Optimization of Anti-Collapse Drilling Fluid Systems with High Potassium Content

The ash mudstone in some oil formations is highly water-sensitive. The oil formation is fractured, and the risk of well leakage and collapse is not negligible. This study presents a countermeasure for well collapse prevention, based on a "force-chemistry synergistic balance" approach and the utilization of environmentally friendly and efficient hydration inhibitors. The relevance of this approach is demonstrated considering a drilling fluid system with the high potassium content. The analysis shows that the system can maintain good rheological properties, filtration loss and suspension stability even after aging at 130 degrees C for 16 h. The primary roll recovery of rock chips is better than 98%. The secondary rolling recovery rate is 89%. The rapid water loss is close to zero. The effects of carrying rock, sand, hydration inhibition and dispersion of drill chips are all noticeable.