The Study of an Inorganic Gel for Profile Modification in High-Temperature and Low-Permeability Sandstone Reservoirs

Chemical water control technique has been successfully used to improve oil recovery of mature waterflooding reservoirs. However, for high-temperature and low-permeability sandstone reservoirs, not many options are available. An inorganic gel composed of aluminum chloride hexahydrate as gelling agent and urea as an activator was developed. Based on the proper gelation time and degree of syneresis, the optimum mass ratio of aluminum chloride and urea was 1:0.625. According to the gel strength and economical cost, the reasonable concentration of aluminum chloride should range from 3.0% to 6.0%. Gel compatibility with various formation brines showed that the gel could tolerate sodium chloride concentrations up to 80 g·L −1 and calcium chloride concentrations up to 40 g·L −1. Long-term thermal stability and sandpack flow results showed that after aging for 60 days at 110°C, the gel showed approximately 82% permeability reduction when about 16% syneresis was observed in bulk samples.