Method for improving recovery factor during cold production of foamy oil

Abstract

Embodiments of the present invention provide a method and apparatus for improving a recovery factor during cold production of foamy oil, and a storage medium. The method comprises the following steps: S1: acquiring oil production data of an oil production-pending well, the oil production data at least comprising a produced gas-oil ratio of the oil well, an initial gas-oil ratio of an oil reservoir, oil reservoir stratum pressure, pseudo-bubble point pressure, oil production of the oil well, a plateau production rate, and a foam proportion in an oil sample; S2, on the basis of the oil production data, screening for an oil well having a poor foamy oil development effect; S3, performing oil production operation on the oil well on the basis of the oil production data, the oil production operation comprising gas injection, well soaking, and swabbing; and S4, successively repeating the gas injection, well soaking, and swabbing until the oil well reaches a cold production limit, the gas injection amount in the gas injection being increased along with the increase of rounds of oil production. The method increases the production of a cold production stage, and achieves the effective treatment of a stripper well and an inactive well.

Description

A method for improving the recovery rate of foam oil cold recovery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202310762016.5 filed on June 26, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The invention relates to the technical field of petroleum extraction, in particular to a method for improving the recovery rate of foam oil cold production. Background Art

[0004] Foamy oil is a type of gas-containing crude oil in which the gas phase is dispersed within the oil phase in the form of tiny bubbles. This unique state of affairs allows for high fluidity and yield. In existing oil production, dissolved gas in the foamy oil reservoir is released from the oil phase only when the formation pressure drops below the bubble point pressure. Initially, the gas phase exists as tiny bubbles. Over time and as pressure drops, the bubbles formed at different locations grow larger and gradually aggregate to form a continuous gas phase.

[0005] However, as the pressure near the oil well decreases (down to the pseudo-bubble point pressure), a free phase gradually forms after the crude oil is degassed, the foam oil effect decreases, the oil phase viscosity increases, the oil well production decreases, and the production gas-oil ratio increases, affecting the normal production of the oil well.

[0006] Summary of the Invention

[0007] The purpose of the embodiment of the present invention is to provide a method for improving the recovery rate of foam oil cold production, which increases the production in the cold production stage and achieves effective treatment of low-yield wells and long-stopped wells.

[0008] To achieve the above object, an embodiment of the present invention provides a method for improving the recovery rate of foamed oil cold recovery, the method comprising the following steps:

[0009] S1: Obtaining oil production data of the oil well to be produced, wherein the oil production data at least includes the oil well production gas-oil ratio, the oil reservoir original gas-oil ratio, the oil reservoir formation pressure, the pseudo-bubble point pressure, the oil well oil production, the peak production, and the foam ratio in the oil sample;

[0010] S2: screening oil wells with poor foam oil development effects based on the oil production data;

[0011] S3: performing oil production operations on the oil well according to the oil production data, wherein the oil production operations include gas injection, well soaking, and pumping back;

[0012] S4: Repeat the gas injection, soaking and pumping in sequence until the oil well reaches the cold production limit. The gas injection volume increases with the increase of oil production rounds.

[0013] Optionally, screening oil wells with poor foam oil development effects based on the oil production data includes:

[0014] When the oil well production gas-oil ratio is greater than the original gas-oil ratio of the reservoir*10, and the reservoir formation pressure is less than the pseudo-bubble point pressure, and the oil well oil production is less than*20% of the peak production, and the foam proportion in the oil sample is less than the foam proportion threshold, then the oil well is an oil well with poor foam oil development effect.

[0015] Optionally, the method further includes:

[0016] If the adjacent wells of the oil well have not reached the cold production limit, performing combined gas injection huff and puff on the oil well and the adjacent wells;

[0017] The combined gas injection and huff-and-puff method allows the production of oil from multiple oil wells to be performed synchronously.

[0018] Optionally, the gas injection amount is:

[0019] Where r is the throughput radius,

[0020] L is the production length of the horizontal well section,

[0021] h is the oil layer thickness,

[0022] is the porosity of the oil layer,

[0023] S o is the oil saturation,

[0024] R is the volume of dissolved gas per unit volume of crude oil under formation conditions,

[0025] ρ is the ground density of gas,

[0026] A is the increase in gas injection volume, and n is the number of oil production rounds.

[0027] Optionally, the gas injection amount is increased by 5%-30%.

[0028] Optionally, the row spacing of horizontal wells in the reservoir is twice the throughput radius.

[0029] Optionally, the maximum number of gas injection throughput rounds is 6, and the throughput radius under the maximum number of rounds is the maximum throughput radius.

[0030] Optionally, the soaking time is related to the nature and injection volume of the gas, the nature of the crude oil, the formation temperature and the formation pressure.

[0031] Optionally, during the gas injection process, the gas injection pressure is lower than the fracture pressure of the formation in which the oil well is located.

[0032] Optionally, during the pumping process, the liquid production rate is 1.0%-4.0% of the controlled reserves of a single well.

