Patent Application
20120070883
Approximately sixty-five percent of all the oil discovered remains trapped underground in reservoirs following primary production (natural reservoir pressure) and secondary production (water or gas flood). Microbial enhanced oil recovery (“MEOR”) holds considerable promise for recovering a significant proportion of trapped global oil reserves.
Conventional MEOR is an empirical process whereby inexpensive nutrients are pumped into an oil reservoir to stimulate growth of indigenous, dormant microorganisms. In theory, the rejuvenated microbial community produces environmentally friendly biometabolites such as gases, acids, solvents, and surfactants that release trapped oil and/or biomass and polymers that plug water channels thereby diverting subsequent water or gas floods into oil bearing zones.
Conventional MEOR has been employed for decades and has been moderately successful but, frequently, the results have been disappointing. A typical MEOR approach is to pump molasses and/or agricultural fertilizer into a watered-out reservoir and hope for the best. This hit-or-miss approach is not based on scientific principles and any positive, negative, or damaging results remain unexplained. In some cases, undesirable bio-metabolites such as hydrogen sulfide have caused irreversible reservoir damage, equipment corrosion, and health threats.
There are many applications of MEOR, but none of them include prior metabolic characterization of microbial communities that inhabit oil reservoirs. According to some culture-based and genetic evidence, microbial communities are markedly different among oil reservoirs depending on rock type, temperature, depth, and various other factors. Therefore, blindly injecting nutrients into an oil reservoir and hoping for beneficial results is an uncertain and potentially damaging process. Pumping the same nutrient into several reservoirs and expecting similar results is unscientific and unreasonable. There is no way currently to predict what bio-metabolic response, if any, can be expected in a given oil reservoir when nutrients are injected. Therefore, it would be beneficial to have a device for growing reservoir microorganisms in a controlled and scientific way to determine the optimal growth conditions and production of metabolic byproducts in a certain reservoir through laboratory experimentation that maintains and replicates the bottomhole temperatures and pressures.
Targeted, scientifically-based MEOR treatments could be devised for individual oil reservoirs if one knew the likely metabolic response of the microbial community to an infusion of nutrients. Then one could stimulate the desirable microbes and suppress the undesirable ones, for example, suppressing the sulfate-reducing bacteria responsible for souring oil. It is important to ascertain what the reactions the microbial community in a given reservoir has to nutrient infusions, what bioproducts they are capable of producing, and exactly what nutrients and co-factors are needed to grow at optimum rates. However, most reservoir microbes die when brought to the surface in a sampler, due to being exposed to air, low temperature, low pressure, and a variety of other stressors. Few, if any, indigenous microbial species survive when hoisted to the surface. Therefore, conventional laboratory culture of oil-reservoir microorganisms in Petri dishes or in flasks of liquid growth media at room temperature is not feasible. Some high temperature high pressure growth chambers have been attempted. Several of these attempts have required the introduction of an inert gas along with the sample to provide the proper pressurization. These methods and growth chambers do not replicate bottomhole conditions. It is also very difficult to simultaneously maintain an elevated pressure and temperature during the entire process of transferring the sample and adding an inert gas which results in losing a substantial portion of the viable material due to changes in temperature or pressure.
Therefore, it would be beneficial to have a microbial reactor that replicates and maintains the anaerobic, high temperature and pressure conditions of an underground reservoir in a laboratory setting without the addition of an inert gas. It is particularly desirable to substantially maintain the anaerobic, high temperature and pressure bottomhole conditions during the transfer of the down-hole fluid sample from the sampler or a transport vessel into a HTHP microbial reactor. It would further be beneficial to have a HTHP microbial reactor that facilitates growing the indigenous, dormant reservoir microorganisms of an underground reservoir under high temperature and pressure conditions while providing instrumentation to observe the results and bi-products of their growth when a variety of nutrients, stimulants or other conditions are present.
