Method for delaying and strengthening foam channeling sealing system and heavy oil steam thermal recovery

Abstract

The invention relates to the field of oilfield chemistry, and discloses a method for delaying and strengthening a foam channeling sealing system and heavy oil steam thermal recovery. The delayed reinforced foam channeling sealing system comprises gas for foaming and a solid-liquid mixed material, wherein the solid-liquid mixed material comprises a coalescence delaying organic particle system, a foaming agent and optional water; the average particle size of coalescence-delaying organic particles in the coalescence-delaying organic particle system is 0.5-20 microns. Based on the coalescence characteristic of the coalescence delaying organic particles, a layer of fornix framework is formed on the surface of the foam, and the channeling sealing performance of the foam channeling sealing system is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil field chemistry, in particular to a gel and a preparation method thereof, a delayed enhanced foam channeling blocking system, and a method for heavy oil steam injection. BACKGROUND

[0002] The viscosity of heavy oil is high, the flowability is poor, and the starting pressure gradient is high. When steam is injected into heavy oil reservoirs, it will point to the flow channel and need to be blocked to effectively start the heavy oil near the flow channel. The existing foam blocking system either has difficulty in solidification and migration, or has limited strength, which cannot meet the needs of thermal recovery.

[0003] The existing heavy oil thermal recovery foam blocking system mainly includes enhanced foam and ordinary foam. The enhanced foam has problems such as uncontrollable solidification time, limited plugging range, and insufficient migration ability, and the ordinary foam has problems such as poor stability and limited channeling blocking ability. The existing two foam systems are difficult to meet the requirements of strong channeling blocking ability and deep migration, and cannot achieve the effect of gradual mobilization of heavy oil.

[0004] CN112358860A discloses a resin foam type channeling blocking and plugging agent active ingredient, system, preparation method and application. The main components include curable resin, foaming agent, foam stabilizer and curing agent. The curable resin is water-soluble resin or water-dispersible resin, which has high strength and good high temperature resistance after solidification, and can be applied in fracture-cave type reservoir plugging. However, the application of heavy oil is not considered, and the solidified foam is difficult to act on the deep formation. CN103740345A discloses a foam channeling blocking composition, preparation method and use, which includes cationic foam agent, anion-nonionic foam agent and gas. It is a conventional low-strength foam, which is difficult to meet the needs of steam channeling blocking. CN109971443A discloses a three-phase foam channeling blocking agent, preparation method and heavy oil recovery and plugging method. The main components include foaming agent, alpha-starch, acrylamide, initiator, crosslinking agent, control agent and solid particles, and the rest is water. The foam is converted into gel by steam huff and puff, and the solid particles are left after the gel is carbonized by steam to block the flow channel and achieve the effect of plugging. The gel foam process is complex, the migration ability is limited, and the gel stability in the formation is uncontrollable. CN111810139A discloses a carbon dioxide foam channeling blocking experimental device and method, which does not develop a heavy oil thermal recovery foam blocking system.

[0005] Therefore, there is an urgent need for a foam channeling blocking system and a channeling blocking process that can migrate and strengthen during steam injection, effectively utilize steam heat to reduce the viscosity of heavy oil, and solve the channeling problem during heavy oil thermal recovery. SUMMARY

[0006] The gel and the preparation method thereof, the delayed enhanced foam channeling sealing system, and the heavy oil steam injection method provided by the present application can effectively solve the problems of uncontrollable solidification time, limited sealing range, and insufficient migration ability of the enhanced foam, and can also solve the problems of poor stability and limited channeling sealing ability of the ordinary foam.

[0007] To achieve the above-mentioned purpose, the present application provides a preparation method of a gel, wherein the preparation method comprises the following steps: mixing and reacting monomers and a crosslinking agent in the presence of a solvent and an initiator, and the reaction is carried out under the condition that the pH value is less than or equal to 7.

[0008] The monomers comprise acrylamide and dopamine methacrylamide, and the crosslinking agent is a phenolic resin prepolymer.

[0009] The present application provides a gel prepared by the preparation method.

[0010] The present application provides a delayed enhanced foam channeling sealing system, wherein the delayed enhanced foam channeling sealing system comprises: a gas for foaming and a solid-liquid mixture material; wherein the solid-liquid mixture material comprises: a delayed coalescence organic particle system, a foaming agent, and optionally water.

[0011] The delayed coalescence organic particle system is prepared from the gel provided by the present application, and the average particle size of the delayed coalescence organic particles in the delayed coalescence organic particle system is 0.5-20 μm.

