A method for preparing a microscopic glass conceptual model

Abstract

The present invention belongs to the technical field of oil development, and specifically relates to a method for preparing a microscopic glass conceptual model. The method comprises: in the step of making an image base film, two different base films are made, one is only a deepened pattern, and the other is a complete pattern; in the step of making a photolithography chrome plate, two photolithographys are performed, the first time the two films are overlapped and aligned, and the deepened part is photolithography; after the deepened part pattern is formed, the film base with all the patterns is retained for secondary photolithography; the glass is etched to form three-dimensional channels of different depths: the first time the depth difference of the deepened part is etched; the second time the complete pattern is etched according to the designed shallower depth. The model prepared by the method of the present invention has three-dimensional channels with different depths, and can be used to study the migration law of fluids in passages of different depths. The present invention improves the simulation ability of the glass model for real cores, the experimental effect is obvious, and fills the gap in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum development, and in particular relates to a method for preparing a microscopic glass conceptual model. Background Art

[0002] At present, there are two main types of microscopic models used in the field of microscopic simulation of oil recovery in the petroleum industry: glass models and real sandstone models. Microscopic glass models appeared in the 1970s and are widely used in scientific research because of their outstanding features of "intuitive visibility". In recent years, with the improvement of equipment accuracy and research level, the research problems have become more precise and detailed, and the requirements for microscopic models have also been continuously improved.

[0003] The microscopic glass model appeared in the 1970s. It is widely used in scientific research because of its outstanding feature of "intuitive visibility". In recent years, with the improvement of equipment accuracy and research level, the research problems have become more precise and detailed, and the requirements for microscopic models have also been continuously improved. The traditional microscopic model is a two-dimensional model with equal height in the vertical direction, that is, the depth of all pores in the model is the same. The three-dimensional problems of the actual reservoir are characterized by analyzing the two-dimensional changes of the fluid in the model. This characterization ignores the influence of fluid gravity and the influence of longitudinal differences, and there is a certain degree of controversy. Although the real sandstone microscopic model is a three-dimensional model with multi-layer distribution of pores in the vertical direction, the overlap of pores in the same field of view seriously affects the imaging effect and does not have "intuitive visibility".

[0004] High-quality microscopic models are an important foundation and guarantee for oil recovery technology research; currently there is a need for a three-dimensional model that can simulate the actual situation of fluid migration in the pores. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing a microscopic glass conceptual model. The model prepared by the method of the present invention has three-dimensional channels with different depths, and can be used to study the migration law of fluids in channels with different depths.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a microscopic glass conceptual model, comprising preparing an image base film, preparing a photolithographic chrome plate, etching glass to form a three-dimensional channel and melting the model. In the step of preparing the image base film, two different base films are prepared, one of which is only a deepened pattern and the other is a complete pattern.

[0008] In the process of making the photolithographic chrome plate, two photolithography processes are performed. In the first process, two films are overlapped and aligned to perform photolithography of the deepening part. After the deepening part pattern is formed, the film base plate with all the patterns is retained for the second photolithography.

[0009] Etching glass to form three-dimensional channels of different depths: the first etching deepens the depth difference; the second etching the entire pattern at a shallower depth as designed.

[0010] Furthermore, the width of the channel at a deeper depth needs to be reduced to half the depth difference.

[0011] Furthermore, the negative film includes at least two dot marks or cross marks for precise positioning.

[0012] Furthermore, during the photolithography chrome plate production process, two negative plate films are overlapped and aligned and placed in a photolithography machine, exposed for 8-10 seconds, and the exposure intensity is set to the highest level.

[0013] Furthermore, chemical chromium removal is carried out in a dark room without solidifying the glue, and the exposed glass part is directly sealed; after sealing, the first etching is carried out, and the sealed photolithography chromium plate is placed upward and horizontally into the etchant, and the depth difference part is etched according to the set time.

[0014] Furthermore, the sealing and the first etching are both performed in a dark room under yellow light illumination.

[0015] Furthermore, during the second photolithography, chemical chromium removal does not require darkroom operation, and after chromium removal, the glue is solidified, the film is sealed, and the second etching is performed.

[0016] Furthermore, during the first etching, the etching time is determined according to the designed depth difference, and the etching time is equal to the ratio of the depth difference to the etching speed; during the second etching, the etching time is determined according to the low depth design requirement.

