Emulsion particle and throat size matching determination method

Abstract

The invention provides a method for determining the size matching of emulsion particles and a throat. The method comprises the following steps: S1, collecting a local microscopic image representing that the emulsion particles play a profile control and displacement role in an emulsifier solution oil displacement microscopic visualization experiment process; s2, in the process of collecting the target image, an image analysis method is adopted, and the equivalent radius of emulsion particles which deform to pass through a throat and play a profile control and displacement role is calculated; s3, determining and calculating the narrowest radius of a throat through which the emulsion particles in the collected target image pass in a deformed manner; and S4, carrying out statistical analysis on the ratio interval of the equivalent radius and the throat radius of the deformed emulsion particles in the experiment process. And the profile control and flooding effect of emulsion flooding or emulsifier flooding is exerted to the maximum extent, the heterogeneity of the reservoir is improved, and the recovery efficiency is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of enhancing oil recovery by emulsion profile control during oilfield exploitation, and particularly to a method for determining the matching between emulsion particles and throat sizes. Background Art

[0002] During the process of enhancing oil reservoir recovery by chemical flooding, in-situ formation or direct injection of O / W emulsions is recognized as one of the effective methods to improve the sweep efficiency and displacement efficiency. The emulsification carrying and emulsification trapping effects of the emulsifier solution to form emulsions are the main mechanisms for enhancing oil recovery. In particular, emulsions have a profile control effect similar to that of "weak gel" particles and cause no damage to the reservoir. Due to the low viscosity of emulsions, they also have good injectability. In the reservoir, the interaction between emulsions and the reservoir porous medium has a good temporary plugging effect, and the Jamin effect is one of the main mechanisms for the temporary plugging effect of emulsions. When the radius of emulsion particles is smaller than the radius of the throat, the emulsion particles do not play a plugging role in the throat; when the size of emulsion particles is larger than the radius of the throat, one phenomenon is that the emulsion particles are stuck at the throat entrance and play a permanent plugging role, and another phenomenon is that the emulsion particles can deform and pass through the throat to play a profile control role. If the matching between emulsion particles and throat sizes is good, the emulsifier solution flooding or emulsion flooding will fully exert the profile control effect, overcome the displacement imbalance caused by reservoir heterogeneity, and thus solve the problem of low oil recovery. Therefore, the quantitative study of the matching between emulsion particles with a profile control effect and throats at the pore scale is of great significance for directly selecting an emulsion system with a reasonable particle size range for emulsion profile control or emulsion flooding, and also has a reference significance for selecting a reasonable range of heterogeneous particles for heterogeneous flooding systems.

[0003] Currently, relevant patents involve the preparation method and profile control effect of emulsion profile control agents, the identification and particle size detection method of crude oil emulsions, and the experimental devices and methods for the seepage of emulsions in porous media. Due to the multi-phase dispersion of emulsion seepage in porous media and the very complex flow process, there is no research on the matching between the size of emulsion particles and the pore size when emulsions interact with porous media to produce a profile control effect in existing invention patents. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a method for determining the matching between emulsion particles and throat sizes to overcome or at least partially solve the above problems.

[0005] According to one aspect of the present invention, a method for determining the matching between emulsion particles and throat sizes is provided, and the determination method includes:

[0006] Step S1: Collect local microscopic images that characterize the profile control effect of emulsion particles during the microscopic visualization experiment of emulsifier solution flooding.

[0007] Step S2: In the acquired target image, use the image analysis method to calculate the equivalent radius of the emulsion particles that play a displacement adjustment role and pass through the deformed throat.

[0008] Step S3: Determine and calculate the narrowest radius of the throat through which the emulsion particles pass through in the acquired target image.

[0009] Step S4: Statistically analyze the ratio interval between the equivalent radius of the deformed emulsion particles and the throat radius during the experiment.

[0010] Optionally, the specific content of step S1: acquiring the local microscopic image characterizing the displacement adjustment effect of the emulsion particles during the microscopic visualization experiment of the emulsifier solution flooding includes:

[0011] Conduct a microscopic visualization experiment of the emulsifier solution flooding using a glass microscopic model, and use a high-speed camera to acquire microscopic images in real time.

[0012] Optionally, in the process of emulsifier solution flooding in step S1, an oil-in-water emulsion is formed, and the emulsion has the functions of emulsification carrying and emulsification trapping. The characteristics of the emulsion particles with displacement adjustment effect are emulsion particles.

[0013] Optionally, in step S1, find and intercept the local microscopic image of the emulsion particles passing through the deformed throat from the microscopic images acquired in real time by the high-speed camera as the target image for analyzing the displacement adjustment effect of the emulsified liquid particles.

