Patent Publication Number: US-6334487-B1

Title: Valve assembly

Description:
RELATED APPLICATIONS 
     This is a division of U.S. Ser. No. 08/845,996 filed Apr. 25, 1997 now U.S. Pat. No. 6,116,336 which is a continuation-in-part of U.S. Ser. No. 08/715,573 filed Sep. 18, 1996 now U.S. Pat. No. 5,743,331 entitled “Wellbore Milling System” both co-owned with the present invention and incorporated fully herein for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is related to wellbore milling processes; milling tools and whipstocks and anchors for them; and in one aspect to single-trip milling methods and systems. 
     2. Description of Related Art 
     Milling tools are used to cut out windows or pockets from a tubular, e.g. for directional drilling and sidetracking; and to remove materials downhole in a well bore, such as pipe, casing, casing liners, tubing, or jammed tools. Various prior art tools have cutting blades or surfaces and are lowered into the well or casing and then rotated in a cutting operation. With certain tools, a suitable drilling fluid is pumped down a central bore of a tool for discharge beneath the cutting blades to assist in the removal from the well of cuttings or chips. 
     Milling tools have been used for removing a section of existing casing from a well bore to permit a sidetracking operation in directional drilling, to provide a perforated production zone at a desired level, to provide cement bonding between a small diameter casing and the adjacent formation, or to remove a loose joint of surface pipe. Also, milling tools are used for milling or reaming collapsed casing, for removing burrs or other imperfections from windows in the casing system, for placing whipstocks in directional drilling, or for aiding in correcting dented areas of casing or the like. Prior art sidetracking methods use cutting tools of the type having cutting blades and use a deflector such as a whipstock to cause the tool to be moved laterally while it is being moved downwardly in the well during rotation of the tool, to cut an elongated opening pocket or window in the well casing. 
     Certain prior art operations which employ a whipstock also employ a variety of tools used in a certain sequence. That requires a plurality of “trips” into the wellbore. For example, a false base (e.g. a plug, bridge plug, packer or anchor packer) is set in a casing or in a borehole that serves as a base on which a whipstock can be set. Certain prior art whipstocks have a movable plunger which acts against such a false base. In certain multi-trip operations, a packer is oriented and set in a wellbore at a desired location. This packer acts as an anchor on or against which tools above it may be urged to activate different tool functions. The packer typically has a key or other orientation indicating member. The packer&#39;s orientation is checked by running a tool such as a gyroscope indicator into the wellbore. In this case a whipstock-mill combination tool is then run into the wellbore by first properly orienting a stinger at the bottom of the tool with respect to a concave face of the tool&#39;s whipstock or by using an MWD tool. Splined connections between a stinger and the tool body facilitate correct stinger orientation. A starting mill is secured at the top of the whipstock, e.g. with a setting stud and nut. The tool is then lowered into the wellbore so that the packer engages the stinger and the tool is oriented. Slips extend from the anchor and engage the side of the wellbore to prevent movement of the tool in the wellbore. Pulling or pushing on the tool then shears the setting stud, freeing the starting mill from the tool. Rotation of the string with the starting mill rotates the mill. The starting mill has a tapered portion which is slowly lowered to contact a pilot lug on the concave face of the whipstock. This forces the starting mill into the casing to mill off the pilot lug and cut an initial window in the casing. The starting mill is then removed from the wellbore. A window mill, e.g. on a flexible joint of drill pipe, is lowered into the wellbore and rotated to mill down from the initial window formed by the starting mill. Typically then a window mill with a watermelon mill mills all the way down the concave face of the whipstock forming a desired cut-out window in the casing. This may take multiple trips. Then, the used window mill is removed and a new window mill and string mill and a watermelon mill are run into the wellbore with a drill collar (for rigidity) on top of the watermelon mill to lengthen and straighten out the window and smooth out the window-casing-open-hole transition area. The tool is then removed from the wellbore. The prior art also discloses a variety of single-trip milling systems each of which requires that a packer, bridge plug, anchor packer, or other securement be provided as a base in a tubular upon which to position the milling. 
     The prior art also discloses a variety of single trip setting systems for whipstocks, usually hydraulically actuated, each of which allows circulation usually only once at setting depth, after which time pins are usually sheared and any additional pumping will only pressurize the system to actuate hydraulic setting devices. 
     There has long been a need for an efficient and effective single trip whipstock setting method that allows for selective pressurization or circulation while fluid is being pumped through the drillstring, and also selectively provides or prevents communication between the inside and outside of the drillstring while no fluid is being pumped through the drillstring. There has long been a need for systems effecting such a method, as well as tools useful in such a method. 
     There has long been a need for an efficient and effective single-trip milling method and systems for effecting the method. There has long been a need for tools useful in such a method. There has long been a need for such systems which do not require a base upon which the system is emplaced and/or which have a selectively settable anchor apparatus which does not require the dropping of a ball, dart, etc. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention, in one embodiment, discloses a system for selectively anchoring a wellbore tool at a desired location in a wellbore or tubular member such as casing or tubing. In one aspect the system has a selectively settable anchor assembly that has a piston that is moved upwardly by fluid under pressure from the surface. The piston moves apparatus that pushes one or more movable slips out from a body of the anchor assembly to set the anchor assembly in place. 
     In one aspect the system as described above has a whipstock connected to the anchor assembly. Fluid under pressure flows to the anchor assembly through the whipstock and/or through tubing on the exterior of the whipstock. In one aspect the whipstock is selectively releasably connected to the anchor assembly. In one aspect a mill (or mills) is releasably connected to the whipstock. In one aspect, fluid under pressure flows through the mill(s) to the whipstock (e.g. but not limited to through a channel in a mill, through a shear stud, through a pilot lug on the mill, and through a channel through the mill intercommunicating with the anchor assembly) or fluid under pressure flows through the mill, through exterior tubing to the whipstock, and through the whipstock to the anchor assembly. 
     In one aspect a selectively actuable valve assembly is provided according to the present invention for selectively controlling the flow of fluid under pressure from an inlet end of the valve assembly out through an outlet end thereof. In one aspect such a valve assembly has a rotatable ratchet sleeve which (in being moved upwardly or downwardly by members responding to increased or decreased fluid pressure) rotates to selectively maintain the valve assembly in a plurality of positions so that fluid under pressure either flows through selected ports to selected flow lines or does not flow at all. In one aspect such a valve assembly is used with a system as previously described to selectively provide actuating fluid under pressure to an anchor assembly as described to set the movable slip(s) thereof and, in one aspect, to then provide jetting fluid to jetting ports of the mill(s). 
     The present invention teaches, in certain embodiments, a system as described herein wherein the valve assembly of the system provides selective circulation or pressurization while a pump at the surface is engaged, the pump providing fluid under pressure to the valve assembly; such a system that provides fluid communication between the inside and the outside of the drillstring while the pumps are not pumping fluid under pressure; such a system wherein the system may be run in the hole on a drillstring so that the drill string fills up with fluid from outside the system that flows into the system to the interior of the drillstring through the system, e.g., to inhibit buoyancy of the drillstring in the hole; such a system which does not require that anything be dropped down thereinto in order to actuate parts of the system or provide for flow of fluid under pressure to and through selected desired conduits and channels; a valve assembly as shown or described herein and such a valve assembly with mill(s) releasably attached thereto, directly or indirectly, the valve assembly in fluid communication with the mill(s); such a valve assembly with a whipstock interconnected therewith, directly or indirectly, and in fluid communication therewith; such a valve assembly interconnected with, directly or indirectly, an anchor assembly as shown or described herein, the valve assembly in fluid communication with the anchor assembly; and an anchor assembly as shown or described herein with a mill and/or whipstock and/or valve assembly as shown or described herein interconnected therewith and in fluid communication therewith. 
