A device and method for improving steam sweep efficiency by establishing a barrier with a plugging agent

Abstract

The application discloses a device for improving steam wave effect by establishing interlayer with plugging agent, comprising an injection well and a production well, the well mouth of the injection well is connected with a plugging agent solution storage device through a first pressure increasing device, the well mouth of the injection well is connected with a non-condensate gas storage device through a second pressure increasing device, and the well mouth of the injection well is connected with a steam boiler generator, and a method for improving steam wave effect by establishing interlayer with plugging agent is also disclosed. The application is suitable for the technical field of heavy oil thermal recovery, a new interlayer is established in a reservoir, steam injected from a lower layer can migrate horizontally along the new interlayer, development of a middle and lower steam cavity is improved, when the horizontal migration distance of the lower steam exceeds the interlayer, the steam can migrate to an upper part of the interlayer to be a region covered by steam, development of an upper steam cavity is promoted, and the non-condensate gas can improve the flowability of crude oil and increase the output capacity of the crude oil due to the dissolution of the non-condensate gas in the heavy oil.

Description

Technical Field

[0001] This invention belongs to the field of heavy oil thermal recovery technology, specifically a device and method for improving vapor sweep efficiency by using a plugging agent to establish an interlayer. Background Technology

[0002] Heavy oil is an important component of oil and gas resources, with abundant reserves accounting for more than half of the world's total oil reserves. my country has relatively rich heavy oil resources, distributed in multiple oil fields in both the east and west of the country. How to effectively utilize these heavy oil resources is of great significance to my country's energy strategic security.

[0003] Thermal recovery is a technology that significantly improves the recovery rate of heavy oil reservoirs. Currently, the main thermal recovery technology is steam injection viscosity reduction development technology. Because steam heat energy is readily available and easy to transport, and has a large specific heat capacity, it is suitable as a heat transfer medium. Steam huff and puff, steam drive, and steam-assisted gravity drainage (SAGD) technologies, which use the heat carried by steam to heat the crude oil in the reservoir, have become the main methods for heavy oil extraction both domestically and internationally. However, during steam injection extraction of heavy oil, the expansion of the steam chamber is extremely uneven, and there is a serious steam over-coverage phenomenon, which greatly affects the thermal utilization efficiency of steam and severely restricts the economics of heavy oil extraction in oil fields.

[0004] Currently, most heavy oil fields in my country have entered the middle to late stages of extraction, with steam over-coverage and cross-flow becoming increasingly serious. In response, profile control agent-assisted steam extraction has become a hot research topic in this field. This method utilizes fluids such as particles and gels with plugging or high viscosity characteristics, injected together with steam, to improve the formation's steam absorption profile and effectively access and utilize heavy oil in low-permeability zones. However, this method places high demands on material performance and requires continuous injection of high-viscosity fluids, with limited consideration given to its compatibility with the inherent flow properties of the steam itself.

[0005] Patent application number CN202010846749.3 discloses a deep plugging system and steam diversion method for heavy oil thermal recovery wells. It injects an elastic and biodegradable particulate plugging and sealing agent system into the formation to form a centrally placed plug to achieve high-strength steam channeling and sealing, causing the steam to divert to the surrounding low-permeability oil-bearing area and expanding the steam wave range.

[0006] The patent application number CN202010824172.6 discloses a gaseous CO2-assisted steam huff and puff method for preventing cross-channeling and increasing injection. It uses foam gel as the outer phase to encapsulate CO2 gas, and injects CO2 gas and foam gel into the formation simultaneously, so as to use the obtained CO2 gas foam gel plugging agent to modify the formation profile.

[0007] Patent application number CN201611243994.5 discloses an air injection and carbon dioxide-assisted steam huff and puff method for oil recovery, which uses air and carbon dioxide to improve the recovery rate of crude oil, both to replenish formation energy and to reduce the viscosity of crude oil in the reservoir.

