Lost Circulation Material and Technology Research of Self-healing Hydrogel

Excessive development of pore fractures in the formation during drilling operations can lead to lost circulation and can easily result in safety incidents. In this research, a self-healing hydrogel based on cation-π, electrostatic, hydrogen bonding was prepared by a free radical polymerisation method for formation plugging, forming a dense sealing layer to contain lost circulation and prevent recurrence. Excellent self-healing properties in harsh conditions, with a self-healing efficiency of 70%, and can effectively seal the pores of 180 D sand discs with a sealing rate of nearly 90%. It also shows good sealing ability for other consolidated sand discs (permeability 2 D, 5 D, 20 D) and unconsolidated sand beds (20-40 mesh, 40-60 mesh, 60-80 mesh). Compared to conventional materials, the hydrogel can be self-healing by reducing the operating pressure drop to achieve an efficient seal. The self-repairing hydrogel can effectively improve the denseness of the sealing layers through secondary reduction of the permeability of the sealing layer, which improves the high temperature stability of the hydrogel and still has good sealing ability after high temperature aging. The hydrogel particles are well dispersed in the salt water and maintain stable rheological properties after hot rolling, which is beneficial for drilling fluid circulation. This study shows the potential of self-healing materials as plugging materials in the oil drilling industry.