The construction process of "carrying liquid + supporting agent" has been adopted in field fracturing. The preparation and transportation of carrying liquid not only cost a lot of manpower and material resources, but also have poor ability to deal with emergencies in the mine. The self⁃suspension proppant has been prepared and injected at the scene, and its product filtration and its influence on reservoir permeability have been highly concerned by petroleum technicians. The experimental study and mechanism analysis of the effect of fluid loss of self⁃suspension proppant on core permeability are carried out. The results show that when the injection speed was constant, with the core permeability increased, the filtration loss got increased, the damage rate decreased. With the gel breaking time increased, the amount of filtration loss got larger and the damage rate decreased. The degree of influence of gel breaking fluid on core permeability had little relation with its viscosity, which mainly depended on the amount of residue retention and erosion resistance in porous media after glue breaking. Under the condition of "constant pressure experiment", the larger the pressure difference of filter loss, the larger the amount of filter loss, and the damage rate presented the trend of "first increase and then tend to be stable". Compared with the constant speed test, although the amount of filtration loss is relatively small, the damage rate is high. Relationship between the damage rate of three kinds of coating materials to reservoir: hydrophobic associative polymer > medium molecular weight polymer > guanidine adhesive.

A comparative experimental study on the fracture conductivity between the self propping agent and the “propping agent + carrier fluid” has been carried out, and the mechanism analysis has been carried out. The results show that whether the self supporting proppant or the “propping agent + carrier fluid”, the fracture conductivity decreases with the increasing of closing pressure. With the increase of sand concentration, the conductivity of fracture increases. Compared with those of quartz sand, the compressive strength and the fracture conductivity of ceramsite are obviously higher. On the one hand, the polymer carrying liquids can enhance the compressive strength of proppant, reduce the crushing rate, and further increase the conductivity of fracture. On the other hand, the retention of carrier fluid among proppant particles will result in decrease in permeability, which will reduce the conductivity of fractures. Therefore, the fracture conductivity is the result of the interaction of permeability and fracture rate. Compared with that of the “proppant + carrier fluid”, the breaking rate of the self propping proppant is slightly higher, which has no obvious effect on fracture conductivity. It can be seen that the process of the self suspension proppant has no effect on the proppant compressive strength and the fracture diversion.

In order to meet the practical needs of profile control and flooding technology in Bohai reservoir, the hydration dynamic characteristics and seepage characteristics of polymer microspheres were studied in this paper. Results indicate that, with the prolonging of hydration time, the expansion ratio of polymer microspheres increases, and the final expansion ratio is about 4.5. When the hydration time is less than 50 h, the expansion velocity is faster, then the expansion velocity slows down, and finally reaches stable after 360 h. Compared with the size distribution of molecular aggregates in the polymer solution, the size distribution of the two polymer microspheres is relatively concentrated. The initial median particle size of 10 ^# microspheres is 4.36μm, and then reaches 20.00 μm after hydration for 240 h. The initial median particle size of 11 ^# microspheres is 8.45 μm, and then reaches 40.0 μm after hydration for 360 h. The expansion ratio is about 4.72. In the injection process of polymer microsphere, the adhesion between particles and the pore filtering effect can cause the retention and temporary plugging of polymer microsphere in the core end, which leads to the abnormal increase of the pressure in the injection process. The polymer microspheres can further hydration expand in the core pore, showing the seepage characteristics of “migration, trapping, re migration and re trapping......”.