Patent Publication Number: US-6209647-B1

Title: Down hole casing string cleaning device and method

Description:
This application is a continuation-in-part application of my application Ser. No. 09/133,913 filed on Aug. 13, 1998 now U.S. Pat. No. 5,947,203, which is a con&#39;t of 08/804,216 filed Feb. 21, 1997 U.S. Pat. No. 5,829,521. This invention relates to a down hole assembly used to clean tubular strings. More particularly, but not by way of limitation, this invention relates to an apparatus and method for cleaning the internal diameter of casing strings with a bristle brush circumferentially arranged about a down hole assembly. 
    
    
     BACKGROUND OF THE INVENTION 
     In the development of oil and gas fields, operators will drill a well to a hydrocarbon reservoir, and thereafter, run a casing string through the production formation. The casing string will then be cemented into place. In turn, the well will then be completed as is well appreciated by those of ordinary skill in the art. 
     The optimization of production is an important criteria of any completion. Studies have shown that residue on the internal diameter of the casing string (such as cement, pipe dope, scale, burrs, etcetera) have a negative impact on productivity. Specialized completion fluids devoid of fines, solids and other debris are used to complete the well. Therefore, a major emphasis has been made to clean the inner diameter of the casing string. 
     Thus, when the operators have finished the pumping of a cement composition through the well casing, a work string is lowered on which a mechanical scraping device is used to scrap the walls of the casing. In the prior art, various types of casing scrapers are in use prior to displacement of a clean completion fluid. That is why it is so important to clean the casing wall as much as possible since it takes less time to ultimately filter the displaced completion fluids. Also, cleaning will eliminate foreign matter such as cement sheaths, scale, burrs and barite which in turn allows the tools used in the completion process to properly perform. 
     The scraping action of traditional scrapers with blades also have been known to leave a fine film of oil base or synthetic fluid residue on the casing wall. Prior art devices also cause problems because of the hardness of their blades cannot get into the casing connections as brushes can. Also, casing scrapers in high deviated holes collapse to the low side of the casing causing a great deal of wear on one side and the top side of the hole is not properly cleaning the high side due to ineffective engagement with the high side. 
     Therefore, there is a need for a down hole assembly that will be effective in cleaning a well bore that contains an oil base and/or synthetic fluid. There is also a need for a cleaning apparatus that will be effective in highly deviated wells. There is also a need for a down hole assembly that will have brush pads that are of sturdy construction and allow for ease of replacement. 
     SUMMARY OF THE INVENTION 
     A down hole cleaning assembly is disclosed. Generally, the down hole assembly is connected to a work string concentrically located within a casing string. In one embodiment, the down hole assembly comprises a mandrel operatively connected to the work string, with the mandrel having an opening therein. A pad member is received within the opening, with the pad member having a groove formed therein. Also provided is a wire brush means, operatively positioned within the groove of the pad member, for cleaning the internal diameter of the casing string. 
     The down hole assembly further comprises a biasing member, operatively positioned between the mandrel and the pad member, adopted for biasing the wire brush means against the inner diameter of the well bore. In the preferred embodiment, the wire brush means comprises a wire bundle having a first end and a second end, a brace disposed about the second end of the wire bundle, and wherein the brace is disposed within the groove of the pad member. 
     The brace herein disclosed includes an open end and a closed end, with the closed end having disposed therein the second end of the wire bundle, and wherein the open end and the closed end cooperate to form a triangular shaped profile. The groove will also contain a triangular shaped profile adapted to slidably receive the triangular brace. 
     In the preferred embodiment, the mandrel contains a second of slot, and wherein the down hole assembly further comprises a second pad member adapted to be received within the second slot, the second pad containing a second groove formed therein. A second wire brush means, operatively positioned within the second groove of the pad member, is also provided for cleaning the internal diameter of the casing string. 
     The down hole assembly may also contain a centralizer means, operatively adopted to the work string, for centralizing the mandrel within the casing string. A dove tail means, operatively associated with the mandrel, is also included for selectively adapting the wire brush means onto the work string. 
     In the preferred embodiment, the first and second wire brush means are arcuate, and wherein said first wire brush means is disposed about the periphery of the mandrel to cover a first 180 degree phase and wherein the second wire brush means is disposed about the periphery of the mandrel to cover a second 180 degree phase so that the first wire brush means and the second wire brush means cover a 360 degree phase about the mandrel. In another embodiment, a plurality of wire brush means may be placed about the periphery of the mandrel, with the wire brush means being staggered circumferentially in relation to each other so that the wire brushes have an effective coverage area of 360 degrees. 