[0012] The present application provides a heavy oil steam injection method, wherein the method comprises the following steps:

[0013] S1, injecting the delayed enhanced foam channeling sealing system provided by the present application into an oil reservoir formation;

[0014] S2, injecting the delayed coalescence organic particle system or water into the oil reservoir formation, preferably injecting the delayed coalescence organic particle system into the oil reservoir formation;

[0015] S3, injecting water into the oil reservoir formation;

[0016] S4, performing the next round of heavy oil steam injection;

[0017] The delayed agglomeration organic particle system is prepared from the gel provided by the present invention, and the average particle size of the delayed agglomeration organic particles in the delayed agglomeration organic particle system is 0.5-20 μm.

[0018] The fifth aspect of this invention provides an application of the gel provided by this invention in reducing cross-flow in the later stage of heavy oil thermal recovery.

[0019] The beneficial effects of the present invention through the above technical solution include at least the following:

[0020] The delayed-agglomeration and strengthening foam sealing system for heavy oil thermal recovery of this invention contains delayed-agglomeration organic particles made from gel. Based on the aggregation characteristics of these particles, a "dome" framework is formed on the foam surface, effectively solving the problems of uncontrollable curing time, limited sealing range, and insufficient migration ability of strengthened foam, as well as the problems of poor stability and limited sealing ability of ordinary foam. It can be strengthened while migrating during steam injection, maximizing the utilization of steam heat to reduce the viscosity of heavy oil.

[0021] Acrylamide groups are water-soluble and readily polymerizable, providing a stable polymer structure. The catechol groups in dopamine methacrylamide can cause particle aggregation through metal ion coordination, π-π association, and electrical effects, forming a "dome" skeleton on the foam surface, which not only improves foam strength but also preserves foam transport ability to a certain extent.

[0022] In a preferred embodiment of the present invention, by selecting appropriate amounts of acrylamide, dopamine methacrylamide, and phenolic resin prepolymer when preparing the delayed agglomeration organic particle system, and by selecting appropriate amounts of the delayed agglomeration organic particle system and the foaming agent when preparing the foaming agent system, the stability and foaming performance of the delayed-reinforced foam sealing system are further improved, thereby further enhancing the sealing ability of the delayed-reinforced foam sealing system. Furthermore, by selecting appropriate gas-liquid ratio, appropriate injection volume, and appropriate sealing method during the sealing process, the sealing effect is further improved. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The first aspect of the present application provides a preparation method of a gel, wherein the preparation method comprises the following steps: mixing monomers and a crosslinking agent to react in the presence of a solvent and an initiator, and the reaction is carried out under the condition that the pH value is less than or equal to 7.

[0025] The monomers comprise acrylamide and dopamine methacrylamide, and the crosslinking agent is a phenolic resin prepolymer.

[0026] In order to further improve the re-coalescence and foam stability of the organic particles prepared from the gel, preferably, the contents of the acrylamide, dopamine methacrylamide, phenolic resin prepolymer and initiator in the mixed solution are 15-25 wt%, 1-5 wt%, 0.3-2.4 wt% and 0.1-0.3 wt%, respectively, based on the total weight of the mixed solution, and more preferably, the contents are 20-25 wt%, 2-3 wt%, 0.9-1.5 wt% and 0.1-0.15 wt%, respectively.

[0027] The present application does not have special restrictions on the specific structure of the phenolic resin prepolymer, as long as it can react with the monomers to form a gel, and in a preferred case, the content of the (part of) methylol formaldehyde in the phenolic resin prepolymer is 10-50 wt%, and more preferably, the content is 30-40 wt%.

[0028] The phenolic resin prepolymer can be prepared in the laboratory or purchased commercially. The phenolic resin prepolymer can be added in the form of pure phenolic resin prepolymer or in the form of a mixture of phenolic resin prepolymer and solvent (for example, the solvent is water). The ratio of phenolic resin prepolymer to solvent in the mixture is not particularly limited, and the content of phenolic resin prepolymer in the mixture can be 20-40 wt%. In the specific embodiments of the present application, the phenolic resin prepolymer is added in the form of a mixture of phenolic resin prepolymer and water, for example, the phenolic resin prepolymer system with the trade name of SD-2 purchased from Shandong Shida Oilfield Technology Service Co., Ltd. can be used, and the content of phenolic resin prepolymer in the phenolic resin prepolymer system is 30 wt%, and the content of methylol formaldehyde in the phenolic resin prepolymer is 33.7 wt%. In the present application, the amount of phenolic resin prepolymer is calculated without water.

[0029] The present application does not have special restrictions on the type of initiator, which can be a conventional initiator used for reaction in the art, for example, at least one of azo initiator, redox initiator, organic peroxide initiator and inorganic peroxide initiator, preferably selected from inorganic peroxide initiator, and more preferably ammonium persulfate.