The present invention is directed toward a high temperature/high pressure (HTHP) reactor that provides a growth chamber for microorganisms collected from or intended for introduction into HTHP (alternatively, HT or HP) environments. The present invention provides pressure and temperature continuity for bottomhole-sampled reservoir microbes that are transported to the laboratory, transferred to the HTHP growth chamber, and then grow and metabolize under conditions of high temperature and high pressure as if they never left the reservoir. This temperature and pressure continuity maintained in obtaining, transporting, inoculating, and studying reservoir microbial consortia in the laboratory is the key discriminator that separates this novel HTHP technology from all other current studies and applications of MEOR. The present invention is configured to be able to simulate reservoir and other HTHP environments in the laboratory, thus facilitating research, development, engineering, and other activities. The primary use of the HTHP reactor is to study growth, metabolism, and product formation of microbes under HTHP conditions, usually in a liquid environment. Other uses include studying biological, chemical, and/or physical interactions of microbes and substrates in HTHP environments, and studying, assessing, and/or evaluating other biological, physical, and/or chemical reactions and phenomena under HTHP conditions.
Potential uses of the HTHP reactor include but are not limited to culturing the following: a) oil and brine reservoir microorganisms ex situ (i.e. in the laboratory) in a variety of growth media under high-temperature high-pressure (HTHP) conditions that mimic reservoir conditions; b) microorganisms collected from other hydrocarbon formations including but not limited to heavy oil formations, oil sands (tar sands), tight oil and tight gas formations, coal seams, natural gas formations, oil shales (kerogen) and other intermediate stages of hydrocarbon formation, and deep-ocean gas hydrates (methyl clathrates); c) any and all extremophiles or facultative microorganisms from other HTHP environments including but not limited to those that colonize uranium, precious metals, and other subterranean ore deposits, deep ocean environments especially hydrothermal vents, salt domes and deposits, aquifers, and nuclear and other deep geological waste-disposal or waste-injection sites; and d) natural and engineered microbes destined for introduction into HTHP environments.
Environmental or experimental samples suitable for inoculation into the reactor chamber include not only fluid samples from subterranean reservoirs, ore bodies and other formations and sources, but also gases, slurries, emulsions, semi-solids, and/or solids especially if in a liquid milieu or if a suitable liquid milieu is added.
In addition, other items can be placed in the reaction chamber to study the various phenomena including (1) small sections of tubing, (2) wire, Teflon® or other mesh, (3) sandstone, carbonate, or other core or rock samples, and (4) other materials and substances that would provide substrates for attachment or otherwise elucidate formation of biofilms, metabolic activity, byproduct production and other phenomena.
The HTHP reactor of the present invention will have direct applications to studying the following: growth and metabolism of microorganisms and the formation of bioproducts involved in Microbial Enhanced Oil Recovery (MEOR); Carbon Capture and Sequestration (CCS) including biomineralization of injected CO2; methanogenesis of hydrocarbons and other substrates; introduction of genetically engineered microbes into subterranean reservoirs for alkane and other hydrocarbon production; bioleaching of uranium, precious metals, and other ores; subterranean upgrading of oil sands, heavy oils, and other hydrocarbons by microbial, chemical, and/or physical means; effects of nutrient infusions into subterranean reservoirs; effects of chemical and physical treatments in HTHP environments, e.g., heat and energy treatments of subterranean and mined kerogen deposits; waste disposal in HTHP environments; various methods for bioreclamation and bioremediation under HTHP conditions; basic and applied studies on microbes from or to be introduced into HTHP environments; and other physical and chemical reactions, effects, and consequences under HTHP conditions.
