Thermo-/pH-Dual-Sensitive PEG/PAMAM Nanogel: Reaction Dynamics and Plugging Application of CO2 Channeling

Abstract

Smart hydrogels, owing to their exceptional viscoelastic and deformable capacity in response to environmental stimulation involving temperature and pH, have been successfully applied in oilfields for purposes such as water and/or gas shutoff treatments. However, the CO2 breakthrough problem in low permeability reservoirs has not been well solved. In this work, a rheological method-based Avrami dynamics model and Dickinson dynamics model were employed to investigate the dynamic gelation process of thermo-/pH-dual-sensitive PEG/PAMAM nanogels to further our understanding of the microstructure of their gelation and pertinence plugging application. Plugging experiments were performed by alternating injections of CO2 and hydrogel solution in a slug type on three fractured low permeability cores with a backpressure of 13 MPa. The nanogels presented a secondary growth pattern from three to one dimension from micrometer to nanometer size with a morphological transformation from a sphere to an irregular ellipsoid or disk shape. The phase transition temperature was 50 °C, and the phase transition pH was 10. If both or either were below these values, the hydrogel swelled; otherwise, it shrank. Plugging results show that the plugging efficiency was higher than 99%. The maximum breakthrough pressure was 19.93 MPa, and the corresponding residual pressure remained 17.64 MPa for a 10 mD core, exhibiting great plugging performance and high residual resistance after being broken through by CO2.

Smart stimuli-responsive injectable gels and hydrogels for drug delivery and tissue engineering applications: A review

“…Frontiers in Bioengineering and Biotechnology frontiersin.org Equilibrium swelling ratio curves of PEG/PAMAM hydrogels under different temperatures and pHs (Liu X. et al, 2022).…”

“…Nanogels and nanocomposite gels are two important examples of gels, which will be explained below. Nanogels are gels with a size of 1 to generally 200 nm, so in addition to the properties of hydrogels, due to their specific dimensions, they have characteristics that we will review below (Liu X. et al, 2022). These substances can escape the elimination process by the body's immune system.…”

“…(B) Transmittance and phase transition temperature and pH curves of PEG/PAMAM hydrogels. (C)Equilibrium swelling ratio curves of PEG/PAMAM hydrogels under different temperatures and pHs(Liu X. et al, 2022).…”

Preparation of CO2-Responsive Biobased Ternary Composite Microgel and Its Application in Reservoir Gas Channeling Plugging

“…Such materials are called “responsive” or “switchable” materials. These external stimuli include light, temperature, , pH, , magnetic field, , etc. These materials have high application value and broad application prospects, , such as controllable drug delivery, − intelligent sensors, catalytic control, and so on.…”

Experimental Evaluation of Combined Plugging System for CO2-Improved Oil Recovery and Storage

“…Studies have found that foam reinforced with cellulose nanocrystals had better stability and improved performance. Liu et al 35 developed a polyethylene glycol-dendrimer polyamidoamine (PAMAM) nanogel with a dual response to heat and pH. When the nano-solution prepared by this system was alternately injected with CO 2 , it had a high plugging capacity and residual resistance coefficient in the core matrix with a permeability of 10 mD and a length of 10 cm.…”