Research And Application On Anti-sloughing Drilling Fluid System In Middle And Deep Formations In Shengli Oilfield

During drilling in middle and deep formations of Shengli Oilfield, mud stone, shale and salt bed are popular. Due to mud-make, slough and electrolyte pollution, rheological properties tend to deteriorate, which brings great difficulty to field monitoring and maintaining. Field data show that the frequent downhole incidents have threatened drilling rate and the exploration and development.To solve these problems, composite anti salt drilling mud system and polysilicic alcohol anti-sloughing drilling mud system are optimized based on the results of lab tests and field data. Field applications show that these newly invented systems are ideal in effect.Composite anti-salt drilling mud system and polysilicic alcohol anti-sloughing drilling mud system are changeable to field reality and have broad usage. Indices of performance of the formula include: 1.10～2.00g/cm3 in density, API water loss less than 3mL, water loss in high temperature and high pressure less than 12mL, 8～30MPa·s in PV and 5～18Pa in dynamic shear force. To keep stable, the system needs to be altered according to the encroaching matters. These two systems are worth publicizing to prevent accidents in complex construction.