     The present invention, in certain embodiments, discloses a milling system for milling an opening in a tubular in a tubular string in a wellbore extending down from a surface of the earth, the milling system having an anchor assembly to set the milling system in the tubular, a whipstock connected to the anchor assembly, a mill apparatus releasably connected to the whipstock, the mill apparatus having auto fill apparatus therein that opens when the milling system is introduced into the wellbore to permit fluid in the wellbore to enter through the mill into the tubular string, and a valve assembly connected at a top end thereof to the tubular string and at a bottom end thereof to the mill apparatus for selectively controlling fluid flow from the surface to the anchor assembly; such a system with a lug/ratchet slot system having the plurality of position recesses including recesses corresponding to an at rest position of the system in which the at least one first valve flow port and the at least one piston flow port are aligned so that as the system is run into the wellbore fluid in the wellbore is permitted to fill the system, a circulate position of the system wherein the at least one piston flow port is aligned with the at least one second valve flow port so that fluid in the piston pumped down from the surface is flowable out from the hollow body, and a set anchor position of the system in which the at least one piston flow port is aligned with the top end of the body channel so that fluid pumped from the surface is flowable past the ratchet sleeve in a channel within the hollow body and out from the hollow body to the anchor assembly to set the anchor assembly; such a system wherein the valve assembly has a plurality of recesses consisting of four recesses in sequence, a first at rest recess corresponding to a first at rest position and mode of operation, a circulate recess corresponding to a circulation position and mode of operation, a second at rest recess corresponding to a second at rest position and mode of operation, and an anchor set recess corresponding to an anchor setting position and mode of operation; such a milling system wherein a fluid pressure level within the milling system indicates that the milling system is in either a pressured up status for anchor setting or at a pressure level for fluid circulation so that inadvertent anchor setting is avoided; and such a milling system with the auto fill apparatus further having the mill apparatus having a flow bore therethrough, a ball seat releasably secured in the flow bore of the mill apparatus by a shearable member. The present invention, in certain embodiments, discloses a mill with a mill body with a top end and a bottom end, a flow bore through the mill body, at least one port in fluid communication with the flow bore and through which fluid is flowable from within the mill to an exterior thereof and from the exterior thereof to within the mill, and auto fill apparatus in the flow bore above the at least one port. The present invention, in certain embodiments, discloses a valve assembly for selectively controlling fluid flow through a hollow tubular in a string of hollow tubulars in a wellbore extending from a surface of the earth into the earth, the valve assembly with a hollow body with a hollow piston mounted for reciprocal up and down rotative movement therein, the hollow body having an inwardly projecting lug, the hollow piston having at least one piston fluid flow port therethrough and the hollow body having at least two body fluid flow ports therethrough, a ratchet sleeve connected to the piston, the ratchet sleeve having a branched slot therearound which is movable on the lug so that the ratchet sleeve and the piston are movable to a plurality of positions, the branched slot with a plurality of position recesses, at least one position in which fluid is flowable from within the hollow body to an exterior thereof and at least one position in which fluid is flowable from outside the hollow body thereinto, the positions limited to at rest, circulate, and anchor set positions so that a fluid pressure indication at the surface indicates only either a pressured up position for anchor setting or a pressured up position for fluid circulation. The present invention, in certain embodiments, discloses a milling system with a mill having a top and a bottom and mill flow bore therethrough extending down from the top thereof, a sub with a top and a bottom and a sub bore therethrough connected at the top of the mill and in fluid communication therewith, a valve in the sub bore permitting fluid flow down through the sub and preventing fluid flow up through the sub, an exit hole in the mill body in fluid communication with the mill flow bore, a rupture disc closing off the mill flow bore and disposed beneath the exit hole so that a charge of fluid is disposable between the valve and the rupture disc; and such a mill system wherein the charge of fluid is clean fluid and the milling system has a wellbore device connected to the mill and in fluid communication with the exit hole so that the charge of clean fluid is movable down to the wellbore device to activate the wellbore device. The present invention, in certain embodiments, discloses a float valve for use in wellbore operations, the float valve with a body with a top and a bottom and a fluid flow bore therethrough, a valve seat on the body, a valve member movably secured to the body for movement to seat against the valve seat to close off flow through the float valve and for movement away from the valve seat to permit fluid flow through the float valve, and a vent hole through the valve member for releasing fluid pressure build up beneath the valve member. The present invention, in certain embodiments, discloses a fill sub with a hollow body with a top, a bottom, a flow bore therethrough from top to bottom, and a fill port through the body permitting fluid communication from an exterior of the body into the flow bore, a fill valve assembly in the hollow body, the fill valve assembly having a first bore and a second bore, the first bore in fluid communication with the fill port and having a ball seat, a ball movably mounted in the first bore, an urging member mounted in the first bore in contact with the ball and releasably urging the ball against the ball seat, the ball movable away from the ball seat in response to fluid entering through the fill port and overcoming force of the urging member so that fluid from the exterior of the fill sub may enter and pass through the fill sub, the second bore in fluid communication with the flow bore so that fluid is flowable from the top of the body, through the flow bore, through the second bore, back into and through the flow bore and out from the bottom of the body, a float valve disposed in the flow bore below the fill valve assembly; such a fill sub wherein the float valve has a body with a top and a bottom and a fluid flow bore therethrough, a valve seat on the body, a valve member movably secured to the body for movement to seat against the valve seat to close off flow through the float valve and for movement away from the valve seat to permit fluid flow through the float valve, and a vent hole through the valve member for releasing fluid pressure build up beneath the valve member. 
     It is, therefore, an object of at least certain preferred embodiments of the present invention to provide: 
     New, useful, unique, efficient, non-obvious selectively actuable wellbore anchoring apparatus; such apparatus in combination with a whipstock; such apparatus and whipstock in combination with one or more mills; valve assemblies for selectively applying fluid under pressure to such apparatus; and milling systems and methods for single-trip milling operations; 
     A milling system and a mill with an auto fill apparatus; 
     A float valve with a vented valve member; 
     A device for releasably containing a charge of fluid for activating a wellbore apparatus; 
     A milling method in which a window is milled at a desired location in a tubular; and 
     A system for such a method. 
     This invention resides not in any particular individual feature disclosed herein, but in combinations of them and it is distinguished from the prior art in these combinations with their structures and functions. There has thus been outlined, rather broadly, features of the invention in order that the detailed descriptions thereof that follow may be better understood, and in order that the present contributions to the arts may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which may be included in the subject matter of the claims appended hereto. Those skilled in the art who have the benefit of this invention will appreciate that the conceptions, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the purposes of the present invention. It is important, therefore, that the claims be regarded as including any legally equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     The present invention recognizes and addresses the previously-mentioned problems and needs and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention&#39;s realizations, teachings and disclosures, other and further objects and advantages will be clear, as well as others inherent therein, from the following description of presently-preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. Although these descriptions are detailed to insure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to claim an invention as broadly as legally possible no matter how others may later disguise it by variations in form or additions of further improvements. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above-recited features, advantages and objects of the invention, as well as others which will become clear, are attained and can be understood in detail, more particular description of the invention briefly summarized above may be had by references to certain embodiments thereof which are illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the appended drawings illustrate certain preferred embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective or equivalent embodiments. 
     FIG. 1 is a side view in cross-section of a system according to the present invention. 
     FIG. 2A is a side view in cross-section of the anchor assembly of the system of FIG.  1 . 
     FIG. 2B is a side view in cross-section of the piston assembly of the anchor assembly of FIG.  2 A. 
     FIG. 3A is a side view in cross-section of the valve assembly of FIG.  1 . 
     FIGS. 3B-3L are side views in cross-section of parts of the valve assembly of FIG.  3 A. 
     FIG. 4 shows part of a ratchet sleeve of the valve assembly of FIG.  3 A. 
     FIGS. 5A-5F show a sequence of operation of the system of FIG.  1 . 
     FIG. 6A is a side cross-section view of a value assembly and mill (partial) according to the present invention. 
     FIG. 6B shows lug positions for the valve assembly of FIG.  6 A. 
     FIG. 7 is a side cross-section view of the mill (entire) of FIG. 6A with a whipstock (partial). 
     FIG. 8 is an enlarged view of the mill of FIG.  7 . 
     FIG. 9A is an enlarged side cross-section view if a setting device of the mill of FIG.  8 . 
     FIG. 9B shows a plug of the device of FIG.  9 A. 
     FIG. 9C is a side cross-section view of an alternative keeper for use with the device of FIG.  9 A. 
     FIGS. 10A-10D show steps in the operation of the valve assembly of FIG.  6 A. 
     FIG. 11A is a side cross-section view of a fill sub according to the present invention. 
     FIG. 11B is an exploded view of the fill sub of FIG.  11 A. 
     FIG. 11C is an enlarged view of part of the fill sub of FIG.  11 A. 
     FIG. 11D is an enlarged view of part of the fill sub of FIG.  11 A. 
    
