Method for assisting high-temperature catalytic cracking of heavy oil reservoir by flue gas carrying composite additive

Abstract

The invention relates to the technical field of oil exploitation, in particular to a method for assisting high-temperature catalytic cracking of a heavy oil reservoir with a composite auxiliary carried by flue gas. The method comprises the steps that S1, a composite auxiliary fluid slug is injected into a heavy oil reservoir of a stratum to be treated, the injection amount is controlled to range from 0.05 PV to 0.1 PV, and the injection speed ranges from 1 m / d to 3 m / d; s2, the whole stratum to be treated is preheated, the temperature of a heating rod in an ignition well is increased to 300-400 DEG C, combustion-supporting gas is introduced to ignite the heavy oil reservoir, and fireflooding oil extraction is conducted; after the fireflooding reaction is triggered, namely the temperature reaches 400 DEG C, injecting the composite additive fluid slug again; the flue gas generated by combustion of the heavy oil further carries catalytic components in the composite auxiliary agent to act on a deep oil layer, and high-temperature catalytic cracking is carried out on a heavy oil reservoir; the re-injection amount of the composite additive fluid slug is controlled to be 0.05-0.1 PV, and the injection speed is 1-3 m / d. According to the invention, by introducing the composite auxiliary agent and combining the combined action of the steam and the flue gas, the efficient development of the heavy oil reservoir is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, and particularly to a method for high-temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying a composite additive. Background Art

[0002] The development of heavy oil reservoirs has always been one of the technical challenges in the global oil industry. Especially in China, the heavy oil resources are rich in reserves, but their exploitation is difficult, and traditional exploitation methods face many limitations. The traditional steam stimulation method is the main means of heavy oil thermal recovery in China at present. This method injects high-temperature steam into the oil reservoir, uses the heat of the steam to heat the crude oil, reduces its viscosity, and thus improves the fluidity of the crude oil for easy exploitation. However, as most oil fields enter the middle and late stages of steam stimulation exploitation, after multiple rounds of stimulation, the thermal efficiency of the oil reservoir decreases significantly, the oil-steam ratio also gradually decreases, and the exploitation effect gradually deteriorates. This is mainly because the heat loss of steam in the oil reservoir is large, and the coverage range of steam is limited, resulting in an unsatisfactory heating effect on the crude oil. In addition, with the deepening of exploitation, the pressure of the oil reservoir gradually decreases, and the injection pressure of steam also increases accordingly, further increasing the production cost. The oil-steam ratio of some oil fields has approached the economic limit, resulting in a significant decline in the exploitation benefit of the steam stimulation method.

[0003] The fire flooding technology, also known as "in-situ combustion" abroad, is a thermal recovery method that injects air (or oxygen) into the oil reservoir and uses the spontaneous combustion or artificial ignition of crude oil to make part of the crude oil in the formation burn in-situ. The heat released during the combustion process can significantly increase the temperature of the oil reservoir, further reduce the viscosity of the crude oil, and enhance the fluidity of the crude oil. At the same time, the gas generated by the combustion can also increase the formation energy and drive the crude oil to flow towards the production well. However, there are still some key problems to be solved in the practical application of traditional fire flooding technology: the high viscosity of heavy oil makes its ignition point relatively high, and a higher temperature is required to initiate the combustion reaction. At the same time, problems such as the poor heat conduction effect and the large environmental pollution caused by flue gas emissions also limit the application of fire flooding technology. Therefore, developing a new oil production method to effectively reduce the viscosity of crude oil and enhance the oil displacement effect has important practical value.

[0004] Glossary:

[0005] Fire flooding technology: Using part of the combustion cracking products of the oil reservoir itself as fuel, and with the help of an external oxygen source and artificial heating and ignition means to ignite the oil reservoir, maintaining continuous combustion of the oil reservoir, using the heat generated by the combustion to heat the oil reservoir, thereby reducing the viscosity of the crude oil, improving the fluidity of the crude oil, driving the crude oil to flow towards the production well, and realizing the exploitation of heavy oil.

