The present invention provides a drain apparatus (200) for use in a subsea pipeline to remove liquid from a multiphase flow in the subsea pipeline. The drain apparatus comprises a first channel (20) for carrying a multiphase flow comprising liquid and gas phases; and liquid extraction means (11, 12, 14, 18) for extracting the liquid phase from the multiphase flow in the first channel (20). The internal diameter of the first channel (20) is substantially the same as an internal diameter of a subsea pipe arranged to carry the multiphase flow in the subsea pipeline, such that a pig travelling along the subsea pipe can pass through the first channel (20). The present invention also provides a subsea pipeline comprising a subsea pipe for transporting a multiphase flow subsea; and at least one drain. The at least one drain is disposed partway along a gradient in the subsea pipe to reduce liquid holdup.

A system and method for removing organic carboxylates from a mono ethylene glycol (“MEG”) stream includes a reaction vessel; means for cooling and diluting the MEG stream being routed to the reaction vessel; means for acidifying the cooled and diluted MEG stream during its residence time within the reaction vessel; and means for removing an acetic-rich overhead stream from the reaction vessel. The acidification of the cooled and diluted MEG stream occurs under a vacuum. The reaction vessel may be located downstream of a calcium removal vessel and receive a filtered bottom stream from that vessel, or it may be a single reaction vessel that cycles between a calcium removal mode and an acetate removal mode, with the pressure of the single vessel being greater during the calcium removal mode than during the acetate removal mode.

The present invention provides a drain apparatus (200) for use in a subsea pipeline to remove liquid from a multiphase flow in the subsea pipeline. The drain apparatus comprises a first channel (20) for carrying a multiphase flow comprising liquid and gas phases; and liquid extraction means (11, 12, 14, 18) for extracting the liquid phase from the multiphase flow in the first channel (20). The internal diameter of the first channel (20) is substantially the same as an internal diameter of a subsea pipe arranged to carry the multiphase flow in the subsea pipeline, such that a pig travelling along the subsea pipe can pass through the first channel (20). The present invention also provides a subsea pipeline comprising a subsea pipe for transporting a multiphase flow subsea; and at least one drain. The at least one drain is disposed partway along a gradient in the subsea pipe to reduce liquid holdup.

The present invention relates to a method to inhibit gas hydrate formation in the field of crude oil and natural gas extraction, transportation and processing.

The present invention relates to a method to inhibit gas hydrate formation in the field of crude oil and natural gas extraction, transportation and processing.

Compositions and methods of using such compositions to inhibit the formation of gas hydrate agglomerates are provided. In certain embodiments, the methods include: contacting a fluid with a hydrate inhibitor composition that includes at least one compound having the structural formula (I) wherein R.sub.1 is hydrogen or any C.sub.1 to C.sub.8 hydrocarbon chain; each of R.sub.2 and R.sub.3 is independently a C.sub.1 to C.sub.8 hydrocarbon chain; R.sub.4 is hydrogen, a C.sub.1 to C.sub.20 hydrocarbon chain, or —CH.sub.2—CH(OH)—R.sub.5; R.sub.5 is a C.sub.1 to C.sub.50 alkyl chain or a C.sub.1 to C.sub.50 alkenyl chain; X.sup.− is a counter anion; and n is an integer from 1 to 8.

##STR00001##

The present disclosure relates to a gas hydrate inhibitor composition comprising A) a compound according to formula (1)

##STR00001##

wherein R1 is an alkyl group having from 1 to 5 carbon atoms; R2 is hydrogen or an alkyl group having from 1 to 5 carbon atoms; R3 is present or not as hydrogen and organic moieties having from 1 to 20 carbon atoms; R4 is selected from —(CH2)t-, —[(CH2-CHR6)t]-, —(CH2-CHR6O)u-(CH2)t- and combinations thereof; R5 is an alkyl or alkenyl group having 4 to 22 carbon atoms; R6 is hydrogen or an alkyl group having from 1 to 4 carbon atoms; R7 is hydrogen or an alkyl group having from 1 to 4 carbon atoms; R8 is present or not as hydrogen or organic moieties having from 1 to 20 carbon atoms; t is 2, 3 or 4; u is an integer between 0 and 100; n is 0 or 1 m is 0 or 2 o is 0 or 2 p is 0 or 1 X− is an anion, and and a a synergistic surfactant which is selected from the group consisting of N-acylated polyhydroxyalkylamines and a method of using the gas hydrate inhibitor composition.

A polymeric anti-agglomerant hydrate inhibitor useful for preventing the formation of hydrate agglomerates in a multi-phase oilfield fluid may be synthesized via a condensation reaction between a cyclic anhydride and a tertiary amine-diol in the presence of a condensation catalyst to form a polyester amine precursor and a reaction of the polyester amine polymer precursor with an organic acid.

The present disclosure relates to a gas hydrate inhibitor composition comprising from an amphiphile having a hydrophobic tail linked to a hydrophilic head group by a linking moiety, the amphiphile having the general formula (1)

[R.sup.5-L-N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.−  (1) wherein each of R.sup.1and R.sup.2 is independently an alkyl group having from 1 to 5 carbon atoms; or wherein the nitrogen atom and the R.sup.1and R.sup.2 groups together form a substituted or unsubstituted heterocyclic group; R.sup.3 is present or not as hydrogen or an alkyl group having from 1 to 8 carbon atoms which optionally bears a hydroxy group or a carboxy group in the 2-position; L is a linking moiety comprising an optionally substituted hydrocarbyl group having at least 2 adjacent carbon atoms, at least one heteroatom selected from nitrogen and oxygen, and optionally one or more further heteroatoms; R.sup.5 is a hydrocarbyl group having from 6 to 22 carbon atoms; and X.sup.− is present as an anion when R.sup.3 is present; and

from a cationic surfactant which is selected from di(C.sub.8-C.sub.18 alkyl)dimethyl ammonium salts.

The present disclosure relates to a gas hydrate inhibitor composition, comprising A) a compound according to formula (1)

##STR00001##

wherein R1 is an alkyl group having from 1 to 5 carbon atoms; R2 is hydrogen or an alkyl group having from 1 to 5 carbon atoms; R3 is present or not as hydrogen and organic moieties having from 1 to 20 carbon atoms; R4 is selected from —(CH.sub.2).sub.t—, —[CH.sub.2—CHR.sup.6).sub.t]—, —(CH.sub.2—CHR.sup.6O).sub.u—(CH.sub.2).sub.t— and combinations thereof; R5 is an alkyl or alkenyl group having 4 to 22 carbon atoms; R6 is hydrogen or an alkyl group having from 1 to 4 carbon atoms; R7 is hydrogen or an alkyl group having from 1 to 4 carbon atoms; R8 is present or not as hydrogen or organic moieties having from 1 to 20 carbon atoms; t is 2, 3 or 4; u is an integer between 0 and 100; n is 0 or 1 m is 0 or 2 o is 0 or 2, p is 0 or 1 X.sup.− is an anion, and B) a compound that is a synergistic surfactant which comprises an quaternary alkyl ammonium compound.