http://ceri-mines.org/documents/28thsym ... nly%5D.pdf
In Situ Conversion of Oil Shale Kerogen
(Microwave Conversion)
http://www.netl.doe.gov/technologies/oi ... ersion.pdf
http://en.wikipedia.org/wiki/Shell_in_s ... on_process
IN-SITU KEROGEN CONVERSION AND RECOVERY
Document Type and Number:
WIPO Patent Application WO/2012/088476
Abstract:
Disclosed herein are methods for extracting a kerogen-based product from subsurface (oil) shale formations. These methods rely on chemically modifying the shale-bound kerogen using a chemical oxidant so as to render it mobile. The oxidant is provided to a formation fluid in contact with the kerogen in the subsurface shale. An alkaline material is also provided to the formation fluid to mobilize organic acids which are produced during oxidation of the kerogen. A mobile kerogen-based product which includes the organic acids is withdrawn from the subsurface shale formation and further processed to isolate the organic acids contained therein. An exemplary method for isolating the acids includes treating the mobile kerogen- based product such that at least a portion of the organic acids form a separate phase from the mobile kerogen-based product. The organic acids may further be extracted from the mobile kerogen-based product using an organic extraction fluid. The isolated organic acids can be upgraded by a reaction process that make the products suitable as refinery feedstocks, fuel or lubricant blendstocks, reaction intermediates, chemical feedstocks, or chemical intermediate blendstocks.
http://www.sumobrain.com/patents/wipo/I ... 8476A2.pdf
http://www.sumobrain.com/patents/wipo/I ... 88476.html
IN-SITU KEROGEN CONVERSION AND RECOVERY
BACKGROUND
[0001] If proponents of Hubbert peak theory are correct, world oil production will soon peak, if it has not done so already. Regardless, world energy consumption continues to rise at a rate that outpaces new oil discoveries. As a result, alternative sources of energy must be developed, as well as new technologies for maximizing the production and efficient consumption of oil. See T. Mast, Over a Barrel: A Simple Guide to the Oil Shortage, Greenleaf Book Group, Austin, Tex., 2005.
[0002] A particularly attractive alternative source of energy is oil shale, the attractiveness stemming primarily from the fact that oil can be "extracted" from the shale and subsequently refined in a manner much like that of crude oil. Technologies involving the extraction, however, must be further developed before oil shale becomes a commercially-viable source of energy. See J. T. Bartis et al, Oil Shale Development in the United States: Prospects and Policy Issues, RAND Corporation, Arlington, Va., 2005.
[0003] The largest known deposits of oil shale are found in the Green River Formation, which covers portions of Colorado, Utah, and Wyoming. Estimates on the amount of recoverable oil from the Green River Formation deposits are as high as 1.1 trillion barrels of oil— almost four times the proven oil reserves of Saudi Arabia. At current U.S. consumption levels (~20 million barrels per day), these shale deposits could sustain the U.S. for another 140 years (Bartis et al.) At the very least, such shale resources could moderate the price of oil and reduce U.S. dependence on foreign oil.
[0004] Oil shale typically consists of an inorganic component (primarily carbonaceous material, i.e., a carbonate), an organic component (kerogen) that can only be mobilized by breaking the chemical bonds in the kerogen, and frequently a second organic component (bitumen). Thermal treatment can be employed to break (i.e., "crack") the kerogen into hydrocarbon chains or fragments, which are gas or liquids under retort conditions, and facilitate separation from the inorganic material. This thermal treatment of the kerogen is also known as "thermal upgrading" or "retorting," and can be done at either the surface or in situ, where in the latter case, the fluids so formed are subsequently transported to the surface.
[0005] In some applications of surface retorting, the oil shale is first mined or excavated, and once at the surface, the oil shale is crushed and then heated (retorted) to complete the process of transforming the oil shale to a crude oil— sometimes referred to as "shale oil." See, e.g., Shuman et al, U.S. Pat. No. 3,489,672. The crude oil is then shipped off to a refinery where it typically requires additional processing steps (beyond that of traditional crude oil) prior to making finished products such as gasoline, lubricant, etc. Note that various chemical upgrading treatments can also be performed on the shale prior to the retorting, See, e.g., So et al., U.S. Pat. No. 5,091,076.
