Abstract:
A system, apparatus and method for cracking, hydrogenating and extracting oil from underground deposits is presented. An apparatus for extracting low viscosity oil from an oil field includes a gasification unit to generate syngas adapted to hydrogenate and hydrocrack high viscosity oil to produce low viscosity oil. At least one injection well injects the syngas belowground to a location near an upper portion of an oil deposit. At least one production well for recovering and bringing aboveground at least some low viscosity oil that was high viscosity oil that was at least partially hydrogenated and cracked by the syngas to produce the low viscosity oil.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. Provisional Application Ser. No. 61/476,480 filed Apr. 18, 2011; the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The current invention relates generally to apparatus, systems and methods for extracting oil. More particularly, the apparatus, systems and methods relate to extracting oil from underground deposits. Specifically, the apparatus, systems and methods provide for syngas assisted oil recovery, including at least partially cracking and hydrogenating the oil with syngas. 
         [0004]    2. Description of Related Art 
         [0005]    A variety of processes are used to recover viscous hydrocarbons such as heavy oil and bitumen from underground deposits. Typically, methods are used in heavy oil or bitumen that are greater than 50 meters deep where it is no longer economic to recover the hydrocarbon by current surface mining technologies. Depending on the operating conditions of the insitu process and the geology of the heavy oil or bitumen reservoir, insitu processes can recover between 25% and 75% of the oil. The primary focus associated with producing hydrocarbons from such deposits is to reduce the insitu viscosity of the heavy oil or bitumen so that it can flow from the reservoir to the production well. The reduction of the insitu heavy oil or bitumen is achieved by raising the temperature and/or dilution with solvent, which is the typical practice in existing processes. 
         [0006]    The Steam Assisted Gravity Drainage (SAGD) is a popular insitu recovery method which uses two horizontal wells (a well pair) positioned in the reservoir to recover hydrocarbons. This method is far more environmentally benign than oil sands mining. In this process, the two wells are drilled parallel to each other by using directional drilling. The bottom well is the production well and is typically located just above the base of the reservoir. The top well is the injection well and is typically located between 15 and 30 feet above the production well. Anywhere between 4 and 20 well pairs are drilled on a particular section of land or pad. All the well pairs are drilled parallel to one another, about 300 feet apart, with half of the well pairs oriented in one direction, and the other half of the well pairs typically oriented 180° in the opposite direction to maximize reservoir coverage. A 15 foot meter separation is often an optimal gap which allows for the maximum reservoir production due to the most effective impact of the injected steam. Although the separation between injector and producer wells are planned for 15 foot, some wells have as high as 30 foot gaps, reducing production capability from that particular zone. 
         [0007]    The top well injects steam into the reservoir from the surface. In the reservoir, the injected steam flows from the injection well and looses its latent heat to the cool heavy oil and bitumen and as a result the viscosity of the heated heavy oil and bitumen drops and flows under gravity towards the production well located below the injection well. 
         [0008]    Given the quantity of steam required for the SAGD, energy needed for the steam generation represents a substantial cost for the SAGD. In addition to the cost, other criteria of the steam generation for the SAGD relate to production of carbon dioxide (CO 2 ) and water input requirements. For example, many governments regulate CO 2  emissions. High costs relative to another option for the steam generation can prevent use of some options for the steam generation regardless of ability to provide desired criteria, such as with respect to the production of CO 2 . Burning gas or oil to fuel burners that heat steam generating boilers creates CO 2 , which is a greenhouse gas that can be captured by various approaches. While further adding to the cost, capturing the CO 2  from flue gases of the burners facilitates in limiting or preventing emission of the CO 2  into the atmosphere. In contrast to indirect heating with the boilers, prior direct combustion processes inject steam and CO 2  together into the formation even though injection of the CO 2  into the formation may not be desired or acceptable in all applications. 
         [0009]    Regarding the water input requirements, inability to recycle all of the steam injected results from having to remove impurities such as sodium chloride from any recovered water prior to the recovered water being combined with other make-up water to feed any steam generation. Limited water supplies for the make-up water at locations of where SAGD is applicable can prevent feasibility of the steam generation. Even if available, expense of purchasing water can incur cost for the SAGD. 