     Also disclosed herein is a method of cleaning a casing string. The method comprises lowering a work string within the casing string. The work string will have provided therewith a down hole cleaning apparatus operatively associated with the work string. The wire bundle of the cleaning apparatus will be urged against the inner diameter of the casing string via the spring to allow for constant pressure of the brushes against the casing wall at all times. The method provides for cleaning the inner diameter of the casing string as the work string is lowered. 
     The method further comprising rotating the work string, and thereafter, lowering the work string. The operator may then circulate a drilling fluid through the inner diameter of the work string. The work string may be stationary or rotating during circulation. 
     In one embodiment, the well casing has a horizontal section so that a low side of the well casing and a high side of the well casing is created. In this embodiment, the apparatus includes a centralizer operatively associated with the work string. Also included will be a second cleaning apparatus, with the first cleaning apparatus covering a 180 degree phase and the second cleaning apparatus covering a complimentary 180 degree phase so that the entire 360 degree periphery is covered. 
     The method would further comprise lifting the apparatus from the low side of the inner diameter of the well casing with the centralizer. Also, the wire bundle of the first cleaning apparatus is urged against the low side of the inner diameter of the well casing with the spring at a constant force. Simultaneously therewith, the wire bundle of the second cleaning apparatus is urged against the high side of the inner diameter of the well casing with its spring at a constant force so that both the low side of the casing and the high side of the casing will be cleaned. 
     In a second embodiment, which in this application is the preferred embodiment, an apparatus for cleaning an inner diameter of a casing string is disclosed. In this embodiment, the down hole assembly comprises a mandrel having a first end and a second end, with the first end of said mandrel being configured to be connected to an opened end of a first tubular member and the second end of the mandrel being configured to be connected to an opened end of a second tubular member. The mandrel contains a first helical opening. 
     The apparatus further contains a first helical pad configured to be positioned within the first helical opening, with the helical pad having a groove therein. A wire brush member is inserted within the groove and a first spring is inserted between the first helical pad and the mandrel, with the spring biasing the helical pad radially outward. 
     The apparatus further contains a dove tail means, operatively associated with the mandrel, for selectively adapting the first second helical pad member with the mandrel. The dove tail means comprises the first tubular member having an opened end with an annular ring formed thereon that engages a first lip extending from the first helical pad, with the first lip being configured to adapt to the annular ring so that the first helical pad is held in place by the annular ring. 
     The apparatus further comprises a second helical opening formed on the mandrel and a second helical pad configured to be positioned within the second helical opening. The second helical pad will have a series of annular ribs disposed thereon. A second spring is inserted between the second helical pad and the mandrel, with the second spring biasing the second helical radially outward. In this embodiment, the dove tail means further comprises the second tubular member having an opened end with an annular ring formed thereon that engages the first lip so that the second helical pad is held in place by the annular ring. 
     The apparatus may further comprise a third helical opening formed on the mandrel, with the third helical pad being configured to be positioned within the third helical opening. The third helical pad contains a series of annular ribs. A third spring is inserted between the first helical pad and the mandrel, with the spring biasing the helical pad radially outward. A fourth helical opening may also be included, with a fourth helical pad configured to be positioned therein. The fourth helical pad will have a series of annular ribs. A fourth spring is inserted between the second helical pad and the mandrel for biasing the fourth helical pad radially outward. 
     In the preferred embodiment, the wire brush member comprises a wire bundle having a first end and a second end, a brace disposed about the second end of the wire bundle, and the brace is disposed within the groove of the pad member. The brace comprises an open end and a closed end, with the closed end having disposed therein the second end of the wire bundle, and wherein the open end and the closed end cooperate to form a triangular shaped profile. The groove will also have an angular shaped profile adapted to slidably receive the wedge of the brace. The first and second wire brush members will be arcuate. In one embodiment, the first wire brush member is disposed about the periphery of the mandrel to cover a first phase and wherein the second wire brush member is disposed about the periphery of the mandrel to cover a second phase. 
     A method of cleaning a casing string with this second embodiment is also disclosed. The method comprises lowering a work string within the inner diameter of the casing string and providing a cleaning apparatus operatively associated with the work string. The method includes urging the wire brush member against the inner diameter of the casing string with a first and second spring biasing a helical pad member and cleaning the inner diameter of the casing string. The method further comprises rotating and lowering the work string. A fluid may be circulated through the inner diameter of the work string which in turn will cause the fluid to be returned on the annulus side, with the fluid being channeled between and through the helical pad. 
     In one embodiment, the well casing has a highly deviated section so that a low side of the well casing and a high side is created, and the apparatus further comprises a centralizer operatively associated with said work string, with the first helical pad covering a first phase and the second helical pad covering a second phase. The method further comprises lifting the apparatus from the low side of the inner diameter of the well casing with the centralizer, urging the wire brush member of the first helical pad against the low side of the inner diameter of the well casing with said spring at a constant force and urging the wire brush member of the second helical pad against the high side of the inner diameter of the well casing with the spring at the constant force. 
