Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons

Definitions

• the invention relates to a gas injection method for enhanced oil recovery.
• Enhanced oil recovery is a term for techniques applied to increase the amount of crude oil that can be extracted from an oil field. Through enhanced oil recovery techniques, 30-60% or more of the reservoir's original oil can be extracted compared with 20-40% using primary and secondary recovery methods. Enhanced oil recovery is also referred to as improved oil recovery or tertiary recovery. Enhanced oil recovery is achieved by gas injection, chemical injection, ultrasonic stimulation, microbial injection, or thermal recovery such as cyclic steam, steamflooding, and fireflooding. Gas injection is presently the most-commonly used approach to enhanced oil recovery. A gas, such as carbon dioxide or natural gas or nitrogen, is injected into the oil-bearing stratum under high pressure. The pressure of the gas pushes the oil toward the production well and assists in driving the oil up to the surface. In addition to providing a source of driving-pressure, the gas can also mix with the oil and thereby reduce the viscosity of the oil.
• a gas such as carbon dioxide or natural gas or nitrogen
• the invention is a system and method for gas injection enhanced oil recovery.
• the method includes the step of burning solid fuel and an oxygen-bearing gas in a combustion chamber.
• the method also includes the step directing an output stream of the burning step through a fluid pathway extending from the combustion chamber and underground to push oil toward a well.
• the method includes the step maintaining the pressure in the combustion chamber above ambient during the burning step.
• Figure 1 is a simplified schematic of a system according to an exemplary embodiment of the invention.
• a system 10 includes a combustion chamber 12 operable to contain solid fuel and an oxygen-bearing gas while burning at a pressure maintained above ambient.
• the system 10 also includes a fluid pathway 14 extending from the combustion chamber 12 and underground 16 for directing an output stream of the combustion chamber 12 to push underground oil toward a well 18.
• the exemplary system 10 can also include a sub-system for power generation.
• a thermal fluid such as water can travel along a closed-loop fluid circuit 20.
• a condenser 22, a pump 24, a heat exchanger 26, and a steam turbine 28 can be positioned along the fluid circuit 20.
• Thermal fluid in liquid state can be pumped by the pump 24 to the heat exchanger 26.
• the thermal fluid can extract thermal energy from the output stream of the combustion chamber 12 to change to vapor state.
• a portion 30 of the fluid pathway 14 can pass through the heat exchanger 26.
• the thermal fluid in vapor state, such as steam can move from the heat exchanger 26 and pass across the steam turbine 28. The energy of the thermal fluid can be extracted and converted to rotation by the steam turbine 28.
• the steam turbine 28 can transmit rotational power to other components, such as a rotor of a generator 32.
• the generator 32 can generate electricity in response to the input of rotational power from the steam turbine 28. It is noted that rotational power can be transmitted directly from the steam turbine 28 or through intermediary structures, such as a transmission or clutch. It is also noted that the steam turbine 28 can transmit rotational power to structures other than the generator 32. After passing across the steam turbine 28, the thermal fluid can pass through the condenser 22 and return to liquid state.
• the solid fuel can be coal.
• Any kind of coal can be used in practicing various embodiments of the broader invention.
• the coal can be of relatively high or relatively low carbon content.
• the coal can be of relatively high or relatively low sulfur content. Burning coal having a higher sulfur content can result in the production of carbon disulfide, which can be helpful in thinning the underground oil. Thinning the oil can be helpful in promoting oil recovery.
• the solid fuel can be directed to the combustion chamber 12 with a solid fuel handler 34, shown schematically.
• the solid fuel handler 12 can be a device, or a plurality of devices working together, operable to receive the solid fuel and deliver the solid fuel to the combustion chamber 12 in a desired form.
• the solid fuel handler 34 can be operable to deliver coal to the combustion chamber 12 in powder form.
• the solid fuel handler 34 can include a pulverizer to reduce the size of individual pieces of solid fuel.