[0014] Optionally, in step 2, for the target image, perform binarization using the image analysis method to obtain the pixel value s occupied by the area of the emulsion particles passing through the deformed throat in the throat, and obtain the equivalent radius R of the emulsion particles before passing through the deformed throat according to the formula 乳 :

[0015]

[0016] Optionally, in step S3, in the binarized target image, the deformed emulsion particles in the throat are white and the background is black. Assume the resolution of the image is X×Y pixels.

[0017] Optionally, in step 3, transform the binarized target image to ensure that the throat is parallel to the horizontal direction, and obtain the binarized image of the transformed target image.

[0018] Optionally, in step S3, perform gray-scale analysis on the binarized image of the transformed target image to obtain the average gray-scale value of the Y pixels corresponding to each pixel x from left to right 0-X of the entire image.

[0019] Optionally, in step S3, if the width of the deformed emulsion particles corresponding to pixel x is L, and the average gray value of Y pixels corresponding to pixel x obtained by image analysis is G, then the following relational expression holds:

[0020]

[0021] From the above formula, the width L of the deformed emulsion particles corresponding to pixel x represented by pixels can be obtained as:

[0022] Optionally, in step S3, the pixel range in the X direction corresponding to the deformed emulsion particles in the throat is x 1 —x 2 ;

[0023] Within the pixel range, select the minimum width L of the contact part between the emulsion and the throat wall min as the narrowest width of the throat, then the radius at the narrowest part of the throat is:

[0024] Optionally, in step S4, for the target images, adopt the image analysis method in step 3, calculate the ratio of the equivalent radius of the emulsion particles to the throat radius in each target image respectively, and conduct statistical analysis

[0025] Optionally, in step S4: the ratio range is the optimal matching range between the emulsion particles playing the profile control role and the throat radius.

[0026] A method for determining the matching between emulsion particles and throat size provided by the present invention, the determination method includes: step S1: collecting local microscopic images characterizing the profile control effect of emulsion particles during the microscopic visualization experiment of surfactant solution flooding; step S2: in the collected target images, adopting the image analysis method to calculate the equivalent radius of the emulsion particles playing the profile control role that deform and pass through the throat; step S3: determining and calculating the narrowest radius of the throat through which the emulsion particles deform and pass in the collected target images; step S4: statistically analyzing the ratio range between the equivalent radius of the deformed emulsion particles and the throat radius during the experiment. Maximize the profile control effect of emulsion flooding or surfactant flooding, improve reservoir heterogeneity, and effectively increase the recovery rate.

[0027] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are specifically exemplified below. Description of the Drawings

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] Figure 1 It is a flowchart of an embodiment of the method for determining the matching between emulsion particles and throat size based on image gray-scale analysis provided by the embodiments of the present invention.

[0030] Figure 2 It is a local microscopic image collected by a high-speed camera in an embodiment of the present invention, which characterizes the displacement driving effect of the emulsion.

[0031] Figure 3 It is a diagram of the image data processing and calculation process of the equivalent radius of the deformed emulsion when passing through the throat in an embodiment of the present invention.

[0032] Figure 4 It is a flowchart of transforming the binary target image in the image data processing and calculation process of the narrowest radius of the throat through which the deformed emulsion passes in an embodiment of the present invention.

[0033] Figure 5 It is a binary image of the target image after transformation in the image data processing and calculation process of the narrowest radius of the throat through which the deformed emulsion passes in an embodiment of the present invention.

[0034] Figure 6 It is a schematic diagram of gray-scale analysis of the binary image of the target image after transformation in the image data processing and calculation process of the narrowest radius of the throat through which the deformed emulsion passes in an embodiment of the present invention.

[0035] Figure 7 It is a schematic diagram of the distribution interval of the statistical analysis ratio in an embodiment of the present invention.

[0036] Figure 8 It is a statistical analysis result diagram of the ratio range between the equivalent radius of the deformed emulsion particles and the narrowest radius of the throat after the image data analysis of the target images collected during the entire displacement process in an embodiment of the present invention. Detailed implementation manners

[0037] The following will describe the exemplary embodiments of the present disclosure in more detail with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0038] In the embodiments of the description, claims, and drawings of the present invention, the terms "comprising", "having", and any variations thereof are intended to cover non-exclusive inclusion. For example, including a series of steps or units.

[0039] The following further describes in detail the technical solutions of the present invention in conjunction with the drawings and embodiments.

