Investigation of Emulsion Flow in SAGD and ES-SAGD

Abstract

Expanding Solvent-Steam Assisted Gravity Drainage (ES-SAGD) was invented to enhance SAGD performance by reducing energy use while increasing oil production rates and recovery factor. ES-SAGD involves co-injection of solvent and steam. The majority of energy losses occur between the steam generator and sandface and at the top of the depletion chamber (to the overburden). ES-SAGD performance improvement is traditionally ascribed to oil phase dilution which in turn leads to oil phase viscosity reduction. However, the amounts of solvent added to the process are typically very small (< 5-6% by volume) thus it remains unclear how the solvent can lead to significant lowering of the steam-to-oil ratio (~25-50%) and large enhancements of the oil rate (~25 to 100%). Here, we report on how SAGD and ES-SAGD (hexane, heptane and octane solvents) can potentially perform in the presence of in-situ emulsification at steam chamber edge. We present a numerical approach which allows incorporation of emulsion modeling into SAGD and ES-SAGD simulations with commercial reservoir simulators via a two-stage pseudo chemical reaction. Numerical simulation results show excellent agreement with experimental data for low-pressure SAGD and ES-SAGD. Accounting for viscosity alteration, multiphase effect and enthalpy of emulsification appear sufficient for effective representation of in-situ emulsion physics during SAGD and ES-SAGD in very high permeability systems. Results also show that, in-situ emulsification may play a vital role within the reservoir during SAGD; increasing bitumen mobility thereby decreasing cSOR. It was concluded that traditional approach to numerical ES-SAGD simulation can significantly over-predict incremental oil recovery. Results from this work extend understanding of ES-SAGD by examining its performance improvement over traditional SAGD in terms of multiphase behavior at the edge of the chamber, thermal efficiency and incremental recovery. Results reveal that dynamics at the edge of the chamber is more complex than simple solvent dilution model.

Comprehensive Design and Manufacturing Solutions for Sand Control and Tooling towards Enhanced Oil Recovery

“…Two flow models are used to analyze flow properties (flow patterns, classifications, transition characteristics, etc) and behaviors such as emulsion [24], [31]. One is the Darcy flow model that covers the flow from the reservoir to the wellbore, and the other is a pipe flow model along the wellbore [24].…”

“…Emulsion is a colloidal system of immiscible fluids in which one is the dispersed phase and the other is the continuous phase. In SAGD systems, the two phases of emulsion is oil and water [31]. REG uses simulators based on the Navier Stokes equations to perform flow simulation, but have not yet arrived at a satisfactory model.…”

“…From a thermal efficiency point of view, a high sub-cool value is desirable because it decreases steam injection rates. However, it also results in a reduced production rate due to a higher viscosity and lower mobility of bitumen [31], [42]. Controlling sub-cool within a target value can enhance the infectivity of the formation and serve as a method to enlarge steam chamber.…”

A Critical Review of Emerging Challenges for the Oil Field Waters in the United States

“…The solvent is used to further lower the viscosity of oil. This solvent is generally an organic compound such as hexane, heptane, or octane (Ezeuko et al 2012). As a result, water produced during an ES-SAGD may have an increased concentration of organic compounds.…”

Field Scale Simulation Study, Investigating the Effect of Geological and Operational Parameters on Solvent Co-Injection Process in Athabasca Bitumen Reservoir

“…The emulsion flow in SAGD and ES-SAGD processes was investigated by Ezeuko et al (2012). They defined three mechanisms for emulsification influences on SAGD and ES-SAGD efficiencies as follows: a) alteration of bitumen viscosity, b) enthalpy of emulsification and alteration of effective thermal properties of the oleic phase, c) modification of relative flow potential of bitumen at any water saturation.…”