Thermally Assisted Oil Production Wells
A method and system are shown that conditions an underground reservoir by flooding the reservoir with a heated fluid to transfer heat to the underground reservoir and cause oil and gas to increase flow during recovery from the underground reservoir, wherein the fluid is heated by heat from a geothermal well, or heated by heat generated by burning gas recovered from the underground reservoir, or heated by heat from both a geothermal well and heat generated by burning gas recovered from the underground reservoir, and recovering the oil and gas with the increased flow.
The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/061,437 filed Oct. 8, 2014, U.S. Provisional Patent Application Ser. No. 62/061,426 filed Oct. 8, 2014, and U.S. Provisional Patent Application Ser. No. 62/061,420 filed Oct. 8, 2014, each of which are hereby incorporated by reference in their entirety.
FIELD OF THE INVENTIONThe present invention relates to thermally-assisted oil production wells, for use in recovering oil from an oil reservoir.
BACKGROUND OF THE INVENTIONIn petroleum geology, a reservoir is a porous and permeable lithological unit or set of units in a formation that hold hydrocarbon reserves such as crude oil and natural gas. The flow rate (Q) of the hydrocarbon reserves through such a formation may be determined according to Darcy's Law:
where Q is the flowrate (in units of volume per unit time), κ is the relative permeability of the formation (typically in millidarcies), A is the cross-sectional area of the formation, μ is the viscosity of the fluid (typically in units of centipoise), and ∂p/∂x represents the pressure change per unit length of the formation that the fluid will flow through.
Crude oil viscosity (κ) is its resistance to flow. It may be viewed as a measure of its internal friction such that a force is needed to cause one layer to slide past another. Newton's law of viscosity states that the shear stress between adjacent fluid layers is proportional to the negative value of the velocity gradient between the two layers. Alternatively, the law may be interpreted as stating that the rate of momentum transfer per unit area, between two adjacent layers of fluid, is proportional to the negative value of the velocity gradient between them. The unit of viscosity in cgs units is dyne·sec/cm2 (1 dyne-sec/cm2 is called a poise (P)). From the units, it will be evident that viscosity has dimensions of momentum per unit area. One Poise (P) in mks units is 0.1 kg·m−1·s−1. The SI unit for viscosity is the pascal·second (Pa·s) which equals 10P. A centipoise is one-hundredth of a poise and one millipascal·second (mPa·s).
API (American Petroleum Institute) gravity is an inverse measure of the relative density, as compared to water, of crude oil. It is measured in units called API degrees (°API). The lower the number of API degrees, the higher the specific gravity of the oil. If greater than 10, the oil floats in water. If less than 10, it sinks in water.
The permeability to flow through a rock for the case where a single fluid is present is different when other fluids are present in the reservoir. Saturation, the proportion of oil, gas, water and other fluids in a rock is a crucial factor in a pre-development evaluation of the reservoir. The relative saturations of the fluids as well as the nature of the reservoir affect the permeability. Crude oil mobility (λ0) is the ratio of the effective permeability (κ0) to the oil flow to its viscosity (μ0):
λ0=κ0/μ0
The effective permeability characterizes the ability of the crude oil to flow through the rock material of the reservoir. As will be evident from the above-mentioned Darcy's Law, permeability should be affected by pressure in the rock material. The millidarcy unit mentioned above in connection with the typical unit used for permeability (κ) is related to the basic unit of permeability measure, m2 in the mks system. The darcy is referenced to a mixture of unit systems. A medium with a permeability of 1 darcy permits a flow of 1 cm3/s of a fluid with viscosity 1 cP (1 mPa·s) under a pressure gradient of 1 atm/cm acting across an area of 1 cm2. A millidarcy (md) is equal to 0.001 darcy. Rock permeability is usually expressed in millidarcys (md) because rocks hosting hydrocarbon or water accumulations typically exhibit permeability ranging from 5 to 2000 md.
Thus, the principle used herein is that heat applied to a reservoir increases its permeability and reduces the viscosity of the crude oil to increase the oil mobility. In other words, lowering oil viscosity with heat increases the flow rate of the oil. Conventional heating methods include cyclic steam injection, steam flooding and fire flooding. For cyclic steam injection, steam may first be injected into a well for a few days or weeks. Then the heat is allowed to dissipate into the reservoir for a few days to reduce oil viscosity. Finally, the production begins with improved flow rate. The three step process is then repeated e.g. after the flow rate diminishes. In steam flooding some wells are used for injecting steam and others for oil production. The steam flood acts to both heat the reservoir and push the oil by displacement toward the production wells. In many cases gravity is also used to move the oil toward the production well. Fire flooding is where combustion generates heat within the reservoir itself.
