| abstract |
An aqueous clay base mud for deep drilling containing as a protective colloid a copolymer which is constituted by the formula I, II and III I, <IMAGE> II, <IMAGE> III <IMAGE> IN WHICH R1 and R2 each is hydrogen of -CH3; R3 is -CO-NH2, -CN or COOCH3; R4 is hydrogen, -CH3 or -C2H5; R5 is -CH3 or -C2H5 or R4 and R5 together represent a propylene group forming a pyrrolidone radical with the inclusion of the radical <IMAGE> Me is ammonium, potassium, sodium or lithium and x is 5 to 50, y 25 to 92 and z 3 to 70, OR BY THE SAPONIFICATION PRODUCTS THEREOF AND WHICH CONTAINS THE COMPONENTS IN THE PARTS BY WEIGHT OF THE STARTING MONOMERS INDICATED BY THE INDICES X, Y AND Z. |