Preparation and Application of Strong Sealing and Anti Collapse Water-Based Drilling Fluid System
The target shale block was selected for analysis of reservoir hydration behavior characteristics, and a high-performance water-based drilling fluid system with strong sealing and anti collapse properties was proposed. The key treatment agents were selected, including plugging agents, filter loss reducing agents, inhibitors and lubricants. The rheological properties, plugging properties, inhibition properties, lubrication properties, temperature resistance and wellbore stability were experimentally evaluated, and on-site application tests were conducted. The results showed that the combination of base slurry, 3.0％ sulfonated asphalt, and 5％ calcium carbonate could achieve the lowest filtration loss in the system. 3％ SAP+6％ PAH+0.5％ HB had the best filtration loss reduction effect, with 6％ PEG and 5％ FH6 as inhibitors and lubricants. The filtration loss of the prepared water-based drilling fluid system was almost zero, and the shale rolling recovery rate was 96.99％, which could effectively prevent wellbore collapse and stabilize the wellbore. The comprehensive performance was not significantly different from that of the oil-based drilling fluid system. During the on-site application test, the high-temperature and high-pressure water loss was as low as 3.9 mL, and the solid mass fraction in drilling was only 5.29％. The extreme pressure lubrication coefficient was significantly lower than that of non test wells, verifying the practicality of the water-based drilling fluid system.
Hydration behaviorWater based fracturing fluidStrong sealingPerformance evaluationflowdispersionmixing
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