Physicochemical combined permeability enhancement method for complex coal seams
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA COAL TECH & ENG GRP SHENYANG ENG CO
- Filing Date
- 2023-10-12
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies lack consideration for the characteristics of complex coal seams, resulting in the inability of a single permeability enhancement technology to effectively improve coal seam permeability, thus affecting the efficiency of coal resource mining.
By measuring the coal seam's firmness coefficient and permeability coefficient, and combining chemical, heating, and mechanical vibration methods, multiple permeability enhancement processes are carried out. A suitable physicochemical combination permeability enhancement method is selected until the permeability meets the requirements.
It improves the permeability of coal seams, avoids hole collapse and blockage, ensures that the permeability enhancement effect of coal seams meets the standards, and provides a theoretical basis for gas drainage.
Smart Images
Figure CN117514100B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal seam permeability enhancement technology, and in particular to a physical-chemical combination method for enhancing permeability in complex coal seams. Background Technology
[0002] Coal seam permeability enhancement technology is a method used to improve the permeability of coal seams and the effective extraction of coal resources. In the coal industry, traditional mining methods typically face problems such as poor coal seam permeability, high mining difficulty, and low mining efficiency, resulting in the underutilization of coal resources. To overcome these problems, coal seam permeability enhancement technology has emerged. However, the practical application of coal seam permeability enhancement technology requires full consideration of geological conditions and coal seam characteristics. Existing permeability enhancement technologies often lack consideration of coal seam characteristics. Furthermore, current methods often employ a single permeability enhancement technique, which cannot achieve satisfactory permeability enhancement effects on complex coal seams. Therefore, there is an urgent need to provide a physicochemical combined permeability enhancement method for complex coal seams. Summary of the Invention
[0003] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide a physical-chemical combination method for enhancing permeability in complex coal seams.
[0004] To achieve the above objectives, the present invention provides the following technical solution:
[0005] This invention provides a physicochemically-based permeability enhancement method for complex coal seams, comprising the following steps:
[0006] Step 1: Determine the coal seam firmness coefficient f;
[0007] Step 2: Test the coal seam gas pressure, borehole flow rate, and coal seam permeability coefficient λ;
[0008] Step 3: Perform initial permeability enhancement on the coal seam based on the coal seam firmness coefficient f and the coal seam permeability coefficient λ.
[0009] Step 4: Determine the permeability coefficient λ of the coal seam after the initial permeability enhancement, and determine whether to perform a second permeability enhancement based on the permeability coefficient λ. Repeat the above steps until the permeability coefficient λ of the coal seam meets the requirements, and the permeability enhancement of the coal seam is completed.
[0010] Further, step 1 specifically involves preparing coal samples on-site and determining the coal seam firmness coefficient f in the laboratory using a fixed-height hammer release method. The fixed-height hammer release method specifically involves: selecting coal samples with a particle size of 20-30 mm or 1-3 mm and dividing them into 5 portions, each weighing 50 g; sequentially pouring each portion of coal sample into a cylinder and a mortar; and allowing the hammer to fall freely from a height of 600 mm from the bottom of the mortar, striking the coal sample 1-5 times for each portion; and tamping all 5 portions of coal sample. After crushing, the coal sample is poured into a sieve with a 0.5mm mesh to separate particles smaller than 0.5mm. The sample is then poured into a graduated cylinder with a diameter of 23mm, and the height h of the powder is measured and recorded. Finally, the firmness coefficient f of the coal sample is calculated according to f = 20n / h, where f is the firmness coefficient (no unit); n is the number of impacts per coal sample (in times); and h is the height h of the powder in each group of coal samples (in mm). Three groups of five coal samples are measured in parallel, and the arithmetic mean is taken as the final coal seam firmness coefficient f.
[0011] Furthermore, the coal seam permeability coefficient λ in step 2 is determined using the unidirectional flow method in the roadway.
[0012] Furthermore, step 3 specifically includes:
[0013] First, determine the coal seam firmness coefficient f, which can be divided into the following three cases:
[0014] (1) If the firmness coefficient f < 0.5, the coal seam permeability coefficient λ is used to perform initial permeability enhancement, specifically as follows:
[0015] When λ < 0.1, the coal seam is initially permeable by chemical modification.
[0016] When 0.1≤λ<1, the coal seam is initially permeated by chemical modification and coal seam heating.
[0017] When 1≤λ<10, the coal seam is initially permeated by chemical modification, coal seam heating, and mechanical vibration.
