Revisiting fracture gradient: Comments on “A new approaching method to estimate fracture gradient by correcting Matthew–Kelly and Eaton's stress ratio”

Abstract

A study performed by Marbun et al. [1] claimed that “A new methodology to predict fracture pressure from former calculations, Matthew–Kelly and Eaton are proposed.” Also, Marbun et al.'s paper stated that “A new value of Poisson's and a stress ratio of the formation were generated and the accuracy of fracture gradient was improved.” We found those all statements are incorrect and some misleading concepts are revealed. An attempt to expose the method of fracture gradient determination from industry practice also appears to solidify that our arguments are acceptable to against improper Marbun et al.'s claims.

Keywords

• Fracture gradient
• Overburden pressure
• Pore pressure
• Matthew–Kelly's stress ratio
• Eaton's stress ratio
• Poisson's ratio
• Pressure safety drilling window
• Geomechanics