Method for oil recovery by in situ exfoliation drive

In a thermal process of oil recovery by "in situ" combustion, the generation of an exfoliation drive front in a bed of oil reservoir rock as a result of alternating heating and cooling therein, the process being initiated by fracturing in order to generate an extensive pan-cake fracture substantially horizontal at the bottom of the bed, the steps of:

• (a) forming a rubble filled reaction chamber fluidly communicating with said fracture at the bottom of the bed by means of an explosion at the same level;
• (b) removing a portion of the rubble created by said explosion;
• (c) drilling a well near the reaction chamber to intersect said fracture;
• (d) injecting an oxidant into the reaction chamber so as to start combustion of organic matter in the reaction chamber until a temperature of about 2000.degree. F. is reached, thereby liberating oil from the reservoir rock, the liberated oil passing through the fracture to said well;
• (e) Pumping the oil from said well;
• (f) stopping the oxidant injection;
• (g) injecting a coolant into the upper part of the reaction chamber, cooling it to about 500.degree. F., thereby exfoliating a layer of rock about the chamber;
• and
• (h) repeating steps (d) through (g) until the reaction chamber reaches said well.

A method for recovering oil from a bed of tight reservoir rock, comprising the steps of:

• forming a chamber partially filled with reservoir rock rubble in said bed;
• and
• thereafter, alternately (a) combusting organic matter in the chamber while recovering oil liberated from the reservoir rock by pyrolysis, whereby the wall of the chamber is concurrently heated by said combustion;
• and (b) injecting a coolant into said chamber to spall the wall of the chamber.