Optimization and characterization of biosurfactant produced by indigenous isolated from a low permeability reservoir for application in MEOR.

Biosurfactants are expected to be a key factor for microbial enhanced oil recovery (MEOR). In this study, we described the novel biosurfactant-producing strain YZ-2 isolated from a low permeability oil reservoir. We purified and characterized the biosurfactants produced by this YZ-2 strain thin-layer chromatography and MALDI-TOF-MS, revealing them to be fengycins.

Tracking alterations of alkyl side chains of N species in heavy crude oil after anaerobic biodegradation with negative-ion electrospray ionization coupled with high-field Fourier transform ion cyclotron resonance mass spectrometry.

Rationale: Heteroatomic compounds are relatively abundant and believed to be bio-resistant in heavy crude oils. However, few studies have focused on the biodegradation of these heteroatomic compounds.

Methods: Heteroatoms, especially N species, in a blank crude oil and in three treated oils co-incubated with anaerobic sulfate-reducing bacteria, nitrate-reducing bacteria and fermentative consortia cultures were detected using negative-ion electrospray ionization coupled with high-field Fourier transform ion cyclotron resonance mass spectrometry.

Deposition of spherical particles onto cylindrical solid surfaces. II. Experimental studies.

This paper presents experimental studies of the deposition of silicone oil drops onto two different solid surfaces in an aqueous solution. A series of deposition tests were conducted to measure the dimensionless mass transfer rate (Sherwood number). The effects of three kinds of aqueous solutions and two solid surfaces on the deposition process were studied and compared with the numerical predictions based on the well-known DLVO theory.

Deposition of spherical particles onto cylindrical solid surfaces. I. Numerical simulations.

In this article, analytical and numerical solutions are given for the deposition of spherical particles onto cylindrical solid surfaces. If only the retarded van der Waals (vdW) force and the electrical double-layer (EDL) force between the spherical particle and the cylindrical surface are considered, such a deposition process is governed by a one-dimensional (1D) mass transfer equation for which both analytical and numerical solutions are obtained. A parametric study was conducted to examine the effects of these two colloidal forces on the deposition process.

Modeling of the adsorption kinetics of surfactants at the liquid-fluid interface of a pendant drop.

This paper presents a theoretical model for simulating the adsorption kinetics of a surfactant at the liquid-fluid interface of a pendant drop. The diffusion equation is solved numerically by applying the semidiscrete Galerkin finite element method to obtain the time-dependent surfactant concentration distributions inside the pendant drop and inside the syringe needle that is used to form the pendant drop. With the obtained bulk surfactant concentration distributions, the adsorption at the interface is determined by using the conservation law of mass.