Postclosure DFIT interpretation: Demystifying the Linear Flow Time Function
![the pressure perturbation during shut-in from a ResFrac DFIT simulation](https://www.resfrac.com/wp-content/uploads/2019/07/da1386_d5aa62ff424d48d4bd8e1a9a4749a323mv2-1024x460.png)
“Postclosure” interpretation is used to infer formation permeability from DFIT pressure measurements. As reviewed in previous posts, the goal of a DFIT is to infer formation properties, of which permeability […]
Curving G-function plots and picking closure
![G-function plot of a typical DFIT.](https://www.resfrac.com/wp-content/uploads/2019/07/da1386_57969f364a7c41c28d79ee4b1315dce8mv2.png)
G-function plots are routinely used to interpret diagnostic fracture injection test (DFIT) transients. Ideally, a plot of pressure versus G and G*dP/dG versus G should form a straight line. However, the G*dP/dG curve is very often curving. A typical DFIT transient is shown below.
Demystifying the G-function
![Derivative of pressure with respect to the G-function](https://www.resfrac.com/wp-content/uploads/2019/07/da1386_24bf0179d2f147f0856aac8ee54b9c9cmv2.png)
Diagnostic fracture injection tests (DFITs) are commonly interpreted by plotting pressure versus a function of time called the G-function. The G-function seems rather arcane and is often misunderstood. However, it has […]
How to plot a DFIT
![Diagnostic fracture injection test in a Cartesian plot.](https://www.resfrac.com/wp-content/uploads/2019/07/da1386_4ae1aa516de34858b52e96ecf9d1462fmv2.png)
Aside from the diversity of terminology, the diversity of plotting techniques is the aspect of DFIT analysis that most often causes confusion. Why don’t we just make a Cartesian plot of pressure […]
DFIT, LOT, XLOT, Minifrac, Microfrac, Fracture Calibration Test: Navigating the Terminology
![DFIT, LOT, XLOT, Minifrac, Microfrac, Fracture Calibration Test: Navigating the Terminology](https://www.resfrac.com/wp-content/uploads/2019/07/da1386_4c092358b9ce4e899216c633a4ee31cfmv2.png)
A bewildering variety of terms are used to describe tests in which a small volume of fluid is injected to create a hydraulic fracture: DFIT, leakoff test (LOT), extended leakoff […]
Diagnostic Fracture Injection Tests: The Basics
![A typical pressure response during injection in a DFIT.](https://www.resfrac.com/wp-content/uploads/2019/07/da1386_170d655ae1d84d2c98e82c1a8bf3316fmv2.png)
In a diagnostic fracture injection test (DFIT), a relatively small volume of fluid is injected into the subsurface, creating a hydraulic fracture. After the end of injection, the pressure in […]