[0006] Combustion improver: A chemical substance injected into the oil layer that can enhance the combustion reaction inside the oil layer and increase the combustion temperature and speed. These chemicals can react with hydrocarbons in the oil layer to produce more heat and combustion products, thereby increasing the recovery rate.

[0007] Artificial ignition: Through electric ignition, chemical ignition and other methods, a high-temperature area is formed near the wellbore. In this area, the crude oil and the injected air undergo a violent oxidation reaction, that is, combustion, thereby igniting the oil layer.

[0008] Oil-gas ratio: reflects the degree of degassing of underground crude oil, refers to the ratio of the amount of natural gas produced by the oil reservoir to the crude oil production. It indicates how many cubic meters of natural gas are produced for every ton of crude oil produced.

[0009] Composite additive fluid segment plug: In the process of oil field development, in order to improve the crude oil recovery rate, a composite additive is injected into the oil layer to form a clear oil displacement zone to optimize the oil displacement effect. Summary of the invention

[0010] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a method for high-temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives. The present invention realizes efficient development of heavy oil reservoirs by introducing composite additives and combining the combined effects of steam and flue gas.

[0011] The technical solution adopted by the present invention to solve the technical problem is:

[0012] A method for high-temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives, specifically comprising the following steps:

[0013] Step S1, injecting a composite auxiliary fluid slug into a heavy oil reservoir in a to-be-treated formation, with the injection volume controlled at 0.05-0.1 PV and the injection speed at 1-3 m / d;

[0014] Step S2, preheating the entire to-be-treated formation for 20 to 50 minutes, raising the temperature of the heating rod in the ignition well to 300 to 400° C., introducing a combustion-supporting gas to ignite the heavy oil reservoir, and performing fire drive oil production; after the fire drive reaction is initiated, that is, the temperature reaches 400° C., injecting the composite auxiliary fluid slug into the heavy oil reservoir of the to-be-treated formation again; the flue gas generated by the combustion of the heavy oil further carries the catalytic components in the composite auxiliary agent to act on the deep oil layer, and performs high-temperature catalytic cracking on the heavy oil reservoir; the re-injection amount of the composite auxiliary fluid slug is controlled to be 0.05 to 0.1 PV, and the injection speed is 1 to 3 m / d.

[0015] The composite additive fluid slug is injected into the heavy oil reservoir of the formation to be treated in two times. Before the fire flooding reaction is initiated, that is, before ignition, a certain amount is injected first. After the fire flooding reaction is initiated, that is, when the temperature reaches above 400 °C, a certain amount is injected again, and the injection amounts in the two times are equal. The mechanism of the two - time injection lies in that: the first injection is to reduce the ignition temperature and initiate the fire flooding reaction, which mainly plays a role in supporting combustion; the second injection is when the reservoir temperature reaches above 400 °C, which mainly plays a catalytic role, further catalyzing viscosity reduction while reducing viscosity at high temperature.

[0016] Furthermore, the composite additive in the steps S1 and S2 specifically includes the following components in mass percentages:

[0017]

[0018] Among them, the alcohol combustion promoter is one or more of methanol, ethylene glycol, isopropyl alcohol, and propylene glycol; the catalyst is one or more of sodium sulfate, ferrous sulfate, and calcium sulfate; the stabilizer is one or more of polyvinyl alcohol, phenolic resin, and dibutyltin oxide acetate.

[0019] Furthermore, the injection amounts of the composite additive fluid slug in the steps S1 and S2 are equal, and the injection amount each time is 0.08 - 0.1 PV, and the injection speed each time is 2 - 3 m / d. Preferably, the injection amount is controlled at 0.1 PV and the injection speed is 3 m / d.

[0020] Furthermore, in the step S2, the pre - heating method of the formation to be treated is electric heating, the pre - heating duration is 30 - 50 minutes, and the temperature of the heating rod in the ignition well is raised to 350 - 400 °C. Preferably, the pre - heating duration is 45 minutes and the temperature of the heating rod in the ignition well is 375 °C.

[0021] Furthermore, the combustion - supporting gas in the step S2 is one or two of compressed oxygen and air.