[0030] The present application does not have special restrictions on the type of solvent, as long as it can make the reaction proceed smoothly, and preferably, the solvent is water.

[0031] In order to further improve the reaction efficiency and make the monomers react more fully, preferably, the reaction temperature is 60-65℃ and the reaction time is 10-12h.

[0032] In order to further improve the reaction efficiency, preferably, the reaction is carried out under acidic conditions, more preferably, the reaction is carried out under conditions with pH value of 5-6.

[0033] According to the present application, preferably, the reaction is carried out under oxygen-free conditions. In the specific embodiment of the present application, the oxygen-free environment is maintained by continuously supplying nitrogen during the reaction.

[0034] In order to further improve the stability of the gel body, in a preferred embodiment of the present application, the reaction is carried out in a device with electromagnetic stirring components, and in a preferred case, the stirring speed is 70-100r / min.

[0035] The second aspect of the present application provides a gel prepared by the preparation method of the present application.

[0036] The third aspect of the present application provides a delayed enhanced foam channeling sealing system, wherein the delayed enhanced foam channeling sealing system comprises: a foaming gas and a solid-liquid mixture; wherein the solid-liquid mixture comprises: a delayed coalescence organic particle system, a foaming agent and optional water.

[0037] The delayed coalescence organic particle system is prepared from the gel provided by the present application, and the average particle size of the delayed coalescence organic particles in the delayed coalescence organic particle system is 0.5-20μm.

[0038] In the present application, the delayed coalescence organic particles have a good synergistic effect with the foaming gas and the foaming agent, and compared with the foam channeling sealing system without adding the delayed coalescence organic particles, the channeling sealing capacity of the foam channeling sealing system is significantly improved.

[0039] According to the present application, in order to maintain the migration and foam stability of the delayed coalescence organic particles, the average particle size of the delayed coalescence organic particles needs to be less than or equal to one sixth of the average pore diameter of the target reservoir. Therefore, the average particle size of the delayed coalescence organic particles is set to 0.5-20μm.

[0040] The method for preparing the delayed coalescence organic particle system from the gel is not particularly limited in the present application, and a physical shearing method can be used, preferably, the preparation method of the delayed coalescence organic particle system comprises: mixing the gel and optional water and grinding.

[0041] According to the present application, preferably, the gel and water are mixed at a weight ratio of 1:(10-15) for grinding, and preferably at a weight ratio of 1:(10-12) for grinding.

[0042] The present application does not have special restrictions on the grinding conditions, as long as the average particle size of the delayed coalescence organic particles in the delayed coalescence organic particle system obtained after grinding is 0.5-20 μm.

[0043] In the specific embodiment of the present application, the grinding preparation of the delayed coalescence organic particle system uses a colloidal grinder IKE, GMSD2000 type, with a rotation speed of 0-14000 rpm, and the rotation speed parameter is obtained by setting the frequency conversion device provided therewith; by adjusting different rotation speed parameters, the delayed coalescence organic particle system with an average particle size of 0.5-20 μm is obtained.

[0044] According to the present application, preferably, the gas for foaming is nitrogen.

[0045] In order to further improve the synergistic effect of each component in the delayed and reinforced foam channeling sealing system, thereby further improving the channeling sealing capacity of the delayed and reinforced foam channeling sealing system, preferably, in the delayed and reinforced foam channeling sealing system, the volume ratio of the gas for foaming to the solid-liquid mixture material is 1:(1-2).

[0046] In order to further improve the synergistic effect of each component in the delayed and reinforced foam channeling sealing system, thereby further improving the channeling sealing capacity of the delayed and reinforced foam channeling sealing system, preferably, based on the total weight of the solid-liquid mixture material, the content of the foaming agent in the solid-liquid mixture material is 0.1-5 wt%, and the content of the delayed coalescence organic particle system is 95-99.9 wt%.

[0047] Further, based on the total weight of the solid-liquid mixture material, the content of the foaming agent in the solid-liquid mixture material is 0.4-1 wt%, and the content of the delayed coalescence organic particle system is 99-99.6 wt%.

[0048] In a preferred embodiment of the present application, the gel obtained after the reaction in the first aspect of the present application does not need to be dehydrated, and the material is in a colloidal form. The colloidal gel is directly mixed with water for grinding, and by adjusting the ratio of the gel and water during grinding, the material obtained after grinding (i.e. the delayed coalescence organic particle system) contains water and delayed coalescence organic particles. When preparing the solid-liquid mixture material, the material obtained after grinding is mixed with the foaming agent, without the need for additional water, and the solid-liquid mixture material can be obtained. In the present application, the content of the delayed coalescence organic particle system in the delayed and reinforced foam channeling sealing system is based on the total amount of water and delayed coalescence organic particles. The content of the delayed coalescence organic particles in the delayed coalescence organic particle system is 6-10 wt%.

