Method of drilling using a sized barite as a weighting agent for drilling fluids

摘要

An additive that increases the density of fluids containing a sized barite weighting agent. The wellbore fluid has rheological properties comparable to a conventional wellbore fluids but does not exhibit problems with sag and resulting variations in density. An illustrative embodiment is directed to a method for making the sized barite weighting agent and a method for using such sized barite weighting agent in a wellbore fluid. In one preferred embodiment the sized barite weighting agent has a particle diameter between 4 μm to 15 μm In another preferred embodiment, the additive has a D₅₀ (by weight) of approximately 1 μm to 6 μm. In another preferred embodiment the additive has a D₉₀ (by weight) of approximately 4 μm to 8 μm. The additive may be used in any wellbore fluid such as drilling, cementing, completion, packing, work-over (repairing), stimulation, well killing, and spacer fluid.