Abstract:
A tool for use in well monitoring is described to insert devices for well fluid level control into a wellhead. The tool also permits removal of the devices for well fluid level control from an operating well for servicing. The tool also permits precise positioning of the components utilized to take measurements in the well annulus.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of prior U.S. provisional application 61009404 filed 28 Dec. 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to maintaining a liquid in a well such as a gas well, an oil well, or water well at a more or less constant level. Incidentally, the level of liquid in a well may be quickly ascertained. 
     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 maximum production from a given well occurs when the fluid level in the well bore is as low as possible compared to the level in the surrounding formation. 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 this 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 may be desired to provide fluid level measurements in wells 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 surface. For example, the well may be 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 an insertion tool comprising: an insertion tool shaft cylinder; 
     said insertion tool shaft cylinder having an insertion tool shaft cylinder first end; 
     said insertion tool shaft cylinder having an insertion tool shaft cylinder second end; 
     said insertion tool shaft cylinder second end having a tapered shape; 
     an insertion tool shaft projection located proximate to said insertion tool shaft cylinder second end; and, 
     said insertion tool shaft projection having a long axis substantially perpendicular to the long axis of said insertion tool shaft cylinder. 
     The present invention further describes an insertion tool component comprising: 
     an insertion tool bell; 
     said insertion tool bell having an insertion tool bell opening on a first region of said insertion tool bell and an insertion tool bell opening on a second region of said insertion tool bell; 
     said insertion tool bell opening being larger in surface area than said insertion tool bell opening and having a common axis with said insertion tool bell opening; 
     an insertion tool bell insert fixedly connected with said insertion tool bell opening and extending toward said insertion tool bell opening; 
     said insertion tool bell insert having an insertion tool bell insert first opening and an insertion tool bell insert second opening; 
     said insertion tool bell insert having an insertion tool bell insert inner surface at least partially defining a channel through said insertion tool bell insert; 
     said insertion tool bell insert having a first insertion tool bell insert bushing recess located near said insertion tool bell insert first opening; said insertion tool bell insert having a second insertion tool bell insert bushing recess located near said insertion tool bell insert second opening; 
     said insertion tool bell insert having an insertion tool bell insert bushing fitted within said first insertion tool bell insert bushing recess; and, 
     said insertion tool bell insert having an insertion tool bell insert bushing fitted within said second insertion tool bell insert bushing recess. 
     The present invention also describes an insertion tool cable carrier tray comprising: 
     a pair of insertion tool cable carrier tray sidewalls; 
     said pair of insertion tool cable carrier tray sidewalls at least partially defining an insertion tool cable carrier tray channel; 
     an insertion tool cable carrier tray receiving piece fixedly connected to one end of said insertion tool cable carrier tray channel; 
     said insertion tool cable carrier tray receiving piece having an insertion tool cable carrier tray receiving piece first channel; 
     said an insertion tool cable carrier tray receiving piece having an insertion tool cable carrier tray receiving piece second channel communicating with said insertion tool cable carrier tray receiving piece first channel wherein the intersection of said insertion tool cable carrier tray receiving piece first channel and said insertion tool cable carrier tray receiving piece second channel is substantially at a right angle; 
     said insertion tool cable carrier tray receiving piece second channel extending above said pair of insertion tool cable carrier tray sidewalls; 
     an insertion tool cable carrier tray receiver locking mechanism fixedly connected to said insertion tool cable carrier tray channel at substantially the opposite end of said insertion tool cable carrier tray channel from insertion tool cable carrier tray receiving piece; 
     said insertion tool cable carrier tray receiver locking mechanism having at least one insertion tool cable carrier receiver locking mechanism first channel; and, 
     said insertion tool cable carrier tray channel having at least one insertion tool cable carrier down hole opening. 