[0022] Furthermore, the mass percentage of the alcohol combustion promoter is 10 - 15%, and the mass percentage of the catalyst is 15 - 20%. Preferably, the mass percentage of the alcohol combustion promoter is 10% and the mass percentage of the catalyst is 20%.

[0023] Furthermore, the preparation method of the composite additive is specifically as follows:

[0024] (1). Material preparation: ferrous sulfate, isopropyl alcohol solution, deionized water, stabilizer;

[0025] (2). Dissolve ferrous sulfate in deionized water, heat to 60 °C, and stir until completely dissolved to obtain a ferrous ion solution;

[0026] (3) slowly adding isopropanol solution to the ferrous ion solution while maintaining stirring, adjusting the solution pH to 7, and when the mixed solution reaches 30° C., using chemical vapor deposition to uniformly attach propoxide ions to the ferrous ions;

[0027] (4) Add stabilizer and continue stirring for 30 minutes to ensure that the stabilizer is completely dissolved;

[0028] (5) The prepared composite auxiliary agent solution is cooled to room temperature, impurities are removed by isopycnic gradient centrifugation and membrane filtration, and then stored in a sealed container.

[0029] Furthermore, the alcohol combustion improver is isopropanol, the catalyst is ferrous sulfate, and the stabilizer is polyvinyl alcohol.

[0030] The beneficial effects of the present invention are as follows: the present invention is reasonably designed; the composite additive of the present invention is a composite additive that integrates a combustion improver and a catalyst; the composite additive can reduce the ignition point and can also catalyze the decomposition of heavy components in crude oil into light components, thereby effectively reducing the viscosity of heavy oil; at the same time, segmented plug injection is adopted during injection: that is, half of the amount is injected first, and the other half of the amount is injected after the fire drive reaction is triggered, thereby effectively making the crude oil more evenly heated laterally during combustion, and better moving the combustion zone forward to displace the crude oil; in this process, the flue gas generated by the combustion of heavy oil further carries the catalytic components in the composite additive to act on the deep oil layer; at the same time, the flue gas generated slows down the condensation of steam, reduces environmental pollution, and further enhances the oil recovery effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 and Figure 2 1 is a graph showing the combustion-supporting and viscosity-reducing effects of the composite additive fluid slug at different injection amounts and injection speeds in Example 11 of the present invention;

[0033] Figure 3 and Figure 4 It is an index diagram of the combustion-supporting and viscosity-reducing effects at different formation preheating times and heating rod temperatures in the ignition well in Example 12 of the present invention. DETAILED DESCRIPTION

[0034] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] The composite additive of this embodiment specifically includes the following components in mass percentage: 10% alcohol combustion improver, 20% catalyst, 69% deionized water and 1% stabilizer; wherein the alcohol combustion improver is isopropyl alcohol, the catalyst is ferrous sulfate, and the stabilizer is polyvinyl alcohol. Isopropyl alcohol, as a combustion improver, provides an oxidant required for combustion and reduces the ignition point; ferrous sulfate provides ferrous ions to reduce the viscosity of heavy oil; deionized water is used as a solvent to dissolve and disperse the components; stabilizer (such as polyvinyl alcohol) can improve the stability of the composite additive.

[0039] The preparation method of the composite auxiliary agent in this embodiment is as follows:

[0040] (1) Material preparation: ferrous sulfate, isopropanol solution, deionized water, stabilizer;

[0041] (2) dissolving ferrous sulfate in deionized water, heating to 60° C., and stirring until completely dissolved to obtain a ferrous ion solution;

[0042] (3) slowly adding isopropanol solution to the ferrous ion solution while stirring, adjusting the pH value of the solution to 7, and when the mixed solution reaches 30° C., using chemical vapor deposition (CVD) to uniformly attach propoxide ions to the ferrous ions;

[0043] (4) Add stabilizer and continue stirring for 30 minutes to ensure that the stabilizer is completely dissolved;

[0044] (5) The prepared composite auxiliary agent solution is cooled to room temperature, impurities are removed by isopycnic gradient centrifugation and membrane filtration, and then stored in a sealed container.

