A Sustainable Fluid System for Sand Consolidation

Abstract

Sand production from unconsolidated sandstone reservoirs can adversely affect reservoir productivity and project profitability. Sand consolidation is a remedial technology that consists of injecting a fluid into the formation to bind the sand grains together and provide strong cohesion. Most existing consolidation technologies use solvent-based fluids, which increases the operational complexity of achieving successful treatment without compromising retained permeability and raises environmental concerns. A novel solvent-free resin system for sand consolidation addresses these challenges by using water-based fluids that are capable of providing high compressive strength while maintaining high permeability, thus simplifying operations and reducing environmental concerns. The new fluid system consists of a resin, a curing agent, and a surfactant dispersed in water. The consolidation mechanism is designed to be triggered downhole by temperature. The fluid system was fully characterized in terms of viscosity, stability at elevated temperature, and performance to provide operational control and reduce pumping risks in a wide range of reservoir applications. Regained permeability and compressive strength of the consolidated sand were quantified for clean sand and sand with different amounts of clays. The consolidation fluid uses limited resin with the balance being predominantly water. The large volume fraction of water acts as a spacer, resulting in high retained permeability (greater than 75%) after the resin has set. Once mixed, the fluid has very low viscosity (less than 5 cP at ambient temperature and 170 s-1) and is stable for at least 24 hours. Additionally, the consolidation mechanism is uniquely triggered by temperature, providing more control and reducing operational risks. This mechanism allows all required components to be mixed together and the treatment to be single stage, thus drastically improving operational efficiency. The new consolidation fluid functions well over a wide temperature range (104°F to 230°F) yielding an unconfined compressive strength of up to 2800 lbf/in2 while maintaining regained permeability of over 75%. It is also compatible with significant amounts of clays, thereby enabling its use in challenging reservoir conditions. The new consolidation fluid system introduces more sustainability into the oilfield. It performs well over wide reservoir permeabilities and temperature ranges and is also compatible with clays and oils. The operational simplicity and efficiency gains offered make this fluid an attractive alternate to existing resin-based sand consolidation products.