GRAVITY DRAINAGE, STEAM-ASSISTED, ALTERED BY MICROBES.

Abstract

A method and system are described for recovering oil from currently inaccessible oil-bearing geological units by activating a deep biosphere microbial seed bank. The enhancement of nutrients and temperature in these oil-bearing geological units stimulates dormant and / or resting microorganisms to proliferate and generate gas. The reduced oil viscosity, combined with the pressure of the gas generated by the activated microbes, increases oil mobility, allowing previously inaccessible oil to flow into extraction wells.

Description

GRAVITY DRAINAGE, STEAM-ASSISTED, ALTERED BY MICROBES TECHNICAL FIELD 5 The present invention relates to the field of oil extraction of underground oil deposits. BACKGROUND Oil reservoirs are geological units found underground that contain an accumulation of petroleum. The oil from these reservoirs is extracted or recovered using a process commonly known as oil extraction. Conventional oil extraction typically involves two stages: primary recovery and secondary recovery. Primary recovery involves using high-pressure natural forces within the reservoir to drive the oil into the extraction wells. Secondary recovery typically involves maintaining this elevated pressure by pumping fluids within the reservoir so that oil extraction can continue. In oil reservoirs containing heavy oil or oil and sands (also known as oil sands, bitumen, or bitumen sands), the oil is too viscous to flow freely into extraction wells using conventional methods. Therefore, alternative oil extraction methods, such as thermal recovery strategies, must be employed. Thermal recovery strategies involve heating the oil reservoirs to improve the oil's mobility and thus facilitate subsequent extraction. The applied heat reduces the oil's viscosity, allowing it to flow into extraction wells. One example of a thermal recovery strategy commonly used in heavy oil recovery is steam-assisted gravity drainage (SAGD). The SAGD method involves the use of a steam injection well 5 and a extraction well 7 in pairs, as shown in Figure 1 and Figure 2 of the previous technique. The steam injection well introduces steam into the clean sand area 8 of an oil reservoir. The injected steam rises until it reaches geological units that prevent further displacement. The injected steam heats the reservoir to temperatures of approximately 200°C, reducing the oil's viscosity and allowing it to flow into the oil wells. This is referred to as steam chamber 10, shown in Figure 2. Steam is continuously injected to decrease the oil's viscosity, facilitating the continuous flow of oil to the wells and helping to displace the oil from the sand. There are several drawbacks to the SAGD process. A major problem is its negative environmental impact. For example, SAGD processes are a significant contributor to greenhouse gas emissions. This is because large quantities of natural gas must be burned to provide the energy needed to heat the water for steam generation. Not only does burning natural gas contribute significantly to greenhouse gas emissions, but it also represents an added cost to bitumen extraction. Furthermore, the SAGD process also consumes large amounts of water resources for steam production. Since steam production is the primary contributor to the environmental and economic impact of the SAGD method, the environmental efficiency of SAGD operations can be expressed in terms of the steam-to-oil ratio (Gates and Larter, 2014, incorporated herein by reference). The steam-to-oil ratio encompasses both the environmental and economic costs of steam generation relative to the amount of crude oil resources recovered. A lower steam-to-oil ratio means fewer greenhouse gas emissions and improved environmental performance per unit of extraction. The energy costs and greenhouse gas emissions associated with the extraction and production of unconventional oil sands, such as SAGD operations, are approximately 100 to 200% higher than for conventional oil extraction (“The Truth About Dirty Oil: Is CCS the Answer?”, Bergerson & Keith, Environmental Science & Technology, 2010, 44, 6010-6015, (incorporated herein by reference). In this way, new strategies and technologies must be developed to improve environmental and economic performance in oil sands extraction to decrease the steam-to-oil ratio with SAGD operations. Extraction from conventional oil deposits is typically inefficient at extracting all the available oil from the target region. Therefore, many strategies aim to increase oil recovery. Some of these strategies include the use of microorganisms in the subsurface. Subsurface environments are microbial habitats and include a wide variety of microbial taxa. Figure 3 of the previous technique shows a histogram of the abundance ranking order of different microbial taxa in a subsurface environmental sample; adapted from