(250k) An Experimental Study of Interfacial Tension and Contact Angles of CO2/Brines/Surfactants/Oil Systems with Dolomite Rock

In this paper the effect of different parameters such as brine salinity, temperature, and pressure, has been studied experimentally in the presence of CO₂ at temperatures of up to 90^oC and pressures as high as 5500 psi for changes in interfacial tension and wettability with dolomite rock using different configurations of a HPHT interfacial tension measuring equipment. Brines are multicomponent with salinities ranging from 8,464 to 67,708 ppm. All experiments were performed with two model oils and Fluorosurfactant. In the final set of experiments the bulk phase is a two-phase mixture that contains CO₂/brine containing surfactant.

Most of the experimental studies on IFT and Contact angle have been conducted on either Gas (CO₂)-with-brine or Brine-with-Surfactants. No work has been done previously for measuring interfacial tension and contact angle of CO₂/Brine/Surfactant/Oil/Dolomite co-existing. These experiments can help better understand the interfacial phenomenon when EOR fluids are co-existing in the reservoir. Also these data sets can serve as a reference for future experimentation of in-situ contact angle measurements in the same medium.

Data Values and trends of different combinations: CO₂/Brine, CO₂/Brine with Surfactants and CO₂/Brine with surfactant/Oil each with 98% pure dolomite have been provided for change of each sensitivity parameter for both interfacial tension and contact angle measurements. Based on these, a correlation has been developed which is a function of brine composition, pressure and temperature for similar kind of oil and surfactants.

The experimental results of this paper will contribute to the literature with more data related to such systems. Results obtained can serve as bases for WAG and SAG in an oil reservoir and the different sets of data can be used to form an EOR model for correlating and predicting the influence of SAG and can be further extended to make a general correlation for a system containing CO₂, surfactants, and brine for given range of pressure and temperature.