Summary

A geologically engineered shale completion optimization program was implemented for a liquid rich area of the Eagle Ford play. This approach included detailed geological characterization, state-of-the-art unconventional 3D hydraulic fracture and reservoir flow modeling, as well as the latest available surveillance technology for model verification. This paper focuses on the fracturing and reservoir flow modeling part of this effort.

Published industry field data -mostly from PLTs- suggest that typical shale completions performance is far from ideal, with between 40 and 60% of the clusters contributing little or no production (Miller et al., 2011). Furthermore, our own PLT data from several plays and fiber optics data in the area has shown that in typical completions, the fracture propagation profile is not uniform, with the presence of both large –dominant- and small – hindered- fractures associated to different clusters within each stage. However, the ever-increasing completion complexity in shale wells has not been matched by a corresponding capability to model and predict the nature and production performance of hydraulic fractures generated from such completions. In this paper, we show the application of a new toolkit, which includes both a 3D non-planar hydraulic fracturing simulator (capable of handling stress shadow, fracture rotation, interaction with natural fractures, and actual shale completions) and a 3D unconventional reservoir simulator (capable of importing and modeling complex fracture geometry). Our results showed that, in typical multi-cluster completion designs, there is high potential for fracture competition/interaction between hydraulic fractures (mainly due to stress shadowing). We have found that, for the same fluid and proppant design, completion efficiency can be noticeably affected by completion variables such as the number of clusters per stage, the distance between such clusters, the pumping rate during the frac job, and the volume being injected.

This workflow is presented via a case study in the Eagle Ford, where an enhanced completion design was measured against the standard completion design in the area. Predictions on both cluster efficiency and well performance were successfully validated in two wells against fiber optics, and actual well production. The enhanced design represented a production uplift of about 30% (as predicted by our workflow) when compared to the standard design.

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