[0040] The method for studying the matching between emulsion particles and throat size based on image gray-scale analysis of the present invention relates to the technical field of enhanced oil recovery technology by emulsion profile control during oilfield exploitation, and includes the following steps: collecting local microscopic images representing the profile control effect of emulsion particles during the microscopic visualization experiment of surfactant solution flooding; in the collected target images, using image analysis methods to calculate the equivalent radius of the emulsion particles that deform and pass through the throat to exert the profile control effect; determining and calculating the narrowest radius of the throat through which the emulsion particles deform and pass in the collected target images; statistically analyzing the ratio range of the equivalent radius of the deformed emulsion particles to the throat radius during the experiment, and this range is the optimal matching range between the emulsion particles and the throat radius when the emulsion particles exert the profile control effect. The present invention realizes the quantitative study of the matching range between emulsion particles and throat size when the emulsion exerts the profile control effect at the pore scale of porous media, provides a method for the evaluation and optimization of the emulsion system when the oilfield improves reservoir heterogeneity through emulsion profile control, ensures that the emulsion system "can be injected, can flow, and can be produced", maximizes the profile control effect, and efficiently improves the oil recovery rate of the reservoir.

[0041] Example 1

[0042] As Figure 1 shown, in a specific Example 1 of applying the present invention, the method for studying the matching between emulsion particles and throat size based on image gray-scale analysis includes the following steps:

[0043] Step 1, collecting local microscopic images representing the profile control effect of emulsion particles during the microscopic visualization experiment of surfactant solution flooding;

[0044] Step 2, in the collected target images, using image analysis methods to calculate the equivalent radius of the emulsion particles that deform and pass through the throat to exert the profile control effect;

[0045] Step 3, determining and calculating the narrowest radius of the throat through which the emulsion particles deform and pass in the collected target images;

[0046] Step 4, statistically analyzing the ratio range of the equivalent radius of the deformed emulsion particles to the throat radius during the experiment, and this range is the optimal matching range between the emulsion particles and the throat radius when the emulsion particles exert the profile control effect.

[0047] The specific steps for collecting local microscopic images that characterize the displacement control effect of emulsion particles during the microscopic visualization experiment of surfactant solution flooding are as follows: During the microscopic visualization experiment of surfactant solution flooding using a microscopic glass model, a high-speed camera is used to collect real-time microscopic images.

[0048] When the oil-in-water emulsion formed during the surfactant solution flooding migrates in the porous medium, the emulsion particles with displacement control effect have a radius larger than the throat radius but deform and pass through the throat, "blocking and migrating" in the throat to play a displacement control role. This phenomenon is a typical characteristic of characterizing the displacement control effect of emulsion particles.

[0049] Find and intercept the local microscopic image of the emulsion particle deforming through the throat from the microscopic images collected in real-time by the high-speed camera as the target image to be analyzed.

[0050] In the collected target image, the specific steps for calculating the equivalent radius of the emulsion particles with displacement control effect that deform through the throat using image analysis method are as follows: For the intercepted target image, perform binarization using image analysis method (the emulsion particles are white and the background is black) to obtain the pixels s occupied by the emulsion particles. According to the following formula, obtain the equivalent radius R of the emulsion particles deforming through the throat in terms of pixels. 乳 :

[0051]

[0052] The specific steps for determining and calculating the narrowest radius of the throat through which the emulsion particles deform in the collected target image are as follows: Assume that the resolution of the binarized target image is X×Y pixels. Transform this image to ensure that the central axis of the throat is parallel to the X horizontal direction to obtain the binarized image of the transformed target image.

[0053] Perform gray-scale analysis on the binarized image of the transformed target image to obtain the average gray-scale value of the Y pixels corresponding to each x in the range of 0 - X from left to right of the whole image. Since the white gray-scale value is 255 and the black gray-scale value is 0, only the white range will affect this average gray-scale value.

[0054] Assume that the width of the deformed emulsion particle corresponding to pixel x is L. Image analysis can obtain that the average gray-scale value of the Y pixels corresponding to pixel x is G. Then there is the following relational expression:

[0055] From the above formula, the width L of the deformed emulsion particle corresponding to pixel x in terms of pixels can be obtained as:

[0056] In the binarized image of the transformed target image, the coordinate range of the deformed emulsion particles in the X direction is (x 1 —x 2)。Within this range, select the minimum average gray value G of the emulsion in contact with the throat wall min The corresponding width is the narrowest width L of the throat min , then the radius at the narrowest part of the throat is:

[0057] During the statistical analysis of the experimental process, the ratio range of the equivalent radius of the deformed emulsion particles to the throat radius is the specific step of the optimal matching range between the emulsion particles and the throat radius when the emulsion particles play the role of profile control: Using the image analysis method, calculate the ratio of the equivalent radius of the emulsion particles to the narrowest radius of the throat in each target image respectively:

[0058] For all local microscopic images of the emulsion particles playing the role of profile control collected during the experiment, calculate the ratio of the radius of the deformed emulsion particles to the narrowest radius of the throat where they are located, and statistically analyze the distribution range of the ratio.

