QUANTIFICATION OF A CLAY-RICH CRETACEOUS OIL RESERVOIR FOR AN EOR PILOT PROJECT

In 2013, the Enhanced Oil Recovery Institute (EORI) collaboratively worked with Osage Partners LLC and TIORCO on aiding in the design of a suitable Alkali/Surfactant/Polymer (ASP) blend for an enhanced oil recovery (EOR) pilot project at the Bradley Unit, Osage Field, Wyoming. EORI characterized 4 wells consisting of 39 core samples and quantified the clays present from Osages’ shallow unconventional Muddy/Newcastle Sandstone. The evaluation of samples collected focused on quantification of clays by X-ray diffraction (XRD), with support of petrographic thin section, field emission scanning electron microscopy (FESEM) and cation exchange capacity (CEC) analysis.

The focus of this presentation will be to describe and compare the evolution of methodologies used for this analysis. As initial results in 2013 were semi-quantitative using the mineral intensity factor (MIF) (Moore and Reynolds, 1997). Now, EORI has re-analyzed the data using Rietveld refinement, which allows for a more accurate quantification of clays present within a reservoir. Significance: Clay quantification will play an important role in all future Wyoming EOR/IOR projects.

Results of this analysis indicated an inverse relative abundance of Chlorite and Illite with depth, mixed layer Illite/Smectite abundance decreases with depth, the most abundant clay mineral is Kaolinite, and the CEC for this reservoir is high.