In general, the HTHP reactor of the present invention includes a main cylinder, and a reversible piston within the main cylinder. The piston separates the interior of the cylinder into two distinct chambers, a pressurization chamber and a reaction chamber. The pressurization chamber is configured to receive the mechanism or method of adjusting the position of the piston Within the cylinder to increase or decrease the pressure within the reaction chamber. The reaction chamber is where the experiments on the growth metabolism and formation of byproducts by microorganisms take place. The HTHP reactor of the present invention is configured such that the piston maintains the bottomhole pressure on the reaction chamber such that no introduction of a foreign inert gas into the reaction chamber is necessary to pressurize the sample. The HTHP reactor of the present invention further includes a thermal jacket that is positioned over at least a portion of the main cylinder corresponding to the reaction chamber. The thermal jacket is configured to regulate and vary the temperature of the chamber to replicate the sample's in situ conditions. One embodiment includes a thermal jacket 16 that allows the passage of a heating or cooling fluid around the outside of the main cylinder. Alternatively, the thermal jacket may include electric heating elements to adjust and maintain the temperature of the reaction chamber.
The HTHP reactor includes a lid that is generally coupled to an end of the main cylinder. The HTHP lid also is configured to be coupled to the vessel jacket and may be in fluid communication with the vessel jacket allowing heating and/or cooling fluid to pass through the lid. The lid is generally configured such that a plurality of instruments can be mounted thereon. The instruments are generally configured to be in communication with the reaction chamber and measure various physical and chemical properties within the reaction chamber. The instruments assist the technicians in monitoring the growth and metabolism of the microorganisms, observe the byproducts made by the microorganisms, and/or provide a means to stimulate the contents in the reaction chamber. One embodiment of the present invention may include one or more of the following instruments: a pH indicator, a thermowell, a thermometer, a pressure gauge, a stirrer, and inlet or outlet valves to introduce or remove agents or samples. It is important to note that the present invention is configured to include active pH monitoring of the reaction chamber during the high temperature high pressure testing that, until now, was not possible in the current state of the art. Any instrumentation known or hereafter developed that would be useful in the experimentation may be mounted to the lid or reactor of the present invention and is within the scope of the present invention.
Further, the HTHP reactor of the present invention includes a closed end opposite the lid. Another embodiment includes an end cap that is coupled to the main cylinder at the end opposite the lid. The end cap may be configured to receive the connection for a pressurization system which may include a hydraulic or air hose, controls for a solenoid motor or other motor or other pressurization system or method known or hereafter developed. An alternative embodiment may include a vessel bottom member configured to be held in place against the end of the cylinder and to receive the pressurization input described above. In this embodiment, the end cap secures the vessel bottom to the main cylinder to seal off the end of the main cylinder. Yet another embodiment includes a closed end opposite the lid wherein the closed end results from welding a plate or cap over the end or machining the entire cylinder from a single piece of solid bar stock.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.
In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views:
The following detailed description of the present invention references the accompanying drawing figures that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.
One novel aspect of the HTHP reactor of the present invention is best understood in view of the circumstances surrounding its use. Therefore, a description how the HTHP reactor of the present invention is used is provided with the detailed description of the HTHP reactor. Once a bottomhole reservoir sample is collected and moved to the HTHP reactor, the HTHP reactor of the present invention substantially replicates the bottomhole temperatures and pressures allowing technicians to experiment with nutrient media formulations and concentrations that will provide for optimum microbial growth, maximum production of desirable byproducts, and suppression of undesirable microbes and byproducts. The sampling, transport, inoculation, and incubation phases are performed such that the HTHP chain is not broken. It is important that these conditions are not broken because a substantial amount of the native microbes will be killed. Based on these results and a review of the geology of the reservoir, a precise nutrient-medium formulation will be devised and injected into the reservoir in optimum quantities and will be allowed to remain for an optimum time to (a) plug watered-out channels, (b) to induce maximum production of other desirable biometabolites, and/or (c) to suppress growth and metabolism of undesirable microbes, especially those that produce H2S and sour oil. The result is enhanced recovery of oil. The objective of this MEOR technology is to increase the amount of oil ultimately produced over what would have been recovered using other treatments.
