Synergistic blends of anti-agglomerant gas hydrate inhibitors with quaternary alkyl ammonium compounds

A gas hydrate inhibitor composition comprising

• (A) from 5 to 95 weight-% of an amphiphile having a hydrophobic tail, R5, linked to a hydrophilic head group, —N(R1)(R2) or —[N(R1)(R2)(R3)]+X−, by a linking moiety, L, the amphiphile having the general formula (1)
• [R5-L-N(R1)(R2)(R3)]+X− (1)
• wherein
• each of R1 and R2 is independently an alkyl group having from 1 to 5 carbon atoms;
• or the nitrogen atom and the R1 and R2 groups together form a substituted or unsubstituted heterocyclic group;
• R3 is optionally present;
• when present, R3 is hydrogen or an alkyl group having from 1 to 8 carbon atoms which optionally bears a hydroxy group or a carboxy group at the 2-position;
• L has the one of formulae (2), (3), (4), (5), (6), (7a), (8a), (8b), (9), (10a), (10b), (11), (12a) and (12b):
• —C(═O)—N(R6)—(CH2)t— (2)
• —N(R7)—C(═O)—(CH2)t— (3)
• —N(R7)—(CH2)2—C(═O)—NH—(CH2)t— (4)
• —N(R7)—C(═O)—(CH2)2—N(R6)—(CH2)t— (5)
• —CH(OH)—CH2—N(R6)—(CH2)t— (6)
• —CH(COOH)—CH2—C(═O)—N(R6)—(CH2)t— (7a)
• —CH(COOH)—CH2—C(═O)—[O—(CH2)t]v— (8a)
• —CH(CH2—COOH)—C(═O)—[O—(CH2)t]v— (8b)
• —N(R7)—C(═O)—(CH2)2—C(═O)—N(R6)—(CH2)t— (9)
• —N(R7)—C(═O)—CH2—CH(OH)—C(═O)—N(R6)—(CH2)t— (10a)
• —N(R7)—C(═O)—CH(OH)—CH2—C(═O)—N(R6)—(CH2)t— (10b)
• —N(R7)—C(═O)—CH(OH)—CH(OH)—C(═O)—N(R6)—(CH2)t— (11)
• —N(R7)—C(═O)—C(OH)(CH2COOH)—CH2—C(═O)—N(R6)—(CH2)t— (12a)
• —N(R7)—C(═O)—CH2—C(OH)(CH2COOH)—C(═O)—N(R6)—(CH2)t— (12b),
• wherein
• t is 2, 3 or 4;
• v is an integer between 1 and 10;
• R6 is hydrogen or an alkyl group having from 1 to 5 carbon atoms;
• and
• R7 is hydrogen or an organic moiety having from 1 to 20 carbon atoms;
• R5 is a hydrocarbyl group having from 8 to 22 carbon atoms;
• and
• X− is present as an anion when R3 is present;
• and
• (B) from 5 to 95 weight-% of a cationic surfactant selected from di(C8-C18 alkyl)dimethyl ammonium salts.