     Yet a further aspect of the present invention is a device for controlling fluid levels in a well comprising: 
     a compressor; 
     a conduit to provide fluid communication between a well annulus and said compressor; 
     a pressure transducer in fluid communication with said compressor, said pressure transducer, for when in use, to control the pressure of a sample of gas to be returned to the well annulus through gas emission tubing; 
     a gas receiving tubing to provide fluid communication between the well annulus and a pressure measurement device; 
     said pressure measurement device, for when in use to determine a return signal from the sample of gas returned to the well annulus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, wherein: 
         FIG. 1  is a side view of one aspect of the invention; 
         FIG. 2  is a partial view according to  FIG. 1 ; 
         FIG. 3  is a cutaway view taken according  FIG. 2 ; 
         FIG. 4  is a partial sectional view according to  FIG. 2 ; 
         FIG. 4   a  is a partial view according to  FIG. 4 ; 
         FIG. 5  is a partial view of an aspect of the invention according to  FIG. 1 ; 
         FIG. 6  is a partial view of an aspect of the invention according of  FIG. 1 ; 
         FIG. 7  is a side view according to  FIG. 6 ; 
         FIG. 8  is a partial plan view of a further aspect of the invention; 
         FIG. 9  is a frontal view according to  FIG. 8 ; 
         FIG. 10  is a side view taken according to  FIG. 8 ; 
         FIG. 11  is a sectional view taken along line  11 - 11 ; 
         FIG. 12  (a continuation of  FIG. 8 ) is a partial plan view of a further aspect of the invention; 
         FIG. 13  is a frontal view according to  FIG. 12 ; 
         FIG. 14  is a side view according to  FIG. 12 ; 
         FIG. 15  is a perspective view of a further aspect of the invention; 
         FIG. 16  is a partial view of a wellhead with various aspects of the present invention; 
         FIG. 17  is a further partial view of a wellhead with various aspects of the present invention; 
         FIG. 18  is a bottom view of an aspect of the invention according to  FIG. 16 ; and, 
         FIG. 19  is a top view of an aspect of the invention according to  FIG. 16 ; 
         FIG. 20  is a partial view of a wellhead with various aspects of the present invention, including a downhole pump. 
     
    
    
     With more particular reference to the drawings the following is set forth. 
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1  a well Insertion tool  10  is described. The insertion tool  10  comprises an insertion tool bell  20 . The insertion tool bell  20  is formed from any convenient metal and given that the insertion tool bell  20  will be in contact with other metals in the area of explosive vapors it should be born in mind to avoid great differences from the other metals with which the insertion tool bell  20  comes in contact. 
     A further feature of the insertion tool  10  is an insertion tool shaft  60 . The insertion tool shaft  60  should also be formed of a similar metal to the insertion tool bell  20  to reduce the potential for static discharge. 
     With reference to  FIG. 2 , the insertion tool bell  20  has insertion tool bell external threading  24 . The insertion tool bell  20  has an insertion tool bell opening  28  at least partially defined by the walls surrounding the insertion tool bell external threading  24 . The interior of the insertion tool bell  20  is partially defined by chamber insertion tool bell void  34 . At the opposite end from the insertion tool bell opening  28  is an insertion tool bell opening  38 . 
     Again with reference to  FIG. 1 , an insertion tool bell insert  100  is fixed within the insertion tool bell  20 . The insertion tool bell insert  100  is also of a similar metal to the insertion tool bell  20 . When in use, the insertion tool bell insert  100  permits passage of the insertion tool shaft  60  through the insertion tool bell opening  38  and out of the insertion tool bell opening  28 . 
     The insertion tool bell insert  100  has an insertion tool bell insert outer wall  106  and an insertion tool bell insert inner wall  110 . As seen in  FIG. 4A  and  FIG. 4 , there are two insertion tool bell insert bushing recesses  112  located within the insertion tool bell insert inner wall  110  at approximately the opposite ends of insertion tool bell insert  100 . 
     The insertion tool bell insert  100  has an insertion tool bell insert first opening  116  at one end. The insertion tool bell insert  100  has an insertion tool bell opening  120  at the other end. The insertion tool bell insert  100  is at least partially defined by the insertion tool bell insert inner surface  110 . As previously noted, the insertion tool bell insert  100  permits fluid communication between the insertion tool bell insert first opening  116  at the insertion tool bell insert second opening  120 . 
     As seen in  FIG. 2 , is a pair of insertion tool bell insert bushings  128  and  132  located within the two insertion tool bell insert bushing recesses  112  in insertion tool bell insert  100 . The insertion tool bell insert bushings  128  and  132  are circular in design and are fixed to the insertion tool bell insert  100 . When in use, the insertion tool bell insert bushing  128  and insertion tool bell insert bushing  132  serve to guide the insertion tool shaft  60  through the insertion tool bell opening  38  so that the insertion tool shaft  60  may exit from the insertion tool bell opening  28 . 