Pedros-Alió (2006) “Marine microbial diversity, can it be determined?”, Trends in Microbiology, Vol 14, No 6, pp 257-263. The bars of the histogram are indistinguishable due to their close proximity. The lighter shaded area 1 on the left of the histogram represents abundant taxa, and the darker shaded area 2 on the right represents rare taxa. Therefore, in a given environmental sample, there is often a large proportion of abundant, reactive microorganisms alongside a variety of low-abundance, inactive, and / or dormant microorganisms.For example, in some microbial communities, one species may comprise up to 20% of the total cells present, while hundreds of rare species may collectively constitute less than 1% of the total. Microbial enhanced oil recovery (MEOR) is a term used to describe conventional oil extraction strategies that aim to use microbial communities to augment and increase oil recovery from conventional oil reservoirs. MEOR is typically used after primary and secondary recovery. With MEOR, microbes are utilized in conventional target regions of the reservoir to enhance oil extraction. MEOR is thought to occur through a variety of mechanisms related to microbial metabolism in oil reservoirs, including the production of Biosurfactants, oil metabolism, and gas production as a metabolic byproduct. Each of the procedures mentioned above helps increase the fluid mobility of the oil, resulting in the production of residual oil still present in the reservoir after primary and secondary recovery strategies. MEOR is typically attempted as a tertiary recovery strategy in conventional oil reservoirs. However, due to the unconventional nature of heavy oil sands bitumen and the unconventional extraction methods used to extract this oil, MEOR strategies are not frequently applied in heavy oil sands. MEOR can be applied to the region that is commonly the target of a heavy bitumen oil unit before or after the application of strategies such as the SAGD method. MEOR involves either: (1) biostimulation, i.e., the injection of nutrients to stimulate the predominant and abundant native taxa, or (2) bioaugmentation, i.e., the injection of foreign bacteria that are considered suitable for the reservoir conditions. The high temperature of the SAGD steam chamber sterilizes the conventional target region of the oil sands reservoir. Therefore, when MEOR is used to increase oil recovery from the SAGD steam chamber of a heavy oil sands reservoir, MEOR can only be applied either before steam is injected into the reservoir or after the SAGD process has ended and the reservoir has cooled to low temperatures. US Patent Application No. 14 / 070,095, incorporated herein by reference, describes a method for injecting foreign bacteria before steam injection as part of SAGD to increase oil fluid mobility in a heavy oil reservoir.In this method, microorganisms are introduced into the tank through both injection and extraction wells, prior to steam injection, to precondition the tank for an increased (shorter) start of the SAGD procedure. USPN 4,475,590, incorporated herein by reference, provides an example of biostimulation in an oil reservoir, Biostimulation in a conventional oil reservoir in conjunction with water flooding technology. Water flooding aims to displace residual oil in the reservoir with water, instead of the steam applied during the SAGD method. Similarly, USPN 4,971,151 and USPN 5,083,611, incorporated herein by reference, describe methods involving nutrient injection into conventional oil reservoirs to enhance oil recovery. However, all these methods focus on active taxa present in relatively high abundance in microbial communities that are adapted for their local prevalence under in situ conditions (temperature, geochemistry, salinity, mineralogy, etc.) and that are easily investigated by microbiological methods. Even so, microbial seed banks exist in almost every environment, comprising many species of microbial taxa present in relatively low abundance. These microbial taxa may be dormant or inactive and may include resting bacterial endospores. Microbial seed banks can constitute significantly less than 0.01% of the total cells present and frequently exist in a dormant state.In this way, they are typically not detected or stand out by most environmental DNA extraction analyses, and other more traditional methods for microbial characterization of petroleum deposit environments. Furthermore, subsurface regions beyond the SAGD steam chamber boundaries, such as inclined heterolithic extracts (IHS), can contain up to twice as many oil sand resources as the targeted steam chamber region. However, oil extraction from the IHS region during SAGD is limited. This IHS oil is interbedded with laterally extensible, low-permeability mudstone layers through which steam cannot penetrate. Therefore, the necessary vapor pressure driving mechanism to displace the oil