Soil geotechnical study is one of the most important issues in the implementation of construction projects .Determining the sequence , thickness , type and slope of geological layers should be considered in choosing the type of foundation .Geotechnical studies are considered as problems of projects due to their high cost and time consuming , so performing shallow well logging along with geotechnical studies reduces data collection time and increases the accuracy of studies. Measurement of layer density along with compression and shear wave velocity to determine the elastic properties of layers in geotechnical studies and earthquake risk in sensitive structures is inevitable. In order to measure the density of the layers it is necessary to use a gamma- gamma probe with cesium-137 radioactive. In order to protect the radioactive material against the fall of the borehole wall, it is necessary to use a PVC casing. Measuring the