     An advantage of the present invention includes the ability to thoroughly clean the internal diameter of the casing of a course material such as cement while at the same time being able to scour the casing of thin films left by oil base and synthetic muds that contain hydrocarbons. Another advantage includes that the design allows easy replacement of the components so that if a brush becomes worn, a new brush may be easily inserted therein at the rig location. 
     Another advantage includes use of wire bristles that are of sufficient hardness to allow for the scraping of the inner diameter of the casing. Yet another advantage includes a staggered configuration of the brushes that allows for the entire 360 degree periphery of the casing to be cleaned with the upper set of brush pads or upper scrapers pads. Another advantage is that the staggered configuration of lower scraper pads or lower brush pads that allows for the entire 360 degree periphery to be cleaned. Still yet another feature is that the device may be used in highly deviated and/or horizontal wells. 
     An advantage of the present invention is that the helical pad allows for channeling of well bore fluid in the annulus area. Another advantage is that the helical brushes and scraper pads (also referred to as ribs) allow for better cleaning of inner diameter of casing string. Yet another advantage is the scraper pads, and brushes are interchangeable with each other. 
     A feature of the present invention includes a novel locking mechanism brace that allows the clamping of a bundle of wire bristles. Another feature is that the novel locking mechanism includes triangular grooves formed within the pad that cooperate with a triangular brace profile fitted therein. Yet another feature is the dove tail locking means for selectively locking the pad onto the mandrel. 
     Another feature includes a spring loaded pad that urges the wire brush against the wall of the casing at a constant pressure. Thus, in a highly deviated well, both the high side and low side of the well will be cleaned. Still yet another feature is use of a centralizer that allows for the wire brush to be centered within well. This feature keeps both brushes centralized which in turn keeps the same pressure about the circumference of the casing walls. 
     Still yet another feature of the present invention includes use of helical brushes inserted into a helical pad. Another feature is the helical ribs that act to clean and centralizer the tool in a well bore. Yet another feature is that in one embodiment an upper row of helical brushes is used and lower row of helical ribs (also referred to as scraper pads) is used. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of the down hole cleaning assembly shown in a first phase. 
     FIG. 2 is a top view of the wire brush member of the preferred embodiment of the present invention. 
     FIG. 3A is an end view of the pad member with wire brush member inserted therein of the preferred embodiment. 
     FIG. 3B is an illustration of FIG. 3A with the end plate inserted thereon. 
     FIG. 4 is a side view detail of the wire brush member clamped with the brace member of the preferred embodiment. 
     FIG. 5 is a side view detail of the pad member of FIG.  3 . 
     FIG. 6 is a cross-sectional view of the down hole cleaning assembly shown rotated to a second phase. 
     FIG. 7 is a cross-sectional view of line A—A taken from FIG.  1 . 
     FIG. 8 is a cross-sectional view of line B—B taken from FIG.  6 . 
     FIG. 9 is a cross-sectional view of an embodiment of the present invention that depicts dove tail means for attaching the pads to the down hole cleaning assembly. 
     FIG. 10 is a perspective view of the down hole cleaning assembly of the preferred embodiment of the present invention. 
     FIG. 11 is a disassembled cross-sectional view of a second embodiment of the pad and wire brush member. 
     FIG. 12 is a perspective view of the pad and wire brush member of FIG.  11 . 
     FIG. 13 is an oblique assembly view of the most preferred embodiment of this application. 
     FIG. 14 is the assembled view of the most preferred embodiment of FIG.  13 . 
     FIG. 15 is a cross-sectional view of the most preferred embodiment of FIG.  13 . 
     FIG. 16 is a front view of the most preferred embodiment of FIG.  13 . 
     FIG. 17 is a cross-sectional view of the most preferred embodiment of FIG. 13 taken along line  17  of FIG.  16 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, a cross-sectional view of the down hole cleaning assembly  2  shown in a first phase will now be described. Generally, the assembly  2  includes a first mandrel  4  that has an outer diameter surface  6  that includes an external thread profile  8 . The external thread profile  8  may be attached to a work string (not shown) such as drill pipe. It should be understood that other types of work strings are available such as snubbing pipe, coiled tubing, production strings, etc. The first FIG.  6 . 
     FIG. 9 is a cross-sectional view of an embodiment of the present invention that depicts dove tail means for attaching the pads to the down hole cleaning assembly. 
     FIG. 10 is a perspective view of the down hole cleaning assembly of the preferred embodiment of the present invention. 
     FIG. 11 is a disassembled cross-sectional view of a second embodiment of the pad and wire brush member. 
