US 3596993 A
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United States Patent (72] Inventor Hu'oldMJuley Kennewlck,Wesb. 211 AppLNo. 799,227  Filed Feb. 14, 1969  Patented Aug.3, 1971  Assignee McDonneliDoughsCorporation s41 METHOD or EXTRACTING 011. AND 111/- PRODUCTS FROM OIL SHALE 4Clalnu,lDrawingFig.
(52] U.S.Cl 299/5, 166/257, 166/261, '166/267, 299/7  [al.Cl. ...E2lb43/24  Fieldolsarch 166/256, 257, 259, 261, 267; 299/4, 5, 7; 208;! l/
[56} ReterenoesCited UNITED. STATES PATENTS 3,480,082 11/1969 Gilliland 166/267X 2,780,449 2/1957 Fisheretal... 166/259 2,958,519 11/1960 Hurley 166/261X I 2,969,226 1/1961 Huntington 166/261X 3,001,775 9/1961 Allred l66/259X 3,044,545 7/1962 Tooke 166/261X Qazawjwmraz WWW/AZ 3,233,668 2/1966 Hamiltonetal 166/259 3,400,762 9/1968 Peacocketal 166/259 3,454,958 7/1969 Parker 166/256 FOREIGN PATENTS 607,541 10/1960 Canada 208/11 Primary Examinerlan A. Calvert Attorneys-Walter .1. Jason, Donald L. Royer and Robert 0.
Richardson ABSTRACT: Oil and by-products are extracted from oil shale by drilling a hole into the shale bed and heating the shale in its bed. Steam and oxygen or air mixtures provide self-sustaining heating that draws oil from the shale in the form of vapor and mist. As the oil is removed, the heat and subsequent water gas reaction changes the hard shale into a whitish, weak structured, friable material. This material falls, of its own weight, to the bottom of the hole, thus exposing new shale for processing. Action of steam with residlual carbon in the shale generates hydrogen nd adds to the gas flow that carries the oil vapor and mist to the surface, together with the friable material in the form of ash particles. The oil, and any other valuable materials, are separated from the ash before it is either converted to a building block material or dumped into a used shale bed cavity,
a al/4111371141! 23781694190440! METHOD OF EXTRACTING OIL AND BY-PRODUCTS FROM OIL SHALE BACKGROUND OF THE INVENTION In oil shale areas, there is usually an overburden of sedimentary rocks as well as sand, soil, etc. This overburden varies in depth, and removal costs are high. The shale is hard stone formed by compression of clays, containing organic material,
over long periods of time. After the stone is mined, it is SUMMARY OF THE INVENTION The process of this invention produces shale oil without removing the overburden of sedimentary rocks, sand, and soil, and mining the shale for processing. Oil is extracted from the shale bed, leaving the exhausted shale in a weakened form that cracks from the bed by its weight and falls to the bottom of the working cavity, thus exposing fresh shale surfaces for processing. Oil vapor and mist, and shale ash and debris at the bottom of the cavity are gas-drawn through a pipe to ground surface. After separation of the oil, any remaining valuable materials may be extracted from the shale residue, and the residue either dumped into previously worked cavities or used in the manufacture of construction materials.
Briefly, this process consists of drilling a hole through the overburden to the bottom of the shale bed. One pipe is placed in the hole to a depth determined by the thickness and composition of, the overburden. An inner pipe is installed from ground level to within a short distance of the cavity floor. When heated gases flow between the inner and outer pipe walls into the cavity, they pass to the end of the inner pipe near the cavity floor, and gas-lift action is generated through the inner pipe to ground level. Oxygen or air, steam, and some residual gases from the refining equipment, all separately metered, provide the necessary gas flow. The temperature of gases flowing into the cavity is raised by the heat of the gases returning through the inner pipe. BRIEF DESCRIPTION OF THE DRAWING AND PROCESS The attached drawing schematically illustrates and supports the subject inventions process description. Numbers in parentheses refer to drawing callouts. Reference is now made to.the drawing, wherein an overburden covers an oil shale bed 12 resting on a rock foundation 14. A hole 16 is drilled from the ground surface 18 through the overburden to the bottom 20 of the shale bed. An inner pipe 22 is positioned in the hole so that it extends to the bottom of the shale, terminating at position 24. One or more pipes 26 are positioned around the inner pipe 22 to form a pathway 28 for the introduction of steam, oxygen or air, and residual gases into the cavity 30 which becomes progressively larger as the process continues in the manner hereinafter described.