    
     DESCRIPTION OF EMBODIMENTS PREFERRED AT THE TIME OF FILING FOR THIS PATENT 
     FIG. 1 shows a system  10  according to the present invention with a valve assembly  20 , a mill  30 , a whipstock  40  and an anchor assembly  50  interconnected with a tubular string, e.g. but not limited to coil tubing or a drill string DS. Tubing  12  conducts fluid under pressure selectively introduced from the surface and through the valve assembly  20  from the mill  30  to the whipstock  40  from which it flows to selectively activate the anchor assembly  50 . The system  10  may be run into a hole and/or tubular member string (e.g. a cased hole) and the whipstock may be oriented using known MWD (measurement-while-drilling) devices, gyroscopic orienting apparatus, etc. 
     The anchor assembly  50  as shown in FIG. 2 has a cylindrical body  501  with an upper neck  502 ; a fluid flow bore  503  from an upper end  504  to a lower threaded end  505 ; and one, two (or more) stationary slips  506  held to the body  501  with screws  507 . One (or more) bow spring  508  has an end  509  screwed to the body to offset the body from the interior of a tubular such as casing through which the body moves to reduce wear thereon and, in one aspect, to inhibit or prevent wear on the stationary slips, the or each bow spring  508  has an end  510  free to move in a recess  511  as the bow spring is compressed or released. 
     A hollow barrel assembly  520  which is cylindrical has an end  521  threadedly connected to the lower threaded end  505  of the body  501 . A hollow anchor sleeve  530  is threadedly connected in a lower end  522  of the hollow barrel assembly  520 . A sleeve plug  531  closes off the lower end of the hollow anchor sleeve  530  to fluid flow and is secured to the barrel assembly, e.g. by welding. 
     A piston assembly  540  has a piston end  541  with fluid flow holes  582  (see FIG. 2A which shows two of four such holes) is mounted for movement within the hollow barrel assembly  520  with a lower end  542  initially projecting into the hollow anchor sleeve  530 . Initially movement of the piston assembly is prevented by one or more shear screws  532  extending through the anchor sleeve  530  and into the lower end  542  of the piston assembly  540 . In one aspect the shear screws  532  are set to shear in response to a force of about 5000 pounds. 
     A fluid flow bore  543  extends through the piston assembly  540  from one end to the other and is in fluid communication with a cavity  533  defined by the lower end surface of the piston assembly  540 , the interior wall of the anchor sleeve  530 , and the top surface of the sleeve plug  531 . A spring  544  disposed around the piston assembly  540  has a lower end that abuts an inner shoulder  523  of the hollow barrel assembly  520  and a lower surface  545  of the piston end  541  of the piston assembly  540 . Upon shearing of the shear screws  532 , the spring  544  urges the piston assembly  540  upwardly. A lower shoulder  546  of the piston assembly  540  prevents the piston assembly  540  from moving any lower than is shown in FIG.  1 . 
     A bar  547  has a lower end  548  resting against the piston end  541  and an upper end  549  that is free to move in a channel  509  of the body  501  to contact and push up on a movable slip  550  movably mounted to the body  501  (e.g. with a known joint, a squared off dovetail joint arrangement, a dovetail joint arrangement, or a matching rail and slot configuration, e.g. but not limited to a rail with a T-shaped end movable in a slot with a corresponding shape). 
     Fluid under pressure for activating the anchor assembly  50  is conducted from the fluid flow bore  503  of the body  501  to the fluid flow bore  543  of the piston assembly  540  by a hollow stem  560  that has a fluid flow bore  561  therethrough from one end to the other. The hollow stem  560  has a lower end  562  threadedly secured to the piston end  541  of the piston assembly  540  and a upper end  563  which is freely and sealingly movable in the fluid flow bore  503 . 
     A shearable capscrew  580  in the body  501  initially insures that the movable slip  550  does not move so as to project outwardly from the body  501  beyond the outer diameter of the body  501  while the system is being run into a hole or tubular. In order to set the anchor assembly, the force with which the bar  547  contacts and moves the movable slip  550  is sufficient to shear the capscrew  580  to permit the movable slip  550  to move out for setting of the anchor assembly. Initially the capscrew  580  moves in a corresponding slot (not shown) in the movable slip  550 . The slot has an end that serves as a stop member that abuts the capscrew  580  and against which the capscrew  580  is pushed to shear it. Similarly the capscrew  581  prevents the movable slip  550  from further movement out from the body  501  as the anchor assembly is being removed from a wellbore and/or tubular member string. The capscrew  581  is held in and moves in a slot in the movable slip  550  and the capscrew  581  thus holds the movable slip  550 . This prevents the movable slip  550  from projecting so far out from the body  501  that removal of the anchor assembly is impeded or prevented due to the movable slip  550 , and hence the anchor assembly  50 , getting caught on or interfering with structure past which it must move to exit the wellbore and/or tubular member string. 
     Various O-rings (e.g. made of 90 DURO nitrile) seal interfaces as follows: O-ring  571 , sleeve-plug  531 /hollow-sleeve  530 ; O-ring  572 , lower-end  542 /hollow-anchor-sleeve  530 ; O-ring  573 , piston-end  541 /lower-end  562 ; O-ring  574 , upper-end  563 /body  501 ; O-ring  575 , bar  547 /body  501 ; and, O-ring  576 , upper-neck  502 /lower-end-of-whipstock  40 . 
     Components of the system may be made of any suitable metal (steel, stainless steel, mild steel, inconel, iron, zinc, brass, or alloys thereof) or plastic. In one aspect the system has two stationary slips and one movable slips. All parts may be painted and/or zinc phosphate coated and oil dipped. 
     To load the piston assembly in the hollow barrel assembly, the piston assembly may be introduced into the top of the barrel assembly with a threaded rod engaging the lower end of the piston assembly and projecting out from the anchor sleeve. The threaded rod is pulled or rotated until recesses on the piston assembly for receiving the shear screws line up with holes through the barrel assembly through which the shear screws are placed. Once the piston assembly is shear screwed in place and stationary, the threaded rod is disengaged and the sleeve plug is secured in place at the end of the anchor sleeve. 
     The fluid under pressure for actuating the anchor assembly may be any suitable pumpable fluid, including but not limited to water, hydraulic fluid, oil, foam, air, completion fluid, and/or drilling mud. 
