8-Allyl-1,3-benzoxazines as Hydrogen Sulfide Corrosion Inhibitors and Biocides in Crude Oil Extraction

The inhibitor and bactericidal properties of a series of allyl-substituted 1,3-benzoxazines and their water-soluble derivatives in hydrogen sulfide saturated water-salt-hydrocarbon systems were studied. The inhibitor properties of the compounds with respect to St.3 steel (St3Gsp, GOST (State Standard) 380-2005) strongly depend on the number of methylene groups in the substituents bonded to the nitrogen atom in the 1,3-oxazine ring. The bactericidal activity toward the growth of sulfate-reducing bacteria (SRB) also strongly depends on the structure of the compounds. With an increase in the number of methylene groups in the molecule, the protective properties of the compounds increase, whereas the bactericidal properties decrease. Compounds with an aromatic substituent at the nitrogen atom of the 1,3-oxazine ring exhibit higher inhibiting (maximal degree of protection similar to 97%) and bactericidal (maximal degree of SRB growth suppression similar to 100%) power.