CO₂ Foamed Viscoelastic Gel-Based Seawater Fracturing Fluid for High-Temperature Wells

Area of Science:

• Petroleum Engineering
• Materials Science
• Rheology

Background:

• High-temperature formations pose challenges for conventional fracturing fluids.
• Developing stable and viscous fracturing fluids is critical for oil and gas well stimulation.
• Carbon dioxide (CO2) foams offer potential but face thermal stability issues.

Purpose of the Study:

• To develop a novel CO2-foamed viscoelastic gel-based fracturing fluid for high-temperature applications.
• To systematically investigate the impact of various parameters on foam viscosity and stability.
• To evaluate the thermal stability and performance of the developed fracturing fluid under simulated field conditions.

Main Methods:

• Rheological experiments using a high-pressure/high-temperature (HPHT) rheometer at 150 °C and pressures up to 20.68 MPa.
• Evaluation of foamability and stability using an HPHT foam analyzer at 100 °C.
• Systematic exploration of parameters including surfactant type, gas fraction, salinity, temperature, and pressure.

Main Results:

• Viscoelastic surfactants yielded a peak foam viscosity of 0.183 Pa·s at 70% foam quality and 100 1/s shear rate.
• Pressure significantly increased foam viscosity at higher foam qualities (>50%).
• Foam viscosity showed a notable enhancement at 65% foam quality; polymers did not improve viscosity.

Conclusions:

• The developed CO2-foamed viscoelastic gel-based fluid shows promise for high-temperature well stimulation.
• Liquid phase chemistry and experimental conditions are key factors influencing foam viscosity.
• Achieving thermal stability of CO2 foams with minimal additives remains an industry challenge.