[0006] A method for in situ retorting of carbonaceous deposits such as oil shale has been described in Kvapil et al, U.S. Pat. No. 4, 162,808. In this method, shale is retorted in a series of rubblized in situ retorts using combustion (in air) of carbonaceous material as a source of heat.
[0007] The Shell Oil Company has been developing new methods that use electrical heating for the in situ upgrading of subsurface hydrocarbons, primarily in subsurface formations located approximately 200 miles (320 km) west of Denver, Colo. See, e.g., Vinegar et al, U.S. Pat. No. 7, 121,342; and Berchenko et al, U.S. Pat. No. 6,991,032. In such methods, a heating element is lowered into a well and allowed to heat the kerogen over a period of approximately four years, slowly converting (upgrading) it into oils and gases, which are then pumped to the surface. To obtain even heating, 15 to 25 heating holes could be drilled per acre. Additionally, a ground-freezing technology to establish an underground barrier around the perimeter of the extraction zone is also envisioned to prevent groundwater from entering and the retorting products from leaving. While the establishment of "freeze walls" is an accepted practice in civil engineering, its application to oil shale recovery still has unknown environmental impacts. Additionally, the Shell approach is recognized as an energy intensive process and requires a long timeframe to establish production from the oil shale.
[0008] In view of the aforementioned limitations of the above methods, simpler and more cost-effective methods of extracting the kerogen from the shale would be extremely useful.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to a process for producing mobile products from the organic matter that occurs in subsurface oil shale. Among other factors, the process is based on the discovery that kerogen in oil shale can be made to react at temperatures below pyrolysis temperatures to produce mobile reaction products that can be removed from the subsurface shale formation, isolated in surface facilities and upgraded to produce useful products, refinery feedstocks, fuel and lubricant blendstocks, reaction intermediates and the like. The process for extracting a kerogen-based product from a subsurface shale formation comprises the following steps: providing an oxidant to kerogen in subsurface shale; contacting the kerogen in the subsurface shale with the oxidant at a temperature in the range from 0°C and 200°C to form organic acids; and mobilizing at least a portion of the organic acids from the subsurface shale to produce a mobile kerogen-based product.
[0010] Further to the invention is a process for extracting a kerogen-based product from a subsurface shale formation comprising subsurface shale, the process comprising the steps of: providing an oxidant to a fluid in a subsurface shale formation that contains kerogen, to produce a formation fluid; contacting the kerogen in the subsurface shale with the formation fluid at a temperature in the range of between 0°C and 200°C to form organic acids; providing an alkaline material to the formation fluid to form a mobile kerogen-based product that contains organic acids; recovering at least a portion of the mobile kerogen-based product from the subsurface shale formation; and isolating at least a portion of the organic acids from the mobile kerogen-based product.
[0011] The composition of the formation fluid is tailored by providing an oxidant to the fluid. In one embodiment, the process comprises providing a reactive fluid containing the oxidant to the formation. In one embodiment, the formation fluid contains in the range from 0.1 wt. % to 40 wt. % of the oxidant.
[0012] In one embodiment, the formation fluid is further tailored for mobilizing at least a portion of the organic acid reaction products from the kerogen conversion reactions. In one embodiment, the formation fluid which is tailored for mobilizing the products has a pH of at least 7. In one embodiment, the high pH formation fluid comprises an alkaline material selected from the group consisting of a carbonate, a bicarbonate, an oxide and a hydroxide. In one embodiment, the alkaline material is supplied to the formation fluid by a reactive fluid
[0013] One or more oxidants are provided to the formation fluid for converting the kerogen. In general, the oxidant is selected for its reactivity for conversion of organic materials in the shale at low temperatures. In general, reaction temperature is in the range from 0°C to 200°C.
[0014] At least a portion of the organic acids that are produced are in the C 35+ range. In one embodiment, at least 50 wt. % of the organic acids in the mobile kerogen-based product is in the C 35+ range. Furthermore, at least 20 wt. % of the C 35- organic acids in the mobile kerogen-based product is in the Cs to C 12 range.
