Adsorption and Squeeze Performance of PAMAM-PGLU Inhibitors for Silicate Scale Mitigation Due to ASP Flooding

Abstract

The dissolution of quartz mineral in sandstone reservoir due to chemical enhanced oil recovery (cEOR) processes, such as alkaline surfactant polymer (ASP) flooding has resulted in the scaling of silica and silicates around the wellbore formation and in the production wells. These scales can block and hinder the flow of producing fluids if left untreated. This will lead to reduced production rates as well as equipment damages eventually. The adsorption and squeeze performance of developed scale inhibitors that made up of polyamidoamine (PAMAM) dendrimers and pteroyl–L–glutamic acid (PGLU) was assessed in this paper. The results were compared to diethylenetriamine penta(methylene phosphonic acid), a commercial phosphonate scale inhibitor known as DETPMP. The crushed Berea sandstone core was soaked in scale inhibitor solutions for static adsorption test. Core flooding was performed to investigate the adsorption and retention of scale inhibitors in sandstone formation. The prediction of scale inhibitor squeeze performance was simulated based on core flooding data obtained. Laboratory results reveal PAMAM–2–PGLU scale inhibitor that comprises second generation PAMAM dendrimer exhibits the highest adsorption and retention in sandstone core. On top of that, the permeability of sandstone core was also increased with the treatment of PAMAM–PGLU scale inhibitors. SQUEEZE IV software also predicted that PAMAM–PGLU scale inhibitors yielded longer squeeze lifetime than DETPMP scale inhibitor. Both experimental and modelling results showed a good fit in terms of adsorption and squeeze lifetime. In this paper, the tested PAMAM–PGLU scale inhibitors demonstrate better adsorption, retention, and squeeze lifetime in sandstone formation. Although commercial scale inhibitors are effective at a wide range of reservoir conditions, the disposal of phosphonate scale inhibitors has raised concern due to their toxicity and low biodegradability. Hence, these developed PAMAM–PGLU scale inhibitors could be offered as environment–friendly and effective alternatives.