[0059] In a specific embodiment 2 of applying the present invention, as Figure 1 shown Figure 1 is a schematic flow chart of the quantitative research method for the matching between emulsion particles with profile control effect and throat at the pore scale of the present invention, including the following steps:

[0060] Step 1: Use a high-speed camera to collect in real time the local microscopic images representing the profile control effect of emulsion particles during the visualization experiment of surfactant solution displacing oil in a glass microscopic model as target images, as Figure 2 shown. In the target image, although the emulsion particles are larger than the size of the throat, they can still deform and pass through the throat, with typical profile control characteristics of "blocking and migrating" in the throat.

[0061] Step 2: Binarize the target image using the image analysis method (the emulsion particles are white and the background is black) to obtain the pixel value s occupied by the area of the emulsion particles, and obtain the equivalent radius R of the emulsion particles before deforming and passing through the throat according to the following formula 乳 , as Figure 3 shown:

[0062] Step 3: Determining and calculating the narrowest radius of the throat through which the emulsion particles deform in the collected target image includes the following steps:

[0063] 1) Transform the binarized target image ( Figure 4 ) to ensure that the central axis of the throat is parallel to the X horizontal direction, and obtain the binarized image of the transformed target image (see Figure 5 );

[0064] 2) Perform gray-scale analysis on the binary image of the transformed target image to obtain the average gray-scale value of Y pixels corresponding to each x within the range of 0 - X from left to right of the image (see Figure 6 ). Since the white gray-scale value is 255 and the black gray-scale value is 0, only the white range will affect this average gray-scale value;

[0065] 3) Assume that the width of the deformed emulsion particle corresponding to pixel x is L. Image analysis can obtain that the average gray-scale value of Y pixels corresponding to pixel x is G (see Figure 5 ), then there is the following relational expression:

[0066] From the above formula, the width L of the deformed emulsion particle corresponding to pixel x expressed in pixels can be obtained as:

[0067] 4) In the binary image of the transformed target image, the coordinate range of the deformed emulsion particles in the X direction is (x 1 - x 2 ). Within this range, select the minimum average gray-scale value G min corresponding to the contact between the emulsion and the throat wall. The corresponding width is the narrowest width L of the throat min (see Figure 6 ), then the radius of the narrowest part of the throat is:

[0068] Step 4: Adopt the image analysis method to calculate the ratio of the equivalent radius of the emulsion particles to the narrowest radius of the throat in each target image respectively:

[0069] In this example, the ratio of the radius of the emulsion particles with the displacement and profile control effect to the narrowest radius of the throat is:

[0070] It shows that when the radius of the emulsion particles is 1.57 times that of the narrowest part of the throat, the deformation can pass through this throat under the experimental conditions.

[0071] For all more than 120 groups of local microscopic images of the emulsion particles playing the displacement and profile control role collected during the experiment, calculate the ratio of the radius of the deformed emulsion particles to the narrowest radius of the throat where they are located, and statistically analyze the distribution interval of the ratio (see Figure 7 ). From Figure 5 it can be seen that when the ratio of the emulsion particle size to the throat size is 1 - 9, the emulsion system within this range is the best emulsion system under the experimental conditions.

[0072] Statistically analyze the proportion of the number of different ratios in the total number (see Figure 8 ), indicating that when the ratio of the emulsion particle size to the throat size is 2 - 4, both the temporary plugging property and the migration performance of the emulsion are relatively excellent.

[0073] Beneficial effects: The method of the present invention visually and vividly observes the seepage characteristics of emulsions in porous media through a microscopic visualization model. Since the matching between the emulsion and the porous medium determines whether the emulsion exhibits the seepage characteristics of plugging and migrating simultaneously, several local microscopic images characterizing the displacement driving effect of emulsion particles during the entire experiment are collected as target images. Through image analysis methods, the equivalent radius of the deformed emulsion particles in the target images and the narrowest radius of the throats where they are located are calculated, and the ratio between the two is the matching value of the emulsion particles exerting the displacement driving effect and the throat radius in the corresponding target images. By statistically analyzing the matching value intervals of the emulsion particles and the throat radius in all target images during the experiment, this interval is the matching range of the emulsion particles and the throat radius under the experimental conditions. This method takes the typical characteristic images of the emulsion exerting the displacement driving effect during seepage in porous media as the research object, uses image analysis methods to quantitatively study the matching value of the radius of the emulsion particles exerting the displacement driving effect and the radius of the throats where they are located. The statistical analysis of a large number of matching values can provide a basis for selecting the size range of emulsion particles that match the throats when exerting the displacement driving effect under experimental conditions. It is of guiding significance for maximizing the displacement driving effect of emulsion flooding or emulsifier flooding, improving reservoir heterogeneity, and effectively enhancing the recovery factor.