It should be realized that the viscosity is affected by temperature, pressure, and by composition. Among others, the following conditions impact oil flow rate:
1) Crude oils contain substantial proportions of saturated and aromatic hydrocarbons with relatively small percentages of resins and asphaltenes and other substances as listed in Table 1. More degraded crude oils contain substantially larger proportions of resins and asphaltenes. Heavy crude oil (API<22) occurs when the oil contains paraffin and/or asphaltenes and the temperature of the oil reservoir is too low. See Table 1 above for melting or liquification points and see also
2) Crude oil (including light crude oil API>30) viscosity increases as it cools due to one or more of the following conditions:
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- a) the oil reservoir is shallow and the temperature of the reservoir is low;
- b) it is heavy crude oil (API<22);
- c) the oil reservoir is deep and the oil cools as it is pumped out of the well;
- d) the ambient temperature is extremely cold and the oil cools quickly as it is exposed to the cold near or at the surface; and
- e) any set of conditions where the oil cools and the viscosity increases and this adversely effects the efficiency of the oil flow in a production well.
As will be appreciated from the foregoing, heating the reservoir to remove barriers to the flow of fluids into a well will tend to lower the viscosity of the fluids so that the existing permeability will allow the oil to flow with an increased rate and hence increased volume to the production wells. An important teaching hereof is to burn crude oil or natural gas extracted from an underground reservoir (or burn both crude oil and natural gas extracted from the underground reservoir), in order to provide thermal energy. In other words, the teaching is to supply the necessary power and materials from the reservoir itself to mobilize the oil and move it to the production wells. A heat source fed by fuel produced from the reservoir accomplishes the production of heat. It does so in such a way, as shown below, as to allow enhanced oil recovery that is environmentally benign.
A gas flare, alternatively known as a flare stack, is a gas combustion device used in industrial plants such as petroleum refineries, chemical plants, and natural gas processing plants as well as at oil or gas production sites having oil wells, gas wells, offshore oil and gas rigs and landfills. When petroleum crude oil is extracted and produced from onshore or offshore oil wells, raw natural gas associated with the oil is produced to the surface as well. In areas of the world lacking pipelines and other gas transportation infrastructure, vast amounts of such associated gas are commonly flared as waste or unusable gas. The flaring of associated gas may occur at the top of a vertical flare stack or it may occur in a ground-level flare in an earthen pit.
Every year, billions of dollars' worth of natural gas goes up in smoke, as companies burn off gas released during oil production—a common practice known as gas flaring. The amount of natural gas being flared and vented annually is astronomical. It is equivalent to 25 percent of the United States' annual gas consumption, 30 percent of the European Union's annual gas consumption, 75 percent of Russia's annual gas exports, and more than the combined gas consumption of Central and South America. In Africa alone, the annual amount of gas flared is equivalent to half the continent's power consumption.
Gas flaring has a global impact on climate change by producing about 400 million tons of greenhouse gas emissions annually. Residents in communities near gas flaring have experienced chronic health problems, including bronchial, chest, rheumatic, and eye problems.
A typical oil production well design is illustrated in
The present invention provides a solution to the aforementioned problems and changes the high viscosity oil to a lower viscosity oil by providing thermally assisted oil production wells using thermal methods based on geothermal well-generated heat and/or flaring gas, and eliminates or reduces the environmental impact of flaring gas or burning fossil fuels in land based and offshore-based crude oil production wells.
The invention can be used for light crude oil, heavy crude oil, extra heavy crude oil, bitumen, tar sands, oil sands and shale oil.
According to a first aspect of the invention, a system for recovering oil, gas or oil and gas from a reservoir beneath a surface is provided. The system includes at least one production pipe for receiving the oil and gas in the reservoir, at least one pump configured to pump the oil and gas to the surface, a casing surrounding the at least one production pipe, and at least one heating element in parallel with the production pipe configured to provide heat to the oil and gas being pumped to the surface.
According to a first embodiment of the first aspect of the invention, the at least one heating element comprises one or more electric heating cables. The one or more electric heating cables can be positioned in a fluid heating chamber within the casing and surrounding the at least one production pipe. The one or more electric heating cables radiate heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe. According to another embodiment, the one or more electric heating cables can extend into a heating cocoon surrounding a portion of the casing. In this embodiment, the reservoir can be underwater and the portion of the casing surrounded by the heating cocoon is underwater, such that the heating cocoon heats the water surrounding the casing and the at least one production pipe.