is not present. Oil in IHS is considered higher quality and more valuable than oil in the steam chamber region because it is less biodegraded and less viscous (“Impact of oil-water contacts, reservoir (dis)continuity”). and reservoir characteristics on spatial distribution of water, gas, and high-water” Fustic et al., 2013, Heavy Oil / Bitumen Petroleum Systems in Alberta & Beyond, Eds. F. J. Hein, J. Sutter, D. A. Leckie, and S. Latter, AAPG Memoir, p. 163-205., incorporado en la presente como referencia en su totalidad). Figure 4 shows a schematic of an example of a geologic unit that is commonly targeted in the Athabasca oil sands subsurface. The lower region represents the target for the placement of steam chamber 10, which is the target region for SAGD. The upper region represents the IHS region 20, which contains oil that is not readily accessible by current methods. Limited oil recovery is documented from the IHS. The diagonal lines in the IHS region represent laterally extensive mud extracts 30 interbedded with decimeter-scale heavy oil or saturated, laterally spreading, porous sands bitumen. Above and below these regions are a lower seal 22 and a lower seal 25, which are not reservoirs and have low permeability. Figure 5 shows a photograph of an oil sands outcrop in Athabasca, near Fort McMurray in Alberta, Canada, by Strobl et al. (1997) from the Canadian Society of Petroleum Geologists, Memoir 18, pp. 375–391. The geologic unit shown in Figure 4 is representative of the geologic unit in the Athabasca oil sands. Referring again to Figure 5, the substantially parallel white lines along the upper half of the geologic unit represent laterally extensive mud extracts from the IHS 20 region and have a slope of approximately six (6) to ten (10) degrees. The lower laterally extensive 35 mudstone layer, as indicated by the arrow, defines the expected upper boundary of the SAGD steam chamber 10 (as demonstrated by subsurface studies, Strobl et al., 1997, Strobl, 2013). Although methods for increasing oil recovery from accessible regions, such as the SAGD steam chamber, are widely researched, accessing oil in the IHS layer remains a challenge using existing technologies. Many initiatives are underway to try to access this oil, such as attempting to break through the shale in the IHS using various methods. Geomechanical, electrical, enhanced solvent extraction incorporating electromagnetic heating (ESEIEH), or thermochemical processes have been explored to access oil. However, these solutions have so far had very limited success. Therefore, there is a need to reduce, if not eliminate, the drawbacks of the previous technique in order to develop, preferably, a method for extracting oil or increasing oil extraction from the IHS regions currently facing challenges from oil deposits. SUMMARY The present invention provides a method and system for recovering oil from currently inaccessible oil-bearing geological units by activating the seed bank of microbes in the deep biosphere. An increase in nutrients and temperature for microorganisms in oil-bearing geological units stimulates dormant and / or inactive microorganisms to proliferate and produce gas. The reduced oil viscosity, combined with the gas pressure produced by the activated microbes, allows previously inaccessible oil to flow into extraction wells. An objective of the present invention is to utilize the conductive heat generated by SAGD, combined with nutrient injection, to enable the extraction of oil trapped in geological formations such as IHS. When used in conjunction with SAGD technology, the present invention may be referred to as the microbe-altered SAGD method or system (MiSAGD). Another objective of the present invention is to access oil deposits that are inaccessible by either conventional oil extraction methods or SAGD, such as units containing oil typically less than 8 meters thick. These thin sediment layers can be thermally treated with hot water (up to 70°C) to reduce viscosity, as well as with nutrients to promote microbial growth (e.g., of dormant thermophiles) to facilitate oil extraction. In such circumstances, the present invention may be referred to as a microbially enhanced thermal oil recovery method or system. (METeOR). In a first aspect, the present invention provides a method for oil recovery from an underground oil reservoir. The method comprises the steps of: (a) using at least one injection well within the subsurface; (b) using a heat source to continuously heat the subsurface; (c) injecting at least one nutrient into the subsurface through at least one injection well; (d) stimulating the activity of at least one gas-producing microorganism located in the subsurface to produce gas pressure; and (e) recovering oil through an extraction recovery well. BRIEF DESCRIPTION OF THE FIGURES The embodiments of the present invention will now be described with reference to