Comprehensive Investigation of Dynamic Characteristics of Amphoteric Surfactant-Sulfonated Polymer Solution on Carbonate Rocks in Reservoir Conditions

Abstract

To recover the remaining oil after water flooding, amphoteric surfactant-sulfonated polymer (S-P) flooding has attracted attention as a tertiary oil recovery technique. Oil recovery by S-P flooding not only is influenced by reservoir heterogeneity but also depends on chemical adsorption and interactions of S-P solution with the surface of rocks. This paper presents comprehensive laboratory results related to the dynamic adsorption, resistance factor (RF), residual resistance factor (RRF), and adsorbed layer thickness of S-P solution on the surface of carbonate rocks. Three core flooding experiments were conducted. The S-P solution was composed of an amphoteric surfactant (0.2 wt %) and sulfonated polymer solution (0.2 wt %) in seawater. The S-P solution was injected until the effluent concentration reached the inlet concentration. Seawater was injected after S-P injection to displace S-P solution until the effluent concentration reduced to a minimum value or constant value for desorption study. Total organic carbon (TOC) and Hyamine methods were used to determine the adsorption of the polymer and surfactant, respectively. The individual amount of dynamic adsorption and the total amount of adsorption of S-P solution onto carbonate rock were determined and compared with the results of single adsorption of a surfactant solution published previously. The residual resistance factor, resistance factor, and adsorbed layer thickness of S-P solution on carbonate rocks were calculated based on the differential pressure before and after injecting the S-P solution. We found that the dynamic adsorption, RF, RRF, and adsorbed layer thickness of the S-P solution strongly depends on pore geometry or reservoir properties. Some of the relationships are proposed for the first time. The loss of injectivity and liquid permeability during S-P solution injection are evaluated in detail in this paper. This paper presents insights into the dynamic adsorption, residual resistance factor, resistance factor, adsorbed layer thickness, and injectivity of S-P solution on carbonate rocks with reservoir parameters, which could help in designing the chemical enhanced oil recovery process in carbonate reservoirs.