| abstract |
Method for inhibiting the hydration of clays and shales during drilling operations comprising the use of a water base drilling fluid, which contains from 0.2 to 5 % by weight of the condensation product of a dicarboxylic acid having 4 to 10 carbon atoms with alkanolamines, diamines or polyalkyleneamines of formula R''R'N-R'-XH, where X is O or NR0; R0 is hydrogen or a linear or branched alkyl group having from 1 to 6 carbon atoms, R' is a linear or branched, aliphatic or cicloaliphatic alkylene group having from 2 to 10 carbon atoms or R' is R””(NH-R””)n where R”” is ethylene or CH(CH3)CH2, n is a number from 1 to 6 and X is NR0; R' and R'' can be equal or different from one another and are hydrogen or a linear or branched alkyl group having from 1 to 6 carbon atoms, optionally substituted with a hydroxyl group, the condensation product being in neutral form or in the form of salt. |