Demulsification of Colombian Heavy Crude Oil (W/O) Emulsions: Insights into the Instability Mechanisms, Chemical Structure, and Performance of Different Commercial Demulsifiers

Abstract

Chemical products such as PEO/PPO block copolymers or alkoxylated resins tend to work well in chemical demulsification of light hydrocarbons (°API > 20) but fail to do so in the presence of heavy and extra heavy crude emulsions. Moreover, a large knowledge gap between the relationship of instability mechanisms at the liquid−liquid interface and the tendency of demulsifier systems to promote phase separation has limited the ability of practitioners in field operations to properly select a system for a particular application. To address this issue, here, an enhanced quantitative protocol is put forward to assess the chemical demulsification of heavy crude oil (HCO) emulsions by coupling transmission/backscattering measurements to traditional bottle tests. The applicability of the method was evaluated by adding a wide variety of commercially available demulsifiers to HCO emulsions from a Colombian oilfield. The collected data on interfacial tension and average droplet size showed that for the complex case of HCO emulsions, interfacial activity and fast kinetics are not sufficient criteria for phase separation. The best performing chemicals (separated water ∼85%) exhibited a low reduction of the interfacial tension at equilibrium (IFT ∼ 20 mN/m). This evidence strongly suggests that separation might be likely triggered after the intermingling of the demulsifier with the oil phase such that the density difference between phases is considerably increased (∼5% change on average). Furthermore, HPLC-MS results showed that spatial and chemical configuration, as well as steric effects, drive the performance of demulsifiers and must be carefully considered for new developments.

Novel Bionanocompounds: Outer Membrane Protein A and Laccase Co-Immobilized on Magnetite Nanoparticles for Produced Water Treatment

“…The 97% calcium chloride (CaCl 2 ) was from PanReac Quimica, SLU, Barcelona, Spain; the ultrapure petroleum ether was Merck KGaA, (Darmstadt, Germany); and the nonylphenol ethoxylate 10 mol (TERGITOL™ NP.10 Surfactant) was from Dow Chemical, Midland, MI, USA. Heavy crude oil (CO) from a Colombian oilfield was used as reported by Acosta et al [ 59 ].…”

Amidated Cellulose Nanofibrils as Demulsifying Agents for a Natural Water-in-Heavy-Crude-Oil Emulsion

“…However, for a water-in-heavy-crude-oil emulsion, only 1.5% of water removal efficiency was observed for dodecyl amine at 2500 ppm. 61 TOCN-AMDC 18 (Figure 3c) showed a water removal efficiency from the w/o emulsion of 69% at 750 ppm, which was maintained at 1500 ppm. The water removal efficiency for TOCN-AMDC 18 decreased to 59% when the concentration was increased to 3000 ppm; this behavior may indicate that the point of inversion of the additive was reached.…”

“…The commercial formulation, a viscous toluene-soluble liquid based on polymeric surfactants and undisclosed additives, is designed to actively interact and disrupt the interface of heavy crude oil emulsions typically formed by a network of self-assembled surfactants (asphaltenes, resins, naphthenic acids) naturally present in the oil. 61 Several physicochemical characteristics make a compound an efficient demulsifier, including amphiphilicity, high molecular weight, dispersibility, and the arrangement of hydrophobic and hydrophilic groups in polymeric chains. 61,62 These surface-active compounds will ideally migrate to the oil−water interface and alter its viscosity and elasticity, allowing water droplets to aggregate and coalesce.…”

“…61 Several physicochemical characteristics make a compound an efficient demulsifier, including amphiphilicity, high molecular weight, dispersibility, and the arrangement of hydrophobic and hydrophilic groups in polymeric chains. 61,62 These surface-active compounds will ideally migrate to the oil−water interface and alter its viscosity and elasticity, allowing water droplets to aggregate and coalesce. For this to happen, the demulsifier has to compete with natural emulsifiers (e.g., fractions of surface-active constituents of asphaltenes, resins, and naphthenic acids that stabilize the interfacial layer), disrupting the water−oil interface by reducing its elasticity and minimizing the interfacial tension gradients.…”

“…29,59,64 Once phase separation occurs, the demulsifier will diffuse into the newly formed larger droplets or remain in the oily phase. 61 The performance of TOCN-AMDC 12 and TOCN-AMDC 18 as water-in-heavy-oil emulsion breakers can be explained from a structural point of view. These high molecular weight biopolymeric materials have a large and active surface area due to the presence of hydrophilic −OH and −COOH groups.…”