Self-aggregating behavior of poly(4-vinyl pyridine) and the potential in mitigating sand production based on π-π stacking interaction

Unconsolidated sandstone reservoirs are most susceptible to sand production that leads to a dramatic oil production decline. In this study, the poly(4-vinyl pyridine) (P4VP) incorporated with self-aggregating behavior was proposed for sand migration control. The P4VP could aggregate sand grains spontaneously through π-π stacking interactions to withstand the drag forces sufficiently. The influential factors on the self-aggregating behavior of the P4VP were evaluated by adhesion force test. The adsorption as well as desorption behavior of P4VP on sand grains was characterized by scanning electron microscopy and adhesion force test at different pH conditions. The result indicated that the pH altered the forms of surface silanol groups on sand grains, which in turn affected the adsorption process of P4VP. The spontaneous dimerization of P4VP molecules resulting from the π-π stacking interaction was demonstrated by reduced density gradient analysis, which contributed to the self-aggregating behavior and the thermally reversible characteristic of the P4VP. Dynamic sand stabilization test revealed that the P4VP showed wide pH and temperature ranges of application. The production of sands can be mitigated effectively at 20−130 °C within the pH range of 4–8.