     Once the movable slip  550  is sufficiently wedged against a casing wall, the spring  544  prevents the piston assembly  540  from moving down to the position shown in FIG. 2A, thus inhibiting or preventing movement of the movable slip  550  which could result in unwanted movement or destabilization of the system  10 . This also makes it possible to decrease fluid pressure in the system  10  or to release fluid pressure while the system  10  is maintained in a set position (e.g. when anchoring of the system is verified, e.g. with the system in the position of FIG. 5D, weight is set down on the system  10  to obtain an indication that setting has been achieved, e.g. a surface weight indicator provides such an indication). 
     The whipstock  40  has a body  401  with a concave  402 ; a shear lug  403 ; a retrieval slot  404 ; a hoisting ring  405 ; and a lower end  406  for interconnection with the upper neck  502  of the anchor assembly  50 . Shear screw(s)  413  extend through the whipstock body  401  and the neck  502  of the anchor assembly  50 . These screws may be set to shear, e.g. at about 27,500 pounds. 
     The tubing  12  has a lower end  14  that communicates with a fluid channel  407  which extends from one side of the whipstock body  401  to a recess  408  where it is connected to a top end  409  of a tubing  410  that has a lower end  411  that communicates with a fluid channel  412  which itself is in fluid communication with the fluid flow bore  503  of the anchor assembly  50 . Alternatively the tubing  12  may be directly connected to the anchor assembly  50  or to the fluid channel  412 . One or more shear screws  413  releasably hold the anchor assembly  50  to the whipstock  40 . In one aspect three shear screws  413  are used which shear in response to a force of about 80,000 pounds. 
     The mill  30  is connected to the whipstock  40  with a shear stud  310  that extends through a lower end of the mill  30  and into the shear lug  403 . The mill  30  has a body  301  to which are secured milling blades  302  as are well known in the art. The mill body  301  has a fluid flow bore  303  which communicates with jetting ports  304  with exits adjacent the blades  302 . A sub-channel  305  provides fluid communication between the fluid flow bore  303  and the tubing  12 . In one aspect the fluid flow bore is sized so that it can receive a plug disengaged from the valve assembly  20  as described below. 
     FIGS. 3A-3J show the valve assembly  20  and parts thereof. The valve assembly  20  has a top bushing  201  threadedly connected to a valve body  202 . A bottom bushing  230  is connected to a lower end of the valve body  202 . A piston  203  is movably mounted in a bore  231  of the valve body  202 . A plug extension  204  is movably mounted in the valve body  202  with a lower end  232  thereof projecting into and through the lower bushing  230  with respect to which the plug extension  204  is movable up and down. An upper end  233  of the plug extension  204  is threadedly connected in a lower end  234  of the piston  203 . 
     A ratchet sleeve  208  is rotatably disposed around the plug extension  204 . A lug  206  projects through the valve body  202  into a multi-branched slot  235  of the ratchet sleeve  208 . A spring  207  abuts an upper end  236  of the lower bushing  230  and pushes against (upwardly) a thrust bearing set  238  at a bottom  237  of the ratchet sleeve  208  (see FIG.  3 C). A releasable plug  205  initially closes off the lower end  232  of the plug extension  204  to fluid flow. A thrust bearing set  239  is disposed between a top  240  of the ratchet sleeve  208  and the lower end  234  of the piston  203  (see FIG.  3 B). This use of thrust bearings inhibits undesirable coiling of the spring  207  and facilitates rotation of the ratchet sleeve  208 . The thrust bearing sets may include a typical thrust bearing sandwiched between two thrust washers. Shear screws  215  secure the plug  205  to the plug extension  204 . In one aspect two shear screws  215  are used and they shear in response to a force of about 4000 pounds. 
     A cap  241  emplaced in and welded to a trough  242  serves to define the outer wall of a channel  243  formed between the cap  241  and the exterior of the body  202 . 
     O-rings seal a variety of interfaces: O-ring  212 , mill  30 /plug extension  204 ; O-ring  213 , plug  205 /interior-of-plug-extension  204 ; O-ring  209 , valve-body  202 /bottom-bushing  230 ; O-ring  211 , plug-extension  204 /piston  203 ; O-ring  246 , piston  203 /valve-body  202 ; O-rings  245  and  247 , piston  203 /valve-body  202 ; O-ring  210 , piston  203 /valve-body  202 ; O-ring  214 , lug  206 /body  202 ; and O-ring  244 , valve-body  202 /top-bushing  201 . 
     The valve body  202  has a series of ports  249  that permit fluid to flow through the valve body  202  and ports  251  that also permit such fluid flow. The top bushing  201  prevents further upward movement of the piston  203 . FIG. 3F shows a cross-section view of the trough  242 . 
     The piston  203  as shown in FIGS. 3A,  3 H and  3 I, has a series of fluid ports  252  and the piston can be moved so the fluid ports  252  align with the valve body ports  249  or  251  for fluid intercommunication therewith. 
     FIGS. 3A,  3 J, and  3 K show the ratchet sleeve  208  and the multi-branch slot  235  in which moves the lug  206 . 
     FIG. 3L shows the plug extension  204 . 
     FIG.  4  and FIGS. 5A-5F illustrate a sequence of operation of the system  10  and the corresponding movement of and positions of the lug  206  and of the ratchet sleeve  208 . 
     FIG. 5A illustrates the system  10  in a “run-in-the-hole” situation. The ports  252  and  249  are aligned so fluid from outside the system  10  (e.g. drilling fluid between the exterior of the system  10  and the interior of borehole casing, not shown) may flow, as indicated by the arrows, through the system  10  and up into a drill string to which the system  10  is connected. The lug  206  is in “Position  1 ” in the multi-branch slot  235 . 
     As shown in FIG. 5B, fluid under pressure is pumped from the surface down the drill string into the system  10  with sufficient force to move the piston  203  to the position shown, with the ports ports  251  aligned with the ports  252  permitting fluid pumped down the drill string to flow out from the system  10 . The lug  206  moves to the “Position  2 ” in the ratchet sleeve  208 . (The multi-branch slot  235  is continuous around the ratchet sleeve  208  so that the sequence of operation of the system is repeatable as required). In this position fluid may be circulated out from the system  10  to clean the hole at the point at which it is desired to set the system  10 , e.g. To-do remove debris and other material that might interfere with proper system functioning and positioning. 
     With the system  10  as shown in the position of FIG. 5C, flow is not permitted through the ports  249 ,  251 , and  252  and fluid does not yet flow down to the anchor assembly  50 . 
