For years, an unresolved question for those drilling horizontal wells has been: Does it matter if it is toe-up or toe-down? Horizontal wells generally follow an up or down slope following the most productive rock with some large changes in elevation from the heel--the curve from vertical to horizontal--to the toe. Results from modeling did not settle the matter. Recently, Devon Energy offered its response based on the performance of more than 300 similar wells drilled in the Cana-Woodford Shale in Oklahoma. The comparison was possible because the company had mass-produced similar wells, giving it a large sample of wells to study with 4,800-ft laterals where it fractured 10 stages with 40 perforation clusters using 3.5 million lb of proppant located in a compact area with similar geology in the three depths studied.