Introduction

Well deliverability analysis predicts the wellbore flowing pressure for a given surface flowrate. Deal with well inflow performance and describe the reservoir variables that control well productivity under different conditions. Wells drilled in oil reservoirs drain a porous medium of porosity ϕ, net thickness h, and permeability k. To understand the process of flow from the reservoir and into the well sandface, a simple expression of Darcy’s (1856) law in radial coordinates can be used first:

where A is radial flow area at a distance r given by A = 2πrh.

Equation (2-1) is general and suggests a number of interesting observations. The flow rate is large if the pressure gradient dp/dr, the permeability k, and the reservoir height h are large or if the viscosity of the flowing fluid, μ, is small. Also, this expression assumes a single-phase fluid flowing and saturating the reservoir.