Method for preventing the formation of calcium carboxylate deposits in the dewatering process for crude oil/water streams

Abstract

The invention relates to the use of compounds comprising three hydrophobic groups as additives to a stream of crude oil containing carboxylic acids, in particular naphthenic acids, and salt water, to prevent the formation of calcium carboxylates when the fluid is exposed to shear forces. Preferably, the compounds are added to a crude oil/water stream containing organic acids Caions at a point between the well and the pressure reduction valve in the crude oil receiving station. The compounds have the formula (I) wherein hydrophobic groups R, R', and R″ are, independently, an optionally substituted hydrocarbyl group or an optionally substituted acyl group having 4-22 carbon atoms; X is N, P═O or CR′″, wherein R′″ is H or a C1-C4 alkyl group; Y is C═O or CH; a, a′, a″ b, b′ and b″ each independently are 0 or 1, the subscript 0-1 meaning that if the subscript is 0, then the group is not present in the molecule, whereas if the subscript is 1, then the group is present in the molecule; n, n′, and n″ are, independently, zero or on average at least 1, and at most 14; the sum of n, n′, and n″ is 0 or on average at least 3, and at most 42; and m, m′, and m″ are, independently, on average 0-6, and the sum of m, m′, and m″ is 0-18.