     FIG. 12 is a perspective view of the pad and wire brush member of FIG.  11 . 
     FIG. 13 is a perspective, disassembled view of the preferred embodiment of the cleaning apparatus. 
     FIG. 14 is a perspective view of the assembled cleaning apparatus shown in FIG.  13 . 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, a cross-sectional view of the down hole cleaning assembly  2  shown in a first phase will now be described. Generally, the assembly  2  includes a first mandrel  4  that has an outer diameter surface  6  that includes an external thread profile  8  The external thread profile  8  may be attached to a work string (not shown) such as drill pipe. It should be understood that other types of work strings are available such as snubbing pipe, coiled tubing, production strings, etc. The first mandrel  4  will have a first internal bore  10  that extends to the second internal bore  12  that will have contained thereon internal thread means  14 . 
     The assembly  2  contains a second mandrel  16  having an outer diameter  18  and an inner bore  20 . The outer diameter  18  will have a series of openings formed therein, with FIG. 1 showing opening  22  and opening  24 . It should be noted that in the preferred embodiment, there will be two rows of openings, with the first row along line A—A of FIG.  1  and the second row along line B—B of FIG.  6 . Each row will contain three openings. 
     The outer diameter  18  may contain other openings that will be described later in the application. The outer diameter  18  will also contain the external thread means  26 . In the embodiment shown in FIG. 1, the second mandrel  16  is made up to a third mandrel  28  The third mandrel  28  will have an outer diameter  30  that in turn extends radially inward to the internal threads  32  which in turn extends to the inner bore  34  that in turn leads to the internal threads  36 . The third mandrel  28  may be attached to another down hole tool such as a bit. 
     The assembly  2  will have included the pad members  38 ,  40  that are operatively positioned within the openings  22 ,  24  respectively. The pad members  38 ,  40  will have a plurality of grooves formed therein with the grooves containing wire brush means  42 ,  44  for cleaning the internal diameter of a casing string. The wire brush means  42 ,  44  is generally a wire bristle arrangement that is commercially available from Spiral Brush, Inc. under the name steel wire. The bristles are manufactured from carbon or stainless steel. 
     The pad members  38  are operatively associated with biasing means  46 ,  48  for urging the pads  38 ,  40  (and in turn the wire brush means  42 ,  44 ) outwardly with respect to the casing. In the preferred embodiment, each opening will have four springs, including, a first spring  46 A/ 48 A, second spring  46 B/ 48 B, and the third spring  46 C/ 48 C. The spring loaded pads will allow for constant pressure of the brushes against the casing wall at all times. It should be noted that additional springs may be employed, for instance, when the device used has a large diameter so that more force is needed to adequately bias the pads. 
     The invention may have a plurality of openings within the outer diameter  18  for placement of additional pad and wire brush means as previously set out. With a staggered configuration of pads about the body of the mandrel  16 , a 360 degree circumference about the inner diameter of the casing may be cleaned. This will be further explanation in reference to FIG.  6 . 
     Referring now to FIG. 2, a top view of the wire brush member  42 ,  44  of the present invention will now be described in greater detail. The wire brush member  42 ,  44  includes a bundle of wires that can be purchased from Spiral Brush. The bundle of wires may be comprised of a carbon or stainless steel material. As depicted in FIG. 2, the bundle of wires  50  will have a first end  52  and a second end  54 . The linear bundle of wires  50  is wrapped about a center rod  55 . The second end  54  will be encapsulated within a brace  56 , with the brace  56  tightly clamping about the second end  54  and rod  55  so that the wires are held together. Further, the brace  56  is arcuate with respect to radial surface  57  and has generally the same radius of curvature as that of the mandrel  16 . 
     In reference to FIG. 3A, an end view of the pad member  38  with wire brush means  42  inserted therein is shown. In the preferred embodiment, the pad member  38  contains an outer surface  58  that slopes to first shoulder  60  that in turn extends to a surface  61  and then to a second shoulder  62 . The second shoulder  62  advances to the internal surface  64  that in turn extends to a third shoulder  66  and surface  67  which in turn stretches to the fourth shoulder  68 . The outer surface  58  will contain a series of grooves  70 ,  72 ,  74 ,  76 ,  78  that are formed in the pad  38  so that series of triangular profiles are formed therein. Thus, the braces  56  may be laterally placed therein. 
     Also, the present invention teaches having a groove  69 B formed within the end face  69 A. The end face  69 A will have two openings  69 C &amp;  69 D that will receive an attachment means such as a set screw. In FIG. 3B, the illustration of FIG. 3A is depicted with an end plate  69 E operatively associated therewith. Thus, the end plate  69 E will be inserted within the groove  69 B, and will further have a pair of set screws that are inserted into the openings  69 C &amp;  69 D. With the end plate in place, the wire brush means  42  are effectively locked into position so that they can not inadvertently back-out during operation. An end plate may be placed on all of the pad members. 
