Sandstone acidizing using a new retarded acid system based on cationic gemini alkyl poly glycoside surfactant

Extending the interaction distance between acid and sandstone formations remains a critical challenge in high-temperature sandstone acidizing. Conventional retarding agents often suffer from limited efficacy, formation damage, or environmental concerns. In this study, a novel cationic gemini alkyl polyglycoside surfactant (CGAPG) was synthesized and evaluated as a retarder for HBF4/HCl acidizing systems. Comprehensive assessments—including high-temperature stability (TGA-IR), retardation mechanisms (contact angle, particle size, XRD, SEM-EDS, FTIR), and performance evaluations (dissolution kinetics, core flooding, ICP)—were conducted using high-clay sandstone cores. The results demonstrate that the synthesized CGAPG exhibits excellent high-temperature stability and strong adsorption capabilities, significantly reducing the reaction rate between the acid and clay minerals. Specifically, in mud acid/bentonite systems, the addition of 1 wt% CGAPG resulted in a solubility reduction of >25% within 60 min; in fluoroboric acid/bentonite systems, the reduction exceeded 20% within 140 min. Furthermore, core flooding and ICP analyses confirmed that pre-flushing with 1 wt% CGAPG minimizes acid-clay/feldspar interactions. This study presents an effective retarded acid system tailored for acidizing high-clay sandstone in high-temperature reservoirs.