The Eagle Ford Shale is a hydrocarbon producing formation of significant importance due to its large potential oil and gas reserves. Several challenges are faced by an operator when developing a shale play: first where to drill for highly productive wells; second how to find out the best zone to land the lateral. This paper states that these two major challenges can be addressed through lithofacies analysis.
The integrated study presented in this paper is based on production data from 173 wells, core data from 36 wells and Multi-mineral processed logs from 74 wells. These data points cover a large part of the Eagle Ford shale formation from LaSalle to Dewitt counties of South Texas. Lithofacies were identified on core data, then calibrated to Multi- mineral processed logs using the Facies analysis tool from the PETRA software.
The Eagle Ford formation is classified into different lithofacies based on three parameters: mineralogy, TOC and hydrocarbon filled porosity. Mineralogy is the prime indicator of brittleness; TOC indicates the hydrocarbon potential, whereas HC filled porosity has a strong relationship with the deliverability of the formation. Eight lithofacies (e.g. HC rich siliceous shale, HC rich mixed shale and HC poor Mudstone etc.) are identified, out of which three are considered as the most productive. The study shows a good correlation between the sum thicknesses of these three productive facies and well productivity.
We have applied the above analysis to identify of the sweet spots within the Eagle Ford formation where there will be a greater chance of getting high productive wells. Additionally the analysis has helped to identify the best landing point, one of the most important elements of an effective completion technique.