     With reference to FIG. 4, a side view detail of the wire brush means  42 ,  44  clamped with the brace member  56  of the present invention will now be described. The brace  56  may comprise a first leg  79 A, a second leg  79 B, and a third leg  79 C, with the legs  79 A,  79 C bent in relation to each other so that a triangular profile is formed as well as clamping the second end  54  of the wire bundle. As stated earlier, the wire bundle will generally have a first end  52  that will serve to clean the casing. As shown, the clamping effect of the brace  56  causes the wire end  52  to expand which enhances the effectiveness of the wire scraping the casing wall as well as serving to clutch the wire bundle and rod  55  in place. 
     In reference to FIG. 5, a side view detail of the pad member  38  of FIG. 3 is shown. It should be noted that like numbers appearing in the various figures correspond to like components. Thus, the pad member  38  will have a series of grooves  70 - 78 . The individual grooves will have a first wall  70 A, a second wall  70 B, and a third wall  70 C, with the three walls forming a triangular profile that is essentially patterned after the brace  56  so that the brace  56  may be slidably disposed therein. The triangular shaped profile allows for lateral placement of the brace  56  therein while at the same time securing the brace  56  from radial release from the grooves  70 - 78 . The grooves  70 - 78  may also contain radial surfaces  70 D,  70 E,  72 D,  72 E,  74 D and  74 E. 
     FIG. 5 also depicts the channels  71 A-D that may be included which receive and cooperate with the springs. Although not shown, the series of rows may be arranged in an inclined orientation relative to the axial bore which gives the series of rows a spiral effect. The inclined orientation allows for the displacement of the particles and compounds that are on the wall of the casing to be more easily channeled as the device is either being lowered into the well, raised from the well, or being rotated in the well. 
     The embodiment of FIG. 5 may also include an end plate member that contains two openings for placement of set screws to affix the plate member onto the pad. The plate member will hold the brushes in place and prevent the brushes from sliding out of the grooves. 
     Referring now to FIG. 6, a cross-sectional view of the down hole cleaning assembly  2  shown rotated to a second phase will now be described. Thus, the drawing shows the second row including the pad member  80  and pad member  82  that will be inserted within the openings  84 ,  86 . The pad members  76 ,  78  will have associated therewith the wire brush means  88  and  90 , respectively for cleaning the internal diameter of the casing string. As set out earlier, the wire brush means  84 ,  86  will include the wire bundles clamped via a brace. 
     The pad member  76  will be urged outward toward the casing inner wall via the springs  92 A,  92 B,  92 C and the pad member  78  will be urged outward toward the casing inner wall via springs  94 A,  94 B,  94 C. As previously set forth, the springs  92 A-C and  94 A-C will urge the wire brush against the wall of the casing at a constant force. Thus, if the work string is being lowered through dog legs, or other highly deviated portions of the well, the springs will allow the retraction or urging as is necessary. 
     The illustration of FIG. 7 depicts a cross-sectional view of line A—A taken from FIG.  1 . Thus, the brush means  42  and  44  are shown along with the brush means  96  in the first row. It should be noted that while three brush means  92  are shown in FIG. 7, the actual number may vary depending on numerous variables such as hole size, work string etc. The brush means  92  will be included within an opening along the pad and spring as previously described. The three brush means will provide for an effective radial cleaning phase area of 360 degrees. 
     In FIG. 8, the drawing illustrates a cross-sectional view of line B—B taken from FIG. 6 wherein FIG. 6 depicts three brush means, namely  84 ,  86  and  98  in a second row. The construction of the pads, openings, springs and brush means is similar to those described in FIGS. 1 through 7. The three brush means will provide for an effective radial cleaning phase area of 360 degrees. As seen in FIG. 8, the individual brush means  84 ,  86 ,  94  are disposed in a different longitudinal phase when compared to the brush means  42 ,  44 ,  92  so that a staggered 360 degree coverage of the inner diameter may be accomplished during an operational trip into the casing string i.e. the entire inner diameter circumference will be cleaned. 
     FIG. 9 is a cross-sectional view of an embodiment of the present invention that depicts dove tail means for attaching the pads to the down hole cleaning assembly  2 . More particularly, the first mandrel  4  will have the internal threads  14  that cooperate with the external threads  100  of the second mandrel  16 . The internal threads  14  lead to a inner bore surface  102 . 
