﻿ Hydrogeologist workbench (ANSQUICK) > Lugeon tests

# Lugeon (packer) tests

ANSDIMAT offers interpretation of packer tests by the Lugeon method, where hydraulic conductivity is calculated from pressure and injection rate measurements.

The dialog window "Lugeon tests" is opened by selecting menu "File > Hydrogeologist workbench > Lugeon test".

Example of dialog window "Lacker test" - data analysis for test stages

Example of dialog window "Lugeon test" - data analysis for inection rate vs pressure plots

Before the start of a test, the maximum testing pressure Pmax is determined based on the depth of the borehole screen.

The testing process aims at sustaining a constant pressure by injecting water volumes and measuring both, pressure and water flow. The standard procedure for packer testing is explained below:

1.Pressure is changed by steps from the lowest to highest pressure as: 0.5Pmax, 0.75Pmax, Pmax, 0.75Pmax, 0.5Pmax.

2.Constant pressure P is maintained for 10 minutes at each step.

3.The water injection rate Q, required to sustain pressure, is measured every minute.

4.The Lugeon value (Lu) is calculated for each step by the formula:

where Q – average injection rate for sustaining constant pressure, l/min, lw –  length of testing interval, m; P – constant pressure at each step, Pa. P0 = 1 MPа – scaling pressure coefficient.

5.Lugeon values are plotted as a bar diagram for each pressure step. Depending on the shape of the plot, hydrodynamic conditions during the test fall into one of the five categories: 1) laminar flow; 2) turbulent flow; 3) opening of fractures; 4) washing out fine material; and 5) filling in voids/fractures.

6.Water injection rates are plotted against pressure values. Depending on the shape of the plot, hydrodynamic conditions during the test fall into one of the five categories: 1) laminar flow; 2) turbulent flow; 3) opening of fractures; 4) washing out fine material; and 5) filling in voids/fractures.

Arrows show the directions of pressure changes from step to step.

7.For each step, the hydraulic conductivity is calculated using one of the three methods below:

– Moye formula:

– Thiem formula:

where ΔP – borehole pressure change , Pa; g – gravity acceleration value, m/s2; ρ – density of injected water, kg/m3.

– Lugeon formula:

1 Lu 1.3∙10-7 m/s 0.011 m/d.

Fracturing can be qualitatively described based on mean lugeon and hydraulic conductivity values.

Explanatory table