         [0010]    Typically, the SAGD process is considered thermally efficient if its Steam to Oil Ratio (SOR) is 3 or lower. The SAGD process requires about 1,200 cubic feet of natural gas to heat the water to produce 1 barrel of bitumen. As of the end of 2010, the National Energy Board (NEB) of Canada estimates the capital cost of $18-$22 to produce a barrel of bitumen by the SAGD method. Because of the high ratio of water requirement for the SAGD, an alternative process, method or system to reduce water consumption is desirable. 
         [0011]    An alternative process that reduces steam usage is an extension of the SAGD process, the Steam and Gas Push (SAGP) where steam and a non-condensable gas are co-injected into the reservoir. The non-condensable gas provides an insulating layer and improves the thermal efficiency of the process, resulting in a reduction of steam. 
         [0012]    Another extension of the SAGD process uses a solvent, called Vapor Extraction (VAPEX). Similar to SAGD, VAPEX consists of two horizontal wells positioned in the reservoir, whereas the top well is the injection well and the bottom well is the production well. In VAPEX, a gaseous solvent such as propane is injected into the reservoir instead of steam. The injected solvent condenses and mixes with the heavy oil or bitumen to reduce its viscosity. Under the action of gravity, the mixture of solvent and bitumen flow towards the production well and are pumped to the surface. A major concern with the VAPEX process is how to control the significant solvent losses to the reservoir, which has a tremendous impact on its economics. Therefore, a better way of extracting heavy oil and bitumen from underground deposits is desired. 
       SUMMARY OF THE INVENTION 
       [0013]    The preferred embodiment of the invention includes a system for cracking, upgrading and extracting oil from underground deposits is presented. The system includes a gasifier, an injection well and a production well. The gasifier creates high pressure, high temperature syngas. The high pressure, high temperature syngas flows through the injection well into a deposit of oil under the ground to crack and hydrogenate the oil to produce upgraded oil with a reduced density and viscosity. The production well of the system receives the reduced density and viscosity oil and transports it above the ground where it may be further separated into a portion that may be sold and a portion that can be gasified in the gasifier. The system can be configured as a syngas assisted gravity drainage (SYAGD) system of oil recovery. In an SYAGD system, the injection well outputs the syngas above an input of the production well so that the reduced viscosity oil can flow downward into an input of the production well. 
         [0014]    In another configuration of the preferred embodiment, the gasifier includes an oxygen input, an oil input and a steam input. Oxygen is input to the gasifier through the oxygen input, oil is input to the gasifier through the oil input and steam is input into the gasifier through the steam input. The gasifier mixes the oxygen, oil and gas to product the syngas. 
         [0015]    In one configuration of the preferred embodiment, the gasifier creates a syngas comprised of hydrogen and carbon monoxide. The ratio of hydrogen to carbon monoxide is about 2 to 1. In another configuration of the preferred embodiment, the ratio of hydrogen to carbon monoxide is about 3 to 1. 
         [0016]    Another configuration of the system for cracking, hydrogenating and extracting oil from underground deposits includes an oxygen compressor and an emulsification vessel. The oxygen compressor creates a stream of high pressure gasification oxygen and a stream of high pressure atomizing oxygen. The emulsification vessel mixes a stream of oil with the stream of high pressure atomizing oxygen to produce mixed oil. The mixed oil, high pressure gasification oxygen and steam are input to the gasifier. 
         [0017]    Another configuration of the system includes a heat recovery unit (HRU). The HRU reduces and controls the temperature of the syngas before it is injected to the deposit of oil. The system can also include a closed loop system to recover the heat given up by the syngas at the HRU as recovered heat to convert the recovered heat into electricity. The closed loop system can be an organic rankine cycle (ORC) system. 
         [0018]    The closed loop system can include a generator, a heat exchanger, an expander turbine and an air heat exchanger. The heat exchanger heats and vaporizes a liquid to create a vaporized liquid. The expander turbine receives the vaporized liquid and generates shaft power to rotate the generator. The generator produces electricity. The air heat exchanger cools the vaporized liquid back into a liquid by exchanging heat with air. The liquid can be a refrigerant. 
