Competitive Adsorption of a Hybrid Surfactant System onto Five Minerals, Berea Sandstone, and Limestone

Abstract This paper presents the adsorption/desorption results for two surfactant systems and for a mixture of the two onto five minerals and two porous media. The systems are composed of Chaser International CD1045™ (CD) and a calcium lignosulfonate (CLS), Lignosite® 100. Two series of experiments were carried out: (1) static adsorption of CLS, CD, and CLS/CD mixtures onto five pure minerals (silica, montmorillonite, kaolinite, dolomite, and calcite); (2) dynamic adsorption of CLS, CD, and CLS/CD mixtures onto core samples of Berea sandstone and Indian limestone. All experiments were performed at 40°C using a 2.0% brine solution with concentrations of 500 mg/l of CD and 5,000 mg/l of CLS. Static adsorption experiment results showed that: (1) CLS adsorption density onto silica is less then back ground noise (zero); on the other four minerals, adsorption density ranged from 0.5 to 10 mg CLS per g of mineral; (2) CD adsorption density onto the five minerals ranged from 0.4 to 1.2 mg CD per g of mineral; (3) CD adsorption density onto the five minerals decreased by 20 to 7 0% when mixed with CLS. Dynamic adsorption experiment results showed that: (1) The times required to reach adsorption equilibrium for both CD and CLS were longer for Berea sandstone than for Indiana limestone and for both porous media, were much longer than those for the non-porous minerals; (2) Competitive adsorption generally took several days to reach equilibrium. Stability and interfacial tension tests on both injected and effluent samples were performed. Results correlated well with the adsorption/desorption tests; for example, foaming capability was lost in some systems due to adsorption.