سروش احمدی

Scale deposition, particularly calcium sulfate, poses a major challenge in carbonate reservoirs, leading to permeability reduction and operational inefficiencies. In this study, the performance of a polymeric scale inhibitor, polyphosphinocarboxylic acid (PPCA), was systematically investigated through dynamic core flooding experiments combined with statistical modeling. To address scale inhibition performance and minimum inhibitor requirements, additional static jar tests and dynamic tube blocking experiments were conducted. The results confirmed a minimum inhibitory concentration (MIC) of 40 ppm PPCA, where inhibition efficiency exceeded 90% at elevated temperatures. Moreover, the desorption behavior of PPCA was evaluated under a wide range of operational conditions, including pore volume (0–40 PV), temperature (50–100 °C), injection rate (2–6 mL/min), and pH (6–8). Effluent concentrations were quantified using a spectrophotometric method and expressed as the Cf/Ci ratio (effluent concentration to injected concentration) to characterize inhibitor return behavior. A comprehensive dataset comprising 224 experimental runs was analyzed using Response Surface Methodology (RSM), leading to the development of two predictive models for low (0–10 PV) and high (10–40 PV) pore volume ranges. The models demonstrated excellent predictive capability, with R2 values of 0.9934 and 0.9979, respectively. In addition, statistical analysis confirmed that pore volume and injection rate were the most influential parameters, while pH exhibited a comparatively minor effect. Results showed that increasing PV, temperature, injection rate, and pH led to a decrease in Cf/Ci, indicating enhanced desorption. For instance, Cf/Ci decreased from approximately 0.12 at 10 PV to 0.06 at 40 PV under reference conditions. Furthermore, optimization results revealed that maintaining an effective inhibitor concentration (Cf/Ci more than 0.05) is strongly dependent on operating conditions. At 60 °C, a wide