According further to the first embodiment of the first aspect of the invention, the at least one pump is configured to pump brine or water from the reservoir to the surface, and provide pumped oil, gas and brine to a separator configured to separate oil, gas and brine. A portion of the separated oil, gas or oil and gas is provided to an electricity generator to fuel the electricity generator. This portion of the separated oil, gas or oil and gas can include flared gas. The electricity generator provides electricity to the one or more electric heating cables. The generation of electricity by the electricity generator further creates an exhaust gas, and the exhaust gas can be mixed with the separated brine to create a mixture of gas and brine that is injected into the reservoir to increase the flow of oil and gas in the reservoir to the at least one production pipe. The mixture of gas and brine can be injected into a perforated pipe positioned in the reservoir beneath the casing.
According to a second embodiment of the first aspect of the invention, the at least one heating element comprises one or more heating pipes transporting a heating substance. The one or more heating pipes can be arranged in a fluid heating chamber within the casing and surrounding the at least one production pipe. The one or more heating pipes include perforations and provide heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe. In an alternate embodiment, the one or more heating pipes extend into a heating cocoon surrounding a portion of the casing. In a further alternate embodiment, the one or more heating pipes include at least one heating pipe within the at least one production pipe.
According further to the second embodiment of the first aspect of the invention, the at least one pump is further configured to pump brine or water from the reservoir to the surface, and provide pumped oil, gas and brine to a separator configured to separate oil, gas and brine. A portion of the separated oil, gas or oil and gas is provided to a heating source configured to heat a fluid. This portion of the separated oil, gas or oil and gas can include flared gas. In one embodiment, the heat source is a boiler configured to heat a fluid, and it creates an exhaust gas in the process. The exhaust gas can be mixed with the separated brine by a heat exchanger and mixer to create a mixture of gas and brine that can injected into the reservoir through the one or more heating pipes to increase the flow of oil and gas in the reservoir to the at least one production pipe. In an embodiment, the mixture of gas and brine is injected into a perforated pipe positioned in the reservoir beneath the casing. The system may further include a plurality of horizontal bore holes in the reservoir, and the one or more heating pipes extend into the plurality of horizontal bore holes.
According to a second aspect of the invention, a method for recovering oil, gas or oil and gas from a reservoir beneath a surface is provided. The method includes providing at least one production pipe for receiving the oil and gas in the reservoir and a casing surrounding the at least one production pipe, pumping oil and gas to the surface with at least one pump; and heating the oil and gas being pumped to the surface with at least one heating element in parallel with the production pipe.
According to a first embodiment of the second aspect of the invention, the at least one heating element comprises one or more electric heating cables. The one or more electric heating cables are in a fluid heating chamber within the casing and surrounding the at least one production pipe, and the one or more electric heating cables radiate heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe. The one or more electric heating cables radiate heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe. According to another embodiment, the one or more electric heating cables can extend into a heating cocoon surrounding a portion of the casing. In this embodiment, the reservoir can be underwater and the portion of the casing surrounded by the heating cocoon is underwater, such that the heating cocoon heats the water surrounding the casing and the at least one production pipe.
According further to the first embodiment of a method according to the invention, the method further comprises pumping brine or water from the reservoir to the surface by the at least one pump together with the pumped oil and gas, providing the pumped oil, gas and brine to a separator, and separating the oil, gas and brine. The method further comprises providing a portion of the separated oil, gas or oil and gas to an electricity generator to fuel the electricity generator. The portion of the separated oil, gas or oil and gas can include flared gas. According further to the embodiment, the method further comprises generating electricity by the electricity generator and providing electricity to the one or more electric heating cables. The generation of electricity by the electricity generator creates an exhaust gas, and the method further comprises mixing the exhaust gas with the separated brine to create a mixture of gas and brine and injecting the mixture into the reservoir to increase the flow of oil and gas in the reservoir to the at least one production pipe. The mixture of gas and brine is injected into a perforated pipe positioned in the reservoir beneath the casing.
According to a second embodiment of the second aspect of the invention, the at least one heating element comprises one or more heating pipes. The one or more heating pipes can be in a fluid heating chamber within the casing and surrounding the at least one production pipe, and the one or more heating pipes comprise perforations and provide heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe. In an alternative embodiment, the one or more heating pipes extend into a heating cocoon surrounding a portion of the casing. In a further alternative embodiment, the one or more heating pipes include at least one heating pipe within the at least one production pipe.