[0049] According to the present application, preferably, the foaming agent is selected from betaine foaming agents, and preferably is octadecyl propyl sulfobetaine.

[0050] The fourth aspect of the present application provides a method for steam flooding of heavy oil, wherein the method comprises the following steps:

[0051] S1, injecting the delayed enhanced foam channeling sealing system provided by the present application into the oil reservoir formation;

[0052] S2, injecting the delayed coalescence organic particle system or water into the oil reservoir formation, preferably injecting the delayed coalescence organic particle system into the oil reservoir formation;

[0053] S3, injecting water into the oil reservoir formation;

[0054] S4, carrying out the next round of steam flooding of heavy oil;

[0055] The delayed coalescence organic particle system is prepared from the gel provided by the present application, and the average particle size of the delayed coalescence organic particles in the delayed coalescence organic particle system is 0.5-20 μm.

[0056] The preparation method of the delayed coalescence organic particle system in the fourth aspect of the present application is the same as the preparation method of the delayed coalescence organic particle system in the third aspect of the present application, which will not be described here. The delayed coalescence organic particle system injected into the oil reservoir formation in the fourth aspect of the present application refers to the material containing water and delayed coalescence organic particles obtained after grinding. Since the ratio of gel and water during grinding is adjusted, the material containing water and delayed coalescence organic particles obtained after grinding can be directly injected into the oil reservoir formation without additional water. The injection volume is based on the total volume of water and delayed coalescence organic particles.

[0057] In the present application, before the delayed enhanced foam channeling sealing system is injected into the oil reservoir formation, the volume of the channeling flow channel of the oil reservoir formation in the later stage of heavy oil thermal recovery needs to be calculated. In the preferred embodiment of the present application, the volume of the channeling flow channel is based on the numerical simulation permeability model, and the pore volume with a permeability exceeding 1 times the average permeability is defined as the volume of the channeling flow channel, i.e. the pore volume of the channeling flow channel of heavy oil thermal recovery.

[0058] According to the present application, in S1, when the delayed enhanced foam channeling sealing system is injected into the oil reservoir formation, the foaming gas and the solid-liquid mixed material can be mixed and injected; the foaming gas can be injected first, and then the solid-liquid mixed material can be injected; or the solid-liquid mixed material can be injected first, and then the foaming gas can be injected. In the preferred case, the delayed enhanced foam channeling sealing system is injected by mixing the foaming gas and the solid-liquid mixed material.

[0059] In the present application, before the material liquid containing delayed coalescence organic particles is injected into the oil reservoir formation, the average particle size of the delayed coalescence organic particles needs to be selected, so that the average particle size of the delayed coalescence organic particles is less than or equal to one sixth of the target reservoir average pore diameter.

[0060] According to the present application, preferably, in S1, the injection amount of the delayed enhanced foam channeling blocking system is such that the injection volume of the delayed enhanced foam channeling blocking system is 100-120% of the pore volume of the channeling passage of the oil reservoir formation.

[0061] According to the present application, preferably, in S2, the injection amount of the delayed coalescence organic particle system or water is such that the injection volume of the delayed coalescence organic particle system or water is 10-15% of the pore volume of the channeling passage of the oil reservoir formation.

[0062] According to the present application, preferably, in S3, the injection amount of water is such that the injection volume of water is 1.5-2 times of the wellbore volume of the oil reservoir formation. The wellbore volume refers to the volume of the pipe string from the wellhead of the oil-water well to the target reservoir.

[0063] In the preferred embodiments of the present application, when the injection amounts of the delayed enhanced foam channeling blocking system, the delayed coalescence organic particle system and water meet the preferred conditions, the steam channeling regulation effect can be further improved.

[0064] The present application does not particularly limit the injection rate of the delayed enhanced foam channeling blocking system when the delayed enhanced foam channeling blocking system is injected into the oil reservoir formation, the injection rate of the delayed coalescence organic particle system or water when the delayed coalescence organic particle system or water is injected into the oil reservoir formation, and the injection rate of water when water is injected into the oil reservoir formation, as long as the requirements can be met.

[0065] The fifth aspect of the present application provides a use of the gel provided by the present application in reducing channeling in the later stage of thermal recovery of heavy oil, in particular, in reducing channeling in the later stage of steam stimulation of heavy oil reservoirs.

[0066] The present application will be described in detail below through examples and comparative examples. In the following examples, unless otherwise specified, all are conventional methods; the reagents and materials used, unless otherwise specified, can be obtained from commercial channels.

