Study and Application of Self-degrading Temporary Plugging Fluid for Offshore Low Permeability Reservoirs

A self-degrading temporary plugging fluid was developed, through one-factor experiment analysis and synergistic compounding of different additives, to address the water sensitive and water block issues resulted from mud losses during working over the low permeability reservoirs in the Weizhou RRX oilfield in the west of South China Sea. Laboratory experimental results showed that the drilling fluid developed has excellent rheology and low filtration rate. Without injecting gel breaker, 50% of the gels developed in the drilling fluid were degraded in 6 days. Surface tension of the drilling fluid filtrate is less than 20 mN/m. The inhibitive capacity of the drilling fluid is at least 95%. Core experiment with the drilling fluid showed that the average percent permeability recovery is 90%. No mud loss and contamination to reservoir were found in field application of the drilling fluid, demonstrating the ability of the drilling fluid to minimize damage to low permeability reservoirs during workover operation.