the following figures, in which identical reference numbers in different figures indicate identical elements and in which: Figure 1 shows a schematic of an example of a geological unit of oil sands in the earth's subsurface with a pair of injection-extraction wells for S AGD typical of the previous technique; Figure 2 shows a schematic of an example of a geological unit of oil sands in the earth's subsurface with a pair of injection-extractor wells for typical SAGD, and the steam chamber resulting from the above technique; Figure 3 shows a histogram of the abundance ranking order of all microbial taxa in a subterranean environment sample from the above technique; Figure 4 shows a schematic of an example of a geological unit of petroleum sands known in the earth's subsurface; Figure 5 shows a photograph of an oil sands outcrop in Athabasca, near Fort McMurray in Alberta, Canada; Figure 6 shows a bar graph representing bacterial metabolism for sediment samples from the Arctic Ocean seabed under various nutrient and temperature conditions of the above technique; Figure 7 shows a time-resolved line graph of the data that They are presented in Figure 6 of the previous technique; Figure 8 shows a line graph of the monitoring of anaerobic bacterial metabolism as a function of time in oil sands samples incubated at 50°C; Figure 9A, Figure 9B and Figure 9C show three phases of MiSAGD, which include a schematic of a long horizontal nutrient injection well drilled into the IHS region above the SAGD steam chamber of an embodiment of the present invention; Figure 10A and Figure 10B show schematics of the two phases of one embodiment of the present invention, wherein thermal energy is provided by the injection of hot water and nutrients, followed by the oil that is recovered. The figures are not to scale, and some features may be exaggerated or minimized to show details of particular elements, while related elements may have been omitted to avoid obscuring novel aspects. Therefore, the specific structural and functional details described herein should not be construed as limiting but merely as a basis for the claims and as a representative basis for teaching those skilled in the art to use the present invention in various ways. DETAILED DESCRIPTION This document refers to petroleum as a generic term. However, the term petroleum may be used interchangeably with the terms heavy oil, extra-heavy oil, natural bitumen, oil sands, oil sands, bitumen sands, or petroleum. The present invention provides a method for recovering petroleum from inaccessible petroleum-bearing geological units by activating the existing microbial seed bank present in situ. By providing nutrients and a change in temperature for dormant, resting, or scarce microorganisms, including bacterial endospores located in the petroleum-bearing geological units, the microorganisms can proliferate and produce gas for enhanced oil recovery by means of increased pressurization. The supplied heat further lowers the viscosity of the oil, Together with the gas pressure produced by activated microbial communities that were previously dormant or at rest, they combine to allow previously inaccessible oil to flow into an oil extraction well. Microorganisms with thermal limits for growth that are higher than the prevailing in situ temperature are known to exist in sediments, as shown in Figure 6 and Figure 7, and further described in this document. These microorganisms typically exist as part of the dormant or resting seed bank unless or until environmental conditions change, for example, through heating or nutrient supply. Prior to SAGD, a typical oil sands deposit and overlying IHS will be found at approximately 10°C in situ. As oil from the IHS and other less accessible regions is considered less accessible due to the extensive nature of the low-permeability mudstone layers, there is currently no technology that effectively recovers oil from the IHS layers. In one embodiment, the present invention utilizes conductive heat generated by existing thermal recovery methods such as SAGD. Although the high temperatures of 200°C of the injected steam effectively sterilize the steam chamber region itself, the steam cannot penetrate the mudstone layers of the IHS. Therefore, while the 200°C steam chamber is sterilized, the surrounding subsurface areas are not necessarily sterilized because they experience a lower temperature. The present invention utilizes injected steam that flows conductively through both the mudstone and the oil-saturated sand extracts of the IHS region in contact with the SAGD chamber. This generates a temperature gradient from the edge of the hot steam chamber (~200°C) to regions at ambient temperature (~10°C). For example, for a SAGD steam chamber located approximately 400 meters below the surface, the temperature gradient due to heat conduction extends upwards for tens of meters to an elevation