[0018] (2) If the firmness coefficient is 0.5 ≤ f < 3, the coal seam is initially permeable by combining the coal seam permeability coefficient λ, specifically as follows:
[0019] When λ < 0.1, the coal seam is initially permeated by coal seam heating and permeation enhancement method;
[0020] When 0.1≤λ<1, the coal seam is initially permeated by coal seam heating permeability enhancement method and chemical modification permeability enhancement method;
[0021] When 1≤λ<10, the coal seam is initially enhanced by coal seam heating enhancement method, chemical modification enhancement method and ultrasonic pulse enhancement method;
[0022] (3) If the firmness coefficient f ≥ 3, and in conjunction with the coal seam permeability coefficient λ, select a suitable permeability enhancement scheme for the initial permeability enhancement of the coal seam, specifically as follows:
[0023] When λ < 0.1, the coal seam is initially permeable by mechanical vibration.
[0024] When 0.1≤λ<1, the coal seam is initially permeated using mechanical vibration permeation enhancement method and chemical modification permeation enhancement method;
[0025] When 1≤λ<10, the coal seam is initially permeated using mechanical vibration permeation enhancement method, chemical modification permeation enhancement method, and coal seam heating permeation enhancement method.
[0026] Furthermore, the chemical modification and permeability enhancement method involves injecting an acid solution, specifically citric acid, into the coal seam.
[0027] Furthermore, the coal seam heating and permeability enhancement method specifically involves injecting heating cables, steam, or thermal oil into the coal seam through a wellbore to increase the coal seam temperature.
[0028] Furthermore, the mechanical vibration permeation enhancement method specifically involves applying mechanical vibration force in the wellbore using a vibration device or vibration tool to cause the coal seam to vibrate.
[0029] Further, step 4 specifically involves: determining the coal seam permeability coefficient λ again after the initial permeability enhancement; if the coal seam permeability coefficient λ < 10, returning to step 3, and performing a second permeability enhancement on the coal seam based on the permeability coefficient λ, repeating the above steps until the permeability coefficient λ ≥ 10, at which point the coal seam permeability enhancement is complete.
[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0031] This invention provides a physicochemical combined permeability enhancement method for complex coal seams. Addressing the shortcomings of existing single traditional permeability enhancement technologies, this method first determines the coal seam's firmness coefficient (f) and permeability coefficient (λ) based on actual conditions. Then, different permeability enhancement methods are selected for initial permeability enhancement based on different coal seams. The combination of different methods clears the coal seam pores, increases permeability, and avoids pore collapse and blockage that can occur during the permeability enhancement process due to the permeability enhancement method being unsuitable for the coal seam's firmness coefficient (f) and permeability coefficient (λ). Secondly, the permeability coefficient (λ) of the coal seam after the initial permeability enhancement is monitored in real time. Whether the permeability coefficient (λ) is ≥10 determines whether the coal seam needs to be further permeated until the permeability coefficient (λ) ≥10, ensuring that the coal seam permeability enhancement effect meets the standards, thus providing a theoretical basis for coal mine gas drainage operations. Attached Figure Description
[0032] Figure 1This is a schematic flowchart of the physical-chemical permeability enhancement method for complex coal seams according to the present invention. Detailed Implementation
[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0034] Example
[0035] Reference Figure 1 A physical-chemical permeability enhancement method for complex coal seams includes the following steps:
[0036] Step 1: Determine the coal seam firmness coefficient f;
[0037] Step 2: Test the coal seam gas pressure, borehole flow rate, and coal seam permeability coefficient λ;
[0038] Step 3: Perform initial permeability enhancement on the coal seam based on the coal seam firmness coefficient f and the coal seam permeability coefficient λ.
[0039] Step 4: Determine the permeability coefficient λ of the coal seam after the initial permeability enhancement, and determine whether to perform a second permeability enhancement based on the permeability coefficient λ. Repeat the above steps until the permeability coefficient λ of the coal seam meets the requirements, and the permeability enhancement of the coal seam is completed.
[0040] Step 1 specifically involves preparing coal samples on-site and determining the coal seam firmness coefficient f in the laboratory using a fixed-height hammer release method. The fixed-height hammer release method specifically involves: selecting coal samples with a particle size of 20-30 mm or 1-3 mm and dividing them into 5 portions, each weighing 50 g; sequentially pouring each portion of coal sample into a cylinder and a mortar; and dropping the hammer freely from a height of 600 mm above the bottom of the mortar, impacting the coal sample, with each portion of coal sample being dropped 1-5 times; after all 5 portions of coal sample are crushed... The coal sample was poured into a sieve with a 0.5 mm aperture to separate particles smaller than 0.5 mm. The sample was then poured into a graduated cylinder with a diameter of 23 mm, and the height h of the powder was measured and recorded. Finally, the coal sample's firmness coefficient f was calculated according to f = 20n / h, where f is the firmness coefficient (no unit); n is the number of impacts per coal sample (in times); and h is the height h of the powder in each group of coal samples (in mm). Three groups of five coal samples were measured in parallel, and the arithmetic mean was taken as the final coal seam firmness coefficient f.