[0033] In another aspect, the present invention provides a device for improving the recovery rate of foam oil cold recovery, the device comprising:

[0034] An acquisition module is used to acquire oil production data of the oil well to be produced, wherein the oil production data at least includes the gas-oil ratio of the oil well production, the original gas-oil ratio of the oil reservoir, the formation pressure of the oil reservoir, the pseudo-bubble point pressure, the oil production of the oil well, the peak production, and the proportion of foam in the oil sample;

[0035] a screening module, for screening oil wells with poor foam oil development effects based on the oil production data;

[0036] An oil production module, configured to perform oil production actions on the oil well according to the oil production data, wherein the oil production actions include gas injection, well soaking and pumping back;

[0037] The gas injection, soaking and pumping are repeated in sequence until the oil well reaches the cold production limit. The gas injection volume increases with the increase of oil production rounds.

[0038] Optionally, screening oil wells with poor foam oil development effects based on the oil production data includes:

[0039] When the oil well production gas-oil ratio is greater than the original gas-oil ratio of the reservoir*10, and the reservoir formation pressure is less than the pseudo-bubble point pressure, and the oil well oil production is less than*20% of the peak production, and the foam proportion in the oil sample is less than the foam proportion threshold, then the oil well is an oil well with poor foam oil development effect.

[0040] Optionally, the oil production module is further configured to perform combined gas injection huff-and-puff on the oil well and the adjacent well if the adjacent well of the oil well has not reached the cold production limit;

[0041] The combined gas injection and huff-and-puff method allows the production of oil from multiple oil wells to be performed synchronously.

[0042] Optionally, the gas injection amount is:

[0043] Where r is the throughput radius,

[0044] L is the production length of the horizontal well section,

[0045] h is the oil layer thickness,

[0046] is the porosity of the oil layer,

[0047] S o is the oil saturation,

[0048] R is the volume of dissolved gas per unit volume of crude oil under formation conditions,

[0049] ρ is the ground density of gas,

[0050] A is the increase in gas injection volume, and n is the number of oil production rounds.

[0051] Optionally, the gas injection amount is increased by 5%-30%.

[0052] Optionally, the row spacing of horizontal wells in the reservoir is twice the throughput radius.

[0053] Optionally, the maximum number of gas injection throughput rounds is 6, and the throughput radius under the maximum number of rounds is the maximum throughput radius.

[0054] Optionally, the soaking time is related to the nature and injection volume of the gas, the nature of the crude oil, the formation temperature and the formation pressure.

[0055] Optionally, during the gas injection process, the gas injection pressure is lower than the fracture pressure of the formation in which the oil well is located.

[0056] Optionally, during the pumping process, the liquid production rate is 1.0%-4.0% of the controlled reserves of a single well.

[0057] On the other hand, the present invention further provides a machine-readable storage medium having stored thereon instructions for causing a machine to execute the above-mentioned method for improving the recovery rate of foamed oil cold recovery.

[0058] A method for improving the recovery rate of foamed oil cold production, according to the present invention, comprises the following steps: S1: obtaining oil production data of a well to be produced, the oil production data including at least the well production gas-oil ratio, the reservoir original gas-oil ratio, the reservoir formation pressure, the pseudo-bubble point pressure, the oil production of the well, the peak production rate, and the proportion of foam in the oil sample; S2: screening wells with poor foamed oil development results based on the oil production data; S3: performing oil production actions on the wells based on the oil production data, the oil production actions including gas injection, well shut-in, and pump-back; S4: repeating the gas injection, well shut-in, and pump-back steps in sequence until the well reaches the cold production limit, wherein the gas injection volume increases with each production cycle. By screening wells with poor foamed oil development results and determining the timing of gas injection, the present invention reduces the viscosity of the degassed crude oil, increases the formation pressure, and reduces the interfacial tension of the crude oil. This, in turn, extends the cold production life cycle of the foamed oil by forming similar foamed oil, allowing the foamed oil production capacity to continue to be utilized, thereby increasing the production during the cold production phase and effectively managing low-yielding wells and wells that have been idle for a long time.

[0059] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0061] FIG1 is a schematic flow diagram of a method for improving the recovery rate of foamed oil cold recovery according to the present invention;

[0062] FIG2 is a schematic plan view of the vertical well gas injection coverage according to the present invention;

[0063] FIG3 is a schematic plan view of the horizontal well gas injection coverage according to the present invention;

[0064] FIG4 is a diagram showing an optimal radius of gas injection for a horizontal well according to the present invention;

[0065] FIG5 is a diagram showing an optimal time for gas injection and soaking of a horizontal well according to the present invention;

[0066] FIG6 is a diagram showing the optimal gas injection and liquid production rates for horizontal wells according to the present invention;

[0067] FIG7 is a diagram showing an optimal increase in gas injection in a horizontal well compared to the previous gas injection according to the present invention. DETAILED DESCRIPTION

[0068] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0069] FIG1 is a flow diagram of a method for improving the recovery rate of foamed oil cold recovery according to the present invention. As shown in FIG1 , step S1 is to obtain oil production data of a well to be produced. The oil production data includes at least the well's production gas-oil ratio, the reservoir's original gas-oil ratio, the reservoir's formation pressure, the pseudo-bubble point pressure, the well's oil production, the peak production rate, and the percentage of foam in the oil sample. The reservoir is a foamed oil reservoir.

