| 摘要 |
<p>Case 5563 GLR/ld June 3, 1981 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 formation, forming a tunnel outwardly from the base of the shaft, and drilling second boreholes outwardly from the tunnel, into the desired formation. Steam is injected into these second boreholes until the viscosity of the material is reduced, and the liberated material is then collected. Variations of this basic procedure are discussed.</p> |