[0045] The method of using flue gas to carry composite additives to assist high-temperature catalytic cracking of heavy oil reservoirs in this embodiment has the following specific process:

[0046] A composite auxiliary fluid segment plug is injected into the heavy oil reservoir, and the injection volume is controlled at 0.1PV. During this process, segmented plugs are used for injection. Half of the volume is injected first, and the other half is injected after the fire drive reaction is induced. The injection rate is 3m / d. The entire formation is preheated using the electric heating preheating method. The preheating time is 45 minutes. The temperature of the heating rod in the ignition well is increased to 375℃, the reservoir is ignited, and fire drive oil production is carried out.

[0047] Embodiment 2 to Embodiment 4

[0048] In order to investigate the best substance to use for alcohol combustion improvers, Examples 2 to 4 are different from Example 1 in that the alcohol combustion improvers are methanol, ethylene glycol and propylene glycol, respectively, and other components and methods of Examples 2 to 4 are the same as those of Example 1.

[0049] A certain mass of crude oil was taken, and the viscosity reduction and combustion support degree of the composite additive under different types of alcohol combustion aids were simulated through experiments during fire flooding. The viscosity of the crude oil was measured to be 4025mPa·s at room temperature. The combustion time, average temperature during the combustion process, and viscosity after the addition of the composite additive were measured. The test results are shown in Table 1.

[0050] Table 1 Test results of Examples 1 to 4

[0051] Example Combustion aid type Burning time / s Average temperature / ℃ Viscosity / mPa·s Example 2 Methanol 21 420 54 Example 3 Ethylene glycol 23 414 62 Example 1 Isopropyl alcohol 25 422 52 Example 4 Propylene glycol 17 430 57

[0052] In addition, under different alcohol combustion aids in Examples 1 to 4, the combustion time × the average temperature during the combustion process is used as an indicator of the degree of combustion support, and (viscosity after the end of combustion - viscosity at room temperature) / viscosity at room temperature is used as an indicator of the degree of viscosity reduction, and the combustion support and viscosity reduction results under different alcohol combustion aids in Examples 1 to 4 are obtained, as shown in Table 2.

[0053] Table 2 Combustion support and viscosity reduction test results in Examples 1 to 4

[0054] Example Combustion aid type Combustion support index Viscosity reduction index Example 2 Methanol 8820 0.98658 Example 3 Ethylene glycol 9522 0.98460 Example 1 Isopropyl alcohol 10550 0.98708 Example 4 Propylene glycol 7310 0.98584

[0055] It can be seen from Table 1 and Table 2 that in the presence of a catalyst (ferrous sulfate) and a stabilizer (polyvinyl alcohol), the addition of isopropanol (Example 1) has excellent combustion-supporting and viscosity-reducing effects.

[0056] Embodiment 5-embodiment 6

[0057] In order to investigate the best material to use as the catalyst, Examples 5 to 6 are different from Example 1 in that the catalysts are sodium sulfate and calcium sulfate, respectively. The other components and methods of Examples 5 to 6 are the same as those of Example 1.

[0058] Example 1, Example 5-Example 6 were tested according to the method of Example 2, and the combustion time, average temperature during the combustion process, and viscosity after the combustion of the crude oil after adding the composite additive were measured. The test results are shown in Table 3.

[0059] Table 3 Test results of Example 1, Example 5 to Example 6

[0060] Example Catalyst type Burning time / s Average temperature / ℃ Viscosity / mPa·s Example 1 Ferrous Sulfate 25 422 52 Example 5 Sodium sulfate 18 424 58 Example 6 Calcium sulfate 22 419 56

[0061] In addition, the combustion-supporting and viscosity-reducing results of Examples 1 and 5 to 6 under different catalysts are shown in Table 4.

