A two-step process to produce oil or gas from a subterranean formation wherein in a first step the subterranean formation is treated with an aqueous composition containing a chelating agent selected from the group of glutamic acid N,N-diacetic acid or a salt thereof (GLDA), aspartic acid N,N-diacetic acid or a salt thereof (ASDA), methylglycine N,N-diacetic acid or a salt thereof (MGDA), and N-hydroxyethyl ethylenediamine N,N′,N′-triacetic acid or a salt thereof (HEDTA) and wherein, in a next step, in the outlet streams from the subterranean formation the aqueous phase is separated from the non-aqueous phase.

Antifoulant compositions and methods are used for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream. Polyamine antifoulants are added to such systems. The polyamine antifoulants may be conjointly used with dispersants and/or fatty acids. The fatty acids have been found to reduce thermal degradation of the polyamine antifoulants.

Antifoulant compositions and methods are used for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream. Polyamine antifoulants are added to such systems. The polyamine antifoulants may be conjointly used with dispersants and/or fatty acids. The fatty acids have been found to reduce thermal degradation of the polyamine antifoulants.

The present disclosure provides a formulation and methods for simultaneously dissolving metal sulfide scales, inhibiting acid gas corrosion, and inhibiting the formation of calcite and barite in a system having low or high shear stress conditions due to fluid movement, in which the formulation contains a THP+ salt, one or more corrosion inhibitors, one or more scale inhibitors, and one or more acid corrosion inhibitors. The formulation may be applied to the system in diluted or undiluted form, and continuously or in batch style.

The present disclosure provides a formulation and methods for simultaneously dissolving metal sulfide scales, inhibiting acid gas corrosion, and inhibiting the formation of calcite and barite in a system having low or high shear stress conditions due to fluid movement, in which the formulation contains a THP+ salt, one or more corrosion inhibitors, one or more scale inhibitors, and one or more acid corrosion inhibitors. The formulation may be applied to the system in diluted or undiluted form, and continuously or in batch style.

The present disclosure provides a bis-quaternary ammonium salt of Formula I

##STR00001##

wherein A is selected from O, NH, S, C(O), C(NH) or C(S); R.sub.1 and R.sub.2 are independently selected from C.sub.1-3 alkyl or H; R.sub.3 is C.sub.1-16 alkyl, C.sub.13-20 aralkyl or C.sub.2-16 allyl; X.sup.− is selected from chloro, bromo, iodo, hydroxide, nitrate or sulphate; and n and m are independently 1 to 6. Furthermore, a corrosion inhibition formulation comprising said bis-quaternary ammonium salt is revealed. Also, convenient processes for the preparation of the salt of Formula I and the formulation are provided.

The present disclosure provides a bis-quaternary ammonium salt of Formula I

##STR00001##

wherein A is selected from O, NH, S, C(O), C(NH) or C(S); R.sub.1 and R.sub.2 are independently selected from C.sub.1-3 alkyl or H; R.sub.3 is C.sub.1-16 alkyl, C.sub.13-20 aralkyl or C.sub.2-16 allyl; X.sup.− is selected from chloro, bromo, iodo, hydroxide, nitrate or sulphate; and n and m are independently 1 to 6. Furthermore, a corrosion inhibition formulation comprising said bis-quaternary ammonium salt is revealed. Also, convenient processes for the preparation of the salt of Formula I and the formulation are provided.

Methods may include admixing an additive composition with a hydrocarbon fluid, wherein the additive composition contains at least one inhibitor and at least one sub-micron particle. Additional methods may include providing an additive composition containing at least one inhibitor and at least one sub-micron particle; adding the additive composition to a fluid capable of precipitating at least one of at least of asphaltenes, wax, scale, and gas hydrates; and transporting the fluid containing the additive composition.

Methods may include admixing an additive composition with a hydrocarbon fluid, wherein the additive composition contains at least one inhibitor and at least one sub-micron particle. Additional methods may include providing an additive composition containing at least one inhibitor and at least one sub-micron particle; adding the additive composition to a fluid capable of precipitating at least one of at least of asphaltenes, wax, scale, and gas hydrates; and transporting the fluid containing the additive composition.

Fouling and/or asphaltene agglomeration (or flocculation) in midstream processes and transportation and in upstream transportation of a hydrocarbon oil is reduced by providing in the oil an additive combination including; (A) a polyalkenyl-substituted carboxylic acid or anhydride, and (B) a metal detergent system comprising a hydrocarbyl-substituted hydroxybenzoate metal salt or a hydrocarbyl-substituted sulfonate metal salt or a mixure of both salts or a complex thereof,
where the mass:mass ratio of (A) to (B) is in the range of 20:1 to 1:20 and the treat rate of the additive is in the range of 5 to 10000 ppm by mass.