This is achieved using one specific measuring tool, lowered inside one water well and pulled upwards with constant speed. The tool measures many physical parameters of the geological layers and transmits them to the surface through one cable.

One computer in the surface collects the signals together with the exact depth information and this record is described as one geophysical log.

The most common geophysical well logs include the measurement of the resistivity of the geological layers, the temperature of the water, the natural gamma ray radiation, the vertical water flow, the conductivity of the water and other. Using one combined interpretation, many useful information can be extracted about the subsurface layers.

DATA ACQUISITION SYSTEM

The following parameters are measured, using specific tools:

Electric resistivity, temperature, conductivity of the water, flow, spontaneous potential, natural gamma ray radiation and well inclination. In addition, one chemical analysis lab is available in the field.

DATA STRUCTURE

Each geophysical log is one continuous measurement of one physical parameter of the geological layers vs depth. In this way, the electrical resistivity variation with depth, helps to locate with accuracy the aquifers in the drilled column and to estimate their productivity in water, the natural gamma ray radiation helps to locate the shale layers in order to exclude them from the well screening procedure.

The conductivity helps to measure the Total Dissolved Solids (TDS) of the water in the well and extract information about his quality. The flowmeter helps to locate water bearing zones. In general the geophysical well logging method is the ultimate tool for the optimal well design.

ADVANTAGES OF THE WELL LOGGING

The wells must be constructed in one way, to "fit" in the layers drilled in the column. The "well logging" method is the only way to achieve this task. It helps to create wells with higher water quality and with a long production life.