• the solid fuel handler 34 can also include devices for containing the solid fuel such as hoppers and/or also include devices for moving the solid fuel such as conveyors from a railroad receiving station and/or injectors projecting into the combustion chamber 12.
• the device or devices of the solid fuel handler 34 can be supplied with rotational or mechanical power directly or indirectly from the steam turbine 28, or can be supplied with electrical power from the generator 32. It is noted that the dashed lines in Figure 1 represent paths for the transmission of electrical power.
• the oxygen-bearing gas delivered to the combustion chamber 12 can be pure oxygen or air.
• the nature of the output stream will be affected by the properties of the solid fuel and the properties of the oxygen-bearing gas.
• the output stream can be substantially pure carbon dioxide. Carbon dioxide is miscible in oil and can therefore be helpful in promoting oil recovery.
• carbon disulfide can be a component of the output stream.
• the output stream can include carbon dioxide, nitrogen, water, ash, as well as trace amounts of other gases. All of these components can be directed underground. Alternatively, one or more of these components can be separated from the rest of the output stream before the remainder of the output stream is directed underground.
• the system 10 can include an oxygen separator 36 on site with the combustion chamber 12 for separating oxygen from air and delivering substantially pure oxygen to the combustion chamber 12.
• the oxygen separator 36 can apply any process for oxygen separation.
• cryogenic air separation can be applied.
• U.S. Pat. No. 6,279,344 is hereby incorporated by reference as one example of a cryogenic air separation method in which a stream of oxygen is generated.
• Another process for separating oxygen from air or generating an oxygen stream occurs in a solid oxide fuel cell. Air can be pressurized to around 300 p.s.i. and injected into a fuel cell. Electric current can be passed through the cell to generate a stream of oxygen.
• 7,531,260 is hereby incorporated by reference as one example of a solid oxide fuel cell that can be applied in embodiments of the invention.
• the oxygen separator 36 can be supplied with rotational or mechanical power directly or indirectly from the steam turbine 28, or can be supplied with electrical power from the generator 32.
• the oxygen generated by the oxygen separator 36, or any other oxygen-bearing gas directed into the combustion chamber 12, can be compressed by a compressor 38.
• the compressor 38 can also compress air directed to the oxygen separator 36.
• the compressor 38 can be operable to compress the oxygen-bearing gas to between 200 p.s.i. and 3000 p.s.i. in various embodiments of the invention. Some embodiments of the broader invention can be practiced wherein the range of pressure is 1500 - 2500 p.s.i. Other embodiments of the broader invention can be practiced over different ranges.
• the combustion chamber 12 is operable to contain the solid fuel and the oxygen-bearing gas while the combination is burned at a predetermined pressure above ambient or while burning over a pressure range.
• the compressor 38 can be supplied with rotational or mechanical power directly or indirectly from the steam turbine 28, or can be supplied with electrical power from the generator 32.
• the combined solid fuel and oxygen-bearing gas can be burned in the combustion chamber at a pressure of between 200 - 3000 p.s.i. and at a peak temperature of between 4500 0 F - 6000 0 F, outlet temperatures will be between 100 and 4000F .
• the combustor chamber 12 can be about 1/100 of the size of a combustion chamber currently used in enhanced oil recovery systems. This benefit can be enjoyed because, generally, a heat transfer coefficient of the output stream changes with changes in pressure. As the pressure during combustion increases, the heat transfer coefficient increases so that more energy can be extracted at the heat exchanger 26. Another benefit that can be enjoyed from higher-than-
• the heat exchanger can be about 1/40 of the size of a heat exchanger currently used in coal fired power plants.
• ash can be a portion of the output stream of combustion. If the ash does not clog the fluid pathway 14 or otherwise hinder oil recovery, the ash can be directed underground with the gases generated by combustion.
• the system 10 can also include ash handling equipment, represented schematically at 40 in Figure 1.