[0067] The phenolic resin prepolymer system was purchased from Shandong Shida Oilfield Technology Service Co., Ltd., with the brand SD-2. The content of phenolic resin prepolymer in the phenolic resin prepolymer system was 30wt%, and the water content was 70wt%. The content of methylol formaldehyde in the phenolic resin prepolymer was 33.7wt%.

[0068] Example 1

[0069] Preparation of the delayed coalescence organic particle system:

[0070] Step 1: At room temperature, 74.9g of water was taken and put into a 300mL round-bottom three-necked flask, and nitrogen was continuously introduced.

[0071] Step 2: 20 g of acrylamide, 2 g of dopamine methacrylamide, 0.1 g of ammonium persulfate, and 3 g of a phenolic resin prepolymer system were slowly added respectively while stirring at 70 r / min;

[0072] Step 3: The pH value was adjusted to 5, the reaction temperature was set to 60°C, and the reaction time was 10 h to obtain a colloid;

[0073] Step 4: The obtained colloid was poured into a colloid grinder with water at a weight ratio of 1:10, and the grinding parameters were adjusted to obtain a delayed coalescence organic particle system A1 (delayed coalescence organic particle content 9.1 wt%, water content 90.9 wt%), and the average particle size of the delayed coalescence organic particles was 0.5 μm.

[0074] Preparation of a foaming agent system:

[0075] At room temperature, 99.5 g of the delayed coalescence organic particle system A1 and 0.5 g of octadecyl propyl sulfobetaine were mixed to form a foaming agent system B1.

[0076] Channeling:

[0077] Step 1: A sandpack tube with a permeability of 2.0 D, a diameter of 2.5 cm, and a length of 50 cm was prepared by wet filling, and the pore volume (PV) of the sandpack tube was 68 mL. In order to facilitate the experiment, the channeling pore volume was set to 2 / 3 of the total pore volume, i.e. 45 mL, and the wellbore system was set to 2 mL;

[0078] Step 2: The sandpack tube was placed in a 60°C constant temperature box;

[0079] Step 3: 15 PV of steam at a temperature of 250°C was injected at a rate of 2 mL / min, and the relative stable pressure P1 was recorded;

[0080] Step 4: A mixture of 25 mL of nitrogen and 25 mL of the foaming agent system B1 was injected into the sandpack tube at an injection rate of 1 mL / min;

[0081] Step 5: 5 mL of the delayed coalescence organic particle system A1 was injected at an injection rate of 1 mL / min;

[0082] Step 6: 3 mL of water was injected at an injection rate of 1 mL / min;

[0083] Step 7: 15 PV of steam at a temperature of 250°C was injected at a rate of 2 mL / min, and the relative stable pressure P2 was recorded.

[0084] Example 2

[0085] Preparation of a delayed coalescence organic particle system:

[0086] Step 1: Take 71.9 g of water and place it in a 300 mL round-bottom three-necked flask at room temperature, continuously passing nitrogen;

[0087] Step 2: Slowly add 20 g of acrylamide, 3 g of dopamine methacrylamide, 0.1 g of ammonium persulfate, and 5 g of a phenolic resin prepolymer system respectively while stirring at 80 r / min;

[0088] Step 3: Adjust the pH value to 6, set the reaction temperature to 60°C, and the reaction time to 10 h to obtain a colloid;

[0089] Step 4: Pour the obtained colloid and water into a colloid grinder at a weight ratio of 1:10, adjust the grinding parameters, and obtain a delayed coalescence organic particle system A2 (delayed coalescence organic particle content 9.1 wt%, water content 90.9 wt%), with an average particle size of the delayed coalescence organic particles being 3 μm.

[0090] Preparation of a foaming agent system:

[0091] Take 99.5 g of delayed coalescence organic particle system A2 and 0.5 g of octadecyl propyl sulfobetaine to prepare a foaming agent system B2.

[0092] According to the method of Example 1, channeling is sealed, except that the foaming agent system B1 is replaced by the foaming agent system B2, and the delayed coalescence organic particle system A1 is replaced by the delayed coalescence organic particle system A2.

[0093] Example 3

[0094] Preparation of a delayed coalescence organic particle system:

[0095] Step 1: Take 66.85 g of water and place it in a 300 mL round-bottom three-necked flask at room temperature, continuously passing nitrogen;

[0096] Step 2: Slowly add 25 g of acrylamide, 3 g of dopamine methacrylamide, 0.15 g of ammonium persulfate, and 5 g of a phenolic resin prepolymer system respectively while stirring at 80 r / min;

[0097] Step 3: Adjust the pH value to 6, set the reaction temperature to 65°C, and the reaction time to 12 h to obtain a colloid;

[0098] Step 4: Pour the obtained colloid and water into a colloid grinder at a weight ratio of 1:12, adjust the grinding parameters, and obtain a delayed coalescence organic particle system A3 (delayed coalescence organic particle content 7.7 wt%, water content 92.3 wt%), with an average particle size of the delayed coalescence organic particles being 20 μm.