[0062] Table 4 Combustion support and viscosity reduction test results in Example 1, Example 5 to Example 6

[0063] Example Catalyst type Combustion support index Viscosity reduction index Example 1 Ferrous Sulfate 10550 0.98708 Example 5 Sodium sulfate 7632 0.98559 Example 6 Calcium sulfate 9218 0.98609

[0064] It can be seen from Table 3 and Table 4 that, in the case of alcohol combustion improver (isopropyl alcohol) and stabilizer (polyvinyl alcohol), the addition of ferrous sulfate (Example 1) has excellent combustion-supporting and viscosity-reducing effects.

[0065] Embodiment 7-Embodiment 8

[0066] In order to investigate the best material to use as a stabilizer, Examples 7 to 8 differ from Example 1 in that the stabilizers are phenolic resin and di-n-butyltin oxyacetate, respectively, and other components and methods of Examples 7 to 8 are the same as those of Example 1.

[0067] Example 1, Example 7 to Example 8 were tested according to the method of Example 2, and the combustion time, average temperature during combustion, and viscosity after combustion of the crude oil after adding the composite additive were measured. The test results are shown in Table 5.

[0068] Table 5 Test results of Example 1, Example 7 to Example 8

[0069] Example Stabilizer Type Burning time / s Average temperature / ℃ Viscosity / mPa·s Example 1 Polyvinyl alcohol 25 422 52 Example 7 Phenolic resin 25 421 53 Example 8 Di-n-butyltin oxyacetate 24 422 52

[0070] In addition, the combustion-supporting and viscosity-reducing results of Examples 1 and 7 to 8 under different stabilizers are shown in Table 6.

[0071] Table 6 Combustion support and viscosity reduction test results in Example 1, Example 7 to Example 8

[0072] Example Stabilizer Type Combustion support index Viscosity reduction index Example 1 Polyvinyl alcohol 10550 0.98708 Example 7 Phenolic resin 10525 0.98683 Example 8 Di-n-butyltin oxyacetate 10128 0.98708

[0073] It can be seen from Tables 5 and 6 that when the optimal alcohol combustion aid (isopropyl alcohol) and stabilizer (polyvinyl alcohol) are selected, the choice of stabilizer has little effect on the experimental results.

[0074] Embodiment 9-embodiment 10

[0075] In order to investigate the optimal ratio of the alcohol combustion improver and the catalyst, the difference between Example 9 and Example 10 is that the ratio of the alcohol combustion improver and the catalyst is changed. The other components and methods of Example 9 and Example 1 are the same.

[0076] The combustion-supporting and viscosity-reducing results under different ratios of Example 1, Example 9 to Example 10 are shown in Table 7.

[0077] Table 7 Combustion support and viscosity reduction test results in Example 1, Example 9 to Example 10

[0078]

[0079] It can be seen from Table 7 that when the alcohol combustion improver (isopropyl alcohol), catalyst (ferrous sulfate) and stabilizer (polyvinyl alcohol) are fixed, the ratio of the combustion improver to the catalyst is 10% and 20% (Example 1), which has excellent combustion-supporting and viscosity-reducing effects.

[0080] Embodiment 11

[0081] The difference between this embodiment and embodiment 1 is that the injection amount and injection speed of the composite auxiliary agent fluid slug are changed, specifically:

[0082] The injection volume was controlled to be unchanged at 0.1 PV, and the injection speed was gradually increased from 1 m / d to 3 m / d;

[0083] The injection speed was controlled at 3 m / d, and the injection volume was increased from 0.05 PV to 0.1 PV.

[0084] Combustion-supporting and viscosity-reducing effects such as Figure 1 and Figure 2 As shown, through Figure 1 and Figure 2 It can also be seen that the larger the injection amount and injection speed are within the specified range, the better the combustion-supporting and viscosity-reducing effects are.

[0085] Example 12

[0086] The difference between this embodiment and embodiment 1 is that the formation preheating time and the temperature of the heating rod in the ignition well are changed, specifically: the preheating time and the temperature of the heating rod in the ignition well are gradually increased within a limited range, and the combustion-supporting and viscosity-reducing effects are as follows: Figure 3 and Figure 4 shown.

[0087] Through Figure 3 and Figure 4 It can be seen that when the preheating duration is 45 minutes and the temperature of the heating rod in the ignition well is 375 °C, the effect is the best.