Using HTHP reactor 10 includes assembling HTHP reactor 10 as described below. An assembled HTHP reactor 10 is illustrated in
Once a target reservoir is selected, bottomhole samples are obtained and the samples are maintained at reservoir temperatures and pressures during sampling, during transport to the laboratory and, using the HTHP reactor of the present invention, during culture in a laboratory. A conventional industry PVT-type sampler may be used to obtain bottomhole samples, usually bringing two each 600-ml fluid samples to the surface. The reservoir samples are usually obtained from the oil/water interface (residual oil zone), but can be harvested from any location within the reservoir. Additional samples can be obtained if required. Bottomhole temperature and pressure are measured by the sampler itself or by a separate probe and recorded while the sample is harvested. Pressure in the sampler's canisters is maintained at bottomhole pressure by hydraulics or nitrogen injection as canisters are retrieved to the surface. In some instances, the samples may be transferred into a transport vessel 500 by the sampling technician or contractor. The high temperature and pressure of the bottomhole environment is maintained through this transfer process such that the sample will continuously be subject to substantially the same temperature and pressure from the instant the sample has been taken though testing the sample in a laboratory using the HTHP reactor of the present invention. Prior to transfer to one or more HTHP reactors 10 of the present invention, reservoir samples contained in the sampler or transfer vessel 500 may be stored in an oven to maintain reservoir temperature. Reservoir bottomhole temperature and pressure are maintained inside the sampler and, if applicable, transfer vessels 500 throughout the entire sampling and transport processes. The chamber of the sampler or transfer vessel that contains the samples are not opened prior to fluid transfer because exposure to oxygen, low temperatures, and low pressures kills virtually all of the microbes.
In one embodiment, a reaction chamber 48 (as described below) of HTHP reactor 10 is loaded with selected sterilized nutrient media at ambient temperature and pressure. Growth and metabolic byproduct studies are often conducted of bottomhole microbial consortia in various liquid growth media including molasses, nitrogen/phosphate fertilizers, and various treatment grades of industrial wastes such as paper/pulp, sugar beet, brewery, feedlot, and municipal sewage that has undergone primary treatment. Further, many types of growth media are suitable for use including those typically used in empirical MEOR applications in the field. Some conventional MEOR solutions include but are not limited to: molasses (an inexpensive carbon source with micronutrients that is commonly used in MEOR), 0.5% aqueous solution (vol/vol) more or less; augmented molasses: 0.5% molasses, 0.15% KNO3 (w/v), and 0.05% Na3PO4 (wlv), or variations thereof; or an aqueous solution of fertilizer: 0.25% KNO3 (w/v), and 0.05% NaH2PO4 (w/v), or variations thereof.
One method of using the present invention (shown in
Only after the nutrient solution or industrial waste stream are brought to the bottomhole temperature and pressure, are about ten (10) milliliters of reservoir fluids from a single well added to reaction chamber 48 from transport vessel 500 at the bottomhole reservoir temperature and pressure, i.e. about a ten percent (10%) inoculum through tube 502. Larger or smaller volume HTHP reaction chambers can be used and inoculum ratios can be modified depending on requirements and growth responses. In addition, volumes of the above components may be increased or decreased from those disclosed herein. Any variations in the volume and percentage of nutrient media or industrial waste streams and inoculum are within the scope of the present invention.
A tubular connection 502 with a pressure gauge enables transfer of a portion of reservoir fluid (inoculum) from the sampler or transport vessel 500 to the loaded reaction chamber 48 of the present invention through inlet valve 118. In one embodiment, inlet valve 118 is opened to pressurize tube 502 and allow the nutrient in the reaction chamber that is at the bottomhole temperature and pressure to fill tube 502. Thus, when the sample is introduced into tube 502, it is already full of nutrient substantially at the bottomhole temperature and pressure. Thus, there is no discontinuity in temperature or pressure when transferring the sample from the sampler or transport vessel 500. The floating piston 14 allows for the nutrient to be introduced into the tube 502 and allows the sample to be pulled into reaction chamber 48 using differential pressures, but while preventing sudden pressure losses that result in killing the microbes in the reservoir fluid. During transfer of the sample of the reservoir fluid, the pressure in reaction chamber 48 is maintained at a pressure that is slightly less than the reservoir sample transport vessel 500 to provide for metered fluid flow into reaction chamber 48. The slightly less pressure is close enough to the actual bottomhole conditions that it does not have an adverse effect upon the sample. The position of the floating piston in main cylinder 12 may be gradually adjusted manually or through a control system to allow for a uniform pressure to be maintained in reaction chamber 48 even though the volume of liquid is increasing.