         [0019]    Another configuration of the preferred embodiment includes a system with a gasification unit, a compressed oxygen line, an oil line, a steam line, an injection well and a production well. The compressed oxygen line carries compressed oxygen into the gasification unit, the oil line carries oil into the gasification unit and the steam line carries steam into the gasification unit. The gasification unit gasifies the compressed oxygen, oil and steam to produce a syngas stream. The injection well carries the syngas stream to an underground deposit of oil where the syngas cracks and hydrogenates oil in the deposit to produce upgraded oil and the production well recovers the upgraded oil and transports the upgraded oil above ground. This system can include a heat recovery unit to reduce and control the temperature of the syngas stream before it is sent to the injection well 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0020]    One or more preferred embodiments that illustrate the best mode(s) are set forth in the drawings and in the following description. The appended claims particularly and distinctly point out and set forth the invention. 
           [0021]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various example methods, and other example embodiments of various aspects of the invention. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. One of ordinary skill in the art will appreciate that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of another element may be implemented as an external component and vice versa. Furthermore, elements may not be drawn to scale. 
           [0022]      FIG. 1  illustrates a preferred embodiment of a system for upgrading and extracting heavy oil from underground. 
           [0023]      FIG. 2  illustrates in more detail the preferred embodiment of the system for upgrading and extracting heavy oil from underground. 
           [0024]      FIGS. 3A and 3B  illustrate how to use the system for upgrading and extracting heavy oil from underground increase the geological matrix to allow oil to more easily flow through the matrix. 
           [0025]      FIG. 4  illustrates a configuration of the preferred embodiment represented as a method for upgrading and extracting heavy oil from underground. 
       
    
    
       [0026]    Similar numbers refer to similar parts throughout the drawings. 
       DETAILED DESCRIPTION 
       [0027]      FIG. 1  illustrates a first configuration of the preferred embodiment of a system  100  for upgrading bitumen, heavy oil or another oil and extracting them from a reservoir  110 .  FIG. 1  illustrates a configuration of the preferred embodiment of the system that generates a syngas with a rather high temperature and pressure that is injected into an injection well. While it may not be practical to inject syngas with such high temperatures and pressures, this Figure is useful for understanding some of the novelty of the invention. After  FIG. 1  is discussed, other figures that implement more detailed and more practical systems and methods such as those which reduce the temperature of the syngas before it is injected into a well are discussed further. 
         [0028]    In  FIG. 1 , fuel is input to a high pressure gasifier  102  through a feed line  101  along with oxygen from line  120  and steam from line  121 . The fuel is partially burned in the gasifier with the oxygen and steam to generate a high temperature, high pressure syngas. The high temperature and high pressure syngas includes primarily hydrogen and carbon monoxide. In this configuration of preferred embodiment, the ratio of hydrogen to carbon monoxide in the syngas is in the range of 2 to 3:1. The high pressure gasifier  102  that generates the syngas can be a market available high pressure gasifier such as the ZEEP (Zero Emissions Energy Plant) gasifier developed by Pratt and Whitney Rocketdyne. U.S. Pat. No. 7,547,423 describes other aspects of a high pressure gasifier the contents of which are incorporated herein by reference. The system  100  injects the syngas at a controlled temperature into the reservoir  110  to heat, crack, hydrogenate and upgrade heavy oil insitu. Cracking the heavy oil in the presence of hydrogen can prevent or reduce the formation of coke. 
         [0029]    The syngas is transported through an upper well line  104  that transports it below the Earth&#39;s surface  106  to an upper region of an oil reservoir  110 . The upper well line  104  may be connected to an upper well horizontal line  108  that can have openings periodically placed in the horizontal line  108  to distribute the syngas at periodic intervals within the reservoir  110 . The heated hydrogen and carbon monoxide of the syngas entering the reservoir  110  heats up, cracks and hydrogenates heavy oil within the reservoir providing a higher recovery rate than a typical SAGD system. The cracked and hydrogenated heavy oil has a lower density and viscosity that allows it to flow generally downward toward a lower well horizontal line  114 . The lower well horizontal line  114  can have holes periodically placed in it to allow the cracked oil to flow into these holes. The cracked oil can then be extracted through a vertical well line  112  and brought to the surface of the earth for further processing and/or storage. 
