Preformed particle gel (PPG) is a particled superabsorbent crosslinking polymer that has been successfully applied to control conformance. The aim of this study was to develop and evaluate the properties of PPGs based on crosslinked partially hydrolyzed polyacrylamide with polyethyleneimine (PEI). The study was conducted into two steps: (1) the preparation of standard hydrogels, which were dried and grounded to obtain preformed particles, using the Sydansk strength code and rheology for evaluation and (2) the determination of the swelling degree from the PPGs under typical reservoir conditions (temperature of 90 °C and salinity int about 29,940 mg/L of total dissolved solids). Sydansk coding is a method that provides semiquantitative measures, and it is expressed in an alphabetic code from A to J. The results showed that the systems in ideal predetermined conditions (20,000 mg/L of HPAM, 4,500 mg/L of PEI, and crosslinking temperature of at 70 °C) allowed obtaining PPGs with Sydansk codes of F or H (highly deformable or slightly deformable nonfluid gel, respectively). According to the rheology tests, the systems had pseudoplastic behavior with characteristics of strong gels (G″/G′ < 0.1). Besides this, the swelling degree under reservoir conditions was independent of gel‐strength F or H that in both cases is around 19%, but increases with increasing temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48554.

Gel systems composed of biopolymers can be used, which block the regions of high water permeability during a previously established period, through the in situ formation of a gel inside the rock pores. Among the biopolymers studied, xanthan gum has attracted the greatest attention due to its viscosifying power and good stability in reservoirs subject to severe salinity and temperature from 27 to 90°C. Xanthan chains have the ability to build up physical networks with metals such as aluminum lactate to form hydrogels. Therefore, the objective of this study was to prepare and evaluate, hydrogels made from xanthan gum (XG) cross‐linked with aluminum lactate. Initially, the influence of the gel formulation (biopolymer concentration and cross‐linker) and the reservoir conditions (pH, temperature, salinity) of the gel strength of the system and the injectivity of the gel systems was investigated through rheological tests. Subsequently, was analyzed the morphology of the systems for 30 days by scanning electron microscopy (SEM). The results showed that the systems based on xanthan gum cross‐linked, were able to form strong gels at pH 8, temperature of 70°C and salinity of 29,940 mgL−1 TDS. In general, the evaluated parameters (pH, temperature, salinity, polymer concentration, and cross‐linker) had a direct effect on the initial strength of the gel. However, after aging for 30 days, a drop in gel resistance was observed, since all systems have similar tan (δ) values and these parameters no longer show significant influence The aging analysis of hydrogel systems by SEM showed a difference in the surface microstructure of the dry hydrogel over the 30 days.