Doctor of Philosophy (PhD), Ohio University, 2010, Chemical Engineering (Engineering and Technology)

The presence of water, even in small amounts, is often the cause of internal corrosion problems in crude oil transportation. Understanding the factors influencing steel pipeline corrosion rates is a safety as well as an economic matter. The objective of this dissertation is to quantify the effects that are known to have an influence on corrosion in crude oil-brine flow. The first effect is the corrosiveness of the brine. Crude oil's compounds can partition between the oil phase and the water phase to create brines with inhibitive or corrosive properties. The second effect is related to which phase wets the pipe wall. This depends on steel wettability and also on the flow pattern. Crude oil's polar compounds can change the steel hydrophilic surface nature. They also change the flow properties. The problem has been investigated at the Institute for Corrosion and Multiphase Technology at Ohio University on a small scale with specifically designed experiments as well as on a large scale, in a 60 meter-long flow loop loaded with 1600 gallons of oil and water. Results show that only a small percentage of the crude oil's complex chemistry controls its corrosion inhibitive and wettability properties. The knowledge generated from these experiments can be used as a useful reference for corrosion engineers and pipeline operators to maintain oil-water flow systems under corrosion-free conditions.

Committee: Srdjan Nesic PhD (Committee Chair); Michael Prudich PhD (Committee Member); Jeffrey Rack PhD (Committee Member); Howard Dewald PhD (Committee Member); Douglas Goetz PhD (Committee Member) Subjects: Chemical Engineering; Chemistry

Doctor of Philosophy (PhD), Ohio University, 2017, Chemical Engineering (Engineering and Technology)

Internal corrosion of oil and gas pipelines made from mild steel is a commonly encountered problem in the oil and gas industry. It is frequently associated with the presence of water that wets the steel surface and carbon dioxide which produces corrosive species in a water phase. This study addresses four aspects related to the role of interfacial chemistry on wetting and corrosion: • Effect of crude oil foaming on corrosion inhibition. • Effect of oil on foams produced by corrosion inhibitors and subsequent corrosion inhibition. • Effect of ionization of naturally present crude oil compounds on wetting and corrosion inhibition. • Effect of residual carbide corrosion products on steel wettability and wetting. The effect of crude oil foaming on corrosion inhibition was investigated with model compounds chosen to represent polar compounds in real crudes with dual foam-forming and corrosion inhibition properties; the investigations were performed in a small scale experimental apparatus. It was found that corrosion inhibition properties of oils were unaffected by the foaming process. The effect of oil on inhibitor-induced foaming was studied in small scale tests with an imidazoline-type corrosion inhibitor and two oils of different chemical composition. The results showed that the hydrocarbon oil can suppress foam generation, effectiveness of corrosion inhibitor can be partially preserved when the layer of oil is in the contact with a foaming aqueous solution. The influence of pH on corrosion inhibition by polar crude oil compounds on their corrosion inhibition and wetting properties was determined using a model oil. Experiments were again performed using an in-house designed and built apparatus for wetting measurements in dynamic conditions. It was shown that pH can significantly alter the corrosion and wetting properties of steel by ionizing crude oil polar compounds. In the last segment of the study the wettability of corroded surfaces was investigate (open full item for complete abstract)

Committee: Srdjan Nesic (Advisor) Subjects: Chemical Engineering; Chemistry; Petroleum Engineering

Master of Science (MS), Ohio University, 2009, Chemical Engineering (Engineering and Technology)

Crude oils contain high molecular weight components such as asphaltenes. These components deposit onto the inner wall of the pipelines and may create a non-uniform barrier between the wall metal surface and the corrosive agents, and reduce the corrosion rates and might affect the wettability of the steel. The aim of the research is to study the potential benefits of asphaltene deposition for corrosion inhibition and its effect on phase-wetting in oil-water two phase flows. Furthermore to understand the role of asphaltene in competitive inhibition with inhibitive compounds naturally occurring in crude oil. Experiments were carried out at four different concentrations of asphaltene, i.e. 0, 0.1, 1, and 5 wt % and in two different solvents i.e. toluene and heptol. Acridine was used as a competitive inhibitor. Open-circuit potential, linear polarization resistance, contact angle, and interfacial tension measurements tests were performed. It was found that asphaltene causes reduction in the corrosion rate and a partial fallout of asphaltene shows even further reduction. A mixture of asphaltene and acridine has strong synergetic effect for both the corrosion rate and the wettability of steel.

Committee: Srdjan Nesic (Advisor) Subjects: Chemical Engineering; Metallurgy; Petroleum Production