[0070] Specifically, the oil well to be produced is generally a long-stopped oil well. Production data such as the well production gas-oil ratio, reservoir original gas-oil ratio, reservoir formation pressure, pseudo-bubble point pressure, well oil production, peak production, and foam percentage in the oil sample are obtained for the long-stopped oil well.

[0071] According to a specific implementation method, the oil field's early data is searched to determine the original gas-oil ratio of the block's crude oil; the oil well's production gas-oil ratio is determined by the volume of gas and crude oil produced by the oil well in a period before gas injection; the ratio of the current production gas-oil ratio of the oil well to the original gas-oil ratio before gas injection is calculated, and the ratio of the production gas-oil ratio to the original gas-oil ratio before the shutdown of the shutdown well is determined using the same method. The pseudo-bubble point pressure of the oil field's crude oil and the reservoir formation pressure are determined using early data, and the pseudo-bubble point pressure and reservoir formation pressure are compared to determine the relationship between the two. The peak oil production of an oil well is the oil production (generally cubic meters / day) during the production period (at least 2 months) when the oil well has a higher production rate, and the oil production of the oil well is the average oil production in a period before gas injection (at least 15 days). Specifically, the original gas-oil ratio, also known as the original dissolved gas-oil ratio, refers to the amount of natural gas dissolved in a unit volume or weight of crude oil under original formation conditions. Reservoir pressure refers to the formation pressure at a certain period after the oil reservoir is put into development.

[0072] The bubble point pressure is the pressure at which the first bubbles appear when a liquid mixture begins to vaporize, as the system pressure is gradually reduced under constant temperature. Heavy oil cold recovery technology utilizes the action of foamed oil to recover heavy oil reservoirs. The pressure range for foam generation is from the bubble point pressure to the pseudo-bubble point pressure. The pseudo-bubble point pressure is used to describe the depletion-type recovery of heavy oil reservoirs and describes the fluid properties of foamed oil based on conventional chamber pressure, volume, and temperature data. When the formation pressure falls below the thermodynamic equilibrium bubble point pressure, dissolved gas in the crude oil precipitates as diffuse gas, forming a freely mobile gas phase until the pressure reaches a lower level, the pseudo-bubble point pressure. Below the pseudo-bubble point pressure, some of the diffused gas becomes free gas. As pressure decreases, the amount of gas diffused in the crude oil decreases until it is completely free gas. As cold recovery of foamed oil reservoirs deepens, the formation pressure further decreases (below the pseudo-bubble point pressure), and the dissolved gas gradually escapes into a continuous phase, eliminating the benefits of the foamed oil. This increases the gas-to-oil ratio of the well, reduces oil production, and may even lead to well shutdown.

[0073] Step S2 is to screen oil wells with poor foam oil development effects based on the oil production data. The oil wells with poor foam oil development effects are oil wells with low cold production output, high production gas-oil ratio, or stopped production oil wells.

[0074] Specifically, screening oil wells with poor foam oil development performance based on the oil production data includes the following steps: When the oil well's production gas-oil ratio exceeds the reservoir's original gas-oil ratio*10, the reservoir's formation pressure is less than the pseudo-bubble point pressure, the oil well's oil production is less than*20% of the peak production, and the foam percentage in the oil sample is less than a foam percentage threshold, then the oil well is identified as having poor foam oil development performance. When the foam oil well's production gas-oil ratio rises to more than 10 times the original gas-oil ratio, the formation pressure falls below the pseudo-bubble point pressure, the oil well's oil production is less than 20% of the peak production, and the foam percentage in the oil sample significantly decreases, then the foam oil well's production performance can be determined to have significantly deteriorated, and gas injection is required to extend the foam oil cold production lifecycle and improve foam oil cold production.

[0075] Step S3 is to perform oil production actions on the oil well according to the oil production data, and the oil production actions include gas injection, well shut-in and pumping back.

[0076] Specifically, the gas injection amount is:

[0077] Among them, r is the throughput radius, L is the horizontal well section production length, h is the oil layer thickness, is the porosity of the oil layer, So is the oil saturation, R is the volume of dissolved gas per unit volume of crude oil under formation conditions, ρ is the surface density of gas, A is the magnitude of the increase in gas injection volume, and n is the number of production cycles. Preferably, the magnitude of the increase in gas injection volume is 5%-30%. Oil production data is related to the average oil saturation within the well's control range. Preferably, the horizontal well spacing in the reservoir is twice the throughput radius. The maximum number of gas injection cycles is 6, and the throughput radius at the maximum number of cycles is the maximum throughput radius.