         [0030]    The system  100  for upgrading and extracting heavy oil of  FIG. 1  has several benefits over a traditional SAGD system. The system  100  uses very little water consumption, the consumed steam is the raw material for the generation of hydrogen through water gas shift reaction. Unlike a typical SAGD, system  100  for upgrading and extracting heavy oil creates little to no emissions, because the products of gasification are injected into the well. The formation of hydrogen in the syngas aids in the hydrogenation of the cracked heavy oil, upgrading it and minimizing the formation of coke. Because hydrogen has a heat capacity of 14.3 J/g.K versus 2.08 for steam, it provides for superior heat transfer to the oil reservoir  110 . Additionally, the system  100  can have no external fuel requirements or associated infra-structure because it can use a slipstream of the produced oil bottoms fraction as fuel which results in lower capital and operating costs per barrel of bitumen produced. Using a slipstream to eliminate or significantly reduce external fuel requirements is discussed in detail below with reference to the system  200  of  FIG. 2 . 
         [0031]      FIG. 2  illustrates a second configuration of the preferred embodiment of a system  200  for upgrading bitumen, heavy oil or another oil and extracting them from a reservoir  110 . Similar to the system  100  of  FIG. 1 , the system  200  of  FIG. 2  includes a high pressure gasifier  102  to generate a high temperature, high pressure syngas of primarily hydrogen and carbon monoxide. Unlike the system of  FIG. 1 , the system  200  of  FIG. 2  includes an ORC system  250  with a hot oil circulating loop to allow for the temperature of the syngas to be lowered and to provide thermal energy to an ORC power generation unit  208 . The components of the ORC system  250  and the details of how it operates are discussed below. Lowering the temperature of the syngas allows it to be injected at temperatures between 300° C. and 500° C. into the reservoir reducing the need to have extremely high performance piping and equipment that would be required at higher pressures and temperatures. Similar to the system of  FIG. 1 , the conditioned high pressure hydrogen and carbon monoxide syngas is routed to the injection well through lines  104  and  114  to heat the formation, crack the heavy oil in the formation and react with the hydrogen in the presence of a natural catalytic environment of fine clays and sand to upgrade bitumen and/or heavy oil in the production well. Again, the high pressure gasifier  102  may be a Pratt and Whitney Rocketdyne ZEEP gasifier or another type of gasifier as understood by those of ordinary skill in the art. 
         [0032]    Before describing further details of the system  200  for upgrading bitumen, heavy oil or another oil, some of the improvements of this system are discussed over prior systems. Whereas a typical SAGD system is limited to heating the oil formation to reduce the oil viscosity, the system of  FIG. 2  provides the capability for the heating, cracking, hydrogenating and upgrading of heavy oil. Moreover, the system  200  of  FIG. 2  can meet on demand temperatures required in the oil formation whereas the SAGD process temperature is limited to the rating of the steam generator pressure which sets the temperature of the injection into the reservoir. The system  200  for upgrading bitumen, heavy oil or another oil, can generate a wide range of injection temperatures on demand. This ability to control injection temperature allows for better control of production and larger gaps between injector and producing wells. As a result, it can reduce capital costs substantially. Little to no external power is required to power the system  200  because the system  200  generates its own power by recovery of thermal energy in controlling the temperature of the syngas to reservoir  110 . 
         [0033]    The system  200  for upgrading bitumen, heavy oil or another oil of  FIG. 2  includes an air blower  222 , a molecular sieve  223  and an oxygen compressor  224  to generate a high concentration oxygen stream to provide the oxygen requirements for the incomplete combustion of the fuel in the gasifier  102 . The air blower  222  is provided to first pressurize atmospheric air. A line carries the compressed air to the molecular sieve  223  where it is separated into O 2  and nitrogen. The nitrogen is released into the atmosphere or it can be recovered if desired. The oxygen compressor  224  further compresses the highly concentrated oxygen. The compressed oxygen leaves the compressor  224  on line  228  which splits into a gasification oxygen line  120  and an atomizing oxygen line  125 . 