[0008] It can be seen that the focus and innovation of existing technologies are all on the selection and development of profile control agents, without effectively utilizing the inherent properties of steam itself. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide an apparatus and method for improving vapor wave effect by using a sealing agent to create a spacer.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] In a first aspect, there is a device for improving steam sweep effect by using a plugging agent to create an interlayer, comprising an injection well and a production well, wherein the wellhead of the injection well is connected to a plugging agent solution storage device via a first pressurization device, the wellhead of the injection well is connected to a non-condensate gas storage device via a second pressurization device, and the wellhead of the injection well is connected to a steam boiler generator.

[0012] Preferably, the portion of the injection well that inserts into the formation is the target perforated section, with several seepage holes opened on its outer side.

[0013] Preferably, the target perforation section is equipped with a packer to prevent backflow of the sealing agent.

[0014] Preferably, the plugging agent in the plugging agent solution storage device is pressurized by a first pressurization device and then injected into the formation.

[0015] Preferably, the plugging agent solution forms a low-permeability interlayer on the outside of the target perforation section.

[0016] Preferably, the outer side of the target perforation section is a steam chamber, which is located above the low-permeability interlayer of the sealing agent.

[0017] Preferably, the steam produced by the steam boiler generator forms a mixed fluid with the non-condensate gas from the non-condensate gas storage device, which has been pressurized by the second pressurization device.

[0018] A method for improving vapor sweep efficiency by using a sealing agent to create a barrier layer includes the following steps:

[0019] Step 1: Based on the reservoir conditions, select interlayers to establish the stratigraphic position, and place packers into the target perforated section of the injection well;

[0020] Step 2: After selecting the plugging agent, the plugging agent in the plugging agent solution storage device is pressurized through the second pressurization device and then injected into the formation;

[0021] Step 3: Open the packer, shut in the well and wait for the plugging agent to cross-link firmly in the formation pores, forming a low-permeability interlayer of the plugging agent;

[0022] Step 4: Well Production. The steam produced by the steam boiler generator 3 and the non-condensate gas from the non-condensate gas storage device, which has been pressurized by the second pressurization device, are injected into the formation to heat and drive out the heavy oil in the formation until production is completed.

[0023] Preferably, in step one, the reservoir of the oil reservoir must be suitable for conventional steam development.

[0024] Preferably, in step one, the thickness of the heavy oil reservoir is ≥6m.

[0025] Preferably, in step one, the depth of the low-permeability interlayer established by the sealing agent is:

[0026] Interlayer depth = oil layer depth + reservoir thickness.

[0027] Preferably, in step two, the sealing agent has a temperature resistance higher than 150℃ and a mineralization tolerance higher than 5×10⁻⁶. 4 mg / L.

[0028] Preferably, in step two, the sealing agent is reinforced / modified alkali lignin or polyacrylamide.

[0029] Preferably, in step three, the shut-in time is greater than or equal to the time required for the plugging agent to achieve optimal plugging performance after injection into the formation.

[0030] Preferably, in step four, the non-condensate gas includes N2, CO2, CH4, and flue gas.

[0031] Preferably, in step four, the steam injection rate is 100-150 t / d, the steam dryness is >0.9, and the non-condensate gas injection rate is 1-2 times the steam injection rate.

[0032] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0033] In this invention, a new interlayer is established in the reservoir, allowing the injected steam from the lower layer to migrate laterally along the new interlayer, improving the development of the steam chamber in the middle and lower parts. When the lateral migration distance of the lower steam exceeds the interlayer, it will migrate to the upper part of the interlayer, which is the area affected by steam, promoting the development of the steam chamber in the middle and upper parts. The dissolution of non-condensable gas in heavy oil reduces the viscosity of crude oil, thereby improving crude oil fluidity and increasing crude oil production capacity. Non-condensable gas inhibits steam condensation, increases the steam flow and migration distance, and can improve steam flow capacity and thermal utilization rate. At the same time, for energy-deficient formations, the co-injection of non-condensable gas can effectively replenish formation energy, avoid ineffective steam injection, and has stronger adaptability. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of a device for improving vapor wave effect by using a sealing agent to create a sandwich layer.