[0088] Example 13

[0089] Through the comprehensive evaluation of Examples 1 to 13, it is concluded that Example 1 is the optimal example of the present invention.

[0090] The practical application of Example 1 is as follows:

[0091] In a certain heavy oil reservoir in the western region, the original formation pressure is 9 Mpa, the original formation temperature is 47 °C, the viscosity of the formation crude oil is 4000 mPa·s, and the density of the formation crude oil is 0.986 g / cm 3 . Two reservoir blocks A and B are selected, and one injection well and one production well are used, that is, one ignition well and one production well.

[0092] The above two reservoir blocks A and B are simultaneously carried out according to the following steps: the entire formation is preheated by the electric heating preheating method, the temperature of the heating rod in the ignition well is increased to 375 °C, the reservoir is ignited, a combustion promoter is injected near the ignition well, and then air is continuously introduced at an injection rate of 10 L / min for 100 min, and the injection rate of the combustion promoter is 150 mL / min.

[0093] When the method of the present invention is applied in an actual reservoir, in reservoir block A with a common combustion promoter added, the recovery degree is 30%, and the recovery rate is 53%. After adding a composite additive in reservoir block B, the recovery degree is 39%, and the recovery rate is 73%, indicating that the effect of Example 1 is good.

[0094] Comparative Examples 1 to 3

[0095] In order to verify the excellent effect of the preferred alcohol-based combustion promoter of the present invention, the differences between Comparative Examples 1 to 3 and Example 1 are as follows: the combustion promoter is other combustible organic solvents, which are propane (alkane), ethylene (olefin) and benzene (aromatic hydrocarbon) respectively. The other components and methods of Comparative Examples 1 to 3 are the same as those of Example 1.

[0096] The combustion promotion and viscosity reduction results of Example 1, Comparative Examples 1 to 3 under different combustible organic solvents are shown in Table 8.

[0097] Table 8 Combustion promotion and viscosity reduction test results in Example 1, Comparative Examples 1 to 3

[0098] Comparative Example Combustion aid type Combustion support index Viscosity reduction index Example 1 Isopropyl alcohol 10550 0.98708 Comparative Example 1 Propane 4321 0.90212 Comparative Example 2 Ethylene 3876 0.88623 Comparative Example 3 benzene 2204 0.78660

[0099] It can be seen from Table 8 that when the catalyst (ferrous sulfate) and the stabilizer (polyvinyl alcohol) are fixed, the preferred alcohol combustion improver of the present invention (Example 1) has excellent combustion-supporting and viscosity-reducing effects.

[0100] Comparative Examples 4 to 6

[0101] In order to verify the excellent effect of the preferred catalyst of the present invention, the difference between Comparative Examples 4 to 6 and Example 1 is that the types of catalysts are copper oxide, copper sulfate and aluminum oxide, respectively, and the other components and methods of Comparative Examples 4 to 6 are the same as those of Example 1.

[0102] The combustion-supporting and viscosity-reducing results of Example 1 and Comparative Examples 1 to 3 under different flammable organic solvents are shown in Table 9.

[0103] Table 9 Combustion support and viscosity reduction test results in Example 1, Comparative Examples 4 to Comparative Examples 6

[0104] Comparative Example Catalyst type Combustion support index Viscosity reduction index Example 1 Ferrous Sulfate 10550 0.98708 Comparative Example 4 Copper sulfate 9032 0.94320 Comparative Example 5 Copper Oxide 7892 0.92242 Comparative Example 6 Alumina 6650 0.91986

[0105] It can be seen from Table 9 that when the combustion-supporting agent (isopropanol) and the stabilizer (polyvinyl alcohol) are fixed, the preferred catalyst of the present invention (Example 1) has excellent combustion-supporting and viscosity-reducing effects.

