Novel visual planar model and application

Abstract

The invention discloses a novel visual plane model and application. The preparation method of the visual plane model comprises the following steps: mixing artificial heterogeneous rock core preparation materials, uniformly spreading the materials on a bottom plate in a mold, and then carrying out pre-compaction and pressure forming; the obtained rock core is cut after being cured; a groove is drilled in each of the two rectangular electric wood blocks, holes a penetrating through the grooves are drilled in the two ends of each rectangular electric wood block, and holes b with the same size as the holes a are drilled in the two square electric wood blocks; the two rectangular electric wood blocks are pasted to the injection-production end of the core obtained through cutting, and the grooves face downwards; the two square electric wood blocks are pasted on the rectangular electric wood block, and the hole b corresponds to the hole a to form a through hole; valves are respectively arranged at the through holes; sealing and curing. The plane mass model has better similarity with a natural core in the aspects of pore structure, property and the like, is simple to prepare and good in physical property repeatability, and can be used for observing the oil displacement effect of water flooding and chemical flooding.

Description

Technical Field

[0001] The invention relates to a novel visual plane model and application thereof, belonging to the technical field of oil and gas field development. Background Art

[0002] After a long period of water injection development, the flushing effect of fluid on the high permeability layer will cause the high permeability layer to form a dominant seepage channel, thereby exacerbating the reservoir heterogeneity, resulting in inefficient and ineffective circulation of injected water, insufficient utilization of medium and low permeability layers, and high oil saturation of remaining oil. In recent years, chemical profile control / displacement has been implemented in Daqing, Dagang, Bohai and other oil fields and has achieved good application results in the mine. In order to further improve the recovery effect of chemical profile control / displacement, various new chemical profile control / displacement systems have been developed. Before being applied to oil fields, chemical profile control / displacement systems need to undergo systematic indoor experimental research to clarify the mechanism and effect of improving oil recovery. Visual cores are widely used as a means of directly observing the mechanism of improving oil recovery in the system, but the existing visualization methods are mostly realized by filling sand, that is, filling transparent glass beads in a transparent mold. The model making steps are cumbersome, requiring high experimental skills of operators, and the repeatability is poor. It is of great significance to prepare a model with high visualization and strong repeatability of physical properties and propose a simple and easy-to-operate visualization model preparation method to strengthen the understanding of indoor research. Summary of the invention

[0003] The purpose of the present invention is to provide a new type of visualized plane model, which can be used to carry out oil displacement experimental research through a visualized large-scale plane model and provide theoretical guidance for field practice.

[0004] The method for preparing a visualized plane model provided by the present invention comprises the following steps:

[0005] S1. Mixing the materials for preparing the artificial heterogeneous core and spreading them evenly on the bottom plate of the mold, and then pre-compacting and pressurizing them;

[0006] S2, cutting the core obtained in step S1 after solidification;

[0007] S3, drilling a groove on each of the two rectangular bakelite blocks, and drilling holes a passing through the groove at both ends, and drilling holes b of the same size as the holes on the two square bakelite blocks;

[0008] S4, using high-viscosity epoxy resin to stick the two rectangular bakelite blocks to the core injection end cut in step S2, with the groove facing downward; stick the two square bakelite blocks on the rectangular bakelite blocks respectively, with the hole b corresponding to the hole a to form a through hole;

[0009] S5. Install valves at the through holes respectively; then pour low-viscosity epoxy resin for sealing, and obtain a visualized plane model after curing.

[0010] The present invention uses rectangular bakelite blocks to make visual plane models, which has multiple advantages: the material is strong and durable, has a smooth surface and is easy to process, and at the same time has excellent electrical insulation and heat resistance stability and is not easy to deform; in addition, bakelite is light in weight and easy to transport, has high cost performance and is environmentally friendly, and is suitable for large-scale model production. These characteristics make it perform well in precision models and industrial applications.

[0011] In the preparation method of the present invention, in step S1, the artificial heterogeneous core preparation materials are quartz sand and a binder, wherein the mass content of the quartz sand (spherical glass beads) is 70-85%, and the remainder is the binder; the binder is transparent powder epoxy, which is a high-performance binder. The powder epoxy can be mixed with a filler to play a dual role of bonding and filling.

[0012] In the preparation method of the present invention, in step S1, after the mixed raw materials are evenly spread on the inner bottom plate of the mold, the upper surface of the raw materials is scraped flat with a sanding board until the raw materials are evenly distributed and the upper surface is smooth, and then the pressing block is placed above the mold to pre-compact the raw materials.

[0013] In the preparation method of the present invention, in step S1, the position of the mold is adjusted to keep it on the center line of the pressure plate of the press, and then the pressure is slowly increased, and the pressure is released after stabilizing for 20-30 minutes. After the pressing is completed, the mold is removed to gradually separate the core from the mold.

