Method for starting air hot miscible flooding by efficient oxygen consumption of catalyst and oxygen-consuming agent

Abstract

The invention discloses a catalyst and oxygen-consuming agent high-efficiency oxygen-consuming starting air hot miscible flooding method. The method comprises the steps that a chromium salt catalyst is injected into an injection well of a target oil reservoir to be subjected to hot miscible phase displacement; a peony seed oil slug is injected into the injection well to serve as an oxygen-consuming agent front slug, and a peppermint oil slug is injected instead to serve as an oxygen-consuming agent rear slug; and a soluble bridge plug is arranged in front of the injection well, and after water-based foam liquid is injected, air is injected according to the set strength until it is determined that hot miscible flooding is started successfully. The method breaks through a high-efficiency oxygen consumption starting blind area of a low-oil-saturation oil layer of a depleted oil reservoir injection well, gives full play to the temperature advantage of an oil reservoir formation, fully utilizes the characteristics of low ignition point of peppermint oil and high combustion temperature of peony seed oil as an oxygen consumption agent through optimization of an injection medium, and adopts chromium salt as a catalyst, so as to realize high-efficiency oxygen consumption starting of the low-oil-saturation oil layer. Crude oil activation energy and heat release threshold temperature are greatly reduced, and efficient and safe oxygen consumption starting of an oil layer is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum development, and in particular to a catalyst+oxygen-consuming agent high-efficiency oxygen-consuming start-up air hot miscible phase flooding method. Background Art

[0002] Air miscible flooding technology injects a catalytic oxygen-consuming agent and air into the formation through an injection well to preheat and activate the reservoir, creating a medium-high-temperature thermal oxidation state between the formation crude oil and air. The resulting miscible gas, under high-temperature conditions, becomes miscible with the liquid crude oil, eliminating interfacial tension and overcoming capillary forces, effectively mobilizing the crude oil within the matrix pores. This air injection development technology significantly improves oil recovery efficiency, boasting low operating costs, high development efficiency, and a wide range of applications. The key to the successful implementation of air miscible flooding technology lies in miscible startup, which involves preheating the near-wellbore reservoir to a medium-high-temperature thermal oxidation state and creating miscible conditions. This process involves two key factors: sufficient air injection and achieving the miscible threshold temperature. Research has shown that the miscible temperature of different crude oils ranges from 250 to 550°C. To achieve this miscible startup condition, artificial miscible startup, including electrical and chemical methods, is necessary.

[0003] The electric heating miscible startup method can achieve miscible startup at different temperatures (200-600°C) depending on the crude oil properties of the reservoir, and can be implemented at depths exceeding 900 m. However, this technology uses continuous cable heating, which is costly and complex. The heating cable, placed in the reservoir, is perpendicular to the wellbore, preventing uniform contact with the injected air. Furthermore, if residual formation oil is retained in the wellbore, it can easily cause a wellbore explosion. The chemical miscible startup method is more flexible and safer, but the preheating temperature for conventional chemical startup is 200-350°C. High-temperature steam injection or electric heating is required to preheat the near-wellbore reservoir to above 200°C, resulting in high implementation costs. Furthermore, both electric and chemical startup methods require reservoir conditions with an oil saturation (So) greater than 50% near the wellbore. However, air miscible flooding technology is often used for the successive development of depleted oil reservoirs. When old oil fields developed with long-term water flooding or polymer flooding enter the high water-cut stage, the residual oil saturation in the area near the injection well is often low, and its distribution is difficult to accurately predict, resulting in the above-mentioned conventional miscible startup technology often being unable to be successfully implemented. Summary of the Invention

[0004] In order to enrich the process routes and increase the selection space, the embodiment of the present invention provides a catalyst + oxygen-consuming agent high-efficiency oxygen-consuming start-up air hot miscible flooding method.

