| 摘要 |
<p>Case 5561 GLR/gs/ejl 10/13/81 Viscous materials, such as bitumen, can be recovered from subsurface earth formations, such as tar sands, by forming a shaft or first borehole to the base of the desired subsurface formation, drilling second boreholes into the formation, injecting steam into these boreholes until the temperature of parts of the formation is such that the viscosity of the material is reduced, and collecting the liberated material. Variations of this basic procedure are discussed.</p> |
