Laboratory Investigation of High-Temperature Surfactant Flooding

Abstract

Experiments were conducted to evaluate the use of surfactants for improving heavy-oil recovery from the hot-water zone in a steamflood. Criteria used to screen surfactants for this high-temperature application included thermal stability, interfacial activity, and surfactant flood performance.The thermal stabilities of several classes of sulfonate surfactants were measured. Surfactants exhibiting no thermal decomposition at elevated temperature (500°F [260°C]) were identified.The phase behavior between heavy crude oil (l4.5°API [0.969 g/cm 3 ]) and surfactant solution was determined over a temperature range from 150 to 350°F [65 to 177°C]. Regions of high interfacial activity were generated by the addition of salt to the brine phase. Interfacial tension (1FT) measurements confirmed the high salinity requirement of the selected surfactant/brine/oil system at elevated temperature.High-temperature (200 to 350°F [93 to 177°C]) surfactant floods were performed to study the effect of several variables on tertiary oil recovery. Variables studied included preflush slug size, surfactant slug size, surfactant concentration, flood temperature, core material, and mobility control. Improved oil recovery was obtained when a salinity-gradient flood design was used. For the most favorable systems, incremental oil recoveries up to 14% PV were achieved.Estimates of field performance indicate an 8 to 32 % increase in oil recovery when surfactant is used with steam.

Mobility Control for Steamflooding With High-Temperature-Resistant Additives

“…3 autoclave with windows designed specifically for these tests. The windows on the front and back each are 3.94 in.…”

“…[3][4][5] The results of these studies then were applied to pilot and field trial runs. 6 -8 Table 1 compares the properties of a German and a California oilfield.…”

Steam-Foam Technology as an Option to Improve Steam Drive Efficiency

“…In a steam flooding process, the steam temperatures can be in the range of 200 to 300°C. Previous studies have shown that only sulfonate surfactants possess the required thermal stability for steam-foam applications (Ziegler 1988). Thermal stability of surfactants is usually reported in terms of the time required for half of the surfactant to decompose at the target temperature.…”

Transient behavior of simultaneous flow of gas and surfactant solution in consolidated porous media

“…Results of IFT studies showing minima with tenlperature [1'2, 54], a minor dependence on temperature [12,54,65], a significant decrease with temperature [51], and an increase withtemperature [65,133] have ali been reported in the literature. The IFT--temperature behavior is a function of Salinity and is highly unpredictable [65].…”