Process and apparatus for enhancing recovery of hydrocarbons from wells

The present invention relates to a method and apparatus for intensifying the production of hydrocarbons from underground formations, for example, intensifying the production of heavy oil by a secondary method from reservoirs of heavy oil and recovering bitumen from oil sands deposits.

State of the art

In some wells, such as those from which heavy oil or bitumen is produced, production can be increased using heat through steam gravity drainage. In another method, such as described in US Patent No. 7644759 (in the name Όανίάδοη), entitled Increasing flow rates through porous media, cold fluid is used to pulse the well fluid in the surrounding parent rock to increase the flow rate of the fluids.

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided a method for intensifying hydrocarbon production from a hydrocarbon containing formation, comprising the steps of heating a hydrocarbon containing formation by injecting heated gas into the wellbore, creating a series of pressure pulses in the wellbore by instantly converting the fluid into gas and directing the pressure pulses into the hydrocarbon containing formation.

According to another aspect of the invention, the liquid can be instantaneously converted to gas using a heat source. The heat source may be heated gas. The fluid may come in contact with a heat transfer surface that is heated by hot gas. The heat source may comprise a heat source of combustion located on the surface and connected to a pipe for transferring heat to the wellbore. The heat source may comprise a downhole heat source, a surface heat source, or both.

According to another aspect of the invention, at least a portion of the heated gas may comprise combustion products or synthesis gas.

According to another aspect of the invention, the liquid may contain water and may contain a hydrogen-forming additive. The hydrogen forming additive may be peroxide.

According to another aspect of the invention, the method comprises injecting heated gases into the wellbore to reduce the viscosity of the oil. Heated gases can be formed at least partially from the exhaust gases of a heating system, such as a jet engine using propane or natural gas as fuel. Exhaust gases are preferred because they contain carbon dioxide, which can be used to increase the density in degrees of the American Petroleum Institute (ANI) of downhole hydrocarbons. When the formation is heated by heated gas, the viscosity of hydrocarbons decreases. By increasing the ANI density and lowering the viscosity, hydrocarbon production can be intensified. To intensify hydrocarbon production, wet steam / water is preferably injected into the wellbore in a pulsed manner. Preferably, each part of the process is controllable. For example, the pulse mode can be adjusted based on the design and length of the exhaust channel.

According to another aspect of the invention, there is provided an apparatus for intensifying hydrocarbon production from a hydrocarbon containing formation, comprising a source of heated gas in communication with a wellbore in a hydrocarbon containing formation, a downhole heating element in a wellbore, and a fluid source controlled by a valve that directs fluid to the downhole heating element to create pressure pulse in the wellbore by instantaneous conversion of fluid into gas. A sealing element is located in the wellbore that holds the source of the heated gas and pressure pulse in the wellbore.

According to another aspect of the invention, the device may comprise a tubing string located in the wellbore, the sealing element may comprise a packer.

According to another aspect of the invention, the source of heated gas may comprise an exhaust gas heater that is connected to a pipe in the wellbore. The heated gas may contain combustion products from an exhaust gas heater. The device may further comprise a downhole heater for heating the heated gas.

According to another aspect of the invention, the downhole heating element may be a heat transfer surface. The heat transfer surface may be heated by a source of heated gas or by a downhole heating element.

According to another aspect of the invention, the heated gas may comprise at least one gas of carbon dioxide, carbon monoxide and hydrogen. Liquid can form hydrogen when it is instantly converted to gas. The liquid may contain water, and the water may contain a hydrogen-forming additive, such as peroxide.

In one embodiment, the method may be referred to as a Pulse Resonant Thermal Synthetic Gas Injection Process. However, it will be understood that variations of this method can be applied. For example, the pulse frequency may not correlate with the resonant frequency of the hydrocarbon-containing reservoir in all circumstances, and gases other than synthetic gas may be used.

