Preparation and Evaluation of a Temporary Plugging Organosilicon Diverting Agent for Fracturing Fluids

Particulate temporary plugging agents presently used in fracturing fluids are mostly rigid, and deficiencies exist in using these plugging agents, such as insignificant pressure buildup, short pressure stabilization time and inability to effectively transfer stress etc. To deal with these problems, an organosilicon hydrogel named LYB was developed through micellar polymerization with main raw materials acrylamide and N,N-methylene bis-acrylamide, as well as an organosilicon hydrophobic monomer. The effects of the monomer concentration, the hydrophobic monomer, the polymerization method and the polymerization conditions on the LYB hydrogel were investigated, and FTIR and element analysis method were used to characterize the LYB hydrogel. The experimental results show that the optimum conditions for the synthesis of the LYB hydrogel are as follows: the concentrations of the water soluble monomers, the organosilicon, the crosslinking agent and the initiator are 8 – 10%, 2%, 0.02% and 0.2%, respectively, the reaction temperature is 50 – 60 °C, and the reaction time is 6 – 8 h. Laboratory evaluation of the LYB hydrogel shows that compared with the commonly used rigid particulates, the LYB hydrogel has higher shear strength, better salt resistance and elasticity. From the fracturing job curves and microseismical monitoring results, it can be seen that when the LYB temporary plugging agents are in place, the in-situ pressure is increased by 7 – 8 MPa. After temporarily plugging the fractures, the flowrate at the same job pressure is reduced by 1.5 m³/min. Using downhole microseisms, the effectiveness of the fracture diversion by the LYB hydrogel is further verified.