[0017] The present invention also provides a microscopic glass conceptual model prepared by any of the preparation methods described above.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The model prepared by the method of the present invention has three-dimensional channels with different depths, and can be used to study the migration law of fluids in channels with different depths. The present invention improves the simulation ability of the glass model to the real rock core, has obvious experimental effects, and fills the gap in the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] Figure 1The conceptual model of pore depth of 50 μm and throat depth of 20 μm prepared by the method described in Example 1 of the present invention: A is a conceptual model diagram of coordination number 4, pore-throat ratio 20, and different depths; B is a schematic diagram of different depths of the cross section and a local actual oil-bearing pore diagram;

[0022] Figure 2 This is a conceptual model of a pore with a middle depth of 40 μm and an edge depth of 20 μm prepared by the method described in Example 1 of the present invention: A is a conceptual model diagram of a three-dimensional pore simulating the enclosed space of large and small rock particles; B is an enlarged diagram of the residual oil in a local pore with a deep middle and shallow edge.

[0023] Figure 3 This is a 100x100mm large-scale model of "one injection and four production", which contains four permeability difference areas composed of ideal channels with different widths and depths. A is the overall physical picture of the model, and B is the parameters of each area. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. 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 invention belongs.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0026] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0027] Example 1

[0028] A method for preparing a microscopic glass conceptual model comprises the following steps:

[0029] Step 1: Image base preparation:

[0030] In order to ensure the manufacturing accuracy, this step solves the impact of side erosion.

[0031] 1) Adjust the design dimensions to eliminate the impact of side erosion: Figure 1For example, the pore diameter is designed to be 280μm, the depth is 50μm, the throat depth is 20μm, the depth difference is 50-20=30 microns, and the side etching effect caused by the etching depth difference is 30 / 2=15 microns. The diameter of all the bottom plate pores is 280-15=265μm.

[0032] 2), make two negative films, the first one is to darken only part of the pattern, e.g. Figure 1 The first one is for the aperture only; the second one is for the entire pattern. The film includes at least two dot marks or cross marks for precise positioning.

[0033] Step 2: Photolithography of chrome plate and first etching:

[0034] This step is carried out in a dark room.

[0035] 1) After obtaining two conceptual model image bases, carefully observe the base quality through a microscope. The black and white are clear and there is no pore adhesion. After overlapping and aligning the calibration points of the two base films under a microscope, put the first darkened pattern on top, put it into the photolithography machine and press it (press it in layers to facilitate the removal of the first one), set the exposure time to 8-10s, set the exposure intensity to the highest level, and photolithograph it on the glass chrome plate. Get the darkened part pattern.

[0036] 2) Perform chemical chromium removal in a dark room, and do not cure the glue (the curing process will expose the resistor wire to light).

[0037] 3) Under yellow light, seal the exposed glass part.

[0038] 4) Under yellow light, place the sealed photolithography chrome plate with the surface facing up in a strong acid etchant horizontally, and etch the depth difference part according to the set time (time = depth difference / etching speed). Quickly take it out and repeatedly wash it in pure water and dry it.

[0039] Step 3: Secondary photolithography and secondary etching

[0040] 1) Place the cleaned chrome plate glass into the fixed position of the photolithography machine. Gently lift the upper laminate, carefully remove the upper film, keep the second film with all the patterns immovable, set the exposure time to 8-10s for secondary photolithography.

[0041] 2) Chemical chromium removal: no darkroom required

[0042] This step is to remove the metal chromium from the exposed part of the chrome plate. First, soak the photolithographic chrome plate in a 6% sodium hydroxide solution for 5-10 seconds, then clean it with pure water, and then soak it in a 15% cerium ammonium nitrate solution for 40-60 seconds to chemically react and remove the chromium, and then clean it with pure water for later use. The chemical reaction time in summer is 5-10 seconds shorter than in winter.

[0043] 3) Glue

[0044] Place the qualified photolithography chrome plate in a high-temperature furnace, heat it to 200℃, and keep it at a constant temperature for 2-4 hours to solidify the glue. Then, use a microscope to check whether the edges of the photolithography image or pattern are flat and smooth and meet the design requirements for use. The purpose of this step is to increase the protection ability of the chrome layer to ensure accuracy.

[0045] 4) Calculate the etching time according to the designed shallow depth and etching speed. Place the sealed photolithography chrome plate horizontally in the strong acid etchant with the surface facing up, and etch according to the set time. Take it out quickly, wash it repeatedly in pure water, and dry it.

[0046] 5) Check the manufacturing accuracy under a microscope. The deepened part is etched twice, the size is measured, the impact of etching is evaluated, and detailed records are made.

[0047] Step 5: Model melting:

[0048] This step can be used in conjunction with model making precision control (see Chinese patent application CN110563340A) to achieve a precision of 10 μm.

[0049] 1) Punch holes at predetermined positions on the etched and inspected glass chrome plate.

[0050] 2) Carefully clean the finished chrome plate glass, including the reaction impurities in the pores. After cleaning, put it into an oven and heat it to 45°C for drying.