[0005] In a first aspect, an embodiment of the present invention provides a catalyst + oxygen consuming agent high-efficiency oxygen-consuming start-up air hot miscible flooding method, comprising:

[0006] injecting a chromium salt catalyst into an injection well of a target oil reservoir to be flooded with hot miscible phase;

[0007] Injecting a peony seed oil slug as a front slug of oxygen consuming agent into the injection well, and injecting a peppermint oil slug as a rear slug of oxygen consuming agent into the injection well;

[0008] A soluble bridge plug is placed in front of the injection well, and after injecting water-based foam liquid, air is injected at a set intensity until it is determined that the hot miscible phase flooding is successfully started.

[0009] In some embodiments, if the injection well of the target oil reservoir to be subjected to hot miscible flooding is an original water injection well or an original gas injection well, before injecting the chromium salt catalyst into the injection well of the target oil reservoir to be subjected to hot miscible flooding, the method further includes:

[0010] A crude oil slug is injected into an injection well of a target oil reservoir to be subjected to hot miscible flooding, and the injection amount of the crude oil slug is determined according to the thickness of the oil layer in the target oil reservoir.

[0011] In some embodiments, the injection volume of the crude oil slug is (2-3)×hm 3 , where h is the oil layer thickness of the target reservoir.

[0012] In some embodiments, injecting a chromium salt catalyst into an injection well of a target oil reservoir to be subjected to hot miscible flooding comprises:

[0013] Inject chromium salt catalyst into the injection well of the target reservoir to be hot miscible flooding, with an injection rate of (0.5~1.0)×hm 3 , where h is the oil layer thickness of the target reservoir;

[0014] The concentration of the chromium salt catalyst is 0.1-0.5 wt%.

[0015] In some embodiments, the injection of peony seed oil slug as an oxygen consuming agent pre-slug comprises:

[0016] Inject peony seed oil slug as oxygen consuming agent pre-slug, the injection amount is (1.0~1.5)×hm 3 , where h is the oil layer thickness of the target reservoir.

[0017] In some embodiments, the injecting of peppermint oil slug as an oxygen consuming agent post-slug comprises:

[0018] Inject peppermint oil slug as oxygen consuming agent post-slug, the injection amount is (0.3~0.8)×hm 3 .

[0019] In some embodiments, the injecting of the water-based foam liquid comprises:

[0020] Inject water-based foam liquid, the injection amount is (2~3)×hm3 , where h is the oil layer thickness of the target reservoir.

[0021] In some embodiments, injecting air at a set intensity includes:

[0022] According to 500~5000Nm 3 / m3 of injected air.

[0023] In some embodiments, the bottom hole residual oil saturation of the injection well is greater than 30%.

[0024] In some embodiments, determining that the thermal miscible flooding is successfully started includes:

[0025] Successful startup of thermal miscible flooding is determined based on at least one of the following factors:

[0026] The pressure of the injection well changes, the pressure of the production well connected to the injection well changes, and the components of the gas produced by the production well change.

[0027] In a second aspect, an embodiment of the present invention provides a hot miscible flooding mining method, comprising:

[0028] Select the injection well of the target reservoir to be flooded with hot miscible phase;

[0029] Oxygen consumption start-up at the bottom of the injection well according to any of the above catalyst + oxygen consuming agent high-efficiency oxygen consumption start-up air hot miscible flooding methods;

[0030] The target oil reservoir is produced by thermal miscible flooding.

[0031] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0032] (1) The catalyst + oxygen consuming agent high-efficiency oxygen-consuming start-up air hot miscible flooding method provided by the embodiment of the present invention sequentially injects a high-efficiency catalyst and an oxygen consuming agent into the injection well, pre-places a soluble bridge plug, injects a water-based foam liquid, and then injects air, effectively achieving chemical startup of hot miscible flooding. The injection of chromium salt catalyst increases the exothermic reaction rate between air and crude oil and reduces the exothermic threshold temperature from 200°C to 60°C. Taking full advantage of the low flash point of peppermint oil and the high combustion temperature of peony seed oil, a specially formulated composite oil is injected as an oxygen consuming agent, and the composite oil is used for self-ignition to achieve safe and efficient oxygen-consuming hot miscible startup of low oil saturation oil layers.