     As shown in FIG. 5D, the pressure of fluid flowing into the system has been increased, further moving the piston  203  so ports  252  align with the channel  243 . The fluid under pressure flows from the channel  243 , past the ratchet sleeve  208 , past the spring  207 , between the bushing  203  and the plug extension  204 , out the sub-channel  305  of the mill body  301  into the tubing  12  (see FIG.  1 ). The lug  206  moves into “Position  4 ” as shown. The fluid under pressure flows through the tubing  12 , through the whipstock  40 , through the anchor assembly  50  into its cavity  533  where it pushes up on the piston assembly  540 , shearing the shear screws  532  so the bar  547  is moved up to move the movable slip(s)  550  and set the anchor assembly  50 , and thereby set the system  10  at the desired location. Once proper anchoring has been achieved and verified, an appropriate load is applied to the string to which the system  10  and the mill  30  are connected (e.g. about 30,000 pounds) to shear the shear stud  310  to separate the mill  30  from the whipstock  40 . Then as shown in FIG. 5E, pressure is increased against the plug  205  which is then released by shearing of the shear screws  215 , thereby releasing pressure which was required to set the moving slip, and the spring  207  has pushed upwardly moving the ratchet sleeve  208  and the piston  203  so that all ports ( 249 ,  251 ,  252 ) are closed to fluid flow and fluid is diverting through the jetting ports  304 . The lug  206  is now in “Position  5 .” Milling now commences. Upon completion of a desired window in casing adjacent the mill  30 , the whipstock  40  may be retrieved by using a hook which is inserted into the retrieval slot  404  or by screwing a die collar onto the outer diameter threads (not shown) provided at the top of the whipstock  40 . Alternatively, an overpull is applied to the whipstock (e.g. about 82,500 pounds) shearing the shear screws  413  allowing retrieval of the whipstock while leaving the anchor assembly in the hole and/or tubular member string. Such a shearable neck is disclosed in pending U.S. application Ser. No. 08/590,747 entitled “Wellbore Milling Guide” filed on Jan. 24, 1996 and co-owned with the present invention and application and incorporated herein by reference fully and for all purposes. 
     Repetition of the cycle of operation of the system as shown in FIGS. 5A-5F, or of only a portion of the cycle, is possible; e.g., but not limited to as shown in FIG. 5F, cycling back to Position  1  is possible if necessary. Also, if when weight is set down there is an indication that the anchor assembly is not set as desired, the setting sequence can be repeated. Fluid under pressure is again circulated down the drill string and out from the system (to again clean the hole, if desired) and the process of FIGS. 5A-5E is begun again. 
     It is within the scope of this invention to use an anchor assembly, a valve assembly, and/or a mill according to this invention with any downhole apparatus, device, tool, or combination thereof. 
     FIG. 6A shows a system  600  which is like the system of FIG. 1, but which has a valve assembly  602  that has a ratchet sleeve  604  (positioned as the ratchet sleeve  208 , FIG. 3A) but with only four positions for a lug  605  (see FIG. 6B) rather than the six positions of the valve assembly  20 . The ratchet sleeve  604  encompasses the 360° circumference of the tool. With the system  600  an operator at the surface has a positive indication that the system has gone from a “fill” or “at rest” position (Position  1 ) to a “circulate” position (Position  2 ). The operator at the surface monitors a pressure level (pressure of fluid at a pump outlet or “standpipe pressure”) and monitors fluid returns from the wellbore; i.e., in the “circulate” position a positive pressure is required and indicated and the operator sees returned to the surface fluid that was pumped down the system. 
     The system  600  has a starting mill  610  with an auto-fill setting device  620 . The auto-fill setting device  620  is in a top part  621  of a mill body  634  that threadedly engages a control valve bushing  606  of the valve assembly  602 . A holder assembly  622  has an upper shoulder  623  that rests on a top end  624  of the top part  621 . An o-ring  625  seals the top part/holder assembly interface. An o-ring  626  seals the interface between the holder assembly  622  and a ball seat  627  that is initially releasably secured in the holder assembly  622  by shear screws  628 . A ball  629 , e.g. made of plastic or metal (e.g. stainless steel) is movably disposed in a flow bore  630  of the holder assembly  622 . The ball  629  is movable to seat against a top seat  631  of the ball seat  627  to prevent fluid passage out through the bottom of the housing  621 . Upon shearing of the shear screws  628 , the ball  629  and ball seat are movable down in a bore  632  of the mill  610  (see FIG. 10D) past eight jet ports  633  of the mill  610 . 
     The  610  is connected to a whipstock  640  (like the whipstock in FIG. 1) which is connected to an anchor assembly, not shown (like that of FIG.  1 ). 
     A pin  637  prevents the ball  629  from exiting the holder assembly  622 . The pin  637  does not close off flow through the holder assembly  622 . A keeper  635  in FIG. 9A is used with the shorter than standard bore back box of the bushing of FIG.  9 A and prevents the holder assembly from exiting from the top of device  620 . FIG. 9C shows an alternative keeper  636  for use with a standard bore back box which is longer than that of FIG.  9 A. 
     FIG. 9B shows an alternative to the ball and seat of the  5  system of FIG. 9A. A plug  646  releasably held by the shear screws  628  may be used with the ball and seat removed. 
     The valve assembly  602  has no fill ports at the top thereof. It does have circulation ports  650 . The eight jet ports  633  of the mill  610  act as fill ports when the system is run into a wellbore so that fluid in the wellbore can enter the system  600 . 
     FIG. 10A shows a “run in” position for the system  600  with the circulation ports  650  closed (i.e., a top end  651  of a piston  652  block fluid flow to the ports  650 ). In the “run in” position of FIG. 10A, fluid in the wellbore enters the system  600  through the ports  633 , pushing the ball  629  off the seat  631 . (Alternatively as shown in FIG.  11 A and described below, a fill sub with a ball/seat mechanism or with solid plug can be used above or below the valve assembly  602  instead of the ball and ball seat of FIG. 6A.) 
     FIG. 10B shows the system in a circulation mode. Fluid pumps at the surface pump fluid (e.g. water, brine, drilling mud, etc.) down into the valve assembly  602 , moving the ball  629  against the seat  631 . Pressure builds up and, due to a pressure differential between the area of the keeper  635  and the larger area at the top of the piston  651 , the piston  652  moves down to uncover the ports  650  for the circulation of fluid into the wellbore annulus. In the position of the system shown in FIG. 10A, a sufficient fluid pumping rate is achieved to activate an MWD tool D (shown schematically in FIG. 10B) to orient the system  600  and the whipstock  640 . The system  600  is properly oriented and operations proceed. 