According further to the second embodiment of the second aspect of the invention, the method further comprises pumping brine or water in the reservoir to the surface by the at least one pump together with the pumped oil and gas, providing the pumped oil, gas and brine to a separator, and separating the oil, gas and brine. The method further comprises providing a portion of the separated oil, gas or oil and gas to a heating source configured to heat a fluid. A portion of the separated oil, gas or oil and gas can include flared gas. In one embodiment, the heat source is a boiler configured to heat a fluid. The heat source creates an exhaust gas, and the method further comprises mixing the exhaust gas with the separated brine to create a mixture of gas and brine and injecting the mixture into the reservoir to increase the flow of oil, gas or oil and gas in the reservoir to the at least one production pipe. The mixture of gas and brine is injected into a perforated pipe positioned in the reservoir beneath the casing. The method can further comprise providing a plurality of horizontal bore holes in the reservoir, and extending the one or more heating pipes into the plurality of horizontal bore holes.
According to a first embodiment of the invention shown in
The well 100a heats the oil in the reservoir 107 and in the oil production pipes 105 so that the viscosity of the oil is always at a point where the oil flows more efficiently. This is accomplished by using geothermally generated heat and/or by burning the flaring gas or other fuels and using the heat generated from the burning fuels. The exhaust from the burning flaring gas or fuel is injected back into the well by mixing it with the separated brine using an injection well drilled for this purpose.
The advantages of this method are delivering heat to the reservoir 107 while also delivering CO2, a byproduct of burning the flaring gas or other fuels in a boiler to the reservoir. The injection provides the benefits of water flooding, thermal flooding and CO2 flooding.
As the well 100a is drilled, a casing 101 is installed. This casing 101 is generally waterproof or can be waterproofed and is insulated. Heating chamber 102 forms a cocoon of heat that surrounds the oil production pipe 105 and isolates and heats the extracting oil keeping it at a low viscosity or lowering its viscosity. The heating chamber 102 is part of a closed loop system that continuously heats the extracting oil. A seal (or plug) 103 is positioned at the bottom of the well at the beginning of the oil reservoir pay zone (i.e., top of the oil reservoir 107), so that a water proof seal is established separating the bore from the oil collection zone (i.e., oil reservoir 107). This seal forms the bottom of the heating chamber 102. The casing 101 is perforated 104 from the seal 103 to the bottom of the well 100a to allow the oil to enter the cased area. An oil production pipe 105 is installed after the well 100a is drilled and after the casing 101 is perforated 104. The seal 103 is installed after the oil production pipe 105 is installed. The oil production pipe 105 is the transport mechanism for delivering the oil to the surface.
A submersible pump 106a and/or a pump 106b on the surface, pump the oil entering the well 100a through the perforations 104 up to the surface. The efficiency of the pump 106a, 106b correlates to the viscosity of the oil. More barrels of oil can be pumped on a per day basis when the viscosity of the oil is lowered. The width of the reserve (pay zone), the saturation of the oil, the permeability of the rock and the viscosity of the oil determine the rate of extraction and the amount of oil that can be harvested form the reservoir 107.
Hot water is pumped through one or more heating pipes 108 into the heating chamber 102. To prevent the hot liquid water from vaporizing into steam, the injected water is pressurized. The heating pipe 108 has specially drilled holes, called heating jets 109, drilled at strategic locations to heat the chamber 102 at various depths. The size and placement of the heating jets 109 has to allow the heat of the water to compensate for the loss of heat of the extracting oil at that position in the well 100a. The heating pipes 108 are installed by drilling through the top of the casing 101 and welding the pipes 108 to the casing 101 or to additional reinforced steel piping that would be installed.
As the oil, gas and brine is extracted from the well the oil, gas and brine 120 goes through a separation system 110 that separates the oil 114, the gas 115 and the brine 116. The separated oil 114 can be shipped to a processing destination. The separated gas 115 is burned and the exhaust 118, mostly comprised of CO2, is merged with the brine 116. The separated brine 116 mixed with the gas exhaust 118 by a heat exchanger/mixer 117 and the mixture 119 is injected into the reservoir 107 in one or more injection wells to maintain reservoir pressure. The CO2 and hot brine mixture 119 interacts with the oil lowering its viscosity.
Hot water is delivered from a heating source 111 into the heating chamber 102 on a continuous basis, and returned to the heating source 111 for re-heating. A heat delivery pipe 112 is a small manifold that supplies several heating pipes 108 with hot water from the heating source 111. After the hot water in the heating chamber 102 delivers heat to the extracting oil, it is returned to the heating source 111 via a heating source return pipe 113 to be reheated in a closed loop system.