Once the inoculum has been introduced into reaction chamber 48, the pressure and temperature are monitored using thermowell 112 and pressure gauge 114 (both shown in
The growth of microbial consortia of various types may be assessed in the various dilutions of growth media by measuring (1) change in turbidity of growth medium, (2) numbers of microbes per ml (i.e., biomass), (3) volume of headspace gases produced, and (4) other measures of growth now known or hereafter developed. Other assessments may be performed and are within the scope of the present invention. Samples of headspace gases and liquid culture medium may be obtained out of outlet valve 120 for (1) chemical and volumetric analyses of headspace gases and (2) chemical nature of metabolic byproducts in the growth medium from microbial growth such as pH change, surfactants produced, polymers produced, and solvents produced.
By measuring biomass and by chemically analyzing bio-metabolites produced in the laboratory, one obtains accurate data to guide nutrient selection for a targeted reservoir, thereby insuring maximum release of trapped oil and mitigating risk of reservoir damage. Under HTHP culture in the HTHP reactor 10 of the present invention, the byproducts of microbes from a specific oil reservoir could be identified and predictions of growth and metabolism of the microbial consortium in the presence of a given nutrient mix could be obtained. By culturing the consortium in a number of nutrient growth media and chemically and physically measuring acids, gases, solvents, surfactants, biomass, and polymers produced, predictions could be made about specific metabolic byproducts to be expected in a given oil reservoir when injected with a specific nutrient medium at a given optimum formulation and concentration, and for a given optimum time for the injected well system to be shut in for the maximum MEOR effect. The optimum time can be determined by analyzing the metabolism rates for the concentration of nutrient medium or other method as now known or hereafter developed.
Measurements of acid, gas, and biomass production may be obtained in real-time using the instrumentation described below. Typical incubations are expected to take approximately two to six weeks each, and the end point is generally determined by cessation of acid and gas production. The volume and composition of metabolic off gases and pH of the nutrient medium may be analyzed in real-time or periodically in samples removed from the growth chamber to obtain gas-generation (via gas chromatograph) and acid-generation (via pH meter) curves for each reservoir-nutrient combination. Instrumentation is generally incorporated into the HTHP reactor of the present invention to monitor one or more of pH, pressure, temperature, gases, and other parameters and constituents remotely and in real time. Biomass is calculated during and at the end of incubation by cell count, turbidity, filtering and weighing, and/or other measurements to obtain microbial growth curves.
Following incubation, liquid samples are transferred to a chemical laboratory for analysis. HTHP reactor 10 may be cleaned and sterilized using acceptable methods. HTHP reactor 10 may also be disassembled, cleaned with a solvent to remove hydrocarbon residues, and then autoclave-sterilized at 121° C. or equivalent to prepare for re-use.
Now turning to
As shown in
As further shown in
An alternative embodiment not shown includes second end 24 of main cylinder being closed. The closed second end 24 may be machined through milling solid bar stock, or may include an end plate or cap seal welded to second end 24 of main cylinder 12, or any other method known or hereafter developed for producing a pressure resistant closed cylinder end. This alternative embodiment may further include a portion of the closed second end 24 of the main cylinder 12 being configured to allow second end 24 to receive, or be removably coupled to, an element of the pressurization system, including an air hose, a hydraulic hose, or other known components that are used to connect the pressurization system to HTHP reactor 10 for pressurizing the contents of pressurization chamber 46 thereby compressing pistion 14 against the contents of reaction chamber 48.