[0041] The coal seam permeability coefficient λ in step 2 is determined using the unidirectional flow method in the roadway.
[0042] Step 3 specifically involves:
[0043] First, determine the coal seam firmness coefficient f, which can be divided into the following three cases:
[0044] (1) If the firmness coefficient f < 0.5, it indicates that the coal seam is soft. In addition, the permeability coefficient λ of the coal seam is used to perform the initial permeability enhancement, specifically:
[0045] When λ < 0.1, the coal seam is initially permeable by chemical modification.
[0046] When 0.1≤λ<1, the coal seam is initially permeated by chemical modification and coal seam heating.
[0047] When 1≤λ<10, the coal seam is initially permeated by chemical modification, coal seam heating, and mechanical vibration.
[0048] (2) If the firmness coefficient is 0.5≤f<3, it indicates that the coal seam is relatively hard. Then, the initial permeability enhancement of the coal seam is performed in conjunction with the coal seam permeability coefficient λ, specifically as follows:
[0049] When λ < 0.1, the coal seam is initially permeated by coal seam heating and permeation enhancement method;
[0050] When 0.1≤λ<1, the coal seam is initially permeated by coal seam heating permeability enhancement method and chemical modification permeability enhancement method;
[0051] When 1≤λ<10, the coal seam is initially enhanced by coal seam heating enhancement method, chemical modification enhancement method and ultrasonic pulse enhancement method;
[0052] (3) If the firmness coefficient f ≥ 3, it indicates that the coal seam is hard. Combined with the coal seam permeability coefficient λ, a suitable permeability enhancement scheme is selected to perform the initial permeability enhancement of the coal seam, specifically:
[0053] When λ < 0.1, the coal seam is initially permeable by mechanical vibration.
[0054] When 0.1≤λ<1, the coal seam is initially permeable using mechanical vibration permeability enhancement method and chemical modification permeability enhancement method;
[0055] When 1≤λ<10, the coal seam is initially permeated using mechanical vibration permeation enhancement method, chemical modification permeation enhancement method, and coal seam heating permeation enhancement method.
[0056] The chemical modification and permeability enhancement method involves injecting citric acid into the coal seam. Citric acid reacts with the minerals in the coal, dissolving the inorganic substances and altering the chemical properties of the coal seam. Acidification modification can change the pore structure of the coal seam, increasing pore connectivity and permeability, and is suitable for low-permeability coal seams.
[0057] The coal seam heating and permeability enhancement method specifically involves injecting heating cables, steam, or thermal oil into the coal seam through a wellbore to increase the coal seam temperature. The purpose of coal seam heating is to raise the internal temperature of the coal seam, promote the release of oil and gas from the coal, and improve permeability.
[0058] The mechanical vibration permeability enhancement method specifically involves applying mechanical vibration force to the coal seam using a vibration device or tool, causing the coal seam to vibrate. This method disrupts the internal structure of the coal seam, breaks down the adhesion forces in the pores, and promotes the formation and expansion of cracks and pores, thereby increasing permeability.
[0059] The ultrasonic pulse permeation enhancement method uses ultrasonic waves to propagate in the coal seam, which causes the coal seam to produce multiple effects such as mechanical vibration, thermal effect and cavitation effect, thereby increasing the porosity and fractures of the coal and enhancing its permeability.
[0060] Step 4 specifically involves: determining the permeability coefficient λ of the coal seam again after the initial permeability enhancement. If the permeability coefficient λ < 10, return to step 3 and perform a second permeability enhancement on the coal seam based on the permeability coefficient λ. Repeat the above steps until the permeability coefficient λ ≥ 10, at which point the permeability enhancement of the coal seam is complete.
[0061] In this invention, the unit of the air permeability coefficient λ is m. 2 / (MPa 2 ·d).
[0062] This invention addresses different coal seam properties by first classifying coal seams according to their firmness coefficient f, and then measuring their permeability coefficient λ. Based on the analysis of permeability in coal seams with different firmness levels, appropriate permeability enhancement methods are selected to enhance the permeability of the coal seams. This invention utilizes a combination of physical and chemical permeability enhancement methods to improve the extraction effect of coal seams, solving the problem of poor extraction effect caused by the lack of a single permeability enhancement technology for complex coal seams in existing technologies.
