Recovery of hydrocarbons from coal
AssigneeExxon Research & Engineering Co.
InventorsRobert E. Pennington, Michael A. Gibson, George T. Arnold
Life of this patent
Estimating the term…
Abstract
Coal liquids and gases are recovered from a thick underground coal seam by drilling one or more boreholes from the earth's surface into the lower part of the seam, burning out the coal over a limited area near the bottom of the seam, collapsing the overlying coal to form a rubblized zone extending vertically to a point near the upper boundary of the seam, driving a flame front vertically through the rubblized zone to liberate hydrocarbon liquids and produce gases, and recovering the liquids and gases from the rubblized zone.
Claims33
A process for the recovery of liquid hydrocarbons from a thick underground coal deposit which comprises drilling at least one borehole into the lower portion of said coal deposit from the earth's surface, burning out the coal near the bottom of said deposit over a limited area in the vicinity of said borehole to form a cavity having a volume equivalent to from about 5 to about 30% of the coal within said deposit overlying said limited area, breaking down the coal overlying said cavity to form a rubblized zone extending vertically in said deposit to a point near the upper boundary of the deposit, establishing a flame front within said rubblized zone, driving said flame front vertically through said zone, and withdrawing liquids and gases from said rubblized zone.
A process for the recovery of liquid hydrocarbons from an underground coal deposit having a thickness of from about 50 to about 1000 feet or more which comprises drilling at least two boreholes into the lower portion of said coal deposit from the earth's surface;
- establishing communication between said boreholes within said coal deposit near the lower boundary of said deposit;
- initiating combustion of said coal near the lower boundary of said deposit through one of said boreholes;
- introducing an oxygen-containing gas into said deposit through one of said boreholes and withdrawing gaseous combustion products from said deposit through another of said boreholes until a cavity has been burned out between said boreholes near the lower boundary of said deposit, said cavity having a volume equivalent to from about 5 to about 30% of the coal overlying an area of from about one-fourth to about two acres in the vicinity of said boreholes near the lower boundary of said deposit;
- breaking down into said cavity the coal overlying said cavity until a rubblized zone extending vertically to a point near the upper boundary of said deposit has been formed;
- igniting said coal in said rubblized zone at a point near the upper end of said zone;
- injecting an oxygen-containing gas downwardly into the upper part of said rubblized zone through one of said boreholes and withdrawing fluids from the lower part of said rubblized zone through another of said boreholes;
- and recovering hydrocarbon liquids from said fluids.
Dependencies are inferred from the claim text.