[0033] (2) The catalyst + oxygen consuming agent high-efficiency oxygen-consuming hot miscible flooding method provided in the embodiment of the present invention can realize high-efficiency oxygen-consuming hot miscible flooding of low oil saturation oil layers in depleted oil reservoirs, thereby creating startup conditions for improving the recovery rate of depleted oil reservoirs by injecting air hot miscible flooding.

[0034] (3) The catalyst + oxygen-consuming agent high-efficiency oxygen-consuming start-up air hot miscible drive method provided in the embodiment of the present invention displaces the catalyst and injectant into the deep oil layer to realize hot miscible start-up in the oil layer. The injection well does not need thermal recovery completion, effectively utilizes the old well, has low investment cost, simple operation, and is safe and reliable.

[0035] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0036] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 This is a flow chart of the catalyst + oxygen-consuming agent high-efficiency oxygen-consuming start-up air hot miscible flooding method in Example 1 of the present invention;

[0039] Figure 2 This is a flow chart of the hot miscible phase flooding mining method in Example 2 of the present invention. DETAILED DESCRIPTION

[0040] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0041] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0042] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail.

[0043] In the description of the present invention, it should be noted that the terms “include”, “including”, “have”, “contain”, etc. are all open terms, which mean including but not limited to.

[0044] The embodiment of the present invention provides a catalyst+oxygen consuming agent high-efficiency oxygen-consuming start-up air hot miscible flooding method.

[0045] Example 1

[0046] The first embodiment of the present invention provides a catalyst + oxygen consuming agent high efficiency oxygen consuming start-up air hot miscible flooding method, see Figure 1 As shown, the following steps are included:

[0047] Step S11: injecting a chromium salt catalyst into an injection well of a target oil reservoir to be subjected to hot miscible flooding.

[0048] Chromium salts are injected into the injection well as a catalyst to significantly reduce the activation energy and combustion threshold temperature of crude oil.

[0049] Preferably, the injection amount of chromium salt catalyst is (0.5~1.0)×hm 3 , where h is the oil layer thickness of the target reservoir.

[0050] Furthermore, the concentration of the chromium salt catalyst is 0.1-0.5 wt %, and the injection temperature is 0-30°C.

[0051] Step S12: injecting a peony seed oil slug into the gas injection well as a pre-slug of the oxygen consuming agent, and injecting a peppermint oil slug as a post-slug of the oxygen consuming agent.

[0052] Preferably, the injection volume of the pre-slug is (1.0-1.5)×hm 3 , the injection temperature is 0~30℃.

[0053] Preferably, the injection volume of the rear slug is (0.3-0.8)×hm 3 , the injection temperature is 0~30℃.

[0054] Step S13: a soluble bridge plug is placed in front of the gas injection well, a water-based foam liquid is injected, and then air is injected at a set intensity until it is determined that the miscible flooding is successfully started.

[0055] After the pre-placed soluble bridge plug, water-based foam liquid is injected into the injection well to displace the catalyst slug injected in step S11 and the oxygen-consuming agent slug injected in step S12 into the oil layer. After the pre-placed soluble bridge plug falls to the bottom of the well (the injection volume of the water-based foam liquid can be used to determine whether the pre-placed soluble bridge plug has been displaced to the bottom of the well), the water-based foam liquid is continued to be injected to displace the catalyst and oxygen-consuming agent slugs to a depth of more than 1.5 m in the oil layer. The total injection volume of the water-based foam liquid is (2-3)×hm 3 .

[0056] The function of the water-based foam fluid is to clean the wellbore so that there is no residual oil in the wellbore.

[0057] Can be adjusted to 500~5000Nm 3 / m3 of injected air.

[0058] Successful startup of thermal miscible flooding can be determined based on at least one of the following factors:

[0059] Pressure changes in the injection well, pressure changes in the production well connected to the injection well, and changes in the gas composition produced by the production well.

