| 摘要 |
Drilling fluids comprising a carrier fluid; a weighting agent that comprises sub-micron precipitated barite; a particle having a specific gravity of greater than about 2.6; and, a bridging agent that is not the submicron-precipitated barite or the particle. The weighting agent has a particle size distribution such that at least 10% of particles in the sub-micron precipitated barite have a diameter below about 0.2 microns, at least 50% of the particles in the sub-micron precipitated barite have a diameter below about 0.3 microns and at least 90% of the particles in the sub-micron precipitated barite have a diameter below about 0.5 microns. The particle has a specific gravity of greater than about 2.6 is not sub-micron precipitated barite. The ratio of the sub-micron precipitated barite to the particle is about 10:90 to about 99:1. The bridging agent comprises a degradable material. |