[0014] In the preparation method of the present invention, in step S2, curing is carried out in a constant temperature box, and the curing conditions are: temperature of 40-50° C. and time of 1.5-2.5 hours.

[0015] In the preparation method of the present invention, in step S2, the solidified material is cut using a wire cutting machine according to the designed shape.

[0016] In the preparation method of the present invention, in step S4, the viscosity of the high-viscosity epoxy resin is 1000-2000 mPa·s, and the viscosity of the low-viscosity epoxy resin is 40-60 mPa·s.

[0017] The preparation method of the high-viscosity epoxy resin is as follows:

[0018] Mix epoxy resin and epoxy curing agent in a ratio of 4:1 and stir evenly, then heat at a constant temperature of 30°C for 50 to 60 minutes, stirring every 10 minutes;

[0019] The epoxy curing agent is 593 type epoxy curing agent, which is a modified fatty amine curing agent prepared by the addition of diethylenetriamine and butyl glycidyl ether, and is a colorless to light yellow transparent liquid.

[0020] In the preparation method of the present invention, the following anti-seepage treatment is performed before installing the valve:

[0021] The high-viscosity epoxy resin is evenly applied to the surface of the core to form a thin layer with a thickness of 1-1.5 mm. After the surface epoxy is solidified, it is placed in a constant temperature box at 40-50° C. for constant temperature curing for 1.5-2.5 hours.

[0022] In the preparation method of the present invention, in order to prevent epoxy from penetrating into the core through the threaded connection between the valve and the bakelite block, 4-5 turns of raw tape are wound around the valve thread before installing the valve.

[0023] The novel plane model provided by the present invention is used for model test and leak test, vacuuming, water saturation and oil saturation, and then water drive, polymer drive and subsequent water drive are carried out in sequence according to the experimental design plan. During the experiment, a camera is used to shoot the distribution of residual oil at different stages.

[0024] During the displacement experiment, a bottom light source needs to be placed under the visualization plane model, and the intensity of the light source remains unchanged during the experiment.

[0025] The plane mass model of the present invention has good similarity with natural cores in terms of pore structure and properties, etc., the model is simple to prepare, has good repeatability of physical properties, and can be used for observing the oil displacement effect of water flooding and chemical flooding. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is an exploded diagram of the visualization model of the present invention.

[0027] Figure 2 To visualize the residual oil distribution at different stages of the experiment. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] The purpose of the present invention is to provide a method for preparing a novel visualization model, which can provide a visualization model with good repeatability and provide an experimental carrier and an experimental method for evaluating the performance of different chemical profile control / displacement agents.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The method for preparing a visual plane model provided by the present invention comprises the following specific steps:

[0032] Step 1. Raw material preparation: The materials for preparing artificial heterogeneous cores include spherical glass beads and transparent powder epoxy. Quartz sand and binder are mixed in weight percentage. According to the target permeability of 2000mD, 320 mesh glass beads (quartz sand) are 80% and transparent binder (transparent powder epoxy) is 20%. The glass beads and transparent powder epoxy are mixed and stirred evenly.

[0033] Step 2: Raw material filling: Spread the mixed raw materials evenly on the inner bottom plate of a rectangular frame mold with a thickness of 0.8 cm, and use a scraper to flatten the upper surface of the raw materials until the raw materials are evenly distributed and the upper surface is smooth, and then place the metal pressing block on top of the mold to pre-compact the raw materials.

[0034] Step 3: Pressurization: Adjust the mold position to keep it on the center line of the pressure plate of the press, then slowly increase the pressure to 4MPa, stabilize the pressure for 30 minutes and then release the pressure. After the pressing is completed, remove the mold to gradually separate the core from the mold.

[0035] Step 4: Temperature-controlled curing: Place the pressed core into a constant temperature box, cure it at 85°C for 4-5 hours, turn off the power of the constant temperature box, and take it out after cooling to room temperature.

[0036] Step 5: Cutting and forming: Use a wire cutting machine to cut the solidified model into a 30cm×30cm square model.

[0037] Step 6. Make injection and production end covers: Use a cutting machine to cut 2 rectangular bakelite blocks and 2 square bakelite blocks. Use a milling machine to drill a groove on the surface of the two rectangular bakelite blocks and drill holes a that pass through the groove at both ends. Use a milling machine to drill holes b of the same size as the rectangular bakelite blocks in the center of the two square bakelite blocks. The dimensions of the rectangular bakelite blocks are 30cm×2cm×1cm, the dimensions of the square bakelite blocks are 2cm×2cm×1cm, the inner diameter of the holes is 0.75cm, the dimensions of the grooves are 27cm×1.5cm×0.5cm, and the grooves are in the rectangular bakelite blocks, facing downward.

