Surfactant-Steam Process: An Innovative Enhanced Heavy Oil Recovery Method for Thermal Applications

Abstract

Surfactant-steam process (SSP) is a novel and potentially cost-effective process that utilizes a small amount of surfactant coinjected with steam to enhance the oil recovery of steam assisted gravity drainage (SAGD) well pairs. The mechanism of this process involves interfacial tension (IFT) reduction, reservoir rock wettability alteration, oil relative permeability enhancement, and in-situ emulsification. SSP is expected to result in oil rate acceleration, steam-to-oil ratio (SOR) reduction and enhanced ultimate oil recovery factor. Analogous enhancement is expected if the SSP is combined with other steam-based or steam-solvent processes. This paper provides an introduction to this concept and presents a unique protocol that has been developed for screening surfactants for co-injection with steam in SAGD process. In particular, the paper presents a scientific approach to surfactant selection for SSP applications, describes the conditions in which the surfactants needs to be deployed within the reservoir, and also predicts the potential synergies if use of different classes of surfactants is made. Novel experimental design on different aspects of surfactant-steam phase behavior indicates the optimum surfactant concentrations for field trial applications. Lab testing of selected surfactants on typical Canadian oilsands sand packs shows an improved incremental oil recovery factor (RF) in the range of 6 to 16% (for different tested surfactants) compared to a SAGD base case. SSP simulations were conducted for one of the surfactants that were tested in the lab. The simulation results indicate that this particular surfactant on average accelerated the oil rate by 15% in the first 30 months of SSP operation, increased the ultimate oil RF by 10%, and reduced the cumulative steam-to-oil ratio (CSOR) by almost 11% relative to a SAGD base case. In addition, a sensitivity analysis was conducted to investigate the effect of surfactant concentration co-injected with steam. The simulation results suggest that there is an optimum concentration for a given surfactant that needs to be explored through lab investigations and field trials. It is evident that once the SSP is successfully developed, the use of surfactant promises to improve environmental performance and project economics of the in-situ oilsands recovery.

Investigation Of Hybrid SAGD Using Carbon Dioxide, Propane, Nitrogen and Methane

“…The steam-surfactant process is one in which chemicals like surfactants are added to steam. The main function of surfactants is to lower the surface tension at the interfaces between liquids or liquids and solids (Zeidani and Gupta, 2013). They may act as detergents, wetting agents, emulsifying and foaming agents or dispersants.…”

“…The biggest challenge in thermal application is the extended exposure of the surfactant to severe temperatures for longer durations that can thermally destabilize the surfactant. Zeidani, K. and Gupta (2013) proposed that a surfactant can be suitable for thermal application if it: can be volatile at application conditions, meaning it can vaporize at downhole SAGD operating conditions; can reduce the IFT at those conditions; is thermally stable at high temperatures; retains its properties and remains effective at high temperatures; preferentially results in oil-in-water emulsions rather than water-in-oil emulsions; enhances the reservoir wettability to water; is compatible with formation water; is readily available and at a price not so high as to make its use uneconomical; and, at downhole reservoir conditions, results in formation of stable emulsions that are easy to resolve on surface.…”

“…Imperial Oil piloted the addition of gas condensate to its SAGD operations in Cold Lake (Zeidani and Gupta, 2013). The operators reported some very encouraging improvements in bitumen production rates and SORs.…”

Recovery Improvement of Gravity Driven Steam Applications Using New Generation Chemical Additives

“…It acts between surfaces to reduce interfacial tensions, change wettability, improve emulsification and create foam. Gupta and Zeidani (2013) outlined the problem of the selection criteria for a suitable surfactant under field condition in a "surfactant-steam process" (SSP) and named the properties that a surfactant should possess: (1) Reduction of IFT, vaporizes at operation conditions, thermally stable at high temperatures (retain its properties and remain effective at high temperature); emulsification (preferentially oil-in-water emulsion); (3) wettability alteration to more water-wet conditions; and (4) compatible with formation water.…”

Study on Steam and Microemulsion Alternate Injection for Enhanced Productivity in Heavy Oil Fields

“…Surfactants are amphiphilic chemical substances that increase the efficiency of oil displacement, mainly due to the reduction of interfacial tension, alteration of rock wettability, and oil solubilization. − In the literature, the use of surfactant solutions associated with steam was successful in several experimental studies, mainly with the use of non-ionic and anionic surfactants. − With this, it is expected that solutions that have surfactants in their formulation, such as microemulsions, are also efficient in the recovery of heavy oil when associated with steam.…”