Preparation And Performance Study Of Hydrochloric Acid Microcapsules

With the increase of development efforts,many carbonate rock petroleum resources have problems such as deep burial,high formation temperature,high purity of carbonate in matrix,low natural yield,etc.,usually require acidification or acid fracturing technology.The reservoir is modified to increase the yield.Acidification or acidification fracturing due to the rapid reaction speed of acid rock,can not form long effective acid corrosion cracks,the effect is not good,and it will produce strong corrosion to pipelines and downhole tools during the construction process.Therefore,how to control the distance of active acid deep into the reservoir to obtain better acid etching seam length and crack conductivity is the key to improve acid fracturing technology.Due to its special core-shell structure,microcapsules can be well embedded in the active substance,and the active substance can be protected while the active substance can be controlled and released.Therefore,in biomedicine,building materials,textiles,food,Cosmetics and many other fields have an extremely wide range of applications.In this paper,microcapsule technology was used to screen the wall materials,and based on W/O/W double emulsion method,combined with photopolymerization reaction,microcapsules with smaller particle size,dense cell wall and temperature controlled release were prepared.The effects of preparation conditions and formulation factors on the particle size and encapsulation rate of microcapsules were studied.The optimal process and formulation of microcapsules were determined.The release properties of microcapsules were studied.The kinetic model fitting and microscopic characterization were used to analyze the microcapsules.The mechanism of capsule release was studied.First,the microcapsule wall material is preferred herein.The non-nuclear particles were prepared by suspension polymerization.The DSC and macroscopic analysis of the polymerized wall materials showed that the polyurethane prepolymer(PUA)and the 1,6-hexanediol diacrylate(HDDA)polymerized glass.It has suitable transformation temperature,small particle size and high crosslinking density,and is suitable as a wall material for microcapsules.Then,the preparation methods of colostrum and double emulsion were studied.The effects of ultrasonic emulsification method and high-speed dispersion homogenization method on the type of colostrum prepared were investigated.The effect of emulsion emulsification intensity on the type of colostrum was investigated.The preparation method of W/O colostrum was prepared by high-speed dispersion first,and the W/O/W double emulsion was prepared by low-speed mechanical stirring method.The preparation process of microcapsules was further explored.Fourier infrared spectroscopy indicated that PUA and HDDA were Photopolymerization can be successful in a strong acid environment.Then,based on the preliminary preparation method of microcapsules,the effects of various factors on microcapsules were investigated based on the emulsion stability and microcapsule particle size and encapsulation efficiency.The process conditions and experimental formula were optimized.The optimum process is as follows:5 mol/L hydrochloric acid as the core material,polymerizable macromolecular surfactant P135 as the lipophilic emulsifier,the addition amount is 7.5%;the ratio of PUA and HDDA is 1:1 as the wall material;The emulsion emulsification speed is 7000;the weighted HLB value after compounding with Span80 and Tween80 is 10 as the hydrophilic emulsifier,the addition amount is 10%,the second step emulsification speed is 600 rpm;the first phase volume ratio is 1:1.5,the first The volume ratio of the two phases was 1:1;the external phase additive PVA was 1.5%,the external aqueous phase NaCl concentration was 5 mol/L,and the emulsion ripening time was 90 min.The colostrum and double emulsion prepared under this formula have high stability,and the microcapsules obtained after curing have a narrow particle size distribution,uniform size,particle size of about 114 μm,and a microcapsule encapsulation ratio of 61.9%.The surface morphology of the microcapsules was characterized by scanning electron microscopy.The results showed that the prepared microcapsules were regular spherical,uniform in size,well dispersed,and the surface was neat and compact,without any pores,indicating that the polymer has a high Crosslink density.Finally,the effects of temperature and salinity on the release properties of microcapsules were investigated.The results showed that the microcapsule wall did not swell at 25℃,and almost no release.With the increase of release temperature,the release rate of microcapsules increased.The maximum cumulative release rate increased,and the maximum cumulative release rate of microcapsules at 100 ℃ was 90.7%,At different salinities,the initial release rate of microcapsules remained basically unchanged,and with the prolongation of release time,the maximum release rate of microcapsules in a highly salinized environment was lower than the maximum release in a low salinity environment.rate.By fitting the microcapsules to the release model,the results show that the microcapsules prepared by this subject have a high degree of fit with the Ritger-Peppas model,R2 is 0.9891,and the n value of the Ritger-Peppas equation is 0.66,indicating that the microcapsules are mainly composed of the skeleton.Release under the dual action of dissolution and Fick diffusion.