[0038] Step 7. Paste the end cap: Epoxy resin and 593 epoxy curing agent are mixed in a ratio of 4:1 and stirred evenly. The stirred epoxy resin is placed in a constant temperature box and heated at a constant temperature of 30°C for 50 to 60 minutes. Stir once every 10 minutes to obtain a high-viscosity epoxy resin (viscosity of 1500mPa·s). Two rectangular bakelite blocks are respectively pasted on the core injection and production ends with the grooves facing downward, and two square bakelite blocks are respectively pasted on the two holes of the rectangular bakelite block to form through holes.

[0039] Step 8. Anti-seepage treatment: Prepare high-viscosity epoxy resin using the method in step 7, and evenly apply the obtained high-viscosity epoxy resin on the surface of the core to form a thin layer with a thickness of 1 mm. After the surface epoxy solidifies, place it in a constant temperature box at 45°C for 2 hours.

[0040] Step 9. Install valves: Install two valves at the through holes of two sets of bakelite blocks respectively. To prevent epoxy from penetrating into the core through the threaded connection between the valve and the bakelite block, wrap 4-5 turns of raw tape around the valve thread before installing the valve.

[0041] Step 10: Casting and sealing: Put the core into the casting mold, prepare 1000g of epoxy with low viscosity (viscosity is 50mPa·s) for casting the core, pour the vacuumed epoxy into the mold and use a fan to dissipate heat, and take out the model after the cast epoxy is cured.

[0042] Displacement experiment: The novel plane model prepared by the present invention was used to conduct model test and leak test, vacuum pumping, water saturation, and oil saturation, followed by 1mL / min water flooding to 95% water content, followed by injection of polymer (functional polymer-heavy oil activator provided by CNOOC Research Institute Co., Ltd.) 0.5PV, and then subsequent water flooding to 95% water content. During the experiment, a camera was used to take pictures of the residual oil distribution at different stages. After converting the pictures into grayscale pictures, the water flooding and subsequent water flooding pictures were compared and analyzed to obtain a 14% reduction in the residual oil saturation. Figure 2 shown.

Claims

1. A method for preparing a visual plane model, comprising the following steps: S1. Mixing the materials for preparing the artificial heterogeneous core and spreading them evenly on the bottom plate of the mold, and then pre-compacting and pressurizing them; S2, cutting the core obtained in step S1 after solidification; S3, drilling a groove on each of the two rectangular bakelite blocks, and drilling holes a passing through the groove at both ends, and drilling holes b of the same size as the holes on the two square bakelite blocks; S4, using high-viscosity epoxy resin to stick the two rectangular bakelite blocks to the core injection end cut in step S2, with the groove facing downward; stick the two square bakelite blocks on the rectangular bakelite blocks respectively, with the hole b corresponding to the hole a to form a through hole; S5. Install valves at the through holes respectively; then pour low-viscosity epoxy resin for sealing, and obtain a visualized plane model after curing.

2. The preparation method according to claim 1, characterized in that: In step S1, the materials for preparing the artificial heterogeneous core are quartz sand and cement, wherein the mass content of the quartz sand is 70-85%, and the rest is the cement.

3. The preparation method according to claim 1 or 2, characterized in that: In step S2, curing is performed in a constant temperature box, and the curing conditions are: temperature of 40-50° C. and time of 1.5-2.5 hours.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In step S4, the viscosity of the high-viscosity epoxy resin is 1000-2000 mPa·s, and the viscosity of the low-viscosity epoxy resin is 40-60 mPa·s.

5. The preparation method according to claim 4, characterized in that: The preparation method of the high-viscosity epoxy resin is as follows: Mix the epoxy resin and epoxy curing agent in a ratio of 4:1 and stir evenly, then heat at a constant temperature of 30°C for 50 to 60 minutes, stirring every 10 minutes.

6. The preparation method according to any one of claims 1 to 5, characterized in that: Before installing the valve, the following anti-seepage treatment is performed: The high-viscosity epoxy resin is evenly applied to the surface of the core to form a thin layer with a thickness of 1-1.5 mm. After the surface epoxy is solidified, it is placed in a constant temperature box at 40-50° C. for constant temperature curing for 1.5-2.5 hours.

7. A visual plane model prepared by the method according to any one of claims 1 to 6.

8. Application of the visualized plane model described in claim 7 in oil displacement experimental research.

9. The use according to claim 8, characterized in that: During the displacement experiment, a bottom light source is placed under the visualization plane model, and the intensity of the light source remains unchanged during the experiment.

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