where the ambient underground temperature no longer changes. In this way, a large portion of the IHS will have This temperature is much higher than previous in situ temperatures (< 10°C) but below what is understood to be the upper temperature limit for microbial life (~ 121°C). These temperatures are favorable conditions for activating dormant members of the microbial seed bank, such as endospores of thermophilic bacteria that germinate and grow in response to the increase in temperature. Furthermore, in this mode, since the oil sediments in the IHS are heated without additional input, the greenhouse gas emissions associated with CO2 and the energy costs associated with oil extraction from a given operation do not necessarily increase. Therefore, overall greenhouse gas emissions per barrel of oil decrease, and the steam-to-oil ratio may decrease. The conductive heat also reduces the viscosity of the oil and mobilizes oil that is otherwise inaccessible to steam in the regions beyond and / or above the steam chambers. However, although the oil heated in the IHS has a viscosity reduced to a level such that it can flow, approximately 10 cP, there is limited pressure to drive it through the lower, laterally extensive mud layers within the SAGD steam chamber where the production well is located (see Figure 1 and Figure 2). In another embodiment, the present invention promotes gas generation by microorganisms in IHS. This gas generation, in turn, provides a pressure boost for oil extraction. In one embodiment of the present invention, the proliferation of these microbial seed bank microorganisms is enhanced by optimizing the environmental conditions for a given group or groups of microbes. This optimization can be achieved by nutrient and / or microbial cell injection into the IHS. In one aspect, the gas generated by the proliferating microbes provides pressure to drive oil into a production well through the oil-saturated intervals interposed between the laterally extensive, gently sloping (often between 6 and 10 degrees) mud layers. Figure 6 shows a bar graph representing metabolism Bacterial activity in sediment samples from the Arctic Ocean seafloor under various nutrient and temperature conditions. This graph is adapted from Hubert et al. (2010) Environmental Microbiology 12: 1089-1104, combined with unpublished data. The analyzed samples are representative of sediments from permanently ground-level subsurface regions (~4°C). Thus, these samples include heterogeneous microbial communities comprising many strains. The samples were incubated for 5 days under four sets of conditions: (1) ~ 4°C without nutrients, (2) ~ 50°C without nutrients, (3) ~ 50°C with simple nutrients (1 mM of seven different organic acids, each composed of 2 to 4 carbon atoms), and (4) ~ 50°C with complex nutrients (2.5 mg-cm' 3 of freeze-dried algae). Microbial metabolism, a measure of microbial proliferation, is determined by measuring sulfate reduction in experiments. At in situ temperature (~4°C) and without nutrients, minimal microbial metabolism or activity is observed. Therefore, thermophilic microorganisms in the sample can be considered dormant at the in situ temperature. When the temperature is increased to 50°C, metabolism by thermophilic microorganisms becomes evident, indicating a temperature-dependent activation of dormant bacterial endospores. Referring again to Figure 6, the addition of simple nutrients at 50°C increases microbial metabolism by up to two times, and by up to five times with more complex nutrients. Therefore, the activation of dormant sediment microorganisms can be stimulated and increased by the addition of heat and nutrients, with more complex nutrients providing a significantly more growth- and metabolism-promoting environment. Figure 7 shows the three 50°C groups presented in Figure 6 as a line graph illustrating microbial metabolism over time. In addition to the relative proliferation of microorganisms under different conditions, this graph also shows that dormant microorganisms are activated up to 50 hours sooner when enriched with nutrients. The type of gas produced by microorganisms depends on prevailing conditions, such as available nutrients, as well as the specific organisms of interest. Therefore, the gases produced include, but are not limited to, carbon dioxide, methane, nitrogen, ammonia, hydrogen, and hydrogen sulfide. With reference to Figure 8, a line graph of bacterial metabolism is presented for sediment samples from an oil sands deposit incubated at 50°C. This graph shows the monitoring of anaerobic bacterial metabolism as a function of time in oil sands samples incubated at 50°C in the presence of nutrients and without added nutrients. Two depths from the same oil sands deposit were tested, and the average for each experimental bottle is shown in duplicate. The experiment is similar to the incubations shown in Figures 6 