A second embodiment of a thermally assisted oil production well, and a variation thereof, are shown in
The wells 100b, 100c shown in
As described with respect to the well 100a of
A submersible pump 106a and/or a pump 106b on the surface, pump the oil entering the well 100b through the perforations 104 up to the surface. Hot and pressurized liquid water is pumped through one or more heating pipes 108 into the heating chamber 102. In contrast to the well 100a shown in
The heating pipes 108 are extended deeper into the oil reservoir 107 by drilling horizontal bores to allow the hot brine or oil to penetrate the oil reservoir 107. The placement of the horizontal bores with the heat pipes 108 installed is modeled to maximize the heating of the reservoir 107. The reservoir heating jets 121 are drilled into the bottom of the heating pipe 108 at one or more locations. Heated brine 116 with the combined exhaust (CO2) 118 from burning flaring gas is pumped into the oil reservoir 107, heating the extractable oil and lowering its viscosity. A toroidal convection can be established which will increase the spread of heat and increase the flow of oil. When the reservoir heating jets 121 are installed, the performance can be increased by drilling the horizontal bore holes to spread the heated brine 116 and CO2 118 into the reservoir 107. The horizontal bore holes can have a slotted liner. The reservoir heating jets 121 can be extended into the horizontal bore holes.
As the oil, gas and brine is extracted from the well the oil, gas and brine 120 goes through a separation system 110 that separates the oil 114, the gas 115 and the brine 116. The separated oil 114 can be shipped to a processing destination. Hot water is delivered from a heating source 111 into the heating chamber 102 on a continuous basis, and returned to the heating source 111 for re-heating.
In the well 100c shown in
The larger the heating pipes 108 are the more heat can be delivered to the oil reservoir 107. Maximizing the heat delivered to the oil reservoir 107 creates a larger change in the oil viscosity and increase the amount of oil that can be extracted. Heating the oil and adding CO2 in the reservoir 107 lowers oil viscosity, changes surface tensions, heats the oil to release gas that pressurizes the oil capsules and creates convection in the reservoir 107 that helps spread the heat.
A third embodiment of a thermally assisted oil production well, and a variation thereof, are shown in
According to an embodiment shown in
Hot water 204 from the boiler 202 is distributed and pumped to heat delivery wells 203. Heated water 204 transfers heat to oil reservoir 214 heating the oil 212 and lowering the oil viscosity. Cooled water is returned to the geothermal well 201 and/or the boiler 202 for re-heating. The exhaust gas 209 (CO2) from the boiler 202 is sent to the heat exchanger/mixer 207 for mixing with the brine 208 to create a mixture 206 of brine and CO2. The cooled water from the heat exchanger 207 is returned to the geothermal well 201 and/or the boiler 202 for re-heating.
A second loop is provided in addition to the loop described above. Oil and brine flows through slotted liners and is pumped to surface by a submersible pump of the production wells 215. Brine 208 and gas 205, usually flared gas, are separated from oil 210.
The flared gas 205 is sent to the boiler 202 for burning. Separated brine 208 from the oil production wells 215 is heated and combined with exhausted gas 209 by the heat exchanger/mixer 207 and pumped back into the reservoir 214 as a mixture 206, for flooding 211 the reservoir 214 as previously described. Replaced heated water and heat expansion maintains reservoir pressure.
A variation on this embodiment is shown in
Additional embodiments for incorporating a thermally assisted oil production well with an offshore oil reservoir are shown in
As shown in
As shown in
Further embodiments of the invention are shown in
The heat source system shown in
A boiler 412 can be used to augment the geothermal well 401 or replace the geothermal well 401 for the heat required. The boiler 412, when used to burn gas 416 that is usually released or flared, has a low cost as it uses heat that is normally wasted. The boiler 412 can also burn fossil fuel and/or crude oil. When the boiler 412 burns gas 416 from the oil extraction, the exhaust is scrubbed by an exhaust scrubber 414 and the exhaust 417 is mixed with brine by a mixer 415 for injection into an oil reservoir. There is therefore an enormous reduction in the negative environmental impact of the flaring of the gas. Flaring gas is estimated to be responsible for over 30% of the world's carbon pollution.
