A gravel packing fluid system was developed for elevated temperature applications above 290°F comprised of xanthan gum and a high-temperature gravel suspension additive. This fluid system has been successfully pumped in four openhole gravel packing operations so far, validating its suitability for Alternate Path gravel packing technology involving shunt tubes. Laboratory qualification testing for this fluid showed excellent gravel suspension, rheology, and breaking profiles for cleanup and minimal damage during production.
Xanthan gels have been used in gravel packing applications for many years. However, by itself, xanthan was unable to suspend gravel at temperatures above 290°F possibly due to onset of thermally activated polymer degradation. This paper demonstrates that gravel suspension ability can be vastly improved with the addition of a recently developed nano-additive. This additive is a specially designed versatile nanosized material that has a proven track record with visco-elastic surfactant fluids in the past. In the present study, we show the successful application of this additive with polymer-based carrier fluids such as xanthan, effectively increasing their application range to 325°F. With the inclusion of this suspension additive, xanthan concentration in the fluid system can also be reduced, which has other potential benefits such as better cleanup after gel break.
Extensive laboratory evaluation for fluid qualification was performed prior to the job. High-pressure/high-temperature (HP/HT) rheology measurements were performed using industry-standard rheometers at various shear rates to match specific viscosity requirements for shunt tube applications. Gravel suspension tests performed using special pressurized cells immersed in oil bath at the required bottomhole static temperature showed improved gravel suspension with the nano-additive. Fluid breaking with conventional oxidative breaker was also demonstrated with viscosity measurements. Formation response tests showed very good fluid cleanup with 90% regained permeability.
Laboratory testing and successful field applications have proven the effectiveness of this new fluid system.