[0078] According to one specific embodiment, the amount of gas injected is determined by the thickness of the oil layer encountered by the well, its porosity, the sweep radius, and the solubility of the gas in crude oil. Oil production data is related to the solubility of oil. Generally, the sweep radius of a vertical well can be considered a cylinder, as shown in Figure 2; the sweep radius of a horizontal well is a rectangular parallelepiped with two semi-cylinders, as shown in Figure 3. The amount of injected gas should be appropriate. Excessive injection will prevent the gas from dissolving in the affected crude oil, making subsequent pumping difficult and wasteful. Excessive injection will fail to achieve the desired effects of boosting pressure, reducing viscosity, and improving oil recovery efficiency. The inventors' research has found that after gas injection, the formation pressure at the bottom of the well within the sweep radius increased by 0.5 MPa, the crude oil viscosity decreased by 50%-80%, and the formation driving force and crude oil fluidity were significantly enhanced. The amount of cold production fluid is related to reservoir pressure and the degree of crude oil degassing, and is related to the solubility of the gas in the crude oil after the subsequent gas injection and the duration of the well shut-in. The soaking duration is related to the nature of the injected gas, the injection volume, the properties of the crude oil, the formation temperature, and the formation pressure. For example, within a certain range, the greater the injection volume, the longer the soaking duration. During the injection process, the injection pressure is lower than the fracture pressure of the formation in which the oil well is located.

[0079] Step S4 is to repeat gas injection, well soaking and pumping in sequence until the oil well reaches the cold production limit, and the gas injection volume increases with the increase of oil production rounds.

[0080] According to a specific implementation method, when the first-round throughput radius is 30-110m, the oil well stage production effect is that as the injection volume increases, the oil production of the oil well increases, but the oil change rate decreases. When the throughput radius is 50m, the decline in the oil change rate slows down. Therefore, the preferred first-round throughput radius of this application is 50m, as shown in Figure 4.

[0081] The soaking time is generally determined by ensuring that the injected gas is fully dissolved in the crude oil and can be utilized. As shown in Figure 5, if the soaking time is too short, the gas will be directly recovered without dissolving, resulting in waste. If the soaking time is too long, the oil well production rate will be low, affecting the output within a certain period of time, and the injected gas may also be wasted away from the bottom of the well. The inventors have found that the gas-to-oil exchange rate decreases with increasing soaking time, so the preferred soaking time is 10 days.

[0082] Among them, the high or low liquid production rate can reflect the size of the gas's drainage effect in the formation. As shown in Figure 6, when the total liquid discharge volume in a period is the same, a liquid discharge rate that is too high will cause the pressure near the bottom of the well to drop too quickly, and the viscosity of the crude oil will increase, which is not conducive to the flow of crude oil. Too low a liquid discharge volume will result in low single-well production and fail to achieve the purpose of increasing production. Therefore, the liquid production rate of this application is 1.0%-4.0%. After the liquid production rate reaches 2.0%, the oil change rate decreases faster, and at this time, a higher single-well production can be guaranteed. Therefore, the preferred liquid production rate of this application is 2.0%.

[0083] The gas injection volume in the gas injection increases with the increase in the number of oil production rounds. Specifically, according to the need to increase the radius of the gas injection, the gas injection volume is increased by a certain proportion compared with the previous time. According to the on-site production effect, if the gas injection volume is too large, it will not be able to be recovered in time during the pumping, and if the gas injection volume is too small, it will lead to the inability to exert the reservoir capacity, affecting the overall production increase effect. Preferably, during the pumping process, the liquid production rate is 1.0%-4.0% of the single well controlled reserves. The single well controlled reserves are the geological reserves within the flow range of the single well controlled fluid. It can be calculated based on the results data obtained from the oil test using the formation test data processing and interpretation method.

[0084] The inventors have found that the best production effect is achieved when the gas injection volume increases by 5%-30% compared with the first round, and as the increment becomes larger, the oil production in the second round gradually increases. When the gas injection volume increases by 20%, the oil change rate decreases slowly. Therefore, the new gas injection volume of this application is increased by 20% compared with the previous one, as shown in Figure 7.

[0085] Moreover, as the number of gas injection cycles increases, the bottomhole oil saturation decreases, and the cyclic oil production decreases to the cold production limit. The preferred maximum gas injection throughput cycle in this application is 6 cycles, at which the gas injection throughput limit radius is obtained. By determining the gas injection throughput limit radius, it can be preliminarily determined that the optimal row spacing of horizontal wells in foam oil reservoirs should be twice the throughput radius. Based on the current status of horizontal well development in foam oil reservoirs, the adaptability of early well spacing is determined, and the adjustment of well spacing in the later well network is guided to achieve economic and efficient foam oil development. Row spacing is the distance between the water well row and the oil well row.

[0086] The oil production method of the present application further includes: if the adjacent wells of the oil well have not reached their cold production limit, performing combined gas injection and huffing on the oil well and the adjacent wells; the combined gas injection and huffing synchronizes the oil production operations of multiple oil wells. Specifically, the combined gas injection and huffing includes: if adjacent oil wells all reach the point where gas injection is required to extend the life cycle of foam oil cold production, the adjacent wells should be gas-injected and started for production simultaneously. This can prevent injected gas from spilling into adjacent wells currently producing, thereby wasting injected gas and affecting production in the adjacent wells.