         [0034]    The system  200  for upgrading bitumen, heavy oil or another oil includes a feed tank  202  for storing oil reclaimed from the reservoir  110 . A portion of this stored oil from the feed tank  202  is carried from the input line  101  to a high pressure oil pump  204  that pumps it into line  206 . Compressed atomizing O 2  from line  225  and the feed oil in line  206  are combined and passed through line  226  to an emulsifier vessel  227  where they are mixed together. 
         [0035]    Steam in line  121 , gasification oxygen in line  120  and the emulsified oxygen and oil in line  228  all enter the high pressure gasifier  102  where they are combined to generate a high pressure, high temperature syngas. As previously mentioned when discussing  FIG. 1 , the gasification generates about a 2 to 3:1 ratio of hydrogen and carbon monoxide. Those of ordinary skill in the art will realize that this ratio is selectable and can be other ranges or values. Before the high pressure, high temperature syngas is injected down line  104  to the reservoir, line  230  first carries it to a gasifier heat recovery unit (HRU)  132  to control (e.g., lower) the syngas temperature. 
         [0036]    Power is generated in an organic rankine cycle (ORC) system  250  which converts the thermal energy captured in the gasifier HRU  132  into electricity. The ORC system  250  includes an ORC heat exchanger  234 , line  240 , a generator  208 , line  241 , an air heat exchanger  242 , line  243 , a refrigerant pump  244  and line  245 . The ORC system  250  receives its energy from a closed loop hot oil circulation system including the gasifier HRU  232 , line  233 , the ORC heat exchanger  234 , line  235 , pump  236 , line  237  and the gasifier HRU  232 . 
         [0037]    The oil circulating system  210  controls the temperature of the syngas for injection into the reservoir  110 . The temperature of the syngas is controlled by feeding hot circulating oil in line  233  into the ORC heat exchanger  234  where it gives up its thermal energy. Line  233  transfers heat from the HRU  232  to the ORC heat exchanger resulting in a cooling of the syngas exiting the HRU on line  104 . The cooled circulating oil travels in line  235  to an oil pump  236 . Then pump  236  pumps the oil through line  237  to a heating coil in the gasifier HRU  237  to complete this loop. 
         [0038]    In another closed loop, a low boiling point fluid (a refrigerant) is pumped by refrigerant pump  244  at a high pressure in line  245  to the ORC heat exchanger  234  where it is vaporized to form a high pressure, low boiling point gaseous fluid. This high pressure, low boiling point fluid gaseous stream enters, from line  240 , an expander turbine so that it can provide shaft horsepower to the generator  208  to provide rotation to an electrical generator. The rotating electrical generator can then produce electricity to power the overall system  200  for upgrading bitumen, heavy oil or another oil. Line  241  carries the lower energy stream after it passed through the generator  208  to the air heat exchanger  242 . At the air heat exchanger  242 , the lower energy stream is further cooled. Line  243  carries the stream from the air heat exchanger  242  back to the pump  244  where the cycle begins to repeat in another cycle. 
         [0039]    The system  200  for upgrading heavy oil pumps the conditioned heavy oil from the HRU  232  in line  104  down to the oil reservoir  110 . The syngas is generally injected into line  104  for travel to the reservoir  110  at about 300° C. to 500° C. Similar to the discussion above with reference to system  100 , the injected syngas heats up the oil formation, cracking, hydrogenating and upgrading the heavy oil, decreasing its density and viscosity allowing it to flow into the production well (e.g., lines  112  and  114 ). The system  200  utilizes the natural catalytic bed of the formation to aid the rate of reaction. For example, the reservoir minerals are composed of clay minerals and non-clay minerals, the clay minerals, such as kaolinites and montmorillonite, are the main catalysts in the process of hydrocarbon source rock organic compounds. Moreover the elements of aluminium, iron and potassium present in the matrices are known to promote catalysis oxidation, decarboxylation and hydrogenation of organic compounds. 
