Pipeline Engineering

HDD Inadvertent Return (Frac-out) Analysis

This tool can evaluate the risk of hydrofracture on HDD projects. It is based on the Cavity Expansion Theory, first published by Luger and Hergarden in 1988 to determine the maximum allowable pressure that can be applied to a specific soil without causing hydrofracture. To improve correlation with actual as-built data, recent publications were also taken into consideration

Estimated Maximum Allowable Drilling Fluid Pressures and Annular Fluid Pressures

Estimated Factor of Safety Against Inadvertent Return

HDD Path Geometry

Section Length (ft)
Entry point to PC1
PC1 to PT1
Horizontal section
PC2 to PT2
PT2 to Exit Point
Total Drill Length, ft

Pilot Hole/ Mud Assumed Properties

Drill Path Information