     With reference to  FIG. 1 , an insertion tool detachable handle  140  is attached to one end of the insertion tool shaft  60 . The insertion tool detachable handle  140  is further described in  FIG. 6  and  FIG. 7 . The insertion tool detachable handle  140  is comprised of the insertion tool detachable handle gripping region  146  and the insertion tool detachable handle cylinder  150 . 
     The insertion tool detachable handle gripping region insertion tool detachable handle gripping region  146  and the insertion tool detachable handle cylinder  150  may be permanently joined together. The insertion tool detachable handle cylinder  150  has an insertion tool detachable handle cylinder  154  that at least partially defines an insertion tool detachable handle cylinder channel  156  passing through the insertion tool detachable handle cylinder  150 . 
     As best seen in  FIG. 1 , an insertion tool detachable handle locking pin  170  is used by means of an insertion tool detachable handle locking pin cylinder  174  to lock the insertion tool detachable handle  140  to the insertion tool shaft  60 . 
     Referring to  FIG. 5  the insertion tool shaft  60  is further defined. The insertion tool shaft  60  is largely comprised of an insertion tool shaft cylinder  62 . At one end of the insertion tool shaft cylinder  62  is an insertion tool shaft first end  68 . At the opposite end of the insertion tool shaft cylinder  62  is an insertion tool shaft second end  72 . 
     The insertion tool shaft first end  68  is a relatively flat circular surface. The insertion tool shaft second end  72  is a pointed surface, as later described, to permit Insertion of the insertion tool shaft  60  through the insertion tool bell insert  100  and into a wellhead. The insertion tool shaft cylinder  62  has an insertion tool shaft channel  78  located proximate to the insertion tool shaft first end  68 . 
     When in use, the insertion tool shaft channel  78  receives the insertion tool detachable handle locking pin cylinder  174  to secure the insertion tool detachable handle  140  to the insertion tool shaft  60 . At the opposite end of the insertion tool shaft cylinder  62  is an insertion tool shaft projection  82  located proximate to the insertion tool shaft second end  72 . The insertion tool shaft projection  82  as later described functions to secure a further aspect of the convention to permit Insertion of communication equipment into a wellhead. 
     Turning to  FIG. 8 , an insertion tool cable carrier  180  is shown. As shown in  FIG. 11  the insertion tool cable carrier  180  has an insertion tool cable carrier sidewall  182  on each side. An insertion tool cable carrier channel  186  extends along the line of the insertion tool cable carrier  180 . The insertion tool cable carrier  180  has an insertion tool cable carrier receiving piece  190  located at one end thereof. 
     The insertion tool cable carrier receiving piece  190  has located therein an insertion tool cable carrier receiving piece first channel  194 . As seen in  FIG. 8 , the insertion tool cable carrier receiving piece first channel  194  makes a right angle turn defined in part by an insertion tool cable carrier receiving piece second channel  198 . 
     Referring now to  FIG. 12 ,  FIG. 13 , and  FIG. 14  the second end of the insertion tool cable carrier  180  is described. An insertion tool cable carrier tray receiver locking mechanism  210  is at the opposite end of the insertion tool cable carrier  180  from the insertion tool cable carrier receiving piece  190 . 
     An insertion tool cable carrier receiver locking mechanism first channel  224  extends through the insertion tool cable carrier receiver locking mechanism  210 . An insertion tool cable carrier receiver locking mechanism second channel  226  also extends through the insertion tool cable carrier receiver locking mechanism  210 . 
     The insertion tool cable carrier receiver locking mechanism first channel  224  and the insertion tool cable carrier receiver locking mechanism second channel  226  are parallel to the long axis of the insertion tool cable carrier  180 . An insertion tool cable carrier down hole opening  232  extends through the insertion tool cable carrier tray receiver locking mechanism  210  of the insertion tool cable carrier  180 . 
     As best seen in  FIG. 15  is a partial assembly of the insertion tool cable carrier  180 . A cable carrier  250  is obtained to fit within the insertion tool cable carrier channel  186  of the insertion tool cable carrier  180 . The cable carrier  250  permits the later described wellhead communication equipment to be transported from a T-head into the wellhead. The sidewalls of the insertion tool cable carrier  180  at least partially define the area within which the cable carrier  250  may traverse. 
