| 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 NR 0 ; R 0 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(CH 3 )CH 2 , n is a number from 1 to 6 and X is NR 0 ; 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. |