A Technology for Stimulating Low Permeability Heavy Oil Reservoirs

A set of technologies, with "reservoir stimulation plus fluid quality improvement" as the core technology, have been developed to stimulate low permeability heavy oil reservoirs, which have poor physical properties and high viscosity crude oil, and show poor stimulation results with conventional fracturing technology. An ionic surfactant was selected through laboratory experiment as the viscosity reducer for crude oil, and the dosage of the viscosity reducer was determined to be 3% through optimization. Physical simulation results showed that time required for the viscosity reducer to show optimum viscosity reducing effect was 1-3 d. A low damage fracturing fluid with ultra-low concentration (0.18%) viscosity reducer was formulated through optimization, and the viscosity of the fracturing fluid was maintained at 100 mPa乌s after shearing the fluid at 60℃ and 170 s^-1 for 120 min. Using this fracturing fluid, a high conductivity tip screen-out fracturing technology has been developed. This technology has been applied on the well X in Huabei Oilfield, and the initial oil production rate after fracturing was 10.06 t/d, 3 times of the oil production rate of the adjacent well, and water production rate was 1.54 m³/d. The total amount of oil increased 3 months after fracturing was 518 t, indicating that the fracturing job was successful. This technology has provided a good clue for stimulating reservoirs of the same type.