In a combustion process for recovering hydrocarbons from a subterranean hydrocarbon-bearing formation comprising an upper permeable hydrocarbon-bearing stratum overlying a lower permeable hydrocarbon-bearing stratum and separated therefrom by a semi-permeable stratum which is substantially permeable to oxygen but not substantially permeable to water; the strata are traversed by injection and production wells, the lower hydrocarbon-bearing stratum is ignited near an injection well and oxygen-containing gas is injected into the lower hydrocarbon-bearing stratum to combust hydrocarbons near the injection well and form a combustion front, an oxygen-containing gas is injected into the lower hydrocarbon-bearing stratum and an aqueous fluid is injected into the upper hydrocarbon-bearing stratum to move the combustion front between the injection and the production wells and to prevent or mitigate channeling through the upper hydrocarbon-bearing stratum, and hydrocarbons are recovered from the strata.
Disclosed is a method for reducing the porosity of a zone within mass of unretorted rubblized oil shale comprising locating the zone; providing fluid communication to the zone; introducing grout slurry by fluid communication to the zone so as to deposit slurry and reduce porosity. Also disclosed is an improved method for the subterranean in situ retorting of oil shale comprising establishing a retorting zone containing a rubblized mass comprising oil shale; establishing an essentially planar flame front within the retorting zone; introducing oxygen containing gas into the retorting zone to support combustion at the flame front thereby forming hot combustion gases which effect retorting of the oil shale; locating an area of the flame front which advanced ahead of the essentially planar flame front; and introducing grout slurry to the advanced area to reduce gas permeability and retard further advancement of that area of the flame front.
Disclosed is a method for recovering viscous oil from subterranean, viscous oil containing formations, particularly from shallow formations which overlie water zones. The production well is completed in the entire oil zone and small amount in the water zone. At least two separate injection means are established in the injection well, the first being in communication with the lower part of the oil formation and upper part of the water formation, with the second injection means being in communication with the upper part of the oil formation. Heated air is injected via the first injection means into the lower part of the oil formation near the oil-water interface, the air channeling through the upper part of the water zone and causing an in situ combustion reaction to occur at the oil water contact. Air injection supports an in situ combustion reaction in the oil water contact zone which heats the oil above by conduction as well as hot gas convection through the oil saturated interval. Steam is then injected into the upper portion of the oil saturated interval by the second injection means while continuing injecting air into the lower portion of the formation to expand the burned out zone upward.
This invention comprises two steps for improving in situ combustion in shallow reservoirs: (1) use small well patterns preferably with injection to producing wells distance about 200 to 250 feet; and (2) after the front reaches a distance where the air flux is about 5 SCF/(ft.sup.2 -hr), or expressed another way, where the rate of frontal advance is about 0.4 ft/day, allow the air to "ride" on top of the pay zone while simultaneously water is injected at the oil-water contact below the air entry at the sand face of the injection well.
A method for conducting an in situ combustion process in a hydrocarbon-bearing subsurface geologic formation wherein water and essentially pure oxygen are injected into a well at essentially the same time but physically separated from one another so that a combined hot water/steam and in situ combustion drive is set up in the formation for the tertiary recovery of hydrocarbons therefrom.
A method for recovering viscous oil from a subterranean, viscous oil-containing formation underlain by a water zone. Steam is injected into the formation via the injection well at the oil/water contact and oil is recovered from the formation until steam breakthrough occurs at the production well thereby forming a hot plate at the oil/water contact. Thereafter, the production well is shut-in and a combustion-supporting gas, preferably pure oxygen, is injected into the formation at the oil/water contact causing an in-situ combustion reaction to occur at the oil/water contact and pressurization of the formation. Injection of the combustion-supporting gas is continued until the formation is pressurized to a specific pressure not to exceed the pressure at which fracture of the overburden above the formation would occur. Thereafter, the injection well is shut-in and oil is recovered from the formation via the production well. If desired, after injection of the combustion-supporting gas is discontinued, the formation may be subjected to a soak period by shutting-in the injection and production wells for a time sufficient to allow the injected combustion-supporting gas to be consumed in the in-situ combustion reaction.
