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

摘要

An additive that increases the density of fluids used in a wellbore during the construction or repair of oil, gas, injection, water, or geothermal wells comprises a wellbore fluid containing a sized barite weighting agent that has an increased density with improved suspension stability without a significant viscosity increase. The wellbore fluid as described herein has rheological properties comparable to a conventional wellbore fluids but does not exhibit problems with sag and resulting variations in density. An illustrative embodiment of the claimed subject matter is further 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 mum to 15 mum. In another preferred embodiment, the additive has a D₅₀ (by weight) of approximately 1 mum to 6 mum. In another preferred embodiment the additive has a D₉₀ (by weight) of approximately 4 mum to 8 mum. The additive may be used in any wellbore fluid such as drilling, cementing, completion, packing, work-over (repairing), stimulation, well killing, and spacer fluid.