Ferric Iron : Valence state +3 iron in solution. A very common catalyst in oil field emulsion and sludge formation. Precipitates at iron hydroxide when the pH exceeds 1.8 to 2.2 (depending on sour conditions)
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}