[0035] Reference numerals: 1. Plugging agent solution storage device; 2. First pressurization device; 3. Steam boiler generator; 4. Injected mixed fluid; 5. Injection well; 6. Second pressurization device; 7. Non-condensable gas storage device; 8. Produced fluid; 9. Production well; 10. Steam chamber; 11. Plugging agent low-permeability interlayer. Detailed Implementation

[0036] The specific embodiments of the present invention are described in detail below.

[0037] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0038] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0039] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0040] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0041] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0042] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0043] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0044] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0045] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0046] The following embodiments further illustrate specific implementations of the apparatus and method for improving vapor sweep efficiency by using a sealing agent to create a spacer layer. The apparatus and method of the present invention for improving vapor sweep efficiency by using a sealing agent to create a spacer layer are not limited to the descriptions in the following embodiments.

[0047] Example 1:

[0048] A device that utilizes a sealing agent to create a spacer layer to improve vapor sweep efficiency, such as... Figure 1 As shown, it includes an injection well 5 and a production well 9. The wellhead of the injection well 5 is connected to the sealing agent solution storage device 1 through the first pressurization device 2. The wellhead of the injection well 5 is connected to the non-condensate gas storage device 7 through the second pressurization device 6. The wellhead of the injection well 5 is connected to the steam boiler generator 3.

[0049] Furthermore, the portion of injection well 5 that inserts into the formation is the target perforation section, with several perforations opened on its outer side; a packer is installed in the target perforation section to prevent backflow of the plugging agent; the plugging agent in the plugging agent solution storage device 1 is injected into the formation after being pressurized by the first pressurization device 2; the plugging agent solution forms a low-permeability interlayer 11 on the outer side of the target perforation section; the outer side of the target perforation section is a steam chamber 10, which is located above the low-permeability interlayer 11; the steam produced by the steam boiler generator 3 and the non-condensate gas from the non-condensate gas storage device 7, which is pressurized by the second pressurization device 6, form a mixed fluid 4.

[0050] Example 2:

[0051] An apparatus and method for improving vapor sweep efficiency by using a sealing agent to create a spacer layer, comprising the following steps:

[0052] Step 1: Based on the reservoir conditions, select the interlayer to establish the stratigraphic position, and place the packer into the target perforated section of injection well 5;

[0053] Step 2: After selecting the plugging agent, the plugging agent in the plugging agent solution storage device 1 is pressurized through the second pressurization device 2 and then injected into the formation;

[0054] Step 3: Open the packer, shut in the well and wait for the plugging agent to cross-link firmly in the formation pores, forming a low-permeability interlayer 11 of the plugging agent;

[0055] Step 4: Well Production. Steam generated by steam boiler generator 3 and non-condensate gas from non-condensate gas storage device 7, which has been pressurized by the second pressurization device 6, are injected into the formation to heat and drive out the heavy oil in the formation until production ends.

[0056] Furthermore, in step one, the reservoir must be suitable for conventional steam development, the heavy oil reservoir thickness must be ≥6m, and the depth of the low-permeability interlayer 11 plugging agent is:

[0057] Interlayer depth = oil layer depth + reservoir thickness.

[0058] Furthermore, in step two, the sealing agent has a temperature resistance higher than 150℃ and a mineralization tolerance higher than 5×10⁻⁶. 4 mg / L, the plugging agent is reinforced / modified alkali lignin and polyacrylamide.

[0059] Furthermore, in step three, the shut-in time is greater than or equal to the time required for the plugging agent to achieve optimal plugging performance after injection into the formation.

[0060] Furthermore, in step four, the non-condensate gases include N2, CO2, CH4, and flue gas.

[0061] Furthermore, in step four, the steam injection rate is 100 t / d, the steam dryness is >0.9, and the non-condensate gas injection rate is 1 times the steam injection rate.

[0062] Example 3:

[0063] An apparatus and method for improving the vapor sweep effect by using a sealing agent to establish a sandwich layer. Other steps are similar to those in Example 2. Further, in step four, the steam injection rate is 125 t / d, the steam dryness is >0.9, and the injection rate of non-condensable gas is 1.5 times the steam injection rate.