and 7 and demonstrates that dormant thermophiles can be activated in oil sands subjected to high temperatures. The addition of nutrients is necessary to stimulate anaerobic metabolism by thermophiles in the oil sands samples.These oil sands were obtained from frozen cores drilled prior to SAGD, so the only heating occurred during the experiments. Two depths (approximately 412 and 430 m below the surface) were tested, each in triplicate. Unadded controls for each depth were tested in duplicate. Figure 9A, Figure 9B, and Figure 9C show a schematic of one embodiment of the present invention. In this embodiment, a long horizontal nutrient injection well 40 is drilled in the IHS region 20 above the SAGD steam chamber 10. In the embodiment shown in Figure 9B, gas 80 can be generated by microbes that have been activated in response to the conductively heated IHS layers. In the embodiment shown in Figure 9C, nutrients 50 are injected from a tank 60 above the surface. The injected nutrients 50 are incubated in the conductively heated IHS region 20 during SAGD, which occurs in the lower steam chamber 10. The dormant microorganisms 70 that can be activated by the conductive heat, as shown in Figure 9B, are further activated and their numbers increased by the nutrients. injected 50 to produce gas 80. In one embodiment, the gas 80 produced by the activated thermophilic microbes 70 provides pressure for the oil between the laterally extensive mud extracts 30 to flow downwards, along the inclined mud extracts into the steam chamber 10 below for oil extraction. In another aspect of the present invention, microbial gas generation is enhanced by determining and utilizing optimal nutrient formulations and temperature changes to promote maximum microbial activation and proliferation. Nutrient formulations can be designed based on either (1) specialized knowledge of the microbial seed bank and anaerobic microbial metabolism, or (2) formulations based on the specific microbial community present in a given reservoir. The latter formulations can be prepared by laboratory testing prior to site-specific characterization of the microbial seed bank of a given IHS region using samples taken from that IHS region. The prior characterization may include studies on how best to stimulate the particular seed bank at different anticipated temperatures.IHS sediment samples will typically be available from drill cores taken during a subsurface exploration survey or during the drilling process of SAGD injector-extractor well pairs. Nutrient formulations may include growth substrates that are carbon-based organic compounds, nitrogen and phosphorus compounds, metal compounds, vitamins, or various electron acceptors such as oxygen, nitrate, metal oxides, and sulfates. Nutrient formulations can be specialized and site-specific, as described above, or they can be applied in a standardized manner based on specialized knowledge of the general physiology of gas-generating anaerobic microbial consortia. In one embodiment, the present invention aims to propel the oil into the steam chamber along the slight slope of the laterally extensive mud extracts, rather than attempting to break down the mudstone boundary of the gas chamber as in existing techniques. Thus, in some embodiments, the present The invention utilizes existing oil extraction wells 7, for example, as shown in Figure 1 and Figure 2, to extract oil from the IHS region. In some embodiments of the claimed invention, additional extraction wells are drilled within the IHS region. One advantage of some embodiments of the present invention is a reduction in oil extraction costs per barrel of oil extracted, compared to the traditional SAGD method, because the costs associated with nutrient injection are likely to be lower than those of steam generation. Thus, the embodiments of the present invention will provide a considerable increase in oil extraction with only an increase in the differential cost for additional nutrient wells and without any change to the SAGD method. An additional advantage of the embodiments of the present invention is that they aim to reduce the steam-to-oil ratio. Therefore, with the same amount of steam used in the traditional SAGD method, the embodiments of the present invention allow for the extraction of a significantly larger quantity of oil, thereby reducing the relative amount of greenhouse gas emissions per unit of oil extracted. Additionally, because the oil in the IHS region is less biodegraded and viscous compared to the steam chamber, it is commercially more valuable. Furthermore, the reduced viscosity requires less energy to flow through oil extraction wells. Furthermore, when heated, the less biodegraded oil in the IHS region is susceptible to supporting gas-producing microbial activity if it can be further biodegraded. Thus, in some embodiments of the present invention, naturally occurring oil in