[0060] The catalyst + oxygen consuming agent high-efficiency oxygen-consuming start-up air hot miscible flooding method provided in Example 1 of the present invention sequentially injects a high-efficiency catalyst and an oxygen consuming agent into the injection well, precedes a soluble bridge plug, and then injects air after injecting a water-based foam liquid, effectively achieving chemical startup of hot miscible flooding. The injection of a chromium salt catalyst increases the exothermic reaction rate between air and crude oil and reduces the exothermic threshold temperature from 200°C to 60°C. Taking advantage of the low flash point of peppermint oil and the high combustion temperature of peony seed oil, a specially formulated composite oil is injected as an oxygen consuming agent, and the spontaneous combustion of the composite oil is used to achieve safe and efficient oxygen-consuming hot miscible startup of low-oil-saturation reservoirs.

[0061] The catalyst + oxygen consuming agent high-efficiency oxygen-consuming hot miscible flooding method provided in Example 1 of the present invention can achieve high-efficiency oxygen-consuming hot miscible flooding startup of low oil saturation oil layers in depleted oil reservoirs, creating startup conditions for improving the recovery rate of depleted oil reservoirs by injecting air hot miscible flooding.

[0062] The catalyst + oxygen-consuming agent high-efficiency oxygen-consuming startup air hot miscible flooding method provided in Example 1 of the present invention displaces the catalyst and injectant into the deep oil layer to achieve hot miscible startup in the oil layer. The injection well does not require thermal recovery completion, effectively utilizes old wells, has low investment cost, is simple to operate, and is safe and reliable.

[0063] Example 2

[0064] The second embodiment of the present invention provides a hot miscible flooding mining method, see Figure 2 As shown, the following steps are included:

[0065] Step S21: selecting an injection well of a target oil reservoir to be subjected to miscible flooding.

[0066] The target reservoir is an oil reservoir that can be developed by air injection, and the bottom hole residual oil saturation of the selected injection well is greater than 30%.

[0067] If the injection well is a former water injection well or a former gas injection well, it is necessary to inject a crude oil slug into the injection well to be hot miscible flooded to increase the oil saturation in the near-wellbore area. The injection volume of the crude oil slug is determined according to the oil layer thickness of the target reservoir. If the selected injection well is a former production well, it is not necessary to inject a crude oil slug.

[0068] Preferably, if the injection well is a former water injection well or a former gas injection well, it is necessary to inject (2-3)×hm2 into the injection well to be hot miscible flooding. 3 Crude oil slug.

[0069] Step S22: oxygen consumption is started at the bottom of the injection well.

[0070] According to the catalyst + oxygen consuming agent high-efficiency oxygen consumption start-up air hot miscible flooding method described in Example 1, high-efficiency oxygen consumption start-up is performed at the bottom of the injection well to start the hot miscible flooding.

[0071] Step S23: Perform miscible flooding on the target oil reservoir.

[0072] Example 3

[0073] A third embodiment of the present invention provides a specific application of a miscible phase flooding mining method.

[0074] (1) Select a reservoir block in the xx oil field. The average burial depth of the reservoir is 3000m, the effective oil layer thickness is 20m, the current gas injection pressure is about 23MPa, the formation temperature is 111℃, the permeability is 5.85mD, and the oil saturation is 55%.

[0075] (2) The air injection well (injection well) was originally a water injection well. Crude oil slugs need to be injected into the injection well to increase the oil saturation in the near-well area. The injection volume is 100m 3 ;

[0076] (3) Inject the catalyst plug into the injection well at a temperature of 20°C, a concentration of 0.1-0.5 wt%, and a volume of 15 m 3 ;

[0077] (4) Inject peony seed oil slug into the injection well as the oxygen consuming agent pre-slug, the injection temperature is 20℃, and the injection volume is 30m 3 ;

[0078] (5) Peppermint oil slugs were injected into the injection well as oxygen consuming agent post-slugs. The injection temperature was 20°C and the injection volume was 15m 3 ;

[0079] (6) Pre-placed soluble bridge plug: inject water-based foam liquid into the injection well. When the pre-placed soluble bridge plug falls naturally to the bottom of the well, continue to inject foam liquid. The foam liquid injection volume is 60m 3 ;

[0080] (7) Continuously inject air into the injection well with an injection intensity of 30,000 Nm 3 / d (N is the standard case) to achieve hot mixed phase startup.