Additionally, if an additional heat source 413, such as waste heat or electrical resistant heat, is available, the other heat source 413 can be used to supply additional heat. For example, on an offshore oil platform where it would be more difficult to implement a geothermal well, waste heat or a combination of waste heat, electrical heat and/or a boiler can be used to supply the heat source for heating and/or flooding the oil reservoir. As shown in
An embodiment of a further system according to the invention is shown in
As shown in
According further to the inventions, embodiments of thermally assisted wells are provided, which in contrast to the wells 100a-100c of
The thermally assisted well 600a of
The well 600a comprises a casing 601, which can be in an embodiment, cement and a steel pipe. The casing 601 should be insulated to reduce heat loss. The fill 602 is also provided, which in many instances is already present in a production well. Examples of a fill 602 include treated water or diesel fuel. One or more seals (or plugs) 603 are provided at the bottom of the well 600a at the beginning of the oil reservoir 607 pay zone (i.e., the top of the oil reservoir 607) to establish a seal separating the bore from the oil collection zone (i.e., the oil reservoir 607). The casing 601 further includes perforations 604 from the seal 603 to the bottom of the well 600a to allow the oil to enter the cased area. An oil production pipe 605 is preferably installed after the well is drilled and after the casing 601 is perforated 604. The seal 603 is preferably installed after the oil production pipe 605 is installed. The oil production pipe 605 is the transport mechanism for delivering the oil to the surface. If the oil production pipe 605 can be insulated, it will decrease the loss of heat and improve the viscosity of the oil being transferred through the oil production pipe 605 from the oil reservoir 607.
A submersible pump 606a and/or a surface pump 606b pump the oil that is entering the well 600a through the perforations 604 up to the surface. The efficiency of the pumps 606a, 606b correlates to the low viscosity of the oil. The submersible pump 606a is located lower in the well 600a also pumps the oil and is effected by the viscosity of the oil.
The width of the reservoir 607, the saturation of the oil, the permeability of the rock, the porosity of the reservoir 607 and the viscosity of the oil determine the rate of extraction and the amount of oil that can be harvested form the reservoir 607.
Oil and/or brine 612 that has been extracted and heated by a heat exchanger 613 is injected into the well 600a through a heating pipe 608 that is installed inside the oil production pipe 605. The oil production pipe 605 has specially drilled holes, called heating jets 609, drilled at strategic locations to heat the oil being extracted at various points in the oil production pipe 605. The size and placement of these jets 609 allows the heat of the injected oil or brine to compensate for the loss of heat of the extracting oil at that position in the well 600a. The brine from heating jets 609 raises the temperature of the extracting fluid in the reservoir 607.
As the oil and brine are extracted from the well 600a, the oil and brine go through a separator 610 that separates the oil 614 from the brine 615. The separated oil 614 can be shipped to a processing destination. The separated brine 615 is usually injected into the reservoir 607 to maintain reservoir pressure or it is shipped to a disposal injection well. If the oil and/or brine 612 are used as the heat delivery fluid the injection volumes are removed from the separator 610. Heat is delivered from a heat source 611, such as a boiler, into the heat exchanger 613. The small portion of the brine and/or oil 612 from the separator 610 is heated by the heat exchanger 613 and injected back into the well 600a by way of the heat pipe 608, to merge with the cooling extracted oil to re-heat the oil and maintain the oil's low viscosity as it rises through the oil production pipe 605.
A further embodiment of a thermally assisted oil production well without using exhaust gas, and a variation thereof, are shown in
The wells 600b, 600c shown in
As described with respect to well 600a of
A surface pump 606b pumps the oil that is entering the well 600b through the perforations 604 up to the surface. The efficiency of the pumps 606a, 606b correlates to the low viscosity of the oil. The submersible pump 606b is located lower in the well 600a also pumps the oil and is effected by the viscosity of the oil.
Oil and/or brine 612 that has been extracted and heated by a heat exchanger 613 is injected into the well 600a through a heating pipe 608 that is installed inside the oil production pipe 605. The oil production pipe 605 heating jets 609 drilled at strategic locations to heat the oil being extracted at various points in the oil production pipe 605. The brine from the heating jets 609 raises the temperature of the extracting fluid in the reservoir 607. As the oil and brine are extracted from the well 600b, the oil and brine go through a separator 610 that separates the oil 614 from the brine 615. The separated oil 614 can be shipped to a processing destination. The separated brine 615 is usually injected into the reservoir to maintain reservoir pressure or it is shipped to a disposal injection well. If the oil and/or brine 612 are used as the heat delivery fluid the injection volumes are removed from the separator 610. Heat is delivered from a heat source 611, such as a boiler, into the heat exchanger 613. The small portion of the brine and/or oil 612 from the separator 610 is heated by the heat exchanger 613 and injected back into the well 600a by way of the heat pipe 608, to merge with the cooling extracted oil to re-heat the oil and maintain the low viscosity of the oil as it rises through the oil production pipe 605.
Additionally, in contrast to the well 600a, the well 600b and its heating pipe 608 are extended deeper into the reservoir 607. One or more reservoir heating jets 616 are drilled into the bottom of the heating pipe 608 at one or more locations. The heated brine or oil that is pumped into the oil reservoir 607 into the reservoir heating jets 616 further heats the extractable oil and lowers its viscosity.