     FIG. 10C shows the cessation of the surface pumps with fluid flow stopped. This is an intermediate position of the system  600  on the way to the position of FIG.  10 D. 
     FIG. 10D shows the system  600  with fluid again pumped from the surface down to the system  600 . The lug  605  moves into “Position  4 ” and the piston  652  does not move down sufficiently to open the ports  652  (i.e., it does not move down as far as it did in “Position  2 ,” (FIG.  10 B). Pressure increases within the system  600  and fluid flows through tubing  660  to an anchor assembly A (shown schematically in FIG. 7) (like the anchor assembly of the system of FIG. 1) to set the anchor assembly in the wellbore. The tubing  660  connects to and is in communication with a hole  643  and thereby with the interior of the top of the mill. 
     After the anchor assembly is set, pumping pressure is increased (e.g. an additional thousand pounds) to shear the shear screws  628  so that the ball  629  and ball seat  627  are moved down into the bottom of the bore  632  of the mill  610 , exposing the ports  633  to fluid flow for fluid jetting action during milling. 
     Prior to increasing fluid pressure, if it is not desired to set the anchor, e.g. if further circulation is desired prior to setting the anchor, the pump(s) are stopped and the system  600  is returned to “Position  1 ” (FIG. 10A) for further circulation (e.g. To-do clean out the wellbore). The system  600  is either in a “pressured up” position, “Position  4 ” or in a “circulate” position, “Position  2 .” An operator is aware of which position the system is in by monitoring the fluid pressure level and the returned well fluids. Thus inadvertent anchor setting is avoided. 
     In one aspect the valve assembly of FIG. 6A acts like a control valve, essentially as an on/off toggle valve which is designed, in one aspect for use with MWD (measurements-while-drilling) orienting systems. If it is pushed down once (with fluid from surface pumps), flow passes through the control valve to the annulus. If it is pushed down again, flow paths are blocked, allowing pressurizing of the string (and hence setting of the whipstock), if the bottom of the string is blocked by a device such as the auto-fill setting device (see FIG.  6 A). When the pumps are again stopped, the pressure is bled off, and the pumps started again, fluid again passes through the circulation ports into the annulus. This cycle is repeated as many times as required during orientation or other circulation activities until proper orientation is achieved, at which time the whipstock is set by simply pressuring up to a preset value while the control valve is in an “anchor set” position. 
     The auto-fill setting device, emplaced in the top of the starting mill  610 , can be used without the control valve in situations where circulation prior to whipstock setting is not required (e.g. when orienting with a gyro). The auto-fill setting device, when run with or without the control valve, allows wellbore fluid to automatically fill up the drill string when running in the hole by allowing the ball to float off its seat. When it becomes necessary to pressure up the string to set the whipstock, the ball remains on its seat, blocking the fill port to allow pressurization. A solid plug may replace the ball and seat if the auto-fill feature is not desired. 
     A keeper is used to keep the auto-fill setting device from moving in the starting mill  610  bore when the starting mill is screwed into a box with a bore-back relief. Minor freedom of movement facilitates proper shouldering of the connector. The box, in one aspect, on the control valve bushing has a bore-back relief that is in some cases one inch shorter than a standard bore-back relief, and therefore requires a keeper one inch shorter than standard. Certain standard keepers have a length of about 1½ inches. 
     The control valve may or may not be screwed directly onto the starting mill  610 . In certain aspects for placement from a hydraulics standpoint, the control valve is placed below an MWD tool so that fluid is allowed to pass through the control valve and through the MWD tool, as required for orientation. 
     Good solids control practices aid in successful operation of the control valve. In certain aspects the operator circulates “bottoms up” across a shale shaker (120 mesh screens in one aspect) prior to pulling out of the hole to pick up the whipstock. The shale shaker remains in operation until the whipstock is set (or until the control valve is no longer required to function). “Sweeps” or “pills” with high solids of any type are avoided prior to setting the anchor. In addition, a drill pipe screen (such as is usually supplied by an MWD contractor) is in place at the top of the drill string while the control valve is in use. Proper valve operation and anchor setting are facilitated if these procedures are followed. 
     In one sequence of operation of a valve assembly (control valve) according to the present invention, an operator initiates circulation carefully, observing pump pressure and fluid returns in order to determine valve position. At the surface control valve position is determined based on whether it allows flow, or does not for minor “leakage” through equalization ports). At depth (or whenever circulation is required during a trip in the hole), pumps are started and pump rate is increased slowly. One thousand p.s.i. pump pressure is not exceeded, in one aspect, to initiate circulation. If a rate of 30 gpm is achieved without significant pump pressure (i.e. less than 100 p.s.i.), the control valve is in a “circulate” position. Once pumps are stopped, the valve shifts to an “at rest” position. In order to initiate circulation again, the control valve is first cycled through an “anchor set” position. The pumps are then brought on slowly to shift the control valve into the “anchor set” position. A 1000 p.s.i. pump pressure is not exceeded, and the operator ensures that the string is being pressurized (i.e. pressure with little or no flow). The pumps are stopped and the standpipe pressure is bled off, pressure is bled through the equalization ports in the control valve. Once pressure is bled off, the control valve is shifted to an “at rest” position. The pumps are started and rate is slowly increased. Again, 1000 p.s.i. pump pressure is not exceeded in order to initiate circulation. If a rate of 30 gpm is achieved without significant pump pressure, the control valve is in the “circulate” position. 
     Pump speed is increased to a desired flow rate, in one aspect the flow rate is within the minimum and maximum flow rates as specified in the chart below. These rates are based on minimum and maximum pressure drops through the control valve of 200 p.s.i. and 700 p.s.i., respectively. Because of these flow rates, based on properly maintained muds: 1) the valve spring remains fully compressed during circulation; 2) the anchor is not prematurely set; and 3) that the circulation ports in the control valve remain closed throughout the milling process. 
     