[0087] A method for improving the recovery rate of foamed oil cold production, according to the present invention, comprises the following steps: S1: obtaining oil production data of a well to be produced, the oil production data including at least the well production gas-oil ratio, the reservoir original gas-oil ratio, the reservoir formation pressure, the pseudo-bubble point pressure, the oil production of the well, the peak production rate, and the proportion of foam in the oil sample; S2: screening wells with poor foamed oil development results based on the oil production data; S3: performing oil production actions on the wells based on the oil production data, the oil production actions including gas injection, well shut-in, and pump-back; S4: repeating the gas injection, well shut-in, and pump-back steps in sequence until the well reaches the cold production limit, wherein the gas injection volume increases with each production cycle. By screening wells with poor foamed oil development results and determining the timing of gas injection, the present invention reduces the viscosity of the degassed crude oil, increases the formation pressure, and reduces the interfacial tension of the crude oil. This, in turn, extends the cold production life cycle of the foamed oil by forming similar foamed oil, allowing the foamed oil production capacity to continue to be utilized, thereby increasing the production during the cold production phase and effectively managing low-yielding wells and wells that have been idle for a long time.

[0088] The present invention also provides a device for improving the recovery rate of foam oil cold production, which includes: an acquisition module for acquiring oil production data of an oil well to be produced, wherein the oil production data at least includes the oil well production gas-oil ratio, the original gas-oil ratio of the oil reservoir, the oil reservoir formation pressure, the pseudo-bubble point pressure, the oil production of the oil well, the peak production, and the proportion of foam in the oil sample; a screening module for screening oil wells with poor foam oil development effect according to the oil production data; an oil production module for performing oil production actions on the oil well according to the oil production data, wherein the oil production actions include gas injection, well shut-in and pumping back; gas injection, well shut-in and pumping back are repeated in sequence until the oil well reaches the cold production limit, and the gas injection amount in the gas injection increases with the increase in the number of oil production rounds.

[0089] The bubble point pressure is the pressure at which the first bubbles appear when a liquid mixture begins to vaporize, as the system pressure is gradually reduced under constant temperature. Heavy oil cold recovery technology utilizes the action of foamed oil to recover heavy oil reservoirs. The pressure range for foam generation is from the bubble point pressure to the pseudo-bubble point pressure. The pseudo-bubble point pressure is used to describe the depletion-type recovery of heavy oil reservoirs and describes the fluid properties of foamed oil based on conventional chamber pressure, volume, and temperature data. When the formation pressure falls below the thermodynamic equilibrium bubble point pressure, dissolved gas in the crude oil precipitates as diffuse gas, forming a freely mobile gas phase until the pressure reaches a lower level, the pseudo-bubble point pressure. Below the pseudo-bubble point pressure, some of the diffused gas becomes free gas. As pressure decreases, the amount of gas diffused in the crude oil decreases until it is completely free gas. As cold recovery of foamed oil reservoirs deepens, the formation pressure further decreases (below the pseudo-bubble point pressure), and the dissolved gas gradually escapes into a continuous phase, eliminating the benefits of the foamed oil. This increases the gas-to-oil ratio of the well, reduces oil production, and may even lead to well shutdown.

[0090] The screening of oil wells with poor foam oil development effect based on the oil production data includes: when the oil well production gas-oil ratio is greater than the original gas-oil ratio of the oil reservoir*10, and the oil reservoir formation pressure is less than the pseudo-bubble point pressure, and the oil well oil production is less than*20% of the peak production, and the foam proportion in the oil sample is less than a foam proportion threshold, then the oil well is an oil well with poor foam oil development effect.

[0091] The gas injection amount is:

[0092] Among them, r is the throughput radius, L is the horizontal well section production length, h is the oil layer thickness, is the porosity of the oil layer, So is the oil saturation, R is the volume of gas dissolved per unit volume of crude oil under formation conditions, ρ is the surface density of gas, A is the increase in gas injection volume, and n is the number of oil production cycles. Preferably, the increase in gas injection volume is 5%-30%.

[0093] According to a specific implementation method, the amount of gas injected is related to the thickness of the oil layer encountered by the oil well to be produced, the porosity of the oil layer, the swept radius and the solubility of the gas in crude oil. Generally, the swept range of a vertical well can be considered as a circle; while the swept range of a horizontal well gas injection is similar to an ellipse (rectangle + two semicircles). The injected gas should be of appropriate amount. Too much injection will cause the gas to be unable to dissolve in the affected crude oil, causing difficulties and waste in the later pumping. Too little injection will result in the inability to achieve the desired effect of pressurization, viscosity reduction and improvement of oil recovery efficiency. The inventors have found that after the gas is injected, the formation pressure at the bottom of the oil well within the swept radius increased by 0.5MPa, the crude oil viscosity decreased by 50%-80%, and the formation driving force and crude oil fluidity were significantly enhanced.

[0094] The oil production module is also used to perform combined gas injection and huffing on the oil well and the adjacent wells if the adjacent wells of the oil well have not reached the cold production limit; the combined gas injection and huffing is a synchronous oil production action of multiple oil wells.