[0106] In summary, the present invention has a reasonable design. The composite additive of the present invention is a composite additive that integrates a combustion improver and a catalyst. The composite additive can reduce the ignition point and catalyze the decomposition of heavy components in crude oil into light components, thereby effectively reducing the viscosity of heavy oil. At the same time, segmented plug injection is adopted during injection: that is, half of the amount is injected first, and the other half of the amount is injected after the fire drive reaction is triggered, thereby effectively making the crude oil more evenly heated laterally during combustion, and better moving the combustion zone forward to displace the crude oil. In this process, the flue gas generated by the combustion of heavy oil further carries the catalytic components in the composite additive to act on the deep oil layer. At the same time, the flue gas generated slows down the condensation of steam, reduces environmental pollution, and further enhances the oil recovery effect.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives, characterized in that: The specific steps include: Step S1, injecting a composite auxiliary fluid slug into a heavy oil reservoir in a to-be-treated formation, with the injection volume controlled at 0.05-0.1 PV and the injection speed at 1-3 m / d; Step S2, preheating the entire to-be-treated formation for 20 to 50 minutes, raising the temperature of the heating rod in the ignition well to 300 to 400° C., introducing a combustion-supporting gas to ignite the heavy oil reservoir, and performing fire drive oil production; after the fire drive reaction is initiated, that is, the temperature reaches 400° C., injecting the composite auxiliary fluid slug into the heavy oil reservoir of the to-be-treated formation again; the flue gas generated by the combustion of the heavy oil further carries the catalytic components in the composite auxiliary agent to act on the deep oil layer, and performs high-temperature catalytic cracking on the heavy oil reservoir; the re-injection amount of the composite auxiliary fluid slug is controlled to be 0.05 to 0.1 PV, and the injection speed is 1 to 3 m / d.

2. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 1, characterized in that: The composite auxiliary agent in step S1 and step S2 specifically includes the following components in percentage by mass: Among them, the alcohol combustion aid is one or more of methanol, ethylene glycol, isopropanol, and propylene glycol; the catalyst is one or more of sodium sulfate, ferrous sulfate, and calcium sulfate; the stabilizer is one or more of polyvinyl alcohol, phenolic resin, and di-n-butyltin oxyacetate.

3. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 1, characterized in that: The injection amount of the composite auxiliary fluid segment plug in step S1 and step S2 is equal, each injection amount is 0.08-0.1 PV, and each injection speed is 2-3 m / d.

4. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 1, characterized in that: In step S2, the preheating method of the to-be-treated formation is electric heating, the preheating time is 30 to 50 minutes, and the temperature of the heating rod in the ignition well is set to 350 to 400°C.

5. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 1, characterized in that: In step S2, the combustion-supporting gas is one or both of compressed oxygen and air.

6. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 2, characterized in that: The mass percentage of the alcohol combustion improver is 10-15%, and the mass percentage of the catalyst is 15-20%.

7. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 2, characterized in that: The preparation method of the composite auxiliary agent is as follows: (1) Material preparation: ferrous sulfate, isopropanol solution, deionized water, and stabilizer; (2) dissolving ferrous sulfate in deionized water, heating to 60° C., and stirring until completely dissolved to obtain a ferrous ion solution; (3) slowly adding isopropanol solution to the ferrous ion solution while maintaining stirring, adjusting the solution pH to 7, and when the mixed solution reaches 30° C., using chemical vapor deposition to uniformly attach propoxide ions to the ferrous ions; (4) Add stabilizer and continue stirring for 30 minutes to ensure that the stabilizer is completely dissolved; (5) The prepared composite auxiliary agent solution is cooled to room temperature, impurities are removed by isopycnic gradient centrifugation and membrane filtration, and then stored in a sealed container.

8. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 2, characterized in that: The alcohol combustion improver is isopropanol, the catalyst is ferrous sulfate, and the stabilizer is polyvinyl alcohol.

9. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 3, characterized in that: The injection volume each time is controlled to be 0.1 PV, and the injection speed each time is 3 m / d.

10. The method of high temperature catalytic cracking of heavy oil reservoirs assisted by flue gas carrying composite additives according to claim 6, characterized in that: The mass percentage of the alcohol combustion improver is 10%, and the mass percentage of the catalyst is 20%.

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