[0015] Further to the invention is the discovery that the mobile reaction products that are produced during the kerogen conversion reactions are organic acids. Accordingly, the process includes a step of isolating at least a portion of the organic acids. Accordingly, the process includes a step of isolating at least a portion of the organic acids. The process for extracting a kerogen-based product from a subsurface shale formation comprises: providing an oxidant to kerogen in subsurface shale; contacting the kerogen in the subsurface shale with the oxidant at a temperature in the range of between 0°C and 200°C to form organic acids; mobilizing at least a portion of the organic acids from the subsurface shale to produce a mobile kerogen-based product; and isolating at least a portion of the organic acids from the mobile kerogen-based product.
[0016] In one embodiment, the process comprises treating the mobile kerogen-based product at a pH such that at least a portion of the organic acids form a separate phase from the mobile kerogen-based product. Exemplary processes include treating the mobile kerogen-based product at a pH in the range from 7 to 12, or at a pH in the range from 1.5 to 7.
[0017] In one embodiment, the process comprises contacting the mobile kerogen-based product with an organic extraction fluid; extracting at least a portion of the organic acids into the organic extraction fluid; and recovering an acid rich extraction fluid. In one embodiment, the process further comprises isolating at least a portion of the organic acids from the acid rich extraction fluid.
[0018] The invention is also directed to an integrated process for extracting a kerogen-based product from a subsurface shale formation comprising subsurface shale, the process comprising: providing an oxidant to kerogen in subsurface shale; contacting the kerogen in the subsurface shale with the oxidant at a temperature in the range of between 0°C and 200°C to form organic acids; mobilizing at least a portion of the organic acids from the subsurface shale to produce a first mobile kerogen-based product; treating the first mobile kerogen-based product at a pH in a range from 7 to 12, isolating at least a portion of the organic acids contained therein, and recovering a second mobile kerogen-based product; treating the second mobile kerogen-based product at a pH in the range from 1.5 to 7, isolating at least a portion of the organic acids contained therein, and recovering a third mobile kerogen-based product; and treating the third mobile kerogen-based product to isolate at least a portion of the organic acids contained therein, and recovering an organic acid lean aqueous fluid.
[0019] Further to the invention is the discovery that the organic acids can be isolated and then upgraded. Accordingly, the process includes a step of upgrading at least a portion of the organic acids. The process for increasing the value of a kerogen-based product from a subsurface shale formation comprises: providing an oxidant to kerogen in subsurface shale at a temperature in the range from 0 °C to 200°C and recovering a mobile kerogen-based product comprising organic acids therefrom; isolating at least a portion of the organic acids from the mobile kerogen-based product; and upgrading the isolated organic acids. In one embodiment, the process further comprises isolating at least a portion of the organic acids from the mobile kerogen-based product by employing an process selected from the group consisting of pH titration, fractional neutralization, esterification, extraction, distillation, membrane separation, froth flotation, phase separation, electrostatic separation, filtering, centrifugal separation, coalescence, precipitation, thermal separation, steam distillation, and any combination thereof, in any order.
[0020] In one embodiment, the process comprises isolating C2 0 + organic acids and C2 0 - organic acids from the mobile kerogen-based product, and cracking at least a portion of the C2 0 + organic acids in a cracking process. In a further embodiment, C2 0 - hydrocarbon products from the cracking process are upgraded using a process selected from the group consisting hydroprocessing, hydrogenation, saturation, hydrotreating, hydrocracking, isomerization, fluid catalytic cracking, thermal cracking, esterification, oligomerization, reforming, alkylation, denitrification, desulfurization, and combinations thereof.
[0021] In another embodiment, the process comprises isolating C35+ organic acids and C35- organic acids from the mobile kerogen-based product, and cracking at least a portion of the C35+ organic acids in a cracking process. The C35- hydrocarbon products from the cracking process are upgraded using a process selected from the group consisting hydroprocessing, hydrogenation, saturation, hydrotreating, hydrocracking, isomerization, fluid catalytic cracking, thermal cracking, esterification, oligomerization, reforming, alkylation, denitrification, desulfurization, and combinations thereof.
[0022] Further to the invention is the discovery that in addition to these organic acids being valuable as hydrocarbon products for creating commercial products, a portion of the organic acids can also be used in the process for extracting the kerogen-based product from the subsurface shale formation. In particular, during separation and isolation, C1 0 + organic acids can be obtained and converted into valuable hydrocarbon products. During separation and isolation an organic acid lean fluid comprising C2 to C 10 organic acids can also be isolated. This fraction has properties that make it desirable to use in the process for extracting the kerogen-based product. Using a portion of the organic acids created creates integration in the process and this integration provides benefits of increased yield, increased efficiencies, and reduced cost.
