Theoritical underpinning for horizontal drillling, and multistage fracking: Horizontal drilling and fracking increase effective area to flow (represented in the Darcy flow equation as rw), to counteract decreasing reservoir quality (represented by kg).
Where: qg=gas production
kg=gas relative permeability
h=height of productive interval
pw=pressure at the wellbore/wellhea
zavg=gas compressibility facto
rw=effective wellbore radius
S=formation damage factors