fluid or a slurry downhole including down production tubing 32 into annulus 59 to flow between string s and production tubing 32 the fluid is indicated as reverse circulating by proceeding down annulus 59 and up the inside of outer tubing 50 and subsequently up inner tubing 52 of string s a production tree or wellhead 58 not shown exists at the surface to control well fluids in production tubing 32 as is known in the art fig6 indicates using string s beginning a cleaning operation of particulate matter p from the bottom of a well which matter is obscuring perforations 36 string s has been lowered and fluid usually water and including possibly gas is indicated as circulating down annulus 59 between production tubing 32 and string s fig6 indicates the fluid reverse circulating up the inside of outer tubing 50 of coiled tubing string s the gas and or the fluid circulated down could include nitrogen creating a nitrified fluid as indicated in fig6 fluid circulating up string s includes the fluid pumped down annulus 59 as well as particulate matter p picked up and any well fluids that may be present in or that may enter the well fig7 illustrates the cleaning process for the well proceeding in time where string s has been lowered further into the mass of particulate matter p fig8 illustrates an internal flow path of string s comprised of an inner and outer tubing in fig8 fluid circulation can include fluid pumped down a well including gases pumped down the well.