Chemical, Magnetic and X-Ray Diffraction Studies of the Sediments from Oil Field in Argentina

Chemical, magnetic, and phase composition analysis of deposits taken from sedimentation tank from oil plant in Argentina was carried out. Energy dispersive spectroscopy indicates iron as a main sediment component with the site dependent fraction ranging from 11% to 78% (weight percentage). Moreover, large fractions of sulfur (4%-33%), oxygen (8%-28%), calcium (1%-14%), and silicon (1%-11%) were found. The chemical analysis performed with wet chemical methods also indicated Fe as a main component (about 35%), additionally a large fraction ( ≈ 15%) of the sulfur and under 10% fractions of calcium ( ≈ 7%), carbon ( ≈ 6%), and silicon ( ≈ 5%) were found in the sample. The phase composition studies performed using X-ray diffraction showed magnetite - $Fe_3O_4$, goethite - α-FeOOH, lepidocrocite - γ-FeOOH, siderite - $FeCO_3$, and iron-sulfur compounds (mackinawite - FeS, stoichiometric FeS, greigite - $Fe_3S_4$) and other compounds like aragonite - $CaCO_3$, calcite - $CaCO_3$, anorthite - $CaAl_2Si_2O_8$, quartz - $SiO_2$ and barium sulphate $Ba(SO_3)_{0.3}(SO_4)_{0.7}$. Studies performed by the Mössbauer spectroscopy, confirmed presence of majority of compounds identified by X-ray diffraction. Magnetic AC susceptibility measurements show that magnetite is a main component of the studied deposit. High concentration of the magnetic compounds deposited in the sedimentation tank points to the advisability to install the magnetic device designed to support water treatment processes, i.e.: flocculation, coagulation, sedimentation, and filtration. This device could simultaneously inhibit microbiological and chemical corrosion.