       
         
           
               
            
               
                   
               
               
                 FLOW RATE WINDOW FOR GIVEN MUD WEIGHT 
               
               
                 (clean, thin mud only) 
               
            
           
           
               
               
               
            
               
                   
                 Minimum 
                   
               
               
                 Mud Weight (ppg) 
                 Flow Rate (gpm) 
                 Maximum Flow Rate (gpm) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 9 
                 150 
                 450 
               
               
                 10 
                 140 
                 425 
               
               
                 11 
                 135 
                 405 
               
               
                 12 
                 130 
                 390 
               
               
                 13 
                 125 
                 375 
               
               
                 14 
                 120 
                 360 
               
               
                 15 
                 115 
                 350 
               
               
                 16 
                 110 
                 340 
               
               
                 17 
                 105 
                 330 
               
               
                 18 
                 100 
                 320 
               
               
                   
               
            
           
         
       
     
     For orientation, fluid is circulated as required (see above circulation procedure) to orient a tool face. The pumps are stopped once orientation has been achieved. The control valve shifts to an “at rest” position, with ports closed. If additional circulation and/or orientation is required, circulation is again initiated carefully, per above procedure. 
     To set an anchor, the pumps are started slowly (5-10 gpm) to shift the control valve to an “anchor set” position. Pumping is continued at a slow rate as the operator watches pressure climb. 
     When the pressure drop through the control valve reaches 1620 p.s.i. (in one aspect) (in one recommended shear pressure—see chart below for other shear pressures), shear screws holding the anchor spring in place shear, allowing the spring to force the traveling slip into the casing. This event may not be observable at the surface. 
     