If it is necessary for the one or more outer pipes 26 to extend beyond the overburden into the shale cavity, the pipe is perforated as shown by dotted line 32 so that incoming hot gases can contact the shale surface 34 and react with the surface before entering the bottom 24 of the inner pipe 22 and being drawn to the surface.
The ground surface end of pipe 22 is connected to a cyclone separator 36 that separates oil mist and vapor while warm form the shale ash. The ash is then transferred to an appropriate vehicle 38 for transportation to a facility where valuable materials such as uranium may be extracted. After final processing, the spent shale may be dumped into a previously worked cavity 40, transported to a facility for processing into building material, such as concrete products for example, or disposed of in any other appropriate manner.
The oil mist and gases separated in the cyclone separator are processed in a conventional manner such as fractional distillation; thereafter; various products ma'y be refined by current state of the art methods.
In the well and shale bed cavity the following processes occur. The preheated gas stream containing oxygen and steam and diluent gases passes between the walls of the outer pipe or pipes 26 and inner pipe 22 through the overburden layer and into the shale bed cavity. The hot gas reacts with the shale to release oil, while some burning takes place in the gas phase to provide heat for the processes. The concentration of the diluent gases serves as a temperature control. As the oil is released, residual carbon reacts with the steam to bring about a water-gas reaction in which carbon is converted to carbon monoxide and carbon dioxide, depending on the temperature. Simultaneously, gaseous hydrogen is created from the steam and from the methane and other gases present in the cavity. Distillation of shale oil in the presence of hydrogen usually results in a larger yield than do other distillation methods. Since the cavity is filled with gas containing a concentration of hydrogen, hydrogenating retorting takes place, resulting in the maximum yield possible under these conditions.
The gaseous mixture containing the vaporized shale oil flows to the bottom of the cavity. As this water-gas reaction takes place at temperatures of approximately 800 C; residual carbon is removed from the shale, and the shale changes from its hard, dark composition to a whitish weak-structured material. This is promoted by some carbon dioxide release from the carbonate materials in the shale. Under its own weight, this material falls from the cavity walls as an ashy substance; the gas flow at the bottom of the cavity moves the ash, together with the oil vapor and mist, residual steam, and residual gases, into the lower end of the inner pipe and up to the cyclone separator for processing.
The residual gases including hydrogen, methane, and ethane, and liquids and solids, rising as a mixture through the inner pipe to ground level, heat the gases flowing from ground level into the cavity between the walls of the inner and outer pipes. Therefore, the portion of inner pipe passing through the overburden serves as a heat exchanger.
Without cooling, the mixture of gases, oil, and solids are drawn from the cavity directly into the cyclone separator. First, the ash is removed; then, the residual gas stream containing the oil vapor and mist passes to a cooler and demister where the oil is recovered. After chilling and fractional distillation, other various products can be extracted. Some of the residual gas may be burned to produce power for the oxygen plant; the remainder can be flared or stored under pressure for commercial use. In addition, some of this gas can be introduced into the steam-oxygen mixture flowing into the cavity as a reaction temperature control and to introduce hydrogen containing materials into the gases.
1. The method of extracting oil and byproducts from oil shale containing an inorganic portion and situated in its bed in the ground and its unmined state and wherein its removal fonns a cavity in the ground, said method comprising the steps of:
introducing oxygen and steam into the upper portion of said bed,
burning carbon in the shale to obtain heat and oil vapor,
said steam reacting with the heated carbon to obtain hydrogen, exposing said oil vapor to said hydrogen, decomposing the inorganic portion of the shale to cause its removal to expose a new work surface to heat,
said step of decomposing being by said. burning of said shale in the presence of said oxygen at a temperature sufficient to change said inorganic portion of said shale to a whitish, weak-structured friable material which falls under its own weight, and
providing a gas flow to carry the fallen friable material in dust particle form from the bottom of said cavity to the earths surface together with said oil vapor where it is then separated from said oil vapor.
2. The method of extracting oil as in claim 1 wherein the organic portion of said oil shale has a calcium carbonate portion therein, and said portion is convened by said buring to carbon dioxide and calcium oxide suitable for manufacture of concrete products.