| 摘要 |
A process for recovering a viscous, combustible material, for example tar from a tar sand or oil and bitumen from heavy oil, from a sub-surface deposit of the material. The process comprises forming a substantially vertical main bore into the deposit and igniting the deposit adjacent the base of the bore. Such ignition may be carried out by any means, for example by burning a fuel, by an explosion or by a laser beam. Generally the ignition is assisted until such time as the material in the deposit is ignited. A supply of air is arranged to the ignition site so that a self-sustaining combustion takes place in the bore once the ignition is properly established. This combustion is supported by a natural draft generated by the combustion. The gaseous products of the combustion can leave the bore and the heat of the combustion and of the gaseous products of combustion as they leave the bore liquefy the material in the deposit. This heat can also be used to develop steam from water supplied to a vessel in the bore, which steam also assists in liquefying the material. The liquefied material is extracted from the bore. The process avoids the high pressure requirements of the prior art processes and, in particular, does not need high fluid pressure to drive the liquefied products from one bore to another bore.
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