The temperature and heat content of the exhaust gases are preferably controlled to match the design performance defined by these parameters and oriented towards maximum performance. Before exiting at the location of the downhole pulse tool, the exhaust gases may pass through the downhole heater, which raises their temperature before passing through the exhaust openings of the downhole pulse tool. Treated water / steam can be introduced to the exhaust side to enhance absorption by the formation surrounding the well as a heat transfer medium and to use the expansion characteristics of steam (high temperature steam). This introduction is preferably carried out in the wellbore at the hot gas outlet using a downhole pulse tool.

The frequency of the pulses generated by the pulse jet installation is preferably controlled based on temperature and amplitude to control the magnitude of the wave oscillation. The purpose of this is to achieve penetration into the formation and create a flow to the production well. In this process, contact with bottom water can be used as a medium for transferring wave energy, preferably in a horizontal well, to optimize production. Preferably, the sound frequency is calculated according to geomechanical methods and tests to ensure that the integrity of the overburden is maintained.

Propane or natural gas, as the main source of fuel, together with a secondary source of fuel and its by-products, is used as a solvent for dissolving gases in accordance with the characteristics of the formation. They may vary depending on the discharge rate, setting the cycle frequency, etc. and additional replenishment gas injection to meet production production conditions. The temperature can be controlled by actions on the surface and / or actions underground using an electronic heating element located inside the pipe string.

In yet another aspect of the invention, injectable fluids increase well productivity by modifying heavy oil or bitumen in situ to produce carbon chain changes that will result from thermal cracking. Conditions can also be created for catalytic cracking when a catalyst solution is injected into the wellbore using a downhole pulse tool. Injected water or steam can be used as a heat transfer medium to increase the mobility of oil or bitumen flowing to a production well when wet steam or water in the wellbore is brought into direct contact with high-temperature gases that are formed when using a downhole pulse tool. Moreover, the expansion characteristics of the vapor are used for the pulsating movement of oil during the expansion of natural cracks in the subterranean formation without compromising the integrity of the overburden. The toe-to-heel well configuration (vertical injection - horizontal production) is preferably used to better maintain on-site modifications with vertical or horizontal injection wells and horizontal production wells. This advantage has been demonstrated in known methods of intensifying oil production and can be adapted to meet the required operational parameters and results.

The method can be used in relation to formations containing, but not limited to, the following: formations with high-viscosity bitumen or heavy oil, formations with moving bottom water, formations with serious problems regarding the integrity of the overburden, formations with depths not exceeding 1,100 m, formations with a narrow or limited productive part of formations over b meters, formations with depletion of the mechanism causing the outflow oil from the reservoir, for the extraction of heavy oil and reservoirs for traditional oil production

Brief Description of the Drawings

These and other features will become clearer from the following description with reference to the accompanying drawings, and the drawings are for illustration only and are not intended to be limiting. The drawings show the following:

FIG. 1 is a diagram of the surface components of a device for intensifying hydrocarbon production by a secondary method;

FIG. 2 is a vertical cross-sectional side view of downhole components of a device for intensifying hydrocarbon production;

FIG. 3 is a vertical sectional side view of a heat-resistant packer;

FIG. 4 is a vertical sectional side view of a tubing string inserted into a heat-resistant packer;

FIG. 5 is an illustration of a method for enhancing hydrocarbon production;

FIG. 6 is a diagram of a drilling site with five wells including one production well;

FIG. 7 is a diagram of a well site with seven wells including two production wells.

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DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 shows an embodiment of a method for enhancing hydrocarbon production from a hydrocarbon containing formation 12. The term hydrocarbon containing formation is used here to describe a geological formation that contains liquid hydrocarbons. In particular, the method described here is intended to intensify production from formations that contain heavy oil or bitumen, since to intensify the production of lighter forms of hydrocarbons, the use of the method would not be required or would be uneconomical. The method consists in the continuous injection of hot gas with periodic energy pulses.

As shown, the wellbore 14 is drilled into a hydrocarbon containing formation 12. As will be described below, in a preferred embodiment, this well is not intended to be productive. The hydrocarbon containing formation 12 is heated by injection of heated gas into the wellbore 14. When this happens, a series of pressure pulses are created in the wellbore 14 by instantly converting the liquid into gas so that the pressure pulses are pressure pulses directed to the hydrocarbon containing formation 12.

