DFIT interpretation has been a theme of the work that we’ve done within ResFrac. Our collaborative 2018 Industry Study, which culminated in one of the ‘Best of URTeC’ papers in 2019, developed significant new advances in interpretation. I’ve recorded a roughly two-hour talk summarizing the findings from that study, along with related work done at UT Austin on this topic from 2013-2015.
The talk covers: (1) what is a DFIT and why they are performed, (2) problems with the often-used ‘tangent’ method of interpreting DFITs, (3) discussion of some of the new methods developed in the 2018 Industry Study, (4) a worked example using a Utica/Point Pleasant example, and (5) miscellaneous examples of practical ‘curve balls’ found in real data.
From our 2018 Industry Study, my favorite new contributions to highlight are: (1) extending the Valko/Economides preclosure method to include wellbore storage and the effect of leakoff during injection, (2) using a method inspired by the Mayerhofer method to extend the preclosure technique to include the effect of changing fluid pressure after shut-in, (3) the discovery that viscosity contrast in a gas shale DFIT causes false radial that can lead to overestimation of the permeability, and (4) integration of these and a variety of other insights into a transparent, validated, theoretically based, practical, and easy-to-use interpretation procedure.