Shallow-gas fracturing is very prevalent in western Canada. Several thousand wells are typically drilled and completed in the shallow-gas fields every year. All these wells are typically hydraulically fractured. Before 1999, after testing for microtoxicity, the flowback fluid was allowed to be land farmed in southeastern Alberta. In that year, the Alberta Energy and Utilities Board began more stringent enforcement of Guide 58, which required that flowback fluid be disposed in a disposal well.
At that time, one operator typically had a project of 300 to 400 wells with an average of 5 fracs per day during spring/summer. When the fluid could no longer be land farmed, attempts were made to recycle the flowback fluid. The chemistry of the surfactant-gel fluid was insensitive to the water quality, which made the recycling concept successful. Several cost advantages were achieved, which will be detailed in the paper. These included freshwater costs, transportation costs, disposal costs, and chemical costs. An additional advantage that was realized involved a 50% reduction in the freshwater requirements for a project--a significant additional benefit because several years of drought conditions have caused water shortages in the area.
This paper will detail the chemistry of the fracturing gel, its field application, the optimized recycling operation, and the details on cost advantages achieved, as well as future direction for further reduction in freshwater usage on a project basis.
Number of Pages
Gupta, D.V.S. and Tudor, E.H. 2005. Method for fracturing subterraneanformations. US Patent No. 6,875,728.