[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A physicochemical method for enhancing permeability in complex coal seams, characterized in that, Includes the following steps: Step 1: Determine the coal seam firmness coefficient f; Step 2: Test the coal seam gas pressure, borehole flow rate, and coal seam permeability coefficient λ; Step 3: Perform initial permeability enhancement on the coal seam based on the coal seam firmness coefficient f and the coal seam permeability coefficient λ. Step 4: Determine the permeability coefficient λ of the coal seam after the initial permeability enhancement, and determine whether to perform a second permeability enhancement based on the permeability coefficient λ. Repeat the above steps until the permeability coefficient λ of the coal seam meets the requirements, and the permeability enhancement of the coal seam is completed. Step 3 specifically involves: First, determine the coal seam firmness coefficient f, which can be divided into the following three cases: (1) If the firmness coefficient f < 0.5, the coal seam is then subjected to initial permeability enhancement in combination with the coal seam permeability coefficient λ, specifically as follows: When λ < 0.1, the coal seam is initially permeable by chemical modification. When 0.1≤λ<1, the coal seam is initially permeated by chemical modification and coal seam heating. When 1≤λ<10, the coal seam is initially permeated by chemical modification, coal seam heating, and mechanical vibration. (2) If the firmness coefficient is 0.5≤f<3, the coal seam is initially permeable by combining the coal seam permeability coefficient λ, specifically as follows: When λ < 0.1, the coal seam is initially permeated by coal seam heating and permeation enhancement method; When 0.1≤λ<1, the coal seam is initially permeated by coal seam heating permeability enhancement method and chemical modification permeability enhancement method; When 1≤λ<10, the coal seam is initially enhanced by coal seam heating enhancement method, chemical modification enhancement method and ultrasonic pulse enhancement method; (3) If the firmness coefficient f ≥ 3, and in conjunction with the coal seam permeability coefficient λ, select a suitable permeability enhancement scheme to perform initial permeability enhancement on the coal seam, specifically as follows: When λ < 0.1, the coal seam is initially permeable by mechanical vibration. When 0.1≤λ<1, the coal seam is initially permeable using mechanical vibration permeability enhancement method and chemical modification permeability enhancement method; When 1≤λ<10, the coal seam is initially permeated using mechanical vibration permeation enhancement method, chemical modification permeation enhancement method, and coal seam heating permeation enhancement method.
2. The physical-chemical permeability enhancement method for complex coal seams as described in claim 1, characterized in that, Step 1 specifically involves preparing coal samples on-site and determining the coal seam firmness coefficient f in the laboratory using a fixed-height drop hammer method. The fixed-height drop hammer method is as follows: Five portions of coal samples with particle sizes of 20-30 mm or 1-3 mm are selected, each weighing 50 g. Each portion is then poured into a cylinder and a mortar, and a drop hammer is allowed to fall freely from a height of 600 mm above the mortar bottom, striking the coal sample 1-5 times. After all five portions are crushed, they are poured into a sieve with 0.5 mm mesh to separate the coal sample with a particle size smaller than 0.5 mm, and then poured into a 23mm diameter sieve. The height h of the powder was measured and recorded in a graduated cylinder of mm. Finally, the strength coefficient f of the coal sample was calculated according to f=20n / h, where f is the strength coefficient, which has no unit; n is the number of impacts per coal sample, in the unit of times; and h is the height h of the powder in each group of coal samples, in the unit of mm. Three groups of five coal samples were measured in parallel, and the arithmetic mean was taken as the final coal seam strength coefficient f.
3. The physical-chemical permeability enhancement method for complex coal seams as described in claim 1, characterized in that, The coal seam permeability coefficient λ in step 2 is determined using the unidirectional flow method in the roadway.
4. The physical-chemical permeability enhancement method for complex coal seams as described in claim 1, characterized in that, The chemical modification and permeability enhancement method involves injecting an acid solution, specifically citric acid, into the coal seam.
5. The physical-chemical permeability enhancement method for complex coal seams as described in claim 1, characterized in that, The coal seam heating and permeability enhancement method specifically involves injecting heating cables, steam, or thermal oil into the coal seam through a wellbore to increase the coal seam temperature.
6. The physicochemical permeability enhancement method for complex coal seams as described in claim 1, characterized in that, The mechanical vibration permeability enhancement method specifically involves applying mechanical vibration force in the wellbore using a vibration device or tool to cause the coal seam to vibrate.
7. The physical-chemical permeability enhancement method for complex coal seams as described in claim 1, characterized in that, Step 4 specifically involves: determining the permeability coefficient λ of the coal seam again after the initial permeability enhancement. If the permeability coefficient λ < 10, return to step 3 and perform a second permeability enhancement on the coal seam based on the permeability coefficient λ. Repeat the above steps until the permeability coefficient λ ≥ 10, at which point the permeability enhancement of the coal seam is complete.