       
         
           
               
            
               
                   
               
               
                 ANCHOR SET PRESSURES 
               
            
           
           
               
               
               
            
               
                   
                 No. of shear screws 
                 Shear value (p.s.i.) 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                   
                 1 
                 90 
               
               
                   
                 2 
                 600 
               
               
                   
                 3 
                 1110 
               
               
                   
                 4 
                 1620 
               
               
                   
                 5 
                 2130 
               
               
                   
                 6 
                 2640 
               
               
                   
                   
               
            
           
         
       
     
     Pump pressure is then increased to 2050 p.s.i. (intermediate pressure between 1620 and 2480 p.s.i.) and maintained. The operator slacks off 10,000 pounds on the string to ensure that the anchor has set while pressure is maintained. Then the weight is picked back up. Pressure is increased further. As the pressure increases, the ball seat or plug at the bottom of the auto-fill setting device shears out at 2480 p.s.i. pressure drop through the tool (a recomended shear pressure—see chart below for other shear pressures). A flow rate of up to 20 gpm may be required to accomplish this, because of flow through equalizing ports. Consequently, pump pressure may actually be slightly higher than this preset value, due to minimal pressure losses in the drill string and annulus. A sudden loss in pump pressure and subsequent fluid returns once the ball seat shears will be observable at the 
     
       
         
           
               
            
               
                   
               
               
                 AUTO-FILL SETTING DEVICE SHEAR PRESSURES 
               
            
           
           
               
               
               
            
               
                   
                 No. of shear screws 
                 Shear value (p.s.i.) 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                   
                 1 
                 620 
               
               
                   
                 2 
                 1240 
               
               
                   
                 3 
                 1860 
               
               
                   
                 4 
                 2480 
               
               
                   
                 5 
                 3100 
               
               
                   
                 6 
                 3720 
               
               
                   
                   
               
            
           
         
       
     
     Once the ball set is sheared out, the valve automatically shifts up to the “at rest” position, where it remains until retrieved from the hole, and flow is directed through the bottom of the control valve through the starting mill ports. Then the operator set downs 25,000 pounds weight (recommended shear stud value—others are available) to shear the stud connecting the starting mill to the cave, and milling operations are commenced. 
     Once a desired window has been established and the whipstock is no longer required, the whipstock is retrieved by latching into a retrieving slot or by screwing a die collar onto outer diameter threads at the top of the concave. If the whipstock body refuses to dislodge, an overpull of 82,500 pounds shears screws holding the concave to the anchor allowing retrieval of the concave while leaving the anchor body available in the hole for subsequent retrieval operations. In one aspect, a 4 inch outer diameter by 9 inch long fishing neck protrudes upward from the anchor body. 
     As an alternative fill up mechanism for allowing the string to fill with fluid as the system is introduced down into a wellbore, an alternative to the auto-fill assembly of the system of FIG. 6A, a fill sub may be used above or below the system of FIG.  6 A. In one aspect a fill sub is used above the valve assembly of the system of FIG.  6 A. Alternatively, a fill sub may be used with the system of FIG.  6 A. Alternatively a fill sub without a float valve may be used above the valve assembly and a float valve used below, or vice versa. 
     A fill sub  660  according to the present invention (see FIGS. A- 11 D) has a top sub  662  with a flow bore  664 , a body  662  with a flow bore  665  connected to the top sub  661 , a ball valve assembly  670  with a flow bore  671 , and a float valve assembly  690  with a flow bore  691 . A spacer sleeve  663  in the flow bore  665  surrounds part of the valve assembly  670  and abuts a top end of a body  680 . 
     A spring seat member  666  is movably disposed with a top part in a retainer  668  and a bottom part in a flow bore  673  of the valve assembly  670 . The retainer  668  is secured in a top end of a body member  674  whose interior walls define the bore  673 . 
     The body member  674  has a lower seat  675  against which a ball  672  seats to selectively prevent fluid from flowing through a hole  676 , into a space in a groove  677 , and through a port  678 . The body  680  is secured in the bore  665 . O-rings  645  seal various interfaces. 
     When the fill sub  660  is used, in one aspect, the ball and ball seat may be deleted from the system of FIG.  8  and the plug of FIG. 9B is used instead. When fluid with sufficient pressure enters the port  678 , the ball  672  is pushed up away from the seat  675  and up against a ball seat  669  of the spring seat member  666 , which in turn is urged against a spring  667 , thus opening the port  678 , bore  783 , and hole  681  to flow for filling the string as it is introduced into a wellbore. 
     The float valve assembly  690  remains shut while the string is being lowered in the wellbore since a spring loaded flapper  692  connected below a body  693  is spring-loaded up or shut. Fluid flows through a bore  695  of a lower body member  696  extending down from the body  693 . An optional vent hole  694  through the flapper  692  vents fluid pressure build-up on the downside (below) the flapper  692  as the system is lowered into a wellbore. 
     In order to have a charge of clean fluid to activate apparatus below the whipstock  640  (e.g. but not limited to an anchor A, see FIG.  7 ), a rupture disc is emplaced in the bore of the starting mill  610 , e.g. set to rupture by pumping fluid downhole at a pressure of 3,000 pounds. The rupture disc, in one aspect, is placed below the valve assembly and between the fill sub  660  and the starting mill  610 . The ball  629  is deleted from the starting mill  610 . Thus a charge of clean fluid is releasably captured between the rupture disc and the float valve  690 . If the optional vent hole  694  is used, this can relieve pressure build up of the clean fluid charge. In one aspect a rupture disc  644  (shown in dotted line in FIG. 8) is positioned above the ports  633  (FIG. 8) and below the hole  643 . Thus contained between the fill sub and mill releasably is a charge of fluid (in one aspect clean fluid free of debris, cuttings, junk etc.) for use in setting an anchor or activate other apparatus. In certain aspects, the tubing  660  contains part of the fluid charge extending down to the anchor or other item or tool and fluid pressure from above pushes the charge down for anchor (or other item) activation. In another aspect a second rupture disc with a burst strength, in one aspect, less than that of the disc  644 , is placed in the mill, in the fill sub, or in a lower part  606  of the valve assembly  602  (or in some other tubular bore above the first rupture disc). 
     In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the described and in the claimed subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form its principles may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. §102 and satisfies the conditions for patentability in §102. The invention claimed herein is not obvious in accordance with 35 U.S.C. §103 and satisfies the conditions for patentability in §103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. §112.