[0064] Example 4:

[0065] An apparatus and method for improving steam sweep efficiency by using a sealing agent to create a sandwich layer is disclosed. Other steps are similar to those in Example 2. Further, in step four, the steam injection rate is 150 t / d, the steam dryness is >0.9, and the injection rate of non-condensable gas is twice the steam injection rate.

[0066] Example 5:

[0067] Step 1: Based on the reservoir conditions, select the interlayer to establish the stratigraphic position, and lower the packer into the target perforated section 12 of injection well 5;

[0068] Step 2: After selecting the plugging agent, the plugging agent in the plugging agent solution storage device 1 is pressurized by the second pressurization device 2 and then injected into the formation;

[0069] Step 3: Open the packer, shut in the well and wait for the plugging agent to cross-link firmly in the formation pores to form a low-permeability interlayer 11;

[0070] Step 4: Well Production. Steam generated by steam boiler generator 3 and non-condensate gas from non-condensate gas storage device 7, which is pressurized by the second pressurization device 6, are mixed together to form a fluid 4 which is injected into the formation to heat and drive out the heavy oil in the formation until production ends.

[0071] It should be noted that hot steam exists in a gaseous state and readily rises in the formation, flowing along the caprock at the top of the reservoir and exhibiting a funnel-like distribution around the injection well. Based on this, the present invention establishes an interlayer in the middle of the reservoir to create a new caprock for the steam flowing in the lower part of the reservoir, increasing the lateral flow distance of the lower steam and making the steam absorption profile of the formation more uniform.

[0072] In the method of using plugging agents to simulate caprocks and improve the effect of steam thermal wave, the well layout of heavy oil thermal recovery is different from the single-well injection and production of steam huff and puff, with the injection well and the production well located in different positions in the reservoir.

[0073] The method provided by this invention is generally applicable to undeveloped heavy oil reservoirs with high homogeneity. The oil layer thickness should not be too thin, with a reservoir thickness of 10m. This is because the reservoir is highly heterogeneous, making it difficult for the plugging agent to form interlayers at the target layer.

[0074] For reservoirs with a development foundation, heterogeneity is already present. Due to steam overburden, the oil saturation at the caprock near the injection well is low, indicating a high-permeability layer. The following additional operational measures can be used to ensure effectiveness: Before establishing the interlayer, inject high-pressure gas at high speed into the entire perforated section downhole, followed by the injection of a foaming agent to form foam. Temporarily plug other layers, only opening the target perforated section for establishing the interlayer, performing flowback, and ensuring a low flowback pressure differential to facilitate the preferential entry of subsequent plugging agents into the target location.

[0075] Furthermore, in step one, the location of the interlayer should be in the middle or upper middle part of the heavy oil reservoir, and the thickness of the layer to which the plugging agent is injected should be as thin as possible, based on the minimum interval required for the packer to be lowered. For example, if the oil layer depth is 1500m and the reservoir thickness is 10m, the recommended depth for establishing the interlayer is 1504-1505m.

[0076] Furthermore, in step two, the plugging agent must possess high temperature and high salt resistance. The timing of stopping the plugging agent injection is determined by the distance the agent flows. The plugging agent must withstand temperatures above 150℃ and mineralization levels above 5×10⁻⁶. 4 The concentration of the plugging agent should not be too high, and the migration distance should not exceed 1 / 3 of the distance between the production well and the injection well to avoid creating an excessively thick interlayer that could affect the normal flow of subsequent steam and non-condensate gas. Enhanced / modified alkali lignin and polyacrylamide are recommended.

[0077] Furthermore, the shut-in time in step three depends on the time required for the plugging agent used in step two to achieve optimal plugging performance after injection into the formation. Taking a reinforced alkali lignin provided in patent CN202110425127.8 as an example, the gelation time at 80℃ is 22 hours, and when the oil reservoir environment is 60℃, the shut-in time is no less than 24 hours.

