Thermal Recovery

Heavy Oil Will Not Flow Cold

Heavy oil is nearly immobile at reservoir temperature, thousands or tens of thousands of centipoise. Its viscosity falls steeply with temperature, by orders of magnitude over a couple hundred degrees, roughly $\ln\mu = A + B/T$.

Inject Heat

So heat is the lever. Steam flooding and steam-assisted gravity drainage raise the temperature, collapse the oil viscosity, and lift its mobility, which varies inversely with viscosity, enough for the oil to flow to a well.

A Coupled Problem

A thermal simulator must solve the energy balance and the temperature-dependent viscosity alongside the flow. An isothermal black-oil model, holding viscosity fixed, cannot represent steam recovery at all.