The challenging nature of drilling and producing shale gas plays has favored the use of oil-based drilling fluids. The growing importance of shale gas has placed greater pressure to address environmental issues associated with the drilling and production of these wells. A pressing goal is the development of a highly inhibitive and environmentally friendly water-based drilling fluid. Specifically, the drilling fluid should address wellbore stability issues associated with specific shale gas plays. Such specialized drilling fluids will better stabilize shales and help control drill time and costs.

This paper discusses the research and development of a novel potassium silicate as a shale stabilizer for certain shale gas plays. This novel potassium silicate differs from conventional potassium silicate by significantly increasing the level of dissolved silicate to potassium. The resulting potassium silicate is chemically more reactive and can more easily undergo the polymerization and precipitation reaction. These reactions are the shale stabilization mechanisms most often associated with sodium and potassium silicate. Laboratory investigation indicates drilling fluids formulated with this more vitreous potassium silicate show a high degree of effectiveness at preventing shale delamination and sealing micro fractures.

Drilling fluids formulated with conventional potassium silicate can often be disposed using surface methods such as mix-bury-cover, land spreading or land spraying. However, depending on receiving soil or the concentration of potassium silicate in the drilling fluid, it sometimes becomes necessary to treat the associated drill waste with a calcium-based amendment or send the waste to an approved waste management facility. The reduced alkalinity and more siliceous nature of high ratio potassium silicates provides for a drilling fluid with lower salinity as measured by electrical conductivity and sodium adsorption ratio. Resulting drill waste can more easily meet the salinity requirements associated with using surface disposal methods.

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