     Gas emission tubing  256  is shown in  FIG. 17 . The gas emission tubing  256  effectively terminates in the well annulus as later described. The gas emission tubing  256  is located within the cable carrier  250 . The gas emission tubing  256  is connected to compressor valve  282 . The compressor valve  282  serves to permit gas flow from compressor  300  through conduit  284 . 
     The conduit  284  is in fluid communication with pressure transducer  286 . The pressure transducer  286  controls the pressure of a sample of gas to be returned to the well annulus through gas emission tubing  256 . The pressure transducer  286  is in fluid communication with a compressor  300 . 
     As seen in  FIG. 16  is a partial assembly of the present invention. A wellhead  258  is the focus of the present invention. The wellhead  258  is comprised of a well casing  260  and an inner well casing  270 . An inner well casing void  272  is effectively defined by the inner well casing  270 . 
     A well annulus  276  is defined as the space between the well casing  260  and inner well casing  270 . The wellhead  258  is capped to prevent communication of fluids from the inner well casing void  272  and well annulus  276  from reaching the atmosphere. In this definition, fluid includes liquids and gases. 
     A wellhead first t-conduit  290  extends from one side of the wellhead  258 . A wellhead first valve  294  regulates the flow of fluids from the wellhead  258 . The wellhead first valve  294  is connected with a wellhead conduit  298 . The wellhead conduit  298  transports fluids to a desired region such as a tank or pipeline. 
     On the opposite side of the wellhead  258  from the wellhead first t-conduit  290  is a wellhead second t-conduit  306 . It is the noted that the wellhead first t-conduit  290  and the wellhead second t-conduit  306  are interchangeable. While the wellhead first t-conduit  290  and a wellhead second t-conduit  306  are described as being on opposite sides and coaxially located to one another on the wellhead  258  such need not be the case. 
     A wellhead second t-conduit takeoff pipe  308  extends from and is in fluid communication with the wellhead second t-conduit  306 . A wellhead takeoff pipe  310  extends from the wellhead second t-conduit takeoff pipe  308 . A filter apparatus  318  is in fluid communication with the wellhead takeoff pipe  308 . 
     The filter apparatus  318  is in fluid communication with a conduit  324 . The filter apparatus  318  serves to remove debris produced through the wellhead which would otherwise pass from the wellhead second t-conduit takeoff pipe  308  through conduit  324  to the compressor  300 . 
     The compressor  300  is the connected with the conduit  324 . The compressor  300  when in use compresses gas from the well annulus  276 . A wellhead second valve  320  regulates communication of fluids to the wellhead second t-conduit takeoff pipe  308 . The wellhead second valve  320  also serves to permit insertion of the other components of the invention such as the insertion tool shaft  60  through the wellhead second valve  320 . 
     A wellhead third valve  330  is located at the opposing side of the wellhead second t-conduit takeoff pipe  308  from the wellhead second valve  320 . A wellhead second conduit  340  is connected to the wellhead third valve  330 . The wellhead second conduit  340  terminates with a wellhead second conduit threaded region  344 . The wellhead second conduit inner threaded region  344  is normally capped off with a standard well cap (not shown). 
     As seen in  FIG. 16 , the cable carrier  250  passes through the open wellhead second valve  320  to permit access of the insertion tool cable carrier tray receiver locking mechanism  210  to the well annulus  276 . 
     The gas emission tubing  256  passes through insertion tool cable carrier receiver locking mechanism first channel  224  and into the insertion tool cable carrier down hole opening  232 . When in use compressed gas from the gas emission tubing  256  exits from a gas injection port  382  and into the well annulus  276 . 
     A gas receiving tubing  356  extends through one of the openings in the insertion tool cable carrier receiver locking mechanism  210  and communicates with a gas injection port  382  in the insertion tool cable carrier down hole opening  232 . The gas receiving tubing  356  is in fluid communication with a pressure measurement device  500 . Conveniently, the pressure measurement device  500  is an accelerometer. 
     The gas injection port  382  and the sample receiving port  402  are positioned in the wellhead such that they may be aligned to the well annulus  276 . An the advantage to having the gas injection port  382  and the sample receiving port  402  aimed directly downhole is to minimize any noise or problems caused by moving the injected gas at right angles as would occur if the injected gas exits the gas injection port  382  in the wellhead takeoff pipe  310 . 
