Encapsulated gel breaker is commonly used as a gel breaker in fracturing of oil and gas wells. At present, the main preparation methods of encapsulated gel breaker are mechanical encapsulation methods, such as fluidized bed method (also known as Wurster method or air suspension spraying method) and rotary drum spraying method. The preparation has also been studied by phase separation and chemical methods
1. Fluidized bed method
Fluidized bed method is the most widely used method for preparing encapsulated gel breaker, and there are many commercial products. The main process of the fluidized bed method is: the gel breaker particles are placed in the coating chamber, and suspended and fluidized under the action of air flow. The circulating flow of particles passes through the nozzle at the bottom of the coating chamber. The nozzle sprays the capsule material liquid (solution or emulsion) onto the particles. The capsule solidifies under the action of air flow. This cycle is repeated until the desired coat thickness is reached.
2. Rotary drum spraying method
Compared with the fluidized bed method, the rotary drum spraying method has lower equipment requirements and can be made by itself. The coating process of drum spraying method is: the gel breaker particles are placed in the drum, and the turntable is started to make the particles tumble. The capsule material liquid (usually solution) is sprayed on the particles by the spray gun head, and an appropriate amount of hot air is pumped in to solidify the capsule membrane. When the required coating thickness is reached, stop spraying, continue rotating and blowing until thoroughly dry.
3. Phase separation method and chemical method
When encapsulated gel breakers are prepared by phase separation and chemical methods (e.g. in situ polymerization, interfacial polymerization and suspension crosslinking), the capsule core can be either solid particle or liquid drop of the gel breaker. When prepared by phase separation method and chemical method, the liquid-liquid or liquid-solid dispersion system must be formed under the action of mechanical stirring and dispersant, and then the coating material is wrapped on the gel breaker by phase separation, polymerization or cross-linking reaction, and sometimes further curing is required.
Compared with the above methods, the appearance, size and wrapping effect of the product prepared by fluidized bed method are better, but the preparation cost is high and the process is complicated and difficult to control. In addition, due to the spray coating process and the use of air as a suspension and drying medium, the solution selection must consider the process operability, toxicity, equipment explosion-proof and exhaust gas treatment and other issues, making the selectivity of the coating material is narrow. Compared with the fluidized bed method, the rotating drum spraying method is easier to operate and control, but it also has the problems of solvent selection and tail gas treatment, and it is easier to produce adhesion and agglomeration between particles, and the product quality is inferior compared to the fluidized bed method. The advantages of the phase separation island method and chemical method are that they are suitable for both solid and liquid adhesives, but they are limited lby the physical and chemical properties of the adhesives.
We Weifang Totpion Chemical Industry Co.,Ltd are the professional encapsulated gel breaker and capsulated sustained-release additives production enterprises and supplier. Please visit our website www.toptionchem.com for more information. If you have any requirement, please do not hesitate to contact us.
Post time: Nov-03-2023