| abstract |
The invention concerns a method for using biodegradable fluid characterised in that it consists, at the very start of drilling, in introducing into the well a biodegradable surface sludge stable up to about 100 DEG C, with filtrate reducing power adjustable from 2 to 13 cm<3> depending on the amount of filtrate reducing agent used, and with electric stability not less than 1000 volts, and when the temperature of the terrain being traversed reaches 100 DEG C, in replacing said surface sludge by a bottom sludge stable at a temperature higher than 200 DEG C, the surface sludge volume representing 60 to 80 % by volume of the total sludge used. |