[0051] 3) Align the glass partition and the matching polishing sheet to form a microscopic model, and gently place it on the tile pad of the high-temperature furnace. Slowly increase the temperature to 200℃ and keep it constant for 1.5 hours.

[0052] 4) Carry out the first sintering, slowly increase and decrease the temperature. Set the temperature to 635℃ and keep it constant for 1.5h.

[0053] 5) After the first sintering is completed, take out the model and check the size under a microscope.

[0054] 6) If you want to make a 10μm precision model, perform the second sintering as above. After completion, take it out and measure the size. If it meets the requirements, the production is completed.

[0055] Figure 1 This is a conceptual model with a pore depth of 50 μm and a throat depth of 20 μm prepared by the method described in Example 1 of the present invention.

[0056] Figure 2The model shown is a conceptual model designed specifically to study the mechanism of heterogeneous composite flooding. Heterogeneous composite flooding technology is a new chemical flooding technology developed by Shengli Oilfield to improve the recovery rate after polymer flooding. The B-PPG viscoelastic particles have the characteristics of "amoeba". Figure 2 The model is more conducive to analyzing its deformation and migration mechanism in three-dimensional pores than ordinary models, and is closer to actual reservoir conditions and solves practical problems. The research on this topic has achieved phased understanding. At present, heterogeneous composite flooding has entered the stage of industrial promotion after expanded testing.

[0057] "One injection, four mining" 100x100mm large size model, such as Figure 3 As shown, the model achieves a combination of high precision, large size and three-dimensional channels.

[0058] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a microscopic glass conceptual model, comprising the following steps: Step 1: Image base preparation: 1) Adjust the design dimensions to eliminate the impact of side erosion; 2) Two negative films are made, the first one is only a darkened part of the pattern; the second one is the whole pattern; the film includes at least two dot marks or cross marks for precise positioning; Step 2: Photolithography of chrome plate and first etching: 1) Obtain two different negative films in a darkroom, observe that the negatives are clearly black and white, and there is no pore adhesion. The first darkened pattern is on top, overlap and align under a microscope, put them into a photolithography machine for layering and pressing, set the exposure time to 8-10s, set the exposure intensity to the highest level, and photolithograph them onto a glass chrome plate to obtain the darkened pattern; 2) Chemically remove chromium without solidifying the glue; Soak the photolithographic chrome plate in 6% sodium hydroxide solution for 5-10 seconds, then rinse it with pure water, soak it in 15% cerium ammonium nitrate solution for 40-60 seconds to chemically react and remove the chromium, then rinse it with pure water; Do not set the glue after the chrome removal is completed; 3) Under yellow light, seal the exposed glass part; 4) Under yellow light, place the sealed photolithography chrome plate with the surface facing up in a strong acid etchant horizontally, and etch the depth difference part according to the set time; time = depth difference / etching speed, then quickly take it out and repeatedly wash it in pure water and dry it; Step 3: Second photolithography and second etching: 1) Place the cleaned chrome plate glass into the fixed position of the photolithography machine, take out the upper film, keep the second film with all the patterns unchanged, set the exposure time to 8-10s for secondary photolithography; 2) Chemical dechroming and film sealing: 3) Glue Place the qualified photolithography chrome plate in a high-temperature furnace, heat it to 200℃, and keep it at a constant temperature for 2-4 hours to solidify the glue. Then, use a microscope to check whether the edges of the photolithography image or pattern are flat and smooth. 4) Calculate the etching time according to the designed shallow depth and etching speed, put the sealed photolithography chrome plate upward, horizontally into the strong acid etchant, etch according to the set time, then quickly take it out and repeatedly wash it in pure water and dry it; 5) Check the manufacturing accuracy under a microscope, where the deepened part is etched twice, the size is measured, and the impact of etching is evaluated; Then remove the sealing film and all chrome layers; Step 4: Model melting: 1) Punch holes at predetermined positions on the etched and inspected glass; 2) Carefully clean the etched glass, including the reaction impurities in the pores. After cleaning, place it in an oven and heat it to 45°C for drying; 3) Align the etched glass and the matching polishing sheet to form a microscopic model, gently place it on the tile pad of the high-temperature furnace, slowly heat it to 200℃, and keep it at a constant temperature for 1.5h; 4) Carry out the first sintering, slowly increase and decrease the temperature, set the temperature to 635°C, and keep the temperature constant for 1.5 hours; 5) After the first sintering is completed, take out the model and check the size under a microscope; 6) If you want to make a 10μm precision model, perform the second sintering as above. After completion, take it out and measure the size. If it meets the requirements, the production is completed.

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