GB1010023A - Heating of underground formations - Google Patents

Abstract

<PICT:1010023/C4-C5/1> <PICT:1010023/C4-C5/2> An underground formation is heated by injecting fuel (such as methane) at a point 1 into the formation, injecting oxygen-containing fluid into the formation at a point 2 spaced from the point 1, igniting the fuel and oxygen-containing fluid mixture to form a combustion front 14, discharging the products of combustion from a point 3 displaced from the points 1, 2, and controlling the rates of injection of the fuel and fluid to maintain the front in a selected area of the formation. Materials in the formation which are converted to liquid or gas are produced through the well 3. In a modification a further well is located on the opposite side of the well 1 to that of the wells 2, 3, and the further well and the well 3, are used alternately for production. In the modification shown in Fig. 5 a barren sand formation 10 is heated by a combustion front 14 formed by fuel and air flows 15, 16 respectively and the formation 10 heats a formation 17 containing oil which may then be driven by fluid supplied through the holes 19 or 20 to be produced through the tubing 8 or 12. The method may be used to pyrolyze material, e.g. coal, into fluid products.