[0099] Preparation of a foaming agent system:

[0100] Take 99.5g delayed coalescence organic particle system A3, 0.5g octadecyl propyl sulfobetaine, and prepare a foaming agent system B3.

[0101] According to the method of Example 1, the sealing and channeling is carried out, except that the foaming agent system B1 is replaced by the foaming agent system B3, and the delayed coalescence organic particle system A1 is replaced by the delayed coalescence organic particle system A3.

[0102] Example 4

[0103] The delayed coalescence organic particle system and the foaming agent system are prepared according to the method of Example 1, and the sealing and channeling is carried out according to the method of Example 1, except that the amount of acrylamide, dopamine methacrylamide and phenolic resin prepolymer system is different when preparing the delayed coalescence organic particle system. Specifically, replace "20g acrylamide, 2g dopamine methacrylamide, 3g phenolic resin prepolymer system" with "23g acrylamide, 1g dopamine methacrylamide, 1g phenolic resin prepolymer system".

[0104] The delayed coalescence organic particle system A4 (delayed coalescence organic particle content 9.1wt%, water content 90.9wt%) is obtained, the average particle size of the delayed coalescence organic particle is 0.5μm, and then the foaming agent system B4 is obtained, and then the sealing and channeling is carried out using the delayed coalescence organic particle system A4 and the foaming agent system B4.

[0105] Example 5

[0106] The delayed coalescence organic particle system and the foaming agent system are prepared according to the method of Example 1, and the sealing and channeling is carried out according to the method of Example 1, except that the gas-liquid ratio of the delayed and enhanced foam sealing and channeling system is different when the sealing and channeling is carried out. Specifically, when the sealing and channeling is carried out, replace "25mL nitrogen gas and 25mL foaming agent system B1 are mixed and injected into the sandpack" with "40mL nitrogen gas and 10mL foaming agent system B1 are mixed and injected into the sandpack".

[0107] Example 6

[0108] The delayed coalescence organic particle system and the foaming agent system are prepared according to the method of Example 1, and the sealing and channeling is carried out according to the method of Example 1, except that the amount of delayed coalescence organic particle system and foaming agent is different when preparing the foaming agent system. Specifically, when preparing the foaming agent system, replace "99.5g delayed coalescence organic particle system A1, 0.5g octadecyl propyl sulfobetaine" with "99.7g delayed coalescence organic particle system A1, 0.3g octadecyl propyl sulfobetaine". The foaming agent system B1-1 is obtained, and then the sealing and channeling is carried out using the delayed coalescence organic particle system A1 and the foaming agent system B1-1.

[0109] Example 7

[0110] A delayed coalescence organic particle system and a foaming agent system were prepared according to the method of Example 1, and a chase was performed according to the method of Example 1, except that, when the chase was performed, "5 mL of water was injected" was substituted for "5 mL of the delayed coalescence organic particle system Al was injected".

[0111] Example 8

[0112] A delayed coalescence organic particle system and a foaming agent system were prepared according to the method of Example 1, and a chase was performed according to the method of Example 1, except that, when the chase was performed, "5 mL of water was injected" was substituted for "5 mL of the delayed coalescence organic particle system Al was injected".

[0113] Comparative Example 1

[0114] A delayed coalescence organic particle system and a foaming agent system were prepared according to the method of Example 1, and a chase was performed according to the method of Example 1, except that, when the delayed coalescence organic particle system was prepared, the pH at the time of the reaction was changed. Specifically, "the pH was adjusted to 8" was substituted for "the pH was adjusted to 5".

[0115] A delayed coalescence organic particle system A5 (delayed coalescence organic particle content: 9.1 wt%, water content: 90.9 wt%) in which stable delayed coalescence organic particles could not be formed was obtained, and a foaming agent system B5 was further obtained using the delayed coalescence organic particle system A5 and the foaming agent system B5, and a chase was performed using the delayed coalescence organic particle system A5 and the foaming agent system B5.