[0074] The above specific embodiments have further elaborated in detail the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining the size matching between emulsion particles and throat, characterized in that: The determination method comprises: Step S1: collecting local microscopic images characterizing the effect of emulsion particles on oil displacement during the microscopic visualization experiment of emulsifier solution oil displacement; Step S2: in the collected target image, an image analysis method is used to calculate the equivalent radius of the emulsion particles that are deformed through the throat and play a driving effect; Step S3: determining and calculating the narrowest radius of the throat through which the emulsion particles deform in the acquired target image; Step S4: Statistically analyzing the ratio range of the equivalent radius of the deformed emulsion particles to the throat radius during the experiment.

2. A method for determining the size matching between emulsion particles and throat according to claim 1, characterized in that: The step S1: collecting local microscopic images characterizing the effect of emulsion particles on oil displacement during the microscopic visualization experiment of emulsifier solution oil displacement specifically includes: A glass microscopic model was used to conduct a microscopic visualization experiment of emulsifier solution flooding, and a high-speed camera was used to collect microscopic images in real time.

3. A method for determining the size matching between emulsion particles and throat according to claim 1, characterized in that: In the step S1, an oil-in-water emulsion is formed during the oil displacement process of the emulsifier solution. The emulsion has emulsification carrying and emulsification capturing functions, and the emulsion particles having the displacement function are characterized as emulsion particles.

4. A method for determining the size matching between emulsion particles and throat according to claim 1, characterized in that: In the step S1, a local microscopic image of the emulsion particles deforming through the throat is found and intercepted from the microscopic image collected in real time by the high-speed camera as a target image to be analyzed to characterize the volatilization and displacement effect of the emulsion particles.

5. The method for determining the size matching between emulsion particles and throat according to claim 1, characterized in that: In step 2, the target image is binarized by using an image analysis method to obtain the pixel value s of the area occupied by the emulsion particles that deform and pass through the throat, and the equivalent radius R before the emulsion particles deform and pass through the throat is obtained according to the formula 乳 :

6. A method for determining the size matching between emulsion particles and throat according to claim 1, characterized in that: In step S3, in the binarized target image, the deformed emulsion particles in the throat are white and the background is black, assuming that the resolution of the image is X×Y pixels.

7. A method for determining the size matching between emulsion particles and throat according to claim 6, characterized in that: In step 3, the binary target image is transformed to ensure that the laryngeal passage is parallel to the horizontal direction, thereby obtaining a binary image of the transformed target image.

8. A method for determining the size matching between emulsion particles and throat according to claim 7, characterized in that: In step S3, grayscale analysis is performed on the binary image of the transformed target image to obtain the average grayscale value of Y pixels corresponding to each pixel x corresponding to 0-X from left to right in the entire image.

9. A method for determining the size matching between emulsion particles and throat according to claim 8, characterized in that: In step S3, the width of the deformed emulsion particle corresponding to the pixel x is L, and the average gray value of Y pixels corresponding to the pixel x obtained by image analysis is G, and the following relationship is obtained: From the above formula, the width L of the deformed emulsion particle corresponding to the pixel x expressed in pixels can be obtained as:

10. A method for determining the size matching between emulsion particles and throat according to claim 9, characterized in that: In step S3, the pixel range in the X direction corresponding to the deformed emulsion particles in the throat is x1-x2; In the pixel range, the minimum width L of the contact area between the emulsion and the throat wall is selected. min As the narrowest width of the throat, the radius of the narrowest part of the throat is:

11. The method for determining the size matching between the emulsion particles and the throat according to claim 1, characterized in that: In step S4, the image analysis method in step 3 is used for the target image to calculate the ratio of the equivalent radius of the emulsion particles to the throat radius in each target image and perform statistical analysis.

12. The method for determining the size matching between the emulsion particles and the throat according to claim 1, characterized in that: In step S4: the ratio interval is the best matching range between the emulsion particles and the throat radius when the emulsion particles play a displacement control role.

Images