[0081] It should be understood that the specific order or hierarchy of steps in the disclosed processes is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0082] In the foregoing detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention comprises less than all the features of any individual disclosed embodiment. The appended claims are therefore hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0083] The foregoing description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purposes of describing the above embodiments, but one of ordinary skill in the art will recognize that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to encompass all such changes, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent the term "comprising" is used in the specification or claims, the term is intended to be encompassed in a manner similar to the term "including," as explained in terms of "including," used as a transitional word in the claims. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or."

Claims

1. A catalyst + oxygen consuming agent high-efficiency oxygen consuming start-up air hot miscible flooding method, characterized in that: include: injecting a chromium salt catalyst into an injection well of a target oil reservoir to be flooded with hot miscible phase; Injecting a peony seed oil slug as a front slug of oxygen consuming agent into the injection well, and injecting a peppermint oil slug as a rear slug of oxygen consuming agent into the injection well; A soluble bridge plug is placed in front of the injection well, and after injecting water-based foam liquid, air is injected at a set intensity until it is determined that the hot miscible phase flooding is successfully started.

2. The method according to claim 1, wherein If the injection well of the target oil reservoir to be subjected to hot miscible flooding is an original water injection well or an original gas injection well, before injecting the chromium salt catalyst into the injection well of the target oil reservoir to be subjected to hot miscible flooding, the method further includes: A crude oil slug is injected into an injection well of a target oil reservoir to be subjected to hot miscible flooding, and the injection amount of the crude oil slug is determined according to the thickness of the oil layer in the target oil reservoir.

3. The method according to claim 2, wherein The injection volume of crude oil slug is (2~3)×hm 3 , where h is the oil layer thickness of the target reservoir.

4. The method according to claim 1, wherein The method of injecting a chromium salt catalyst into an injection well of a target oil reservoir to be subjected to hot miscible flooding comprises: Inject chromium salt catalyst into the injection well of the target reservoir to be hot miscible flooding, with an injection rate of (0.5~1.0)×hm 3 , where h is the oil layer thickness of the target reservoir; The concentration of the chromium salt catalyst is 0.1-0.5 wt%.

5. The method according to claim 1, wherein The peony seed oil injection slug as the oxygen-consuming agent pre-slug comprises: Inject peony seed oil slug as oxygen consuming agent pre-slug, the injection amount is (1.0~1.5)×hm 3 , where h is the oil layer thickness of the target reservoir.

6. The method according to claim 5, wherein The method of injecting peppermint oil into a slug as an oxygen consuming agent post-slug comprises: Inject peppermint oil slug as oxygen consuming agent post-slug, the injection amount is (0.3~0.8)×hm 3 .

7. The method according to claim 1, wherein The water-based foam liquid is injected, comprising: Inject water-based foam liquid, the injection amount is (2~3)×hm 3 , where h is the oil layer thickness of the target reservoir.

8. The method according to claim 1, wherein The injecting of air according to the set intensity comprises: According to 500~5000Nm 3 / m3 of injected air.

9. The method according to any one of claims 1 to 8, wherein: The bottom hole residual oil saturation of the injection well is greater than 30%.

10. The method according to any one of claims 1 to 8, wherein: Determining that the hot miscible drive is successfully started includes: Successful startup of thermal miscible flooding is determined based on at least one of the following factors: The pressure of the injection well changes, the pressure of the production well connected to the injection well changes, and the components of the gas produced by the production well change.

11. A hot miscible phase flooding mining method, characterized in that: include: Select the injection well of the target reservoir to be flooded with hot miscible phase; Starting the injection well by oxygen consumption at the bottom of the injection well according to the method of any one of claims 1 to 10; The target oil reservoir is produced by thermal miscible flooding.

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