Abstract

A reliable geochemical tracer has yet to be developed which can be beneficial to hydraulic fracturing schemes for enhanced production of gas and oil from organic-rich shale beds. Our preliminary study on rare-earth elements in various fluids collected from hydraulic fracturing of Woodford Shale at a location (Sec. 21, T.1N., R.10E.) in Coal County, Oklahoma shows that relative rare-earth element distribution patterns of temporally different flow-back fluids, normalized to the pre-frac fluid used, could prove to be a useful geochemical tracer, giving additional insights into the geometry of the induced-fracture system. The tracer can be particularly useful to determine whether or not induced fractures from a hydro-fracturing event might have been extended to adjacent stratigraphic units beyond the production formation. The preliminary results of this study opens a promising window for more extensive studies to be conducted in conjunction with engineering plans and microseismic controls in many different areas where hydraulic fracturing of organic-rich shale beds are intended for enhanced production of gas and oil.