Amphiphilic polymer with ultra-high salt resistance and emulsification for enhanced oil recovery in heavy oil cold recovery production

The thermal recovery is a significant method of developing heavy oil. With global environmental governance and carbon management, the energy loss and carbon emissions caused by thermal recovery restrict its development. The non-thermal recovery (cold recovery), as a nascent green and clean production technology, has garnered attention within the petroleum industry. In this paper, an amphiphilic polymer viscosity reducer (P(AM/AMPS/C16), abbreviated as PAAC) used for cold recovery was synthesized, to solve the weak emulsification and poor flowability control in ultra-high salt heavy oil reservoirs. The PAAC's salt resistance can be contributed by two aspects. Firstly, the inner salt bond formed by the electrostatic interaction between the sulfonic and the ammonium groups can resist the compression double-layer effect of salt ions. Secondly, the association effect enhances the thickening ability. The improvement of salt resistance has been demonstrated to have a substantial impact on the flowability control of polymer in ultra-high salt heavy oil reservoirs. The hexadecyl chain endows PAAC with the ability to emulsify heavy oil, which can significantly reduce the oil-water interfacial tension to 10⁻² mN/m and form an oil in water emulsion (O/W). The PAAC achieves effective heavy oil utilization through three functions: emulsification carrying, peeling, and deformation and stretch. PAAC with an injection volume of 0.5 PV increases the heavy oil recovery by 16.13 %. The study provides valuable insights into the use of polymer viscosity reducers and enhanced heavy oil recovery in cold recovery, representing a new perspective on the application of polymers in ultra-high salt reservoirs.