Extension to a Generalized Well Model

Introduction

A review of the work by Helmy et al in the Horizontal Model documentation shows that the their horizontal well is effectively a vertical well (with partial penetration) rotated 90 degrees. This implies:

• The Helmy et al model works for both vertical and horizontal wells

• Vertical wells can be fully penetrating if sp=0, or partially penetrating if sp > 0. The same applies for the horizontal configuration

• The Helmy model can be extended to include skin due to other considerations including:

• skin due formation damage (sf)

• skin due to a well being slanted (sl)

• skin due to turbulence (Dq)

• and any other skin condition such as completition skin

• Refer to the documentation on skin components for additional information.

As a result, a generic model arises for a variety of scenarios as shown below. Although a turbulence factor is shown for all three phases, skin due to generally only applies to gas wells

References:

• Michael Economides, Xiuli Wang, Advanced Natural Gas Engineering, Gulf Publishing Company, 2009

• M. Wael Helmey, & R. A. Wattenbarger, Simplified Productivity Equations for Horizontal Wells Producing at Constant Rate and Constant Pressure