In the depicted embodiment, the heated gas is produced on the first platform 16 and sent to the wellbore 14. The gases in the wellbore preferably contain carbon monoxide and / or carbon dioxide, as, for example, they could be present as a combustion product, and hydrogen. Synthetic gas, which is a mixture of gases containing carbon monoxide and hydrogen, and may also include carbon dioxide and other components, and therefore can be used in the method. Synthetic gas can be generated in a variety of ways, such as steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, gasification of coal, biomass, and in some types of plants for gasification of waste with electricity production. The name comes from its use as intermediates in the creation of synthetic natural gas and for the production of ammonia or methanol. However, for the purposes of the process currently being described, synthetic gas is not used as such. Instead, a mixture is used to heat the formation, reduce the viscosity, and at least partially modify the hydrocarbons in the formation 12. Hydrocarbons are modified by exposure to heat and hydrogen, resulting in thermal cracking, while carbon monoxide and / or carbon dioxide increase the ANI density of liquid hydrocarbons. As a result, the production of liquid hydrocarbons from productive wells is greatly facilitated.

As depicted, heated gas is obtained using a heater 20, in which, for example, propane, natural gas or other hydrocarbons are burned, and combustion air is supplied by a fan 22 and an optional oxygen supply 24. The heater 20 may be similar to a jet engine. A secondary heater 29, for which acetylene can be powered, for example, is used to raise the temperature and remove any oxygen during the combustion process before being injected into the wellbore 14. Additional synthesis gas or other components may be supplied from additional source 30 prior to injection. Some cooling may occur, and the well heater 31 shown in FIG. 2, such as an electric, catalytic heater or combustion chamber. Heater 31 could be controlled by control device 86 shown in FIG. 1. Actual temperature will depend on the reservoir and hydrocarbons produced. However, for the target temperature in the wellbore from 300 to 340 ° C. The surface temperature may be in the range from 500 to 570 ° C. The fall can be mainly due to the energy needed to instantly turn water into steam. In the described method, combustion products are injected into the wellbore, while the hydrogen component is formed from the water system, as will be described below. Alternatively, a mixture of carbon dioxide / carbon monoxide and hydrogen, such as synthesis gas, can be formed and injected immediately after heating. It will be understood that the actual composition of the heated gas may vary depending on the hydrocarbon containing formation and user preferences.

In addition to the heated gas, the formation 12 is also affected by pressure pulses. They are preferably created by instantly converting water to steam in the wellbore to create steam pressure. As shown in FIG. 1, water is pumped from a water source 40 by a pump 42 located on a second platform 43 into a wellbore 14 after pre-heating with a heat exchanger 26. As shown in FIG. 2, water turns into steam in the wellbore when it comes in contact with a heat source. As shown, water is ejected from nozzles 44 or holes in the small diameter flexible tubing 76 onto a heat transfer surface, which, as shown, is a series of partitions 46. Partitions 46 are preferably heated by a heated gas stream 48. Water can also partially or completely turn into steam when it comes in contact with heated gas 48. It will be understood that various designs can be applied to initiate the instantaneous conversion of water to steam. For example, the heat transfer surface can take many forms to optimize the process outside of the partitions 46. Alternatively, the partitions 46 can be heated by sources other than heated gas 48, such as borehole

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Well steam generators are known, but other designs may also be used. However, a steam generator of any design must be capable of causing instantaneous conversion of water into steam. In this context, instantaneous conversion means converting sufficient quantities of water into steam at a speed sufficient to create a pressure pulse. When water turns into steam, the volume increases dramatically. If this occurs at a sufficiently high rate, the bottomhole zone of the well can be filled, and a pressure pulse in the formation can be created. The pressure increase is preferably fast enough and of sufficient intensity so that it can create a longitudinal wave in the formation. To achieve the required pressure pulse, steam must be formed within a very short period of time. Accordingly, it is preferable to form steam in the wellbore. In addition to steam generation, flash water can also be used to generate hydrogen, which is used in the thermal cracking of hydrocarbons. Accordingly, the water injected into the wellbore preferably contains an additive, such as peroxide, which promotes the formation of hydrogen.