     In operation, a pump  710  is employed to control the fluid level  600  in the well annulus  276 . The inner well casing void  272  and the well annulus  276  are in fluid communication below the fluid level  600 . 
     To maximize fluid flow through perforations  700  into the wellbore, the fluid level  600  should be maintained as low as possible with respect to the perforations to reduce the hydrostatic head in the well casing  260 . The pump is set to operate at a desirable fluid level and the desirable fluid level is controlled by implementing changes in the pumping based upon readings from the pressure measurement device  500 . 
     To correctly position the equipment of the present invention the insertion tool  10  is assembled as shown in  FIG. 1 . A cap (not shown) is removed from the wellhead second conduit threaded region  344 . The insertion tool  10  is then screwed on to the wellhead second conduit  340  by the insertion tool bell external threading  24 . The insertion tool shaft  60  may then be inserted through the wellhead third valve  330 . 
     As shown in  FIG. 16  and  FIG. 17 , the cable carrier  250  carries and protects the emission tubing  256  and gas receiving tubing  356  through the wellhead second t-conduit takeoff pipe  308 . The cable carrier  250  is positioned in the insertion tool cable carrier channel  186 . The cable carrier  250  is fastened at the insertion tool cable carrier tray receiver locking mechanism  210 . 
     The insertion tool shaft  60  as previously noted is inserted through the wellhead third valve  330  and is connected with the insertion tool cable carrier  180  at the insertion tool cable carrier receiving piece  190 . That is the insertion tool shaft  60  is inserted through the insertion tool cable carrier receiving piece first channel  194  and makes contact with the back wall of the insertion tool cable carrier receiving piece  190 . 
     The insertion tool shaft  60  is then rotated 90 degrees in the insertion tool cable carrier receiving piece second channel  198  as the length of the insertion tool shaft  60  is known and the length of the wellhead second conduit  340  is known as well as the width of the wellhead third valve  330  one may determine with a fair degree of accuracy that the insertion tool shaft  60  has correctly engaged the insertion tool cable carrier  180 . 
     Once the insertion tool shaft  60  has been inserted through wellhead third valve  330  and locked to the insertion tool cable carrier  180  previously disposed within wellhead second t-conduit takeoff pipe  308 , the insertion tool cable carrier  180  is then used to urge the insertion tool cable carrier  180  forward through the open wellhead second valve  320  and through the wellhead second t-conduit  306  to correctly position the insertion tool cable carrier tray receiver locking mechanism  210  above the annulus. 
     The insertion tool shaft  60  may then be disengaged by rotating the insertion tool shaft projection  82  from the insertion tool cable carrier receiving piece second channel  198  and withdrawing the insertion tool shaft  60  from the insertion tool cable carrier receiving piece first channel  194 . The insertion tool shaft  60  may then be further withdrawn through the insertion tool bell  20  to a point sufficient in the wellhead second conduit  340  to permit the closing of the wellhead third valve  330 . 
     The insertion tool bell  20  may then be unscrewed from the wellhead second conduit inner threaded region  344 . The insertion tool  10  may be utilized for several wells rather than having a single insertion tool  10  permanently connected to each well. For the servicing of the components the entire operation may be reversed. That is, the insertion tool  10  is connected to the wellhead second conduit  340  and the wellhead third valve  330  valve is opened. 
     The insertion tool shaft  60  is then engaged to the insertion tool cable carrier receiving piece  190 . The insertion tool cable carrier  180  is then drawn in the direction of the wellhead second conduit  340  and the insertion tool cable carrier  180  and the insertion tool cable carrier tray receiver locking mechanism  210  are removed through the wellhead second valve  320 . The wellhead second valve  320  is then closed. The insertion tool cable carrier tray receiver locking mechanism  210  may then be completely withdrawn through the wellhead third valve  330 . 
     At this point the wellhead third valve  330  may also be closed although it is noted that as the wellhead second valve  320  is in the closed position the well is not in fluid communication with the atmosphere. The gas injection port  382  and the sample receiving port  402  may then be serviced outside of the well. 
     Alternatively the insertion tool cable carrier  180  may be withdrawn through the wellhead second t-conduit takeoff pipe  308  for service. As the well is normally furnished with the wellhead first valve  294  and the wellhead second valve  320  in place the entire segment of the wellhead second t-conduit takeoff pipe  308  may be added by the supplier of the communication equipment. 
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.