[0078] Furthermore, the commonly used non-condensable gases in step four include N2, CO2, CH4, and flue gas, but are not limited to these. The steam injection rate is 100–150 t / d, and the steam dryness fraction is >0.9. The non-condensable gas injection rate is 1–2 times the steam injection rate. Steam and non-condensable gas are mixed and injected until the water content of the produced fluid exceeds 98 wt%, at which point production is stopped.

[0079] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A device for improving vapor sweep efficiency by using a sealing agent to create a spacer layer, characterized in that, It includes an injection well (5) and a production well (9). The wellhead of the injection well (5) is connected to the sealing agent solution storage device (1) through a first pressurizing device (2). The wellhead of the injection well (5) is connected to the non-condensate gas storage device (7) through a second pressurizing device (6). The wellhead of the injection well (5) is connected to the steam boiler generator (3).

2. The device for improving vapor sweep efficiency by using a sealing agent to create a spacer layer as described in claim 1, characterized in that: The portion of the injection well (5) inserted into the formation is the target perforated section, with several seepage holes opened on its outer side.

3. The device for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 2, characterized in that: The target perforation section is equipped with a packer to prevent backflow of the sealing agent.

4. The device for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 3, characterized in that: The plugging agent in the plugging agent solution storage device (1) is pressurized by the first pressurization device (2) and then injected into the formation.

5. The apparatus for improving vapor sweep efficiency by using a sealing agent to create a spacer layer as described in claim 4, characterized in that: The plugging agent solution forms a low-permeability interlayer (11) on the outside of the target perforation section.

6. The apparatus for improving vapor sweep efficiency by using a sealing agent to create a spacer layer as described in claim 5, characterized in that: The outer side of the target perforation section is a steam chamber (10), which is located above the low-permeability interlayer (11) of the sealing agent.

7. The apparatus for improving vapor sweep efficiency by using a sealing agent to create a spacer layer as described in claim 1, characterized in that: The steam produced by the steam boiler generator (3) forms a mixed fluid (4) with the non-condensate gas from the non-condensate gas storage device (7) after being pressurized by the second pressurization device (6).

8. A method for implementing the apparatus as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Based on the reservoir conditions, select the interlayer to establish the stratigraphic position, and place the packer into the target perforated section of the injection well (5); Step 2: After selecting the plugging agent, the plugging agent in the plugging agent solution storage device (1) is pressurized through the second pressurization device (2) and injected into the formation; Step 3: Open the packer, shut in the well and wait for the plugging agent to cross-link firmly in the formation pores to form a low-permeability interlayer of the plugging agent (11); Step 4: Well production. The steam generated by the steam boiler generator 3 and the mixed fluid (4) formed by the non-condensate gas from the non-condensate gas storage device (7) and pressurized by the second pressurization device (6) are injected into the formation to heat and drive out the heavy oil in the formation until production ends.

9. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 8, characterized in that, In step one, the reservoir must be suitable for conventional steam development.

10. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 8, characterized in that, In step one, the thickness of the heavy oil reservoir is ≥6m.

11. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 8, characterized in that, In step one, the depth of the low-permeability interlayer (11) of the sealing agent is: Interlayer depth = oil layer depth + reservoir thickness.

12. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer layer as described in claim 8, characterized in that, In step two, the sealing agent has a temperature resistance higher than 150℃ and a mineralization tolerance higher than 5×10⁻⁶. 4 mg / L.

13. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer layer as described in claim 8, characterized in that, In step two, the sealing agent is reinforced / modified alkali lignin or polyacrylamide.

14. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 8, characterized in that, In step three, the shut-in time is greater than or equal to the time required for the plugging agent to achieve optimal plugging performance after injection into the formation.

15. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 8, characterized in that, In step four, the non-condensate gas includes N2, CO2, CH4, and flue gas.

16. The method for improving vapor sweep efficiency by using a sealing agent to create a spacer as described in claim 8, characterized in that, In step four, the steam injection rate is 100-150 t / d, the steam dryness is >0.9, and the non-condensate gas injection rate is 1-2 times the steam injection rate.

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