CN-119954673-B - Coal seam wetting reversal agent and preparation method thereof

CN119954673BCN 119954673 BCN119954673 BCN 119954673BCN-119954673-B

Abstract

The invention belongs to the technical field of coal seam development, and discloses a coal seam wetting reversal agent and a preparation method thereof. The coal seam wetting reversal agent provided by the invention has excellent pH influence behavior, and the change of the wettability of the surfactant EBMAA-DMA12 on the surface of the coal sample can be realized by adjusting the pH value of the solution. When the pH value of the solution is smaller than 6.87, the solution is favorable for reducing the capillary force, can be used as a waterproof locking agent, and when the pH value of the surfactant solution is larger than 6.87, the solution is favorable for reducing the free energy of the surface of the coal bed, and can be used as a coal bed methane desorbing agent. In addition, the method for preparing the coal seam wetting reversal agent is obtained by synthesizing a dibasic acid intermediate N, N '-ethylene bismaleimide acid (EBMAA) by adopting MAH and EDA and then carrying out neutralization reaction on the N, N' -ethylene bismaleimide acid (EBMAA) and N, N-dimethyl dodecyl amine. The preparation method has the advantages of easily available raw materials, simple process, high repeated stability and good popularization value.

Inventors

LI XIAOJIANG
JIA ZHENFU
ZHANG XINGQIAO
SU XIAODONG
BAO DAN
ZHANG PENG
ZHOU CHENGYU
TU QING
ZHANG YINLONG

Assignees

重庆科技大学

Dates

Publication Date: 20260505
Application Date: 20241224

Claims (8)

1. The coal seam wetting reversal agent is characterized by comprising the following molecular structural formula: 。
2. The method for preparing the coal seam wetting reversal agent according to claim 1, comprising the following steps: 1) After uniformly stirring and mixing maleic anhydride and absolute ethyl alcohol, dropwise adding ethylenediamine to carry out a synthetic reaction, and then washing and drying a reaction product to obtain white solid powder N, N ́ -ethylene bismaleimide acid; 2) And (2) uniformly mixing the N, N ́ -ethylene bismaleimide acid prepared in the step (1) with absolute ethyl alcohol, dropwise adding N, N-dimethyl dodecyl amine for synthesis reaction, and evaporating and drying a solvent to obtain a light yellow viscous target product, namely the coal seam wetting reversal agent.
3. The method of preparing a coal seam wetting reversal agent according to claim 2, wherein the molar ratio of maleic anhydride to ethylenediamine in step 1) is 2:1.
4. The method for preparing the coal seam wetting reversal agent according to claim 3, wherein the condition of the synthesis reaction in the step 1) is that the reaction is carried out for 12-15 hours in a water bath at 0-5 ℃.
5. The method for preparing a coal seam wetting reversal agent according to claim 4, wherein the drying condition in the step 1) is that the drying is carried out for 2-3 hours at a temperature of 60-80 ℃.
6. The method for preparing a coal seam wetting reversal agent according to claim 2, wherein the molar ratio of N, N ́ -ethylene bismaleimide acid to N, N-dimethyldodecanamine in step 2) is 1:2.
7. The method for preparing the coal seam wetting reversal agent according to claim 6, wherein the condition of the synthesis reaction in the step 2) is that the reaction is carried out for 18-24 hours at 15-25 ℃.
8. Use of the coal seam wetting reversal agent according to claim 1 in the field of coal seam development technology.

Description

Coal seam wetting reversal agent and preparation method thereof Technical Field The invention belongs to the technical field of coal seam development, and particularly relates to a coal seam wetting reversal agent and a preparation method thereof. Background The exploitation of the coal bed gas is not only beneficial to reducing the occurrence of coal mine gas sudden accidents, but also can be used as clean fuel to meet the world energy demand, however, the coal bed permeability is generally low, and the exploitation of the coal bed gas is limited. The hydraulic measures such as hydraulic fracturing can effectively improve the air permeability of the coal bed, but after a large amount of external water invades the coal bed, the water content in the coal bed is increased due to the existence of capillary force to form a water locking effect, so that a coal bed gas diffusion channel is blocked, and the coal bed gas is prevented from being produced. Changing the wettability of the coal bed is a key for promoting the desorption of the coal bed gas and eliminating the water lock, but the current wetting reversal agent has single function, and most of the wetting reversal agents are compound surfactant systems, so that the purposes of promoting the desorption and the water lock release of the coal bed in large-scale volumetric fracturing are difficult to simultaneously meet. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, the main object of the present invention is to provide a coal seam wetting reversal agent which is a novel pseudo gemini surfactant. The invention mainly aims at providing a preparation method and application of the coal seam wetting reversal agent. The invention aims at realizing the following technical scheme: The coal seam wetting reversal agent is characterized by comprising the following molecular structural formula: The preparation method of the coal seam wetting reversal agent comprises the following steps: 1) After MAH and absolute ethyl alcohol are stirred and mixed uniformly, EDA is added dropwise for synthesis reaction, and then the reaction product is washed and dried to obtain white solid powder EBMAA; 2) And (2) uniformly mixing EBMAA prepared in the step (1) with absolute ethyl alcohol, dropwise adding DMA12 for synthesis reaction, and then evaporating and drying a solvent to obtain a light yellow viscous target product EBMAA-DMA12. In certain embodiments, the molar ratio of MAH to EDA in step 1) is 2:1. In certain embodiments, the conditions for the synthesis reaction in step 1) are such that the reaction is carried out in a water bath at 0-5℃for 12-15 hours. In certain embodiments, the drying conditions in step 1) are drying at a temperature of from 60 to 80 ℃ for from 2 to 3 hours. In certain embodiments, the molar ratio of EBMAA to DMA12 in step 2) is 1:2. In certain embodiments, the conditions for the synthesis reaction of step 2) are such that the reaction is carried out at 15-25℃for 18-24 hours. An application of the coal seam wetting reversal agent in the technical field of coal seam development. Compared with the prior art, the invention has at least the following advantages: 1) The coal seam wetting reversal agent has excellent pH influence behavior, and can change the wettability of the surfactant EBMAA-DMA12 on the surface of a coal sample by adjusting the pH value of the solution. Specifically, when the pH value of the solution is smaller than 6.87, the solution is favorable for reducing capillary force, can be used as a waterproof locking agent, and when the pH value of the surfactant solution is larger than 6.87, the solution is favorable for reducing the free energy of the surface of the coal bed, and can be used as a coal bed methane desorbing agent. 2) According to the preparation method, a binary acid intermediate N, N ́ -ethylene bismaleimide acid (EBMAA) is synthesized by adopting MAH and EDA, and then a neutralization reaction is carried out on N, N ́ -ethylene bismaleimide acid (EBMAA) and N, N-dimethyl dodecyl amine, so that a novel pseudogemini surfactant is obtained. The preparation method has the advantages of easily available raw materials, simple process, high repeated stability and good popularization value. Drawings In order to more clearly illustrate the embodiments of the present invention, the drawings that are used in the description of the embodiments or the prior art will be briefly described below. FIG. 1 shows an infrared spectrum (a) of MAH, EDA, EBMAA in step 1) of the preparation method of example 1 of the present invention, and an infrared spectrum (b) of DMA12, EBMAA-DMA12 in step 2); FIG. 2 is a graph showing the relationship between the surface tension and mass fraction of EBMAA-DMA12 in example 1 of the present invention; FIG. 3 shows the change in surface tension of a solution of surfactant EBMAA-DMA12 at different pH values; FIG. 4 sho