Piston 14 generally is housed inside cylinder 12 as shown in
As further shown in
Thermal jacket 16 of HTHP reactor 10 generally facilitates adjusting the temperature of reaction chamber 48. In one embodiment of the present invention, thermal jacket 16 is capable of reaching and maintaining a temperature in reaction chamber 48 in a range of about zero degrees Celsius (0° C.) to about one-hundred degrees Celsius (100° C.). As best seen in
The embodiment of thermal jacket 16 shown in
For the most efficient transfer of heat through the cooling channels, the interface between main cylinder 12 and thermal jacket 16 and thermal jacket 16 and lid 18 may be sealed by a plurality of o-rings or other sealing members. Thermal jacket 16 includes at least one seal 84 housed in a notch in inner face 66 proximate second end 62. Thermal jacket 16 may be configured to be secured to lid 18 to create flange seal 76 as shown in
Alternatively, in an embodiment not shown, thermal jacket 16 may include electric heating elements embedded in a thermal jacket or the electric heating elements being otherwise applied to a portion of main cylinder 12. This embodiment necessarily includes a source of electricity including, but no limited to one or a combination of batteries, a generator, or a conventional plug into the public electricity grid. The thermal jacket of this embodiment may be fabric, plastic, carbon fiber, metal or any other configuration now known or hereafter developed that facilitates heat transfer from electric heating elements to main cylinder 12. One embodiment includes thermal jacket being flexible such that thermal jacket can be wrapped around main cylinder 12. The electric heat element is preferably radiant; however, any known electric heating method now known or hereafter developed is within the scope of the present invention. In any event, a thermostat (not shown) or other temperature control device or switch as now known or hereafter developed may be in communication with the thermal jacket of the present invention and activate the thermal jacket as necessary to maintain a temperature that substantially matches the actual bottomhole temperature for that sample.
Lid 18 of HTHP reactor 10 is generally configured to be removably coupled to main cylinder 12 using any pressure resistant connection type known in the art or hereafter developed. Lid 18 is also generally disposed to allowing a technician to mount a plurality of various instruments in communication with reactor chamber 48 to observe the conditions and results of the tests. Lid 18 is generally a solid piece of material wherein the above features are milled or machined into the final piece.
One embodiment of lid 18 shown in
An alternative embodiment shown in
Flange 100, 208 of lid 18, 18′ may also include coupling apertures 104, 218 that compliment the pattern of coupling apertures 86 through flange 72 of thermal jacket 16. The coupling apertures 86 and 104, 218 are configured to facilitate the two members 16 and 18 being temporarily secured together. The temporary coupling of the two flanges 72 and 100, 208 may be achieved using any coupling method now known or hereafter developed including set screws, bolts, and clamps.
As shown in
End cap 20 is generally coupled to second end 24 of main cylinder 12 providing a pressure resistant connection thereby allowing pressure to build up in pressurization chamber 46 and thereby applying pressure to reaction chamber 48 via piston 14. Now turning to
Another embodiment, illustrated in
To construct one embodiment of the HTHP reactor 10 of the present invention, piston 14 is placed within main cylinder 12. Cylinder bottom 142 is placed adjacent to second end 24 of main cylinder 12. End cap 20 is twisted over cylinder bottom 142 about main cylinder 12 and tightened to sandwich cylinder bottom 142 between end cap 20 and main cylinder 12 such that an air tight, pressure resistant connection results. Thermal jacket 16 is slid over first end 22 of main cylinder 12 and lid 18 is twisted upon the threaded first end 22 of main cylinder 12. Thermal jacket 16 is coupled to lid 18, 18′ using fasteners through apertures 84 and 104, 218. The instrumentation desired is selected and mounted in housings 106, 220 on lid 18, 18′. HTHP reactor 10 may be assembled in various different ways and is not restricted to an assembly in a certain order or configuration.
From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.
This application claims the benefit of U.S. Provisional Patent Application No. 61/243,472 having a filing date of Sep. 17, 2009 and is a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 12/884,693 having a filing date of Sep. 17, 2010. The disclosures and teachings of both related applications identified above are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12884693 | Sep 2010 | US |
| Child | 13110758 | US |
