referring to fig1 an embodiment is illustrated that mounts a seal 10 to the work string 12 . seal 10 can be any one of a variety of styles but a downwardly oriented cup seal is preferred . not shown in fig1 is the top end of the work string 12 that is connected to a device described in u . s . pat . nos . 3 , 390 , 190 or 6 , 415 , 862 or another surface mounted device that can connect the top of the work string 12 to separation equipment so the debris can be removed prior to the fluid returning to the mud pit . while the seal 10 is advanced downhole , it cleans the debris from the inner wall 14 of the casing 16 . fluid in the annular space 18 below seal 10 is forced into the work string 12 , as indicated by arrows 20 . any suspended debris or debris scraped from the inner wall 14 goes into the work string 12 as a result of advancement of seal 10 . annulus 22 above seal 10 can have fluid added into it to compensate for the downhole movement of seal 10 and to prevent high differential pressure from forming across seal 10 , which could retard the further advancement of the apparatus . the displaced fluid and debris that gets into the work string 12 will be directed through a connection apparatus of the type described in u . s . pat . nos . 6 , 390 , 190 or 6 , 415 , 862 or another device into surface separation equipment of known design ( not shown ) so that the screened fluid can be returned to the mud pit for future use . optionally , the separation equipment can be eliminated . fig2 adds a brush 24 and a casing scraper 26 to the assembly shown in fig1 . other equipment to dislodge debris could be added and individual items or other combinations of equipment can be used to dislodge the debris so that it can be carried off into the work string 12 , as indicated by arrows 28 . fig3 , shows the equipment in fig2 with the difference in method being that a reverse flow is pumped into annulus 22 from the surface . this flow displaces the seal 10 to enter annulus 18 and into the work string 12 as shown by arrows 30 . in this embodiment , the movement of seal 10 downhole displaces fluid into work string 12 , while at the same time the reverse circulation sweeps debris into work string 12 . it is understood that while reverse flow can be used when the apparatus is fully deployed into the well so that all fluid and solids which have entered the work string 12 will be moved to the surface , it is not necessary ( though it would be advantageous ) to reverse circulate while the equipment is being lowered into the well . fig4 shows the addition of ports 32 just below the seal 10 . in this embodiment , regardless of whether reverse circulation is used , the debris is displaced into ports 32 as well as into the lower end 34 of the scraper 26 . the advantage here is that as soon as the debris is agitated , whether by the seal alone , as shown in fig1 , or by the brush 24 and scraper 26 , the debris moves right into the ports 32 so it has less of a chance to settle and a greater chance to be taken to the surface with the high velocity fluid within work string 12 . ports 32 can be used with the assembly shown in fig1 or 2 or some other combination of debris removal tool or tools known in the art . those skilled in the art will appreciate that with surface equipment that makes connecting and releasing from the work string 12 an easy matter as it is being run in , an improved well debris removal technique of the present invention can be implemented . in its various forms , it can use a cup seal such as 10 with or without ports to do the dislodging and collection of loosened debris . alternatively , scraping equipment , involving a number of different combinations of known devices such as brushes 24 or scrapers 26 or other equipment can be used to return the debris to the surface . the cup seal 10 can be mounted on a sleeve to allow the tubular string 12 to rotate items such as brushes 24 or scrapers 26 while the seal 10 remains stationary . tubular string 12 could be rigid tubing or coiled tubing . here again ports such as 32 can be used or omitted and the collection of debris can proceed with only fluid displacement when moving seal 10 or in combination with reverse circulation . seal 10 can be a downwardly oriented cup seal or it can have other forms . it need not form a perfect seal as long as it is capable of displacing enough fluid when advanced to allow debris collection in the manner described . in that sense it can be a ring that occludes the annular space and is not a seal at all . in addition it is understood that completion fluid can be placed in the annulus above seal 10 as the apparatus is being inserted into the well thereby reducing the time required to reverse the mud from the well to displace the mud system with completion fluid . the foregoing disclosure and description of the invention are illustrative and explanatory thereof , and various changes in the size , shape and materials , as well as in the details of the illustrated construction , may be made without departing from the spirit of the invention .