Research and Application of Workover Fluid Protection Technology in High Pour Point and High Viscosity Reservoir

The reservoir properties of Wangguantun block in Dagang Oilfield are complex, with high shaliness content, high condensate and viscosity of crude oil.. Foreign liquids entering the reservoir can easily cause damage such as water sensitivity and water lock. At the same time, as the wellbore temperature decreases, it can cause cold damage to crude oil and form organic scale blockage; The reservoir formation water type is complex and diverse, and the incompatibility between the inflow fluid and the fluid can easily produce inorganic scale, affecting the oil flow channel and leading to a significant decrease in oil well production, seriously affecting the economic benefits of the oilfield.By compounding efficient inhibitors indoors, the centrifugal anti swelling rate of the system can reach 92.1%, effectively suppressing reservoir water sensitivity; Preferred anionic nonionic surfactants with strong salt resistance as waterproof locking agentst. When the dosage is 0.5%, the surface tension of the aqueous solution is less than 15mN/m, and the interfacial tension is less than 0.2 mN/m; Developing a new type of anti scaling well killing fluid technology, with a system anti scaling rate of up to 97.8%, which can effectively prevent the generation of inorganic scale. This technology has been applied in 20 wells in Dagang Oilfield, with an average production recovery rate of 98.5% after oil well operation, and the oil reservoir protection effect is remarkable.