Enhanced Drag Reduction in Extended-Reach Wells Using In-House Synthesized Zwitterionic Surfactant

Extended-reach drilling facilitates access to previously unreachable oil and gas reservoirs, which were particularly constrained by high costs, challenging terrain, and environmental concerns. Notwithstanding its benefits, this drilling method has substantial operational challenges, including high friction between the drill string and the wellbore, leading to increased torque and drag. To address these challenges, we developed two in-house synthesized zwitterionic surfactants: Lauryl polyoxyethylene amido propyl hydroxy sulfobetaine (S1) and Lauryl polyoxyethylene amido propyl carboxybetaine (S2). Solubility of these surfactants with different brine including seawater, formation water, and completion brine were tested at room temperature and at 90 °C. Compatibility was assessed using different volume ratios of formation brines and completion brine. A lubricity tester was used to measure lubricity by mixing the surfactants in brine and then hot rolling the brines at 200 °F. Both surfactants displayed pronounced effectiveness, significantly increasing lubricity while decreasing drag. S1 notably reduced friction in CaBr₂ by 8%, whereas S2 reduced it by only 4% compared to the original brine. A significant reduction was observed in NaCl brines, where S1 and S2 achieved friction reductions of 42% and 44%, respectively. In contrast, for CaCl₂ brines, the reduction was 5% for S1 and 6% for S2. These results are crucial for maintaining operational efficiency during the completion phase. Furthermore, these surfactants exhibited excellent solubility and stability in different brines under elevated temperatures, maintaining clear solutions even after aging of one week at 90 °C. Compatibility tests demonstrated that surfactants-mixed brines, when combined with formation water showed stable properties without any precipitation or scaling. However, slight scale formation was observed when brines were mixed with formation water in equal proportions. These results highlight the zwitterionic surfactant's excellent efficiency in friction reduction, with a reduction in viscosity observed following surfactant addition. Furthermore, using in-house synthesized surfactants helps to improve the economic and operational sustainability of well completions in the region.