[0116] Comparative Example 2

[0117] A delayed coalescence organic particle system and a foaming agent system were prepared according to the method of Example 1, and a chase was performed according to the method of Example 1, except that, when the delayed coalescence organic particle system was prepared, dopamine methacrylamide was substituted for an equal weight of acrylic acid. A delayed coalescence organic particle system A6 (delayed coalescence organic particle content: 9.1 wt%, water content: 90.9 wt%) in which the average particle diameter of the delayed coalescence organic particles was 0.5 μm was obtained, and a foaming agent system B6 was further obtained, and a chase was performed using the delayed coalescence organic particle system A6 and the foaming agent system B6.

[0118] Comparative Example 3

[0119] The delayed coalescence organic particle system and the foaming agent system were prepared according to the method of Example 1, and the channeling was performed according to the method of Example 1, except that the delayed coalescence organic particle system was prepared by replacing the same weight of phenol-formaldehyde resin prepolymer with a chromium acetate crosslinking agent. A delayed coalescence organic particle system A7 (delayed coalescence organic particle content 9.1 wt%, water content 90.9 wt%) was obtained, the average particle size of the delayed coalescence organic particles was 0.5 μm, and then a foaming agent system B7 was obtained, and then the channeling was performed using the delayed coalescence organic particle system A7 and the foaming agent system B7.

[0120] Test Example

[0121] The average particle size of the delayed coalescence organic particles in the delayed coalescence organic particle systems A1-A7 prepared in each example was measured, and the results are shown in Table 1; the foaming properties of the foaming agent systems B1-B7 and B1-1 prepared in each example were measured, and the results are shown in Table 2; and the channeling properties of each example were measured, and the results are shown in Table 3.

[0122] Particle size measurement method: laser particle size analyzer was used for particle size analysis characterization.

[0123] Foaming property measurement method: 80 mL of the foaming agent system was taken and poured into a high-pressure stirring visual foam evaluation device, the internal environment pressure was controlled at 2 MPa using nitrogen, and the temperature was raised to 150°C; stirring was performed at 1000 r / min for 2 min, and the foaming volume and half-life were observed and recorded.

[0124] The channeling property is represented by P2 / P1, which is the ratio of the relative stable pressure after channeling to the relative stable pressure before channeling, and the larger the ratio, the better the channeling effect.

[0125] Table 1

[0126] No. Design particle size / μm Measured particle size / μm A1 0.5 0.52 A2 3.0 3.04 A3 20.0 19.85 A4 0.5 0.63 A5 0.5 Unable to granulate A6 0.5 0.63 A7 0.5 0.38

[0127] Table 2

[0128] No. Foaming volume / mL Half-life / s 1 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2. B1 148 79 B2 142 77 B3 146 73 B4 145 48 B1-1 136 55 B5 143 36 B6 145 42 B7 146 25

[0129] Table 3

[0130]

[0131]

[0132] It can be seen from the results of Tables 1-3 that the delayed enhanced foam channeling sealing system of the application used in Examples 1-8 has good stability and foaming performance, and the delayed enhanced foam channeling sealing system of the application has excellent channeling sealing capacity. In Comparative Example 1, the pH value during the preparation of the delayed coalescence organic particle system is changed, and in Comparative Examples 2 and 3, the monomer type and the crosslinking agent type are changed, respectively, compared with Examples 1-8, the stability of the foaming agent systems B5-B7 prepared in Comparative Examples 1-3 is reduced, and the channeling sealing performance of the delayed coalescence organic particle systems A5-A7 and the foaming agent systems B5-B7 used for channeling sealing is also significantly reduced.

[0133] In addition, in Example 4, the amounts of acrylamide, dopamine methacrylamide and phenolic resin prepolymer used in the preparation of the delayed coalescence organic particle system are changed, compared with Example 1, the half-life of the foaming agent system B4 prepared is reduced, and the ratio P2 / P1 of the relative stable pressure after channeling sealing to the relative stable pressure before channeling sealing is also reduced. In Example 6, the amounts of the delayed coalescence organic particle system and the foaming agent used in the preparation of the foaming agent system are changed, compared with Example 1, the half-life of the foaming agent system B1-1 prepared is reduced, and the ratio P2 / P1 of the relative stable pressure after channeling sealing to the relative stable pressure before channeling sealing is also reduced. In Example 5, the gas-liquid ratio of the delayed enhanced foam channeling sealing system is changed during channeling sealing; in Example 7, the injection amount of the delayed enhanced foam channeling sealing system is changed during channeling sealing; and in Example 8, water is used instead of the delayed coalescence organic particle system during channeling sealing, compared with Example 1, the ratio P2 / P1 of the relative stable pressure after channeling sealing to the relative stable pressure before channeling sealing is reduced. Therefore, when the amounts of acrylamide, dopamine methacrylamide and phenolic resin prepolymer used in the preparation of the delayed coalescence organic particle system, and the amounts of the delayed coalescence organic particle system and the foaming agent used in the preparation of the foaming agent system meet the preferred conditions, the stability and foaming performance of the delayed enhanced foam channeling sealing system can be further improved, thereby further improving the channeling sealing capacity of the delayed enhanced foam channeling sealing system; when the gas-liquid ratio of the delayed enhanced foam channeling sealing system, the injection amount of the delayed enhanced foam channeling sealing system, and the channeling sealing method meet the preferred conditions, the channeling sealing effect can be further improved.