the IHS region can contribute as a nutrient source for microbial growth. In another embodiment of the present invention, gas-producing microorganisms can be injected into the IHS region as a form of bioaugmentation. Site-specific laboratory testing is required to determine the ideal nutrient and / or bioaugmentation formulations. In one embodiment of the present invention, the The injected gas-generating microorganisms may originate from seed bank microorganisms isolated and cultured from the corresponding deposit core samples. In another embodiment of the present invention, the injected gas-generating microorganisms may be standard microbial species or consortia known as gas generators under high-temperature anoxic conditions. In some embodiments of the present invention, access to a large portion of the subsurface region may be desirable. Therefore, the present invention includes embodiments that incorporate more than one nutrient injection well. The nutrient injection wells can be drilled at different heights and depths (shallow or deep), horizontally, directionally, and / or vertically, depending on the target area for nutrient injection. The decision to drill fewer or more nutrient injection wells, or horizontal and / or vertical wells, can be determined based on the characteristics of a particular site and the calculated cost-benefit ratios. In some embodiments of the present invention, horizontal wells can be used to target the stimulation of particular areas within the geological unit based on temperature or microbiological conditions. In another embodiment of the present invention, the horizontal wells can be similar to horizontal SAGD wells. The horizontal wells can also be up to 1 km in length or larger horizontally and / or have access to the entire oil reservoir area. In one embodiment of the present invention, nutrient injection wells can be drilled from the same surface location or infrastructure as existing extraction wells, such as SAGD extraction well pads. Therefore, in these embodiments, where the technology is used in conjunction with another oil recovery method, such as SAGD, these additional wells are likely to represent a smaller incremental deployment cost. In another embodiment, the present invention can be used in a normally inaccessible area, such as the IHS region before or after the SAGD method. The heat generated from oil recovery strategies such as For example, the SAGD method is only accessible while the SAGD method is active and in operation. Therefore, when the present invention is used before or after the SAGD method, hot water can be injected as a thermal enhancement to maintain optimal temperature conditions for microbial seed bank activation, microbial proliferation, and gas generation. The hot water can be injected continuously or periodically. In some embodiments of the present invention, the hot water can be injected with nutrients and / or microbes. In another embodiment of the present invention, hot water can be injected during the SAGD method to supplement the heat of a particular region of the IHS. In another embodiment, the method of the present invention may involve site-specific local monitoring tests and preparations for enhanced oil recovery, including: (i) show from one or more underground deposit cores from one or more petroleum deposit sites of interest, e.g., IHS core samples; (ii) microbial diversity analysis targeting rare seed bank organisms and laboratory-based characterization of in situ deposit microbial communities in sediments - this may involve temperature gradient incubations simulating SAGD conductive heating of overlapping IHS; (iii) laboratory-based determination of substrates, nutrients, and temperatures that are optimal for gas generation from dormant microbial communities present in the sediments of the site of interest; (iv) simulation of thermal heat with respect to time, for example by conductive heating modeling in a steam chamber, to identify high temperature conditions for optimal microbial gas generation based on the physiology of the seed bank microorganisms without additional intervention; (v) modeling of additional gas generation if nutrients are provided to the resting microbial community and / or search for germination of bacterial endospores that can be found in response to temperature and / or nutrients; and (vi) implementation of the enhanced oil recovery strategy at the oil deposit site of interest. The present invention includes a method for recovering oil from a petroleum reservoir in the earth's subsurface. In this method, an injection well is used in the subsurface to inject at least one nutrient. A heat source is used to continuously heat the subsurface before, during, or after the injection of the at least one nutrient. Gas-generating microorganisms located in the subsurface are incubated to produce gas pressure, which forces the oil toward the extraction