[0095] Specifically, the combined gas injection and huff-and-puff includes: if adjacent oil wells all reach the time when gas injection is required to extend the life cycle of foam oil cold production, the adjacent oil wells should be injected with gas and started to produce oil at the same time, so as to avoid the injected gas from flowing along the high-permeability channel to the adjacent well that is currently recovering oil, thereby causing waste of injected gas, affecting the production of adjacent wells, and causing the current well to fail to meet the expected gas injection requirements, and also affecting the production effect of the current well.

[0096] In the process of cold production of foam oil wells, due to the effect of foam oil, the stage production is higher, but as production continues, some wells are due to long production time, and the formation deficit near the bottom of the well is large, and the pressure is reduced (below the pseudo-bubble point pressure). The bubbles originally dispersed in the oil phase will gradually escape to form free gas in a free state. And the viscosity of crude oil increases after degassing, the fluidity of crude oil deteriorates, and the production of oil wells will decline. Even some oil wells will be shut in because the production gas-oil ratio is too high, which causes the overall production effect of oil wells to deteriorate. The present application selectively injects gas in oil wells, which can cause crude oil to expand and increase formation pressure, improve oil displacement efficiency, reduce crude oil viscosity, form the effect of dissolved gas drive, and even form secondary foam, and continue to apply the foam oil mechanism to play a role in increasing production and resuming production.

[0097] According to a specific embodiment, the injected gas enters the bottom of the well and gradually dissolves in the crude oil after contacting it. The length of the dissolution time is related to the properties of the gas, the amount of gas injected, the properties of the crude oil, and the temperature and pressure of the formation. During this dissolution process, the oil well will be closed, that is, the soaking time is related to the properties of the gas injection, the injection amount, the properties of the crude oil, the formation temperature and the formation pressure. After a period of soaking, when the gas and crude oil are fully dissolved (the bottom hole pressure is relatively stable), the oil well can be timely organized to be pumped back at a certain liquid production rate, so that the oil well production should be increased compared to before the gas injection. The production of the shut-down well will also increase significantly compared to before the shutdown; after a period of production, when the oil well production gradually decreases (generally not higher than before the gas injection), the oil well can be shut down and the next round of gas injection can be carried out, with the gas injection volume increased by a certain proportion compared to the previous time; repeat the gas injection, soaking, and pumping until the oil well reaches the cold production limit. This method not only extends the life cycle of foam oil cold production and improves the development effect of the cold production stage, but also enhances fluid drive, reduces crude oil viscosity, and improves oil washing efficiency.

[0098] The soaking time is generally determined by ensuring that the injected gas fully dissolves in the crude oil and can be utilized. If the soaking time is too short, the gas will be recovered without dissolving, resulting in waste. If the soaking time is too long, the well production rate will be low, affecting the output within a certain period of time, and the injected gas may also be wasted away from the bottom of the well. The inventors have found that the gas-to-oil exchange rate decreases with increasing soaking time, so the optimal soaking time is 10 days.

[0099] Among them, the high or low liquid production rate can reflect the extent of the gas's drainage effect in the formation. When the total liquid discharge volume in a period is the same, a liquid discharge rate that is too high will cause the pressure near the bottom of the well to drop too quickly, increase the viscosity of the crude oil, and be unfavorable for the flow of crude oil. A liquid discharge volume that is too low will result in low single-well production and fail to achieve the goal of increasing production. Therefore, the liquid production rate of this application is 1.0%-4.0%. After the liquid production rate reaches 2.0%, the oil change rate decreases faster, and at this time, a higher single-well production can be guaranteed. Therefore, the preferred liquid production rate of this application is 2.0%.

[0100] The gas injection volume in the gas injection increases with the increase in the number of oil production rounds. Specifically, according to the need to increase the radius of the gas injection, the gas injection volume is increased by a certain proportion compared with the previous time. According to the on-site production effect, if the gas injection volume is too large, it will not be able to be recovered in time during the withdrawal, and if the gas injection volume is too small, it will lead to the inability to exert the reservoir capacity, affecting the overall production increase effect. The inventors have found that the production effect is best when the gas injection volume is increased by 5%-30% compared with the first round, and as the increment becomes larger, the oil production of the second round gradually increases. When the gas injection volume increases by 20%, the oil change rate decreases slowly. Therefore, the new gas injection volume of this application is increased by 20% compared with the previous time.

[0101] Furthermore, as the number of gas injection cycles increases, the bottomhole oil saturation decreases, and the cyclic oil production decreases, reaching the cold production limit. This application prefers a maximum gas injection throughput of six cycles, at which the gas injection throughput radius is determined. By determining the gas injection throughput radius, we can preliminarily determine that the optimal horizontal well spacing in foam oil reservoirs should be twice the throughput radius. Based on the current status of horizontal well development in foam oil reservoirs, we can determine the adaptability of early well spacing and guide subsequent well pattern spacing adjustments to achieve economically efficient foam oil development.