     The external threads  96  extend to the openings  22 ,  24  that have radial shoulders  104 ,  106 . The openings  22 ,  24  are generally slots that are formed on the periphery of the mandrel  16  and are adapted to receive the pads  38 ,  40  as previously described. The slots formed will terminate at the shoulders  108 ,  110  that in turn extends to the lip  112 ,  114 . The lips  108 ,  10  then lead to the outer diameter surface  18 . It should be noted that while two openings  22 ,  24  are shown in FIG. 9, the preferred embodiment will contain three staggered openings about the periphery as shown in FIG.  7 . 
     Therefore, when the tool is to be assembled, the operator may place the springs  46 A- 46 C and  48 A- 46 C within the openings  22 ,  24 . The pads  38 ,  40  are then placed within the openings  22 ,  24 . The surface  67  of the pad member  40  is placed within the opening  24  such that the surface  67  and lip  110  abut each other and with the pads  38 ,  40  up against the shoulder  104  and  106 . Next, the first mandrel  4  is threadedly connected with the second mandrel  16  by making up threads  14  with threads  96 . The inner bore surface  97  will slide-over the lip  61 . With the lip  61  in place, the inner bore surface  97  will hold the pads  38 ,  40  so that the pads may be biased radially outwardly via springs  46 A- 46 C and  48 A- 48 C. Meanwhile, the surface  67  will engage the lip  108 ,  110  so that the pad members  38 ,  40  are held in position. 
     Thus, the individual pad members may be replaced on location by threadedly removing the mandrel  4 , withdrawing the old pad member, and thereafter placing a new pad member with new brush means thereon into the openings. Next, the operator could then threadedly make up the mandrel  4  onto mandrel  16  as previously set forth. 
     Also, the mandrel  28  will have similar thread means with an inner bore surface for making up to the mandrel  16  so that the second series of pad members  76 ,  78  may be similarly dove tailed for selectively adapting said pad members  76 ,  78  with the mandrels  16 ,  28 . 
     The invention is illustrated in a perspective view in FIG.  10 . Thus, in the preferred embodiment, the brush means  42 ,  44 ,  92  are positioned in a first row while the brush means  84 ,  86 ,  94  are positioned in a second row. Also, the FIG. 10 depicts the pads  38 ,  40 ,  76 ,  78  disposed within openings contained on the mandrel  16  as previously described. 
     There is yet another embodiment possible with the teachings of the present invention. Referring now to FIG. 11, the embodiment includes a different type of wire brush means  122  operatively associated with the pad member  124 . The pad member  124  includes the first plate  126  and the second plate  128  which allows for the back side placement of the brush means  122  through the second plate  128 . 
     The pad member  124  of FIG. 11 will be received within the openings  22 ,  24 ,  84 ,  86  etc. previously mentioned. The plates  126 ,  128  are arcuate so that they fit into the contour of the outer diameter of the mandrel  16 . The second plate  128  will have an outer surface  130  that extends to the ledges  132 A-B which in turn extends to the inner surface  134 . The second plate  128  has disposed therein the openings  136 A-F and the ledge  132  has openings  138 A-B. 
     Also depicted in FIG. 11 is the wire brush means  122  for cleaning the internal diameter of said casing string as previously described. The wire brush means  122  is also commercially available from Spiral Brush Inc. In this embodiment, the individual wire brush means  122  are disposed through the openings  126 A-F and are generally circular arranged about a base  140 . The base  140  is of a diameter greater than the diameter of the opening  136  so that the wire brush means  122  can not pass therethrough. 
     The first plate  126  contains the first surface  142  that stretches to a second surface  144 . The second surface  144  will have disposed therein openings  146 A,  146 B. A fastener, such as a screw, may be placed therethrough and be operatively attached with the second plate  128  via the openings  138 A,  138 B. In this manner, the wire brush means  122  will fit through the openings and once the plates  126  and  128  are fastened together, the wire brush means  122  are locked into position. 
     The spring means  148 A-D will be positioned so that one end of the spring is up against the surface  144  while the other end is against the surface  102 , for instance. Thus, the spring means  148 A- 148 D will bias the pad member  124  axially outward into engagement with the wall of the casing string as previously set forth. FIG. 12 is a perspective view of the pad  124  and wire brush member  122  of FIG. 11 assembled. 
     Referring now to FIG. 13, the preferred embodiment of this application will now be described. A first tubular member  200  is provided, with the tubular member  200  being concentrically disposed within a casing string. The tubular  200  is generally part of a work string such as a drill string, production string, coiled tubing, snubbing, etc. The tubular  200  has an open end  202  that contains internal thread means (not shown in this figure). 
     FIG. 13 also depicts the mandrel  204 , with the mandrel  204  having a generally cylindrical outer surface and an internal bore section  206 . The mandrel  204  has a first end that contains external thread means  208  that will mate and cooperate with the internal thread means of the tubular  200 . The mandrel has a second end that contains the external thread means  210  that will threadedly attach to the internal thread means  212  of the second tubular member  214 . The second tubular member  214  may be further connected to other tubular members. The open end  202  will have an annular ring, also referred to as an inner bore surface  102  shown in FIG.  9 . The open end of second tubular member  214  also contains this inner bore surface (also referred to as an annular ring  280  in FIG.  13 ). 
