Average pressure value along the boundary of drainage area

p_e = \frac{1}{L_e} \int_0^{L_e} p(x,y,z) dl

where is the boundary of drainage area

This definition is based on the idea that there is a boundary line which restricts radial flow around a well, which is a fair assumption in most practical cases.

The advantage of this method over is that:

• it provides more accurate estimate of the pressure away from a given well
• is not dependent on convention, which may be not valid for a given well