In the well 600c shown in
A heat delivery system efficiency example using any one of the wells described herein is as follows.
A well is provided with the following schematics:
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- Production Oil Pipe (“POP”) Diameter=6 inches
- POP Area=28 square inches
- Heating Pipe (“HP”) Diameter=1.5 inches
- HP Area=1.77 square inches
- Fluid Flow Rate of Oil & Brine=5,000 Bands per day (example)
- Fluid Flow Rate of Oil & Brine=156 gallons per minute
Proportion Flow rate of PO after HP=1−((HP Area·2)/POP Area)≈87.5%
-
- (assumes flow rates are equivalent)
Because the oil viscosity is the denominator of the pertinent formula described previously herein, if the viscosity is reduced by one-half, the flow rate is doubled. As shown in
The net effect is as follows:
Flow=(156/(100/1,000))·0.875=1,365 (an increase of 8.7 times the original extraction rate)
Additional factors that impact the ability to change the flow rate include the pumping rate of the oil production pipe, the pumping rate of the heat pipes, the number and placement of the heating jets, the temperature of the injected brine/oil/gas, the viscosity of the extracting oil, the characteristics of the oil reservoir, and the heat conductivity of the oil production pipe, fill and casing. A more complex model can determine the parameters for optimization of the system that will make the flow of oil most efficient.
Referring back to previous embodiments that address heating the oil being extracted as it nears the top of the well, it should be realized that the fluid in the heating chamber that surrounds the oil production pipe may be heated by heating elements powered by electricity. Electrical current is passed through an electrical heating element placed in a fluid surrounding the oil production pipe. The element conducts and/or radiates heat to the oil production pipe via the fluid.
The electric power may be provided from any source but may also be generated as shown for instance in
One way to heat the oil is by means of electric heating resistant cables. Such a case is shown in
Referring now to
While there have been shown and described and pointed out fundamental novel features of the invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods described may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice.
Claims
1. A system for recovering oil, gas or oil and gas from a reservoir beneath a surface comprising:
- at least one production pipe for receiving the oil and gas in the reservoir;
- at least one pump configured to pump the oil and gas to the surface;
- a casing surrounding the at least one production pipe; and
- at least one heating element in parallel with the production pipe configured to provide heat to the oil and gas being pumped to the surface.
2. The system according to claim 1, wherein the at least one heating element comprises one or more electric heating cables.
3. The system according to claim 2, wherein the one or more electric heating cables are in a fluid heating chamber within the casing and surrounding the at least one production pipe, and the one or more electric heating cables radiate heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe.
4. The system according to claim 2, wherein the one or more electric heating cables extend into a heating cocoon surrounding a portion of the casing.
5. The system according to claim 4, wherein the reservoir is underwater and the portion of the casing surrounded by the heating cocoon is underwater and the heating cocoon is configured to heat the water surrounding the casing and the at least one production pipe.
6. The system according to claim 2, wherein the at least one pump is further configured to pump brine or water from the reservoir to the surface, and provide pumped oil, gas and brine to a separator configured to separate oil, gas and brine.
7. The system according to claim 6, wherein a portion of the separated oil, gas or oil and gas is provided to an electricity generator to fuel the electricity generator.
8. The system according to claim 7, wherein the portion of the separated oil, gas or oil and gas includes flared gas.
9. The system according to claim 7, wherein the electricity generator provides electricity to the one or more electric heating cables.
10. The system according to claim 9, wherein generation of electricity by the electricity generator creates an exhaust gas, and the exhaust gas is mixed with the separated brine to create a mixture of gas and brine that is injected into the reservoir to increase the flow of oil and gas in the reservoir to the at least one production pipe.
11. The system according to claim 10, wherein the mixture of gas and brine is injected into a perforated pipe positioned in the reservoir beneath the casing.
12. The system according to claim 1, wherein the at least one heating element comprises one or more heating pipes transporting a heating substance.
13. The system according to claim 12, wherein the one or more heating pipes are in a fluid heating chamber within the casing and surrounding the at least one production pipe, and the one or more heating pipes include perforations and provide heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe.
14. The system according to claim 12, wherein the one or more heating pipes extend into a heating cocoon surrounding a portion of the casing.
15. The system according to claim 12, wherein the one or more heating pipes include at least one heating pipe within the at least one production pipe.
16. The system according to claim 12, wherein the at least one pump is further configured to pump brine or water from the reservoir to the surface, and provide pumped oil, gas and brine to a separator configured to separate oil, gas and brine.
17. The system according to claim 16, wherein a portion of the separated oil, gas or oil and gas is provided to a heating source configured to heat a fluid.
