Which of the following is a thermal EOR method?

• A. Gas Injection
• B. Chemical Injection
• C. Thermal Recovery
• D. Waterflood

Answer: (C)

Thermal EOR relies on heat to change the oil’s properties and make it easier to move to the production well. Injecting steam into the reservoir raises temperature, which lowers the oil’s viscosity and helps it flow more readily, often enabling steam-assisted drives or cyclic steam processes. This approach is especially effective for heavy or highly viscous crude where heating significantly reduces flow resistance. Other options use fluids or chemicals to improve displacement without adding heat: gas injection uses a gas to alter sweep and pressure, chemical injection uses polymers or surfactants to modify interfacial tension and mobility, and waterflood simply drives oil toward the well with water. Hence, the method that uses heat is Thermal Recovery.