Preformed particle gels with potential applicability for conformance control of oil reservoirs

ABSTRACT 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′