18. The system according to claim 17, wherein the portion of the separated oil, gas or oil and gas includes flared gas.
19. The system according to claim 17, wherein the heat source is a boiler configured to heat a fluid.
20. The system according to claim 19, wherein the heat source creates an exhaust gas, and the exhaust gas is mixed with the separated brine by a heat exchanger and mixer to create a mixture of gas and brine that is injected into the reservoir through the one or more heating pipes to increase the flow of oil and gas in the reservoir to the at least one production pipe.
21. The system according to claim 20, wherein the mixture of gas and brine is injected into a perforated pipe positioned in the reservoir beneath the casing.
22. The system according to claim 20, wherein the system further comprises a plurality of horizontal bore holes in the reservoir, and wherein the one or more heating pipes extend into the plurality of horizontal bore holes.
23. A method for recovering oil, gas or oil and gas from a reservoir beneath a surface comprising:
- providing at least one production pipe for receiving the oil and gas in the reservoir and a casing surrounding the at least one production pipe;
- pumping oil and gas to the surface with at least one pump; and
- heating the oil and gas being pumped to the surface with at least one heating element in parallel with the production pipe.
24. The method according to claim 23, wherein the at least one heating element comprises one or more electric heating cables.
25. The method according to claim 24, wherein the one or more electric heating cables are in a fluid heating chamber within the casing and surrounding the at least one production pipe, and the one or more electric heating cables radiate heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe.
26. The method according to claim 24, wherein the one or more electric heating cables extend into a heating cocoon surrounding a portion of the casing.
27. The method according to claim 26, wherein the reservoir is underwater and the portion of the casing surrounded by the heating cocoon is underwater and the heating cocoon is configured to heat the water surrounding the casing and the at least one production pipe.
28. The method according to claim 24, further comprising
- pumping brine or water from the reservoir to the surface by the at least one pump together with the pumped oil and gas,
- providing the pumped oil, gas and brine to a separator, and
- separating the oil, gas and brine.
29. The method according to claim 28, further comprising providing a portion of the separated oil, gas or oil and gas to an electricity generator to fuel the electricity generator.
30. The method according to claim 29, wherein the portion of the separated oil, gas or oil and gas includes flared gas.
31. The method according to claim 28, further comprising generating electricity by the electricity generator and providing electricity to the one or more electric heating cables.
32. The method according to claim 31, wherein generation of electricity by the electricity generator creates an exhaust gas, and the method further comprises mixing the exhaust gas with the separated brine to create a mixture of gas and brine and injecting the mixture into the reservoir to increase the flow of oil and gas in the reservoir to the at least one production pipe.
33. The method according to claim 32, wherein the mixture of gas and brine is injected into a perforated pipe positioned in the reservoir beneath the casing.
34. The method according to claim 23, wherein the at least one heating element comprises one or more heating pipes.
35. The method according to claim 34, wherein the one or more heating pipes are in a fluid heating chamber within the casing and surrounding the at least one production pipe, and the one or more heating pipes comprise perforations and provide heat to the fluid heating chamber for heating the oil and gas being pumped to the surface in the at least one production pipe.
36. The method according to claim 34, wherein the one or more heating pipes extend into a heating cocoon surrounding a portion of the casing.
37. The method according to claim 34, wherein the one or more heating pipes include at least one heating pipe within the at least one production pipe.
38. The method according to claim 34, further comprising:
- pumping brine or water in the reservoir to the surface by the at least one pump together with the pumped oil and gas,
- providing the pumped oil, gas and brine to a separator, and
- separating the oil, gas and brine.
39. The method according to claim 38, further comprising providing a portion of the separated oil, gas or oil and gas to a heating source configured to heat a fluid.
40. The method according to claim 39, wherein the portion of the separated oil, gas or oil and gas includes flared gas.
41. The method according to claim 39, wherein the heat source is a boiler configured to heat a fluid.
42. The method according to claim 41, wherein the heat source creates an exhaust gas, and the method further comprises mixing the exhaust gas with the separated brine to create a mixture of gas and brine and injecting the mixture into the reservoir to increase the flow of oil, gas or oil and gas in the reservoir to the at least one production pipe.
43. The method according to claim 42, wherein the mixture of gas and brine is injected into a perforated pipe positioned in the reservoir beneath the casing.
44. The method according to claim 42, wherein the method further comprises:
- providing a plurality of horizontal bore holes in the reservoir, and
- extending the one or more heating pipes into the plurality of horizontal bore holes.
Type: Application
Filed: Oct 8, 2015
Publication Date: Aug 31, 2017
Inventor: Michael J. PARRELLA (Weston, CT)
Application Number: 15/517,572