The injected water or steam will be used as a heat transfer medium and as a means of increasing the mobility of bitumen flowing into a production well, bringing wet steam or water in the wellbore into direct contact with high-temperature gaseous fluids. The vapor expansion characteristics provide pulsating oil movement due to the expansion of natural cracks without causing damage to the integrity of the overburden. In addition, an increase in pressure will affect the surface tension of the liquid hydrocarbons and therefore encourage liquid hydrocarbons to be released from the hydrocarbon containing formation. For better preservation at the site of modification, a toe to heel configuration with vertical or horizontal injection wells and horizontal production wells is preferably used, as will be discussed in more detail below. Modification is maintained by moving oil over short distances.

Pressure pulses can be created at regular or irregular intervals in continuous mode or in groups. The frequency of the pressure pulses can be controlled by the valve 50. The frequency and intensity of the pressure pulse is controlled by the timing and duration of opening of the valve 50. The heat needed to maintain the process can be determined based on the frequency and intensity of the pressure pulse or, in other words, the volume of water subjected to instant evaporation and the temperature difference between the water temperature and the target steam temperature.

In some circumstances, it may be advantageous to generate pulses at the resonant frequency of the hydrocarbon containing formation 12. This results in deeper penetration into the formation and increased flow into the production well. Resonance occurs when the frequency of pulses created in the wellbore corresponds to the frequency of the formation in its natural state, and allows you to create pulses in the formation with a maximum amplitude. The propagation of a pressure wave is proportional to the rate of change of hydrostatic pressure in the reservoir (piezoconductivity). Permeability, porosity, general compressibility and viscosity of oil are important parameters of the pulse propagation range. At a resonant frequency, the penetration of the pulse into the formation increases, and a short-range increase in the mobility of the fluid increases. The maximum amplitude of the pulses makes the question of the geomechanical integrity of the overburden relevant in order to avoid damage to the overburden that can occur at its resonant frequency. The frequency should preferably be calculated according to geomechanical methods and tests to ensure that the integrity of the overburden is maintained. It is assumed that pressure pulses will be generated in a regular sequence at a frequency of about one per second or less, for example, between 0.1-1 Hz. However, the actual frequency may be higher or lower than this range, depending on the characteristics of the formation.

The longitudinal wave is similar to an earthquake - a sharp shock change in pressure in a rock mass.

Pressure pulses should facilitate fluid production, but should not exceed hydraulic fracturing pressure. Other factors that determine pressure include formation pressure, formation pressure, overburden pressure, and underlying rock pressure. The pulse pressure decreases as the steam cools and scatters in the reservoir 12. The rate of decline will depend on the formation, and this is one factor that is taken into account when determining the frequency of pulses. The background pressure or the pressure between the pulses is preferably determined mainly by the pressure of the heated gas, which should be greater than the pressure in the wellbore, to allow further passage of the heated gas into the wellbore 14. Preferably, it is as low as possible. As shown in FIG. 5, this reduces the likelihood of pressure pulses and exhaust gases creating through channels through the formation, such as through plantar water in the underlying rock 98. Instead, plantar water 54 can be used as a medium for transmitting energy of pressure pulses.

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In FIG. 3 shows an embodiment in which the device is installed in the wellbore with a heat-resistant packer 70 placed on the casing 72. As shown in FIG. 4, a tubing string 74 is inserted into the heat-resistant packer 70. The heat-resistant packer 70 has a plug 75, which is closed at this point. As shown in FIG. 2, a small diameter flexible tubing 76 is inserted into the tubing string 74 through an oil seal 74 with a hole 80 for passing hot gases through it, which pushes the plug 75 and opens the hot gas passage 48. The small tubing 76 diameter can be used to introduce lines of instrumentation, plumbing 82 and other supply pipelines into it. Alternatively, the water supply pipe 82 may be routed outside the small diameter flexible tubing 76 and passes through an opening in the oil seal 78. An additional downhole heating element may form part of the tubing string around the small diameter flexible tubing 76 (not shown) . As shown in FIG. 1, instrumentation lines can be connected to temperature and pressure sensors 84 and can also provide control signals to valve 50. Sensor readings are received and control signals are sent by control device 86, which is preferably placed on the surface, as shown in FIG. one. It will be understood that the above description is one example of downhole equipment that can be used to pump heated gas to generate pressure pulses in the wellbore, and modifications or other arrangements may be made by those skilled in the art.