     The mandrel  204  will contain a plurality of helical openings, for instance helical opening  216  and helical opening  218 . A third helical opening is provided but not shown in the FIG.  13 . The helical openings will have disposed therein the helical pads  220 ,  222 ,  224 . The helical pads contain an arcuate body with parallelogram sides. The pads  220 ,  222 ,  224  will contain slotted grooves for placement of the row of brushes as was previously explained as well as seen in FIGS. 2,  3 ,  4 ,  5 ,  6 . The pad  220  will contain the brush means  226  the pad  222  will contain the brush means  228  and the third pad  224  will contain the brush means  230 . The brush means  226 ,  228 ,  230  are also constructed as previously set out and as seen in FIGS. 2,  3 ,  4 ,  5 ,  6 . 
     The openings  216 ,  218 ,  220  will leave formed on the mandrel body the arms  232 ,  234 ,  236  thereby forming the slotted area the helical pads  220 ,  222 ,  224  are fitted into. The opening  216  also contains the partial radial annular groove  238 , the opening  218  contains a partial radial groove  247 , and the opening  220  contains a partial radial groove (not shown in this figure). The helical pad  220  contains the lip section  240  that will cooperate with the annular groove on the tubular  200 . The helical pad  220  also has the lip section  242  that will cooperate with the partial radial annular groove  238 . The helical pad  222  contains the lip section  244  that will cooperate with the annular groove on the tubular  200 . The helical pad  222  also has the lip section  246  that will cooperate with the partial radial annular groove  247 . The helical pad  224  contains the lip section  248  that will cooperate with the annular ring on the tubular  200 . The helical pad  220  also has the lip section  250  that will cooperate with the partial radial annular groove on the mandrel  204 . The lip sections cooperate with the openings and the annular ring of the tubular member  200  in order to form means for selectively attaching the pads to the mandrel  204 , which is also referred to as dove tail means, operatively associated with the mandrel, for selectively attaching the helical pad members to the mandrel. 
     FIG. 13 also depicts a plurality of centralizer means which include helical pads  252 ,  254 ,  256 . The pads  252 ,  254 ,  256  are inserted into the three helical openings  258 ,  260  (the third opening is not shown in this figure). The pads centralize as well as scrape and clean the inner diameter. The pads  252 ,  254 ,  256  have a series of annular ribs arranged in a slanted fashion  262 ,  264 ,  266 , respectively. Each of the pads  252 ,  254 ,  256  have a lip section, namely lip section  268 ,  270  for pad  252 ; lip section  272 ,  274  for pad  254 ; lip section  276 ,  278  for pad  256 . A partial radial annular groove is provided within each window. Thus, lip section  268  will fit into a partial radial groove, lip section  272  will fit into a partial radial groove, and lip section  276  will fit into a partial radial annular groove. 
     The tubular member  214  will have an annular ring  280  (also referred to as an inner bore surface) in its open end. Thus, the lip section  270  will cooperate with annular ring  280 , lip section  274  will cooperate with annular radial groove  280 , and lip section  278  will cooperate with annular radial groove  280  when the thread means  212  is threadedly engaged with thread means  210  so that pads  252 ,  254 ,  256  are held in the three openings ( 258 ,  260 ). These pads  252 ,  254 ,  256  are to clean as well as centralize the mandrel  204 . Other stabilizer means may be added to the work string if desired. For instance, a stabilizer may be added above or below the mandrel  204 . An example is shown in FIG.  6 . 
     Also included is means for biasing the pads radially outward. When the apparatus is concentrically disposed within a well bore, the biasing means will bias the pads radially outward against the casing walls at a constant force, regardless if the well bore is highly deviated or horizontal. Thus, FIG. 13 depicts the conical springs  282   a,    282   b,    282   c,    282   d  that will have one end inserted into an aperture milled into the mandrel  204 , such as the apertures  284   a,   284   b.  In the preferred embodiment, each spring will be associated with a hole; in FIG. 13, the apertures for  282   c  and  282   d  are not shown due to the curvature of the mandrel  204 . 