[0102] This application also proposes a specific embodiment, specifically: a certain heavy oil reservoir, with oil well production exhibiting foamy oil characteristics. The reservoir is 800 meters deep, with an average oil layer thickness of 22 meters. The work area is pure oil, and the original gas-oil ratio is 15 cubic meters. This reservoir is developed using horizontal well cold recovery. Peak production at the horizontal well was 122 tons per day. Eleven years after production began, production dropped to 23.4 tons per day before shutdown. The production gas-oil ratio was 21.7 times the original gas-oil ratio, indicating poor cold recovery effectiveness.

[0103] Two years after the well was shut down, gas was injected to resume production. The initial impact radius was estimated to be approximately 50 meters. After 10 days of gas injection, the well was then shut down and production resumed. While controlling the production rate at 2.5%, the well initially produced 95 tons of oil per day. The well was shut down when production dropped to the level before the shutdown. The second gas injection volume was increased by 20% compared to the first, and production continued. Six cycles of cyclic gas injection were performed, with production during the cyclic gas injection phase accounting for over 40% of the initial foam oil cold production. This example demonstrates that the method for extending the lifecycle of foam oil cold production effectively extends the cold production phase of a foam oil well.

[0104] The method of improving the recovery rate of foamed oil cold recovery of the present invention is to inject a certain amount of gas into the oil well when the foamed oil cold recovery effect deteriorates or has been shut down, so that the gas is in contact with crude oil for a certain period of time and dissolved into the crude oil, causing the crude oil to expand and thereby increase the formation pressure, reduce the viscosity of the formation crude oil, reduce the interfacial tension of the crude oil, and reduce the residual oil saturation, thereby increasing the oil displacement efficiency, increasing the oil well pumping output, extending the foamed oil cold recovery time, and improving the effect of cold recovery development.

[0105] On the other hand, the present invention also provides an electronic device, which includes: at least one processor; a memory connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the at least one processor implements the above-mentioned method for improving the recovery rate of foam oil cold recovery by executing the instructions stored in the memory.

[0106] The processor includes a core that retrieves the corresponding program unit from the memory. One or more cores can be provided. By adjusting the core parameters, the production during the cold production phase is increased, achieving effective treatment of low-yield wells and long-stopped wells.

[0107] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0108] An embodiment of the present invention provides a storage medium having a program stored thereon. When the program is executed by a processor, the method for improving the recovery rate of foam oil cold recovery is implemented.

[0109] An embodiment of the present invention provides a processor, which is used to run a program, wherein the program executes a method for improving the recovery rate of foam oil cold recovery when running.

[0110] An embodiment of the present invention provides a device comprising a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, the following steps are performed: (method claim steps, sole claim + subordinate claim). The device herein may be a server, a PC, a PAD, a mobile phone, or the like.

[0111] The present application also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialized program having the following method steps: obtaining oil production data of an oil well to be produced, the oil production data at least including the oil well production gas-oil ratio, the original gas-oil ratio of the oil reservoir, the oil reservoir formation pressure, the pseudo-bubble point pressure, the oil production of the oil well, the peak production, and the proportion of foam in the oil sample; screening oil wells with poor foam oil development effect based on the oil production data; performing oil production actions on the oil wells based on the oil production data, the oil production actions including gas injection, well shut-in and pumping back; repeating the gas injection, well shut-in and pumping back in sequence until the oil well reaches the cold production limit, and the gas injection amount in the gas injection increases with the increase in the number of oil production cycles. The method of screening oil wells with poor foam oil development effects based on the oil production data includes: identifying an oil well as having poor foam oil development effects when the oil well's production gas-oil ratio is greater than the reservoir's original gas-oil ratio*10, the reservoir's formation pressure is less than the pseudo-bubble point pressure, the oil well's oil production is less than *20% of the peak production, and the foam percentage in the oil sample is less than a foam percentage threshold. The method further includes: if an adjacent well of the oil well has not reached its cold production limit, performing combined gas injection and huff-and-puff on the oil well and the adjacent well; the combined gas injection and huff-and-puff comprises performing oil production operations simultaneously on multiple oil wells.

[0112] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0113] The present application is described with reference to the flow chart and / or block diagram of the method, device (system), and computer program product according to the embodiment of the present application. It should be understood that each flow process and / or box in the flow chart and / or block diagram and the combination of the flow process and / or box in the flow chart and / or block diagram can be realized by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processing machine or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for realizing the function specified in one flow chart flow or multiple flows and / or one box or multiple boxes of the block diagram.

[0114] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0115] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0116] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0117] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0118] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0119] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0120] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for improving the recovery rate of foamed oil cold recovery, characterized in that: The method comprises the following steps: S1: Obtaining oil production data of the oil well to be produced, wherein the oil production data at least includes the gas-oil ratio of the oil well production, the original gas-oil ratio of the oil reservoir, the formation pressure of the oil reservoir, the pseudo-bubble point pressure, the oil production of the oil well, the peak production, and the proportion of foam in the oil sample; S2: screening oil wells with poor foam oil development effects according to the oil production data; S3: performing oil production actions on the oil well according to the oil production data, wherein the oil production actions include gas injection, well shut-down and pumping back; S4: Repeating gas injection, well shut-down and pumping in sequence until the oil well reaches the cold production limit output, wherein the gas injection volume increases with the increase of oil production rounds.