• the ash handling equipment 40 is shown positioned between portions 42, 44 of the fluid pathway 14, but the ash handling equipment 40 could be positioned at another location in alternative embodiments of the invention.
• the ash handling equipment 40 could be an electrostatic precipitator or could remove ash by another process.
• the ash handling equipment 40 can be supplied with rotational or mechanical power directly or indirectly from the steam turbine 28, or can be supplied with electrical power from the generator 32.
• the system 10 can include a recirculation pathway 46.
• a portion of the output stream of combustion can be returned to the combustion chamber 12 after the output stream has passed the ash handling equipment 40 and the heat exchanger 26.
• seventy-five percent (if nearly pure 02 is the oxidizing stream input to the coal combustor, or approx 0-30% if the oxidizing stream is air) of the output stream can be directed back to the combustion chamber.
• the recirculation pathway 46 can be omitted and all of the output stream can be directed underground.
• the recirculation pathway 46 is shown extending from a portion 52 of the fluid pathway 14, but the recirculation pathway 46 could extend from another position along the fluid pathway 14 in alternative embodiments of the invention.
• the system can include a compressor 48 downstream of the combustion chamber 12.
• compression of the output stream can be desirable. For example, if the output stream is compressed, the oxygen-bearing gas can be directed into the combustion chamber 12 at a lower pressure and the combustion chamber 12 can be less robust.
• the compressor 48 can be supplied with rotational or mechanical power directly or indirectly from the steam turbine 28, or can be supplied with electrical power from the generator 32.
• Another basis for compressing the output stream can be that more energy can be extracted from the output stream at the heat exchanger 26.
• the output stream can enter the heat exchanger 28 at a temperature of between 4500 0 F - 6000 0 F and a pressure of between 200 - 3000 p.s.i.
• the output stream can exit the heat exchanger 26 at a temperature of between 200 0 F - 1000 0 F (approximately 3% - 25% of the combustion temperature in the exemplary embodiment) and a pressure of between 160 - 2400 p.s.i. (approximately 80% - 100% of the combustion pressure in the exemplary embodiment).
• the amount of energy extracted, or the rate of energy extraction, from the output stream can be selected based on the power needs of the system 10.
• the system 10 can include the compressor 48.
• the amount of energy extracted can be greater than the amount of power needed to power the system 10.
• the operator of the system 10 can choose to generate power in excess of the needs of the system 10 and can then sell the excess power to a customer, referenced at 50 in Figure 1.
• embodiments of the invention can be practiced wherein the operator of the system is a power supplier rather than a purchaser of power.
• Another aspect of the operation of the system 10 is the temperature of the output stream at entry into the ground.
• the operator of the system 10 can direct the output stream into the ground at relatively higher temperatures or at relatively lower temperatures.
• a higher temperature will exacerbate thinning of the oil and thereby promote oil recovery.
• higher temperatures could increase the cost of injection piping since larger and more robust piping may be required.
• a portion 54 of the exemplary fluid pathway 14 extends from the compressor 48 and extends underground.
• the output stream of combustion can be injected underground at one or more locations in embodiments of the invention. It is noted that U.S. Pub. No. 2008087425 and U.S. Pat. Nos. 5,065,821 and 5,803,171 are incorporated by reference as exemplary teachings of how the output stream, or a portion of the output stream, can be applied to move oil. Other injection schemes can be applied in embodiments of the invention.
• system 10 can include a central controller to control the operation of the individual components of the system.

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• Life Sciences & Earth Sciences (AREA)
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• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
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• Geochemistry & Mineralogy (AREA)
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• 2009
  • 2009-07-10 US US12/500,966 patent/US20110005747A1/en not_active Abandoned
• 2010
  • 2010-07-06 CN CN2010800402673A patent/CN102648331A/zh active Pending
  • 2010-07-06 WO PCT/US2010/041014 patent/WO2011005725A2/en active Application Filing

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