         [0040]    The high pressure, high temperature gasifier  102  can be controlled so that the generated syngas includes carbon dioxide. When the syngas steam condenses in the reservoir  110  it combines with the carbon dioxide to form carbonic acid. Referring to  FIGS. 3  A/B, the carbonic acid dissolves the cement bridges  352  between quartz particles and thus increases the pore space at the geological matrix in the reservoir which will allow the passage (increases the release) of more oil toward the output well lines  112  and  114  increasing the production of the reservoir.  FIG. 3A  illustrates a blown up example of a geological matrix before the creation of carbonic acid and  FIG. 3B  illustrates what the same geological matrix may look like after it has interacted with carbonic acid. Dissolution of CO 2  in the formation water results in the formation of carbonic acid, which in turn dissolve the formation minerals during injection, this process improves formation permeability. 
         [0041]    Additional carbon dioxide can be injected into the reservoir to further act as a pressurizing agent and when dissolved underground in the heavy oil, it significantly reduces its viscosity, enabling the oil to flow more easily through the wider pore formation into the production well. The system may leave this carbon dioxide underground in the deposit after the oil has been extracted. 
         [0042]    The amount of hydrogen that is injected into the reservoir  110  by lines  104  and  108  affect the cracking hydrogenation reactions process and the quality of the oil extracted from the reservoir  110 . Therefore, the system  200  for upgrading bitumen, heavy oil or another oil can include an API gravity meter  300  for monitoring the quality of upgraded oil being extracted from the reservoir  110 . The API gravity can be monitored and when it falls out of range of values that system  100  is monitoring, a controller  302  can be configured to adjust the amount of oxygen, steam and/or oil input to the high pressure gasifier  102  to control; the amount and composition of hydrogen in syngas stream; the pressure and temperature of the syngas being injected into the reservoir  110  to move the API gravity to a more acceptable range. 
         [0043]    Lines  112  and  114  carry the upgraded oil that is recovered in the production well and carry it aboveground to a separator  260 . The separator  260  splits the produced upgraded oil into two streams. Line  261  carries a portion of the heavy ends for gasification and line  262  carries the light ends for sales. 
         [0044]    Example methods may be better appreciated with reference to flow diagrams. While for purposes of simplicity of explanation, the illustrated methodologies are shown and described as a series of blocks, it is to be appreciated that the methodologies are not limited by the order of the blocks, as some blocks can occur in different orders and/or concurrently with other blocks from that shown and described. Moreover, less than all the illustrated blocks may be required to implement an example methodology. Blocks may be combined or separated into multiple components. Furthermore, additional and/or alternative methodologies can employ additional, not illustrated blocks. 
         [0045]      FIG. 4  illustrates a configuration of the preferred embodiment as a method  400  for cracking and extracting oil beneath the ground. The method  400  is especially well suited to extract oil from deposits beneath the earth&#39;s surface. The method  400  begins by creating a high pressure, high temperature syngas, at  402 . As previously mentioned, the syngas can be created by partial combustion of a mixture of oil, oxygen and steam in a gasifier. Next, the syngas is injected into a deposit of oil under the ground, at  404 , to crack and hydrogenate the oil to produce upgraded oil with a reduced viscosity. Some configurations of the method  400  will cool the syngas in a heat recovery unit before it is pumped below ground. The reduced viscosity oil is extracted and brought above the ground, at  406 . This oil can be separated into light oil that is ready for sales and heavier oil that can be used to create the syngas in a gasifier. 
         [0046]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Therefore, the invention is not limited to the specific details, the representative embodiments, and illustrative examples shown and described. Thus, this application is intended to embrace alterations, modifications, and variations that fall within the scope of the appended claims. 
         [0047]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described. References to “the preferred embodiment”, “an embodiment”, “one example”, “an example”, and so on, indicate that the embodiment(s) or example(s) so described may include a particular feature, structure, characteristic, property, element, or limitation, but that not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element or limitation. Furthermore, repeated use of the phrase “in the preferred embodiment” does not necessarily refer to the same embodiment, though it may.