Development and blocking assessment of high softening point asphalt system

Abstract The technology of oil and gas well plugging and profiling currently represents a favourable means of promoting the development of water injection and ensuring stable production from oil reservoirs in oil fields. The use of emulsified asphalt is significantly limited by several factors, including its insufficient resistance to high temperatures, demanding requirements for sealing strength, and susceptibility to destabilisation in high salinity conditions. Nevertheless, it presents favorable injection performance and does not cause soil contamination. To improve the selective water plugging in seam-hole reservoirs with high salt content and temperature, a novel high softening point emulsified asphalt blocker was developed in this work using petroleum asphalt powder, sodium lauryl diphenyl ether disulfonate, and propylene glycol alginate as the primary monomers. The stability of the system in terms of temperature and salt resistance as well as the sealing performance under different permeable seam hole layers were investigated. The studies showed that the novel blocking agent remained stable for at least 20 days at room temperature and remained fluid for at least 3 h at 130 °C. The system exhibited excellent salt resistance and maintained a suitable viscosity in highly mineralized conditions. With an injection volume of 1 PV and a permeability ranging from 2,014 mD to 3,321 mD, the slit reservoirs achieved an average blocking rate of 88.9 %.