[0134] The above describes the preferred embodiments of the application in detail, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.

Claims

1. A method of preparing a gel, characterized in that, The preparation method comprises the following steps: mixing monomers and cross-linking agents to react in the presence of a solvent and an initiator, wherein the reaction is carried out under the condition of pH value less than or equal to 7. The monomers comprise acrylamide and dopamine methacrylamide, and the cross-linking agent is a phenolic resin prepolymer.

2. The production method according to claim 1, characterized by, The contents of acrylamide, dopamine methacrylamide, phenolic resin prepolymer and initiator in the mixed solution are 15-25 wt%, 1-5 wt%, 0.3-2.4 wt% and 0.1-0.3 wt% respectively, preferably 20-25 wt%, 2-3 wt%, 0.9-1.5 wt% and 0.1-0.15 wt% respectively, based on the total weight of the mixed solution; Preferably, the initiator is ammonium persulfate; and / or, the solvent is water; Preferably, the content of methylol formaldehyde in the phenolic resin prepolymer is 10-50 wt%, preferably 30-40 wt%.

3. The production method according to claim 1 or 2, characterized by, The reaction is carried out at a temperature of 60-65℃ for 10-12 hours. Preferably, the reaction is carried out under the condition of pH value of 5-6. Preferably, the reaction is carried out under the condition of oxygen-free.

4. A gel prepared by the preparation method of any one of claims 1-3.

5. A delayed strength foam conformance control system characterized by, The delayed enhanced foam channeling sealing system comprises a foaming gas and a solid-liquid mixture, wherein the solid-liquid mixture comprises a delayed coalescence organic particle system, a foaming agent and optional water. The delayed coalescence organic particle system is prepared from the gel of claim 4, and the average particle size of the delayed coalescence organic particles in the delayed coalescence organic particle system is 0.5-20 μm.

6. The delayed strength foam conformance barrier system of claim 5, wherein, The preparation method of the delayed coalescence organic particle system comprises mixing the gel and optional water to grind. Preferably, the gel and water are mixed to grind at a weight ratio of 1:(10-15), preferably at a weight ratio of 1:(10-12). Preferably, the foaming gas is nitrogen.

7. The delayed strength foam conformance barrier system of claims 5 or 6, wherein, In the delayed enhanced foam channeling sealing system, the volume ratio of the foaming gas to the solid-liquid mixture is 1:(1-2). Preferably, the content of the foaming agent in the solid-liquid mixture is 0.1-5 wt%, preferably 0.4-1 wt%, and the content of the delayed coalescence organic particle system in the solid-liquid mixture is 95-99.9 wt%, preferably 99-99.6 wt%, based on the total weight of the solid-liquid mixture. Preferably, the foaming agent is selected from betaine foaming agents, preferably octadecyl propyl sulfobetaine.

8. A method for steam assisted heavy oil recovery, characterized in that, The method comprises the following steps: S1, injecting the delayed enhanced foam channeling sealing system of any one of claims 5-7 into an oil reservoir formation; S2, injecting the delayed coalescence organic particle system or water into the oil reservoir formation, preferably injecting the delayed coalescence organic particle system into the oil reservoir formation; S3, injecting water into the oil reservoir formation; S4, carrying out the next round of heavy oil steam thermal recovery. The delayed coalescence organic particle system is prepared from the gel of claim 4, and the average particle size of the delayed coalescence organic particles in the delayed coalescence organic particle system is 0.5-20 μm.

9. The method of claim 8, wherein, In S1, the injection volume of the delayed enhanced foam channeling sealing system is such that the injection volume of the delayed enhanced foam channeling sealing system is 100-120% of the pore volume of the channeling passage of the oil reservoir formation; Preferably, in S2, the injection volume of the delayed coalescence organic particle system or water is such that the injection volume of the delayed coalescence organic particle system or water is 10-15% of the pore volume of the channeling passage of the oil reservoir formation; Preferably, in S3, the injection volume of water is such that the injection volume of water is 1.5-2 times of the wellbore volume of the oil reservoir formation.

10. Use of the gel of claim 4 in reducing channeling in the later stage of thermal recovery of viscous oil.

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