Aqueous geochemistry techniques for water analysis have not traditionally been utilized in the petroleum industry, but with the rise of unconventional plays, unconventional analysis of the reservoir has become necessary. We can use total ion chemistry and isotope geochemistry to differentiate waters from different hydrocarbon bearing zones as one direct indicator of the zones accessed by induced fractures in horizontal wells. Additionally, using these chemical data, we can distinguish water injected during fracture stimulation (frac water) from subsurface waters in the production flow stream. Because frac water is easily distinguished from formation water, we are able to determine that water produced immediately on flowback is dominantly formation water. Frac water returns to the surface as periodic or episodic slugs of mixed formation and frac water, with the frac water contribution typically about 50% or less of the produced water load. Accordingly, the industry practice of monitoring frac water load produced at the surface is relevant only in terms of volume, not water composition, since most of the water produced initially during well flowback is formation water.

This content is only available via PDF.
You can access this article if you purchase or spend a download.