Viscoelastic behavior of hydrogel-based xanthan gum/aluminum lactate with potential applicability for conformance control

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 degrees 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 degrees 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 (delta) 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.