| In recent years,as the strength and depth of coal mining continue to increase in our country,all kinds of coal and rock power disasters such as rock burst and gas outburst occur frequently.With the continuous in-depth research on the pressure relief and permeability improvement technology of high gas and low gas permeability coal seam and the theory of hydraulic fracturing weakening coal rock mass,hydraulic fracturing has achieved a good effect and function in preventing gas outburst and rock burst.However,hydraulic fracturing technology still has two shortcomings:(1)coal surface hydrophobicity is strong,the wetting effect of pure water on coal is not ideal,and the effect of pressure relief and reflection improvement in the process of hydraulic fracturing needs to be further optimized;(2)The current monitoring and evaluation technical means of hydraulic fracturing effect of coal strata still need to be improved in order to achieve effective,economic and eco-friendly effects.To solve the above problems,this paper mainly proposed the use of two monomer surfactants compound and optimize the formation of compensatory biionic surfactants,in order to enhance the hydrophilicity of coal surface,improve the wetting efficiency of coal surface,and analyze its wetting mechanism.The diffusion and migration of P.fluorescein in coal was studied by using p MJ67 L.acidophilus SP.as an example.At the same time,this paper designed a similar simulation test system and carried out similar simulation test based on the static pressure water injection condition of coal seam to regulate p MJ67 L.acidophilus SP with compensatory dual ions.The diffusion and migration effect of fluorescein bacteria in coal is verified,which provides theoretical support for the application of surfactant in hydraulic fracturing process and fluorescent biomarker technology in monitoring and evaluation of hydraulic fracturing effect.The surface modification experiments of coal were carried out.The results showed that sodium dodecyl sulfate(SDS)and Pingjiao-25(PPJ)were obtained in 40-60 mesh,80-100 mesh,<.The average wetting time of 120 mesh particles was shorter than that of sodium dodecylbenzene sulfonate(SDBS)and sodium stearate(SS).The monomic surfactants sodium dodecyl sulfate(SDS)and Pingjia-O-25(PPJ)have good permeability and diffusivity,which can reduce the surface tension of solution,increase the activity of the solid-liquid interface between solution and coal,improve and promote the penetration and diffusion of solution to the pore structure of coal,and have good coal surface modification effect.The optimal analysis of the compensatory biionic surfactant was carried out by orthogonal test.The results showed that:(1)compared with the monomer surfactant,the wetting effect of the surfactant composed of sodium dodecyl sulfate(SDS)and Pingplus O-25(PPJ)is more significant.(2)For 40-60 mesh,80-100 mesh,<A comparative analysis of the range values of 120 mesh coal particles shows that A-PPj solution concentration,B-SDS solution concentration,the interaction between C-A and B,and D-temperature have consistent regularity on the significant degree of influence on the wetting time.The four factors in descending order were A-PPJ solution concentration > B-SDS solution concentration > D-temperature > C-A and B interaction.The optimal configuration scheme of the compensatory biionic surfactant can be determined as PPJ solution concentration of 2.25%,SDS solution concentration of 3.75%and ambient temperature of 45℃.(3)In the process of mixing surfactants,the larger molecules of Pingpinga-O-25 and the smaller molecules of sodium dodecyl sulfate were arranged in a Mosaic pattern,and the small molecules were coupled to compensate each other,forming a cross arrangement of small molecules,complementary effect mode of action.Under the combined action of large and small molecules,the effects of the two monomer surfactants are superimposed and complementary,forming a compensatory bi-ionic surfactant,which can improve the hydrophilicity of the coal surface and significantly improve the wetting effect of the solution on the coal surface.A compensatory biionic surfactant was used to improve the wettability of coal surface and regulate p MJ67 L.acidophilus SP.Study on the diffusion law of fluorescent Bacillus in coal.Based on the characteristics of micro-pore structure in coal,a spherical stacking model of coal particles was proposed.The length of micro-pore channel was expressed by the distance between two adjacent spherical tangential points,and the multi-scale micro-fracture length was characterized by the composite particle size of40-100 mesh coal particles.The accuracy and applicability of the particle size of 40-100 mesh coal particles selected in similar simulation tests were verified.A similar simulation test system was set up to regulate the homogeneous distribution of Bacillus fluorescein coal with compensatory biionic surfactant.The results of the similar simulation test show that the seepage velocity of liquid is inversely proportional to the seepage height,and the arrival time is proportional to the seepage height,and the distribution is power curve.The percolation velocity,percolation height and arrival time of the solution increased significantly,and the improvement effect was obvious.With the increase of the concentration of the compensatory biionic surfactant,the modification effect and the wettability of the coal surface are improved significantly.At the same time,after adding different concentrations of compensatory biionic surfactants,the concentration of Bacillus fluorescein at each seepage height increased obviously.The concentration difference of microbial solution measured by each height sampling unit of the same solution concentration test is small,which basically achieves the effect of uniform diffusion distribution in coal seam.In contrast,within a certain concentration range,the higher the concentration of the compensatory biionic surfactant,the better the wetting effect of the solution on the coal body,and the higher the adsorption efficiency of fluorescein bacteria in the coal seam.There are 63 pictures,27 tables,and 115 references. |
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