2. The method according to claim 1, characterized in that The step of screening oil wells with poor foam oil development effects according to the oil production data comprises: When the oil well production gas-oil ratio> the original gas-oil ratio of the oil reservoir*10, and the reservoir formation pressure<the pseudo-bubble point pressure, and the oil well oil production<*20% of the peak production, and the foam proportion in the oil sample<the foam proportion threshold, then the oil well is an oil well with poor foam oil development effect.

3. The method according to claim 1 or 2, characterized in that: The method further includes: If the adjacent wells of the oil well have not reached the cold production limit, a combined gas injection and huff-and-puff method is performed on the oil well and the adjacent wells; the combined gas injection and huff-and-puff method is a method for synchronously performing oil production actions of multiple oil wells.

4. The method according to any one of claims 1 to 3, characterized in that: The gas injection volume is: Where r is the throughput radius, L is the production length of the horizontal well section, h is the oil layer thickness, is the porosity of the oil layer, S o is the oil saturation, R is the volume of gas dissolved in unit volume of crude oil under formation conditions, ρ is the surface density of gas, A is the increase in gas injection volume, and n is the number of oil production rounds.

5. The method according to claim 4, characterized in that The increase range of the gas injection amount is 5%-30%.

6. The method according to any one of claims 1 to 5, characterized in that: The row spacing of horizontal wells in the oil reservoir is twice the throughput radius.

7. The method according to any one of claims 1 to 6, characterized in that: The maximum number of gas injection throughput rounds is 6, and the throughput radius under the maximum number of rounds is the maximum throughput radius.

8. The method according to any one of claims 1 to 7, characterized in that: The duration of soaking is related to the nature and amount of gas injection, the nature of crude oil, the formation temperature and the formation pressure.

9. The method according to any one of claims 1 to 8, characterized in that: During the gas injection process, the injection pressure is lower than the fracture pressure of the formation where the oil well is located.

10. The method according to any one of claims 1 to 9, characterized in that: During the pumping process, the liquid production rate is 1.0%-4.0% of the controlled reserves of a single well.

11. A device for improving the recovery rate of foam oil cold recovery, characterized in that: The device includes: An acquisition module is used to acquire oil production data of the oil well to be produced, wherein the oil production data at least includes the gas-oil ratio of the oil well production, the original gas-oil ratio of the oil reservoir, the formation pressure of the oil reservoir, the pseudo-bubble point pressure, the oil production of the oil well, the peak production, and the proportion of foam in the oil sample; A screening module, used for screening oil wells with poor foam oil development effects according to the oil production data; An oil production module, used for performing oil production actions on the oil well according to the oil production data, wherein the oil production actions include gas injection, well soaking and pumping back; The gas injection, well soaking and pumping are repeated in sequence until the oil well reaches the cold production limit production, and the gas injection volume in the gas injection increases with the increase of oil production rounds.

12. The device according to claim 11, characterized in that The step of screening oil wells with poor foam oil development effects according to the oil production data comprises: When the oil well production gas-oil ratio> the original gas-oil ratio of the oil reservoir*10, and the reservoir formation pressure<the pseudo-bubble point pressure, and the oil well oil production<*20% of the peak production, and the foam proportion in the oil sample<the foam proportion threshold, then the oil well is an oil well with poor foam oil development effect.

13. The device according to claim 11 or 12, characterized in that The oil production module is also used to perform combined gas injection huff and puff on the oil well and the adjacent well if the adjacent well of the oil well has not reached the cold production limit production; The combined gas injection and huff-and-puff method allows the production of oil from multiple oil wells to be performed synchronously.

14. The device according to any one of claims 11 to 13, characterized in that The gas injection volume is: Where r is the throughput radius, L is the production length of the horizontal well section, h is the oil layer thickness, is the porosity of the oil layer, So is the oil saturation, R is the volume of gas dissolved in unit volume of crude oil under formation conditions, ρ is the surface density of gas, A is the increase in gas injection volume, and n is the number of oil production rounds.

15. The device according to claim 14, characterized in that The increase range of the gas injection amount is 5%-30%.

16. The device according to any one of claims 11 to 15, characterized in that The row spacing of horizontal wells in the reservoir is twice the throughput radius.

17. The device according to any one of claims 11 to 16, characterized in that The maximum number of gas injection throughput rounds is 6, and the throughput radius under the maximum number of rounds is the maximum throughput radius.

18. The device according to any one of claims 11 to 17, characterized in that The duration of soaking is related to the nature and amount of gas injection, the nature of crude oil, the formation temperature and the formation pressure.

19. The device according to any one of claims 11 to 18, characterized in that During the gas injection process, the injection pressure is lower than the fracture pressure of the formation where the oil well is located.

20. The device according to any one of claims 11 to 19, characterized in that During the pumping process, the liquid production rate is 1.0%-4.0% of the controlled reserves of a single well.

21. A machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the method for enhancing the recovery efficiency of foamed oil cold recovery as claimed in any one of claims 1 to 10.

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