Asphaltene deposition is one of the major flow assurance problems in upstream and downstream crude oil recovery operations. In order to prevent potential loss and reduce downtime due to asphaltenes, it is critical to understand the physics of asphaltene adsorption. This study presents a preliminary investigation of asphaltene adsorption from crude oils onto stainless-steel surfaces using the quartz crystal microbalance with dissipation (QCM-D) technique and proposes a theoretical interpretation of the deposition mechanism for asphaltene molecules. The kinetics of deposition at different concentrations was examined, and the sizes of the deposited asphaltene molecules were estimated from the initial adsorption kinetics. Numerical analysis of the experimental data using the theoretical two-step deposition model was attempted, and the optimized adsorption parameters proved to be quite close to those values obtained for some rock types in earlier adsorption studies. Despite asphaltene precipitation increasing with increasing heptane percentage, the deposition of asphaltenes was found to be maximum at 70 vol% heptane content. The performance of a commercial inhibitor was then assessed under different conditions using the developed experimental metrics, and the inhibitor was found to be able to reduce the maximum deposition amount at the solubility with 70 vol% heptane fraction, which happens to be the same condition that generates the largest amount of deposition. The information gained on the solubility effect and inhibitor performance is essential to help the industry better manage asphaltene-related flow assurance problems in crude oil recovery.

Gatifloxacin and moxifloxacin showed good penetration into the anterior chamber with no obvious adverse reaction to the cornea. The concentrations in the anterior chamber exceeded the minimal inhibitory concentration (MIC) 90 of most organisms responsible for postoperative endophthalmitis (POE).

No abstract

No abstract