well for recovery. In one embodiment of the present invention, the injection, incubation, and extraction steps described above can be repeated cyclically. In another embodiment of the present invention, oil extraction can be carried out concurrently with the incubation of the microbes with injected nutrients. In a further embodiment, the present invention can be applied to microbial seed bank organisms in underground heavy oil reservoirs that are currently inaccessible by, or attractive to, conventional and / or thermal recovery methods (i.e., SAGD), such as relatively thin layers of oil-saturated sand. In these thin reservoir zones, the SAGD method is generally not used because it is considered not economically justifiable. In this embodiment, since thermal energy cannot be obtained from a concurrent thermal strategy such as the SAGD method, thermal energy must be introduced into the sediment by other means. In one embodiment of the present invention, thermal energy can be supplied to the target area by hot water injection, as previously mentioned. Figure 10A shows the first phase of this embodiment. A nutrient injection well 40 injects hot water, nutrients, and optionally microbes 55 from a tank 60 above the surface. In one embodiment of the present invention, the hot water, nutrients, and optional microbes 55 are flowed in a manner stable within the oil reservoir 25 to reduce viscosity by heat and activate and incubate the microbial community, which includes a resting seed bank so that it generates gas that provides pressure to drive oil extraction. Figure 10B shows an embodiment of the second phase of the embodiment of the present invention shown in Figure 10A. In this embodiment, the nutrient injection well 40 can also function as an extraction well. In one embodiment, the heated and therefore less viscous oil is propelled by the gas generated by the microorganisms in phase one (Figure 10A) into the extraction well (Figure 10B). The temperature of the hot water can vary based on the preferences of the target microbial community. The hot water heats the sediments and, along with nutrients, reduces the viscosity of the oil and can help pressurize the reservoir. This activates the high-temperature-adapted microbes, causing them to proliferate and generate gas that increases the in-situ pressure, resulting in increased flow and oil extraction. In one embodiment of the present invention, hot water can be injected to facilitate oil extraction, and the injection / extraction process is repeated at the injection / extraction site. In some embodiments, the period of the injection / extraction cycles can be specific to the reservoir and can be determined by prior attempts at a conventional cold oil extraction temperature. In one embodiment of the present invention, these alternating sites can continue until oil extraction ceases. In another embodiment of the present invention, the incubation of microorganisms in underground sediments with hot water and nutrients can last for more than several months. In a further embodiment of the present invention, oil extraction can last up to 6 months or more. In some embodiments of the present invention, nutrient injection wells and / or hot water injection wells can also be used for oil extraction. In some embodiments of the present invention, the supplementary thermal energy provided by the hot water can be used to supplement the primary cold temperature oil extraction or secondary oil extraction such as with water flooding technology. A person understands that this invention can now be conceived with alternative structures and modalities or variations thereof, the entirety of which is intended to be within the scope of the invention as defined in the following claims.

Claims

CLAIMS 1. A method for recovering oil from the subsurface of an underground oil reservoir, characterized in that it comprises the steps of: (a) use at least one injection well within the subsoil; (b) use a heat source to continuously heat the subsoil; (c) inject at least one nutrient into the subsoil through at least one injection well; (d) stimulate the activity of at least one gas-producing microorganism located in the subsoil to produce gas pressure; and (e) recover oil through an extraction recovery well.

2. The method according to claim 1, characterized in that the heat source is a heat-conducting byproduct of gravity-drained oil recovery, assisted by steam.

3. The method according to claim 1, characterized in that the heat source is hot water.

4. The method according to claim 1, characterized in that steps (b) and (c) are interchangeable in the method.

5. The method according to claim 1, characterized in that steps (b) and (c) are performed concurrently.

6. The method according to claim 1, characterized in that at least one gas-generating microorganism is bacterial.

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