     The springs  286   a,    286   b,    286   c,    286   d  will have the apertures  288   a,   288   b,   288   c,   288   d,  respectively, for biasing the pad  222  outward. The placement of the springs is along a helical path, as shown, which is also parallel to the arms e.g.  232 . The helical pads of this embodiment will have a corresponding aperture for placement of the second end of the various springs. FIG. 13 depicts this feature as apertures  290   a,    290   b.  With reference to the lower helical pads of the embodiment depicted in FIG. 13, the springs  292   a,    292   b,    292   c,    292   d  are associated with apertures within the mandrel body  204  as previously stated. The apertures  294   a,    294   b  are shown. Further, there is included the springs  296   a,    296   b,    296   c,    296   d  operatively associated with the apertures within the mandrel body  204 ; those depicted in FIG. 13 include apertures  298   d,    298   b,    298   c.  It should also be noted that an aperture  300   a  within helical pad  256  is also depicted. 
     FIG. 14 depicts the assembled view of the most preferred embodiment of FIG.  13 . Thus, the pad  220  is seen with the brush means  226  and pad  222  is seen with brush means  228 . The pad  252  is seen with the annular rib pattern  262  and the pad  254  is seen with the annular rib pattern  264 . Note that the rib pattern is slanted in a first direction and the brush means is slanted in the same direction. However, the rib pattern may be slanted in a first direction and the brush means may be slanted in an opposite direction. Further, with the unique design herein disclosed, all of the scraper pads and brush pads are interchangeable with each other. The operator can then have all brush pads; or all scraper pads; or a combination of brush pads and scraper pads. In other words, top row can have just brush pads, or just scraper pads, or a combination of the two. The bottom row can have just brush pads, or just scraper pads, or a combination of the two. 
     The line  227  in FIG. 14 depicts the fact that with this novel design, the top brushes means  226   a  and the bottom brush means  228   a  effectively overlap so that a 360 degree phase coverage or more is produced by this spiral design. Without the spiral design, it was not possible in the prior art to have the top brush (located on a first pad) and the bottom brush (located on a second pad) to cover a 360 degree phase. In other words, with the prior art designs of longitudinal straight pads, a gap in coverage existed and effectively required a lower set of completely independent brush means and/or scraper pads to fill-in this gap. This design solves this problem. 
     Referring now to FIG. 15, a cross-sectional view of the preferred embodiment of this invention is illustrated. FIG. 15 is similar to FIGS. 1 and 6 in that they depict the dove tail means for selectively attaching the pads to the mandrel. More particularly, the lip  240 ,  244  is surrounded by the annular ring surface  316  contained on the tubular  200 . Further, FIG. 15 depicts the annular radial groove  238  with lips  242 ,  246  positioned therein. Also included is the annular radial groove  318 ,  319  that has contained therein the lips  268 ,  272 . The annular ring  280  is configured to selectively attach the lips  270 ,  272 . 
     FIG. 16 illustrates a front view of the apparatus and in particular the helical pads. The front view of the helical pad  222  depicts generally a parallelogram having the side  320  that is slanted and parallel with the side  322 , as well as parallel top and bottom sides. Note that the angle of the slant can be varied. In the most preferred embodiment, there is a 360 degree of peripheral coverage when cleaning a casing string. In other words, the brushes will effectively cover the entire 360 degree phase of the inner diameter. The lower pads with the annular ribs  264 ,  262 ,  266  may be slanted in the same direction and can also be designed to cover an effective 360 degree phase. It should be noted that it is also possible to have the slant of the upper brushes in an opposite slope than the lower annular ribs. As shown, there is a plurality of rows of brushes/ribs. The fluid being circulated within the annulus of the well bore can, therefore, be directed through the individual helically arranged brushes/ribs rows as well as channeled along the arms  232 ,  234 ,  236  during operation. Also, rotation of the work string is enhanced by the helically arranged brushes. 
     Referring now to FIG. 17, a cross sectional view of the apparatus taken along line  17  of FIG. 16 will now be described. The mandrel  204  with the internal bore  206  is shown, with the openings  216 ,  218 ,  324  is illustrated. The apertures  284   b,    288   b,    326  are shown with the springs  282   a,    286   a,   328  mounted therein, respectively. The brushes  226 ,  228 , 230  are shown. The side arms of the openings are also depicted at  232 ,  234 ,  236 . It should be noted that the brushes are inserted into a groove within the respective pads as previously described. The brush end  330  concludes so that there is a channel or gap between a complementary brush end  332 . The channel, along the arms  232 ,  234 ,  236  provides a passage for fluid, debris and solids to channel through the tool. 
     It should be noted that in the preferred embodiment of FIGS. 13,  14 ,  15 ,  16 , and  17 , that the lower helical pads are comprised of a series of annular extending ribs. Thus, the helical pads  252 ,  254 ,  256  are constructed similar to that seen in FIG. 17, except that annular extending ribs are used rather than the brush means. The annular extending ribs will be formed on the pad such as by milling as is well understood by those of ordinary skill in the art. The types of metals that the pads and ribs may be constructed of include metal, aluminum, plastic, etc. 
     Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.