Prediction and Experimental Measurements of Water-in-Oil Emulsion Viscosities During Alkaline/Surfactant Injections

Abstract

Oil production is generally a complicated multiphase flow inside pipelines, with possible water-in-oil (W/O) emulsions present with other usual phases such as free water and free oil. The W/O emulsions formed can present significant hurdles in production facilities for pumping fluids and during pipeline transport. It is well known that high shear rates provided by pumps, chokes, or valves result in stable emulsion behavior for a field in primary production. Several field tests are under way to test the potential of surfactant flooding as a tertiary-recovery mechanism. The effect of addition of surfactants on the emulsion rheology of production fluids, as in alkaline/ surfactant/polymer (ASP) flooding, is not very well understood. This understanding of W/O-emulsion rheology in ASP-injection oil recovery is essential for design of pumps and pipelines as well as for handling flow-assurance issues. In this paper, we report results from experiments as well as modeling of W/O-emulsion rheology that can form during ASP injections. We focus here only on the alkaline/surfactant (AS) part of these injections in order to clearly understand the impact of surfactants, removing the uncertainities that come with large rheology changes with polymer addition. The effect of surfactants on the rheology of W/O emulsions was studied by making two different types of emulsions: (1) native-brine W/O emulsions without surfactants to provide a baseline and (2) brine W/O emulsions with surfactants used in ASP injections. This way, the impact of ASP injections on emulsion rheology can easily be quantified. A new correlation is developed, based on in-house historical experimental data, to describe rheology of emulsions without surfactants. This correlation should assist in managing the uncertainties that come from extrapolating emulsion rheology measured in the laboratory to actual field conditions. Further, to understand the effect of ASP injections, new experimental measurements were made by adding surfactants to brine solutions. The addition of surfactants resulted in different rheology as compared with emulsions formed by brine solutions. These differences have been attributed to the W/O interfacial tension (IFT), and IFT was added to modify the original correlation. To our knowledge, this is the first study that explicitly relates emulsion rheology with IFT.

Agentes emulsificantes aplicados à estabilização de emulsões o/a com intuito de melhorar o transporte de óleos pesados através das tubulações: Um estudo bibliométrico

“…De acordo com os trabalhos analisados, a viscosidade apresenta um comportamento que depende da concentração de óleo presente na emulsão. Kalra et al (2012) observaram que à medida que surfactante é adicionado ao óleo cru, a viscosidade da emulsão resultante aumenta com o teor de água até o ponto de inversão de fase, e reduz em concentrações maiores de água.…”

Experimental study on the performance of emulsions produced during ASP flooding

“…A study by Khan et al (2015) focused on water in oil (W/O) emulsions imposed by ASP flooding for an EOR field in Malaysia to understand the stability of the emulsion layer under typical process conditions. Another group of researchers (Kalra et al 2012) have attempted to present the rheology of the problematic water in oil emulsion produced at the facility site. They stated that oil production is generally a complicated multiphase flow inside pipelines.…”

“…It is well known that high shear rates provided by pumps, chokes, or valves result in stable emulsion behavior for a field in primary production. Kalra et al (2012) also reported that understanding W/O-emulsion rheology in ASP-injection oil recovery was essential for the design of pumps and pipelines and handling flow-assurance issues. The formation of a W/O emulsion with chemical injection is a renowned problem on the facility side, as it stabilizes the emulsion (Dalmazzone et al 2012).…”