Acrylamide-Based Active Quadripolymer as an Efficient and Robust Foam Enhancer for Gas Mobility Control

Polymer-enhanced foam (PEF) can effectively improve the conformance profile and delay the gas breakthrough during gas flooding, but it suffers from low foamability and poor stability under harsh reservoir conditions. This research aims to improve the performance of the PEF by applying a synthesized acrylamide-based quadripolymer, named MACS, that contained active and rigid functional groups. The foamability, thermal stability, blocking performance, and conformance control of MACS-enhanced foam (MEF) were evaluated under varying testing conditions, and the conventional partially hydrolyzed polyacrylamide-enhanced foam (HEF) was used as the control group. Meanwhile, the migration of the MEF in the porous medium and its interaction with the crude oil were also investigated in both 2-D and 3-D models under ambient conditions. Furthermore, the mobility control capability and EOR performance of the MEF and HEF were assessed and compared. The results demonstrated that 0.15 wt % MACS effectively enhanced the durability of the foam in adverse environments (55 °C and 30 000 ppm of NaCl) and the foaming-complexed index (FCI) of MEF was approximately two times greater than that of HEF under identical conditions. MEF performed well in blocking the high-permeability layers and diverting the displacing fluid into the low-permeability region in the 2-D and 3-D models, and relatively uniform displacement fronts were clearly observed. Besides, due to the presence of active functional groups in the MACS, residual oil could be better emulsified and displaced. Moreover, the retention of MACS in the porous medium barely caused any permeability reduction. Finally, core flooding experiments showed that the recovery factor of MEF flooding reached 78.69%, while the counterpart HEF merely recovered 70.27% of the OOIP. In all, this work may provide valuable insights for the development of novel foam boosters, which could find potential uses in reservoirs experiencing difficulties with gas channeling during gas injection.