Laboratory development and field application of a novel water-based drill-in fluid for geopressured horizontal wells

Research has identified a novel water-based drill-in fluid for drilling and completing geopressured horizontal wells. This fluid has a unique combinat ion of properties which make it especially suitable for geopressured applic ations. They include the use of calcium and/or zinc bromide as a base brine , minimal concentration of calcium carbonate as bridging material, low plas tic viscosity, tight fluid loss control good filter-cake properties, and ex cellent return permeability. This drill-in fluid has been used successfully to drill a 1,200-ft production interval, 4.75-in. diameter wellbore in the Gulf of Mexico with a system weight of 13.2 lbm/gal, bottomhole temperatur e of 185 degrees F, and a 1,400 to 1,700 psi overbalance. The system functi oned very well in both the drilling and the completion operations. Fluid rh eology was easily maintainable and the hole conditions were excellent witho ut torque or drag problems. Initial production data suggest that the well i s producing at expected rates with low drawdown pressure.