fail in the open position. 
     Once the chemical stick  18  is lodged in the delivery tube section  100 , and the upper valve  108  has been reclosed, the central processor unit opens the fill valve  140  for a predetermined period at  220  before reclosing the fill valve. This permits filtered gas from the well head to pass into the delivery tube section  100  to equalize the pressure between the delivery tube and the well head. Once the pressure is equalized, the central processor operates at  222  to open and subsequently close the lower valve  106  to drop the chemical stick into the well head. This is achieved by activation of the solenoid valve  132  and air cylinder and piston  126 . Now the bypass valve  150  is opened for a predetermined period to vent the gas pressure from the delivery tube and return the delivery tube to atmospheric pressure. 
     With the delivery tube at atmospheric pressure, the central processor unit again activates the drive motor at  226  and senses at  228  when a chemical stick is moved into the opening  160 . With the chemical stick in place, the drive motor is deactivated at  230  and the system is ready for a new cycle of operation. However, if no chemical stick is sensed, the drive motor continues to rotate until the predetermined number of hole pairs passing over the opening  160  are sensed at  232  and then the drive motor is deactivated at  230 .