[0023] As such in one embodiment is provided an integrated process for extracting a kerogen-based product from a subsurface shale formation comprising kerogen in an inorganic matrix. The integrated process comprises (a) providing an oxidant to the kerogen in the subsurface shale formation; (b) contacting the kerogen in the subsurface shale formation with the oxidant at a temperature in the range from 0°C and 200°C to form organic acids; (c) mobilizing at least a portion of the organic acids as organic acid reaction products from the subsurface shale to produce a mobile kerogen-based product; (d) treating the mobile kerogen- based product to provide a product stream comprising C 12 and higher organic acids and an organic acid lean fluid comprising C 2 to C 10 organic acids; and (e) recycling the organic acid lean fluid to the subsurface shale formation.
[0024] In another embodiment the integrated process for extracting a kerogen-based product from a subsurface shale formation comprising kerogen in an inorganic matrix comprises (a) providing an oxidant to the kerogen in the subsurface shale formation; (b) contacting the kerogen in the subsurface shale formation with the oxidant at a temperature in the range from 0°C and 200°C to form organic acids; (c) mobilizing at least a portion of the organic acids as organic acid reaction products from the subsurface shale to produce a mobile kerogen-based product; (d) treating the mobile kerogen-based product to provide a product stream comprising C 12 and higher organic acids and an organic acid lean fluid comprising C 2 to Cio organic acids; (e) combining the organic acid lean fluid comprising C 2 to C 10 organic acids with an oxidant to provide a recycling fluid; and (f) recycling the recycle fluid to the subsurface shale formation and contacting the kerogen in the subsurface shale formation with the oxidant in the recycle fluid.
[0025] In a further embodiment the integrated process for extracting a kerogen-based product from a subsurface shale formation comprising kerogen in an inorganic matrix comprises (a) providing an oxidant to the kerogen in the subsurface shale formation; (b) contacting the kerogen in the subsurface shale formation with the oxidant at a temperature in the range from 0°C and 200°C to form organic acids; (c) mobilizing at least a portion of the organic acids as organic acid reaction products from the subsurface shale to produce a mobile kerogen-based product; (d) treating the mobile kerogen-based product to provide a product stream comprising C 12 and higher organic acids and an organic acid lean fluid comprising C 2 to Cio organic acids; (e) isolating the organic acid lean fluid comprising C 2 to C 10 organic acids as a recycling fluid; and (f) recycling the recycle fluid to the subsurface shale formation and mobilizing at least a portion of the organic acids as organic acid reaction products to produce a mobile kerogen-based product. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Fig. 1 is a block diagram illustrating an exemplary sequence of steps involving the provision of a reactive fluid to a subsurface shale formation that contains kerogen, the recovery of a mobile kerogen-based product from the formation and the isolation of organic acid products from the mobile kerogen-based product.
[0027] Fig. 2 is a block diagram illustrating the added step of passing an organic extraction fluid to the mobile kerogen-based product for extracting at least a portion of the organic acids contained in the mobile kerogen-based product.
[0028] Fig. 3 is a block diagram illustrating an exemplary sequence of steps involving the provision of a reactive fluid to a subsurface shale formation that contains kerogen, the further provision of an extractive fluid for mobilizing organic acids that are generated from kerogen reactions, the recovery of a mobile kerogen-based product from the formation and the isolation of organic acid products from the mobile kerogen-based product.
[0029] Fig. 4 illustrates carbon chain-size distribution of low molecular weight acids in kerogen permanganate oxidation products determined by gas chromatography/mass spectrometry.
[0030] Fig. 5 illustrates carbon chain-size distribution of hydrocarbon products formed by pyrolysis of high molecular weight organic acids in kerogen permanganate oxidation products determined by pyrolysis gas chromatography/mass spectrometry.
[0031] Fig. 6 is a block diagram illustrating an embodiment of the process for isolating organic acids from the product in which they are produced from the kerogen in the subsurface shale. Fig. 6 further illustrates upgrading the organic acids in the preparation of the organic acids as finished products, as feedstocks or as blendstocks.