As shown in FIG. 5, the method is preferably used in a toe-to-heel configuration, with stimulation by injection well 62 toward the bottom 90 of horizontal well 66 of production well 60. The heated gas, steam, and pressure pulses are represented by clouds 92 and are introduced as discussed above. The method provides an easier flow of hydrocarbons in zone 94 into the horizontal barrel 66, where they are pumped to the surface. As shown, the method is used below the overburden 96 and above the underburden 98. Care must be taken not to damage the overburden 96. In addition, the pressure is adjusted to avoid any sealing problems of the overburden, into which the compressed gas escapes from the hydrocarbon containing formation 12, and to also avoid the creation of channels into the bottom water in or on the underburden 98, which would lead to an increased flow of water and more likely its extraction, rather than hydrocarbons.

As shown in FIG. 6, the method can be used in a layout with five wells, that is, a horizontal production well 60, two injection wells 62 and two observation wells 64. A horizontal production well 60 would be drilled with a core prior to drilling a horizontal section 66 of the well. The purpose of this is to ensure the correct location of the bend in a horizontal section at the bottom of the productive zone and to guarantee the use of natural cracking during production. Injection wells 62 were drilled into the upper part of the productive zone. All wells were developed using thermal logging instructions and equipped with downhole monitoring equipment (not shown) to help assess reservoir dynamics and production stability. Although a five-well example has been described, other well layout schemes may also be applied. For example, in FIG. 7 shows yet another toe-to-heel configuration with two production wells 60, three injection wells 62, and three observation wells.

In FIG. 6 shows two injection wells 62 located within an area designed to provide communication between two wells. One injection well 62 was offset by a distance and an angle to provide increased optimal delivery parameters based on formation boundary determination requirements. They were predefined by reservoir modeling. Two observation wells 64 were also developed using thermal logging data. Units for the operation of injection wells were designed to comply with the permission of the authorities using approved technological standards. Regulatory instructions were developed during the operational hazard analysis phase of the design and are included in the method. Practical benefits and advantages that can be realized include, but are not limited to, the following.

one. Increased oil production due to the effective attenuation of the negative impact of heterogeneity due to both the application of the configuration of the socks to the heel, and pulsating injection technology.

2. On-site modification due to high temperature achieved in combination with the action of hydrogen when the synthesis gas contains hydrogen.

3. Increased process control capabilities not only by regulating the total injection rate and composition of the injected steam, but also by regulating the parameters of the pulsed wave in connection with the productivity of oil production.

four. Significant reduction in fuel gas consumption for steam generation and efficient use of any emitted by-products that are reintroduced into the process.

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5. Significantly improved design economic indicators, since production using the Impulse-resonant thermal synthesis gas injection process is estimated to be almost 65% more efficient than other known technologies, and both capital and operating costs are estimated to be significantly lower than in comparable projects of this nature.

6. A huge reduction in water consumption due to the use of both characteristics, including heat transfer medium and steam expansion, to optimize production by evaluating reservoir productivity, modifying or making the necessary adjustments to intensify production without stopping production operations.

In the present description, the word containing is used in its non-limiting sense to indicate that objects following the word are included, but objects not specifically mentioned are not excluded. A reference to an element in the singular does not exclude the possibility of using several elements, unless the context clearly states that there is one and only one of the elements.

The following claims should be understood as containing everything that is specifically illustrated and described above, which is conceptually equivalent and that can be obviously substituted. Skilled artisans will appreciate that various adaptations and modifications of the described embodiments may be made without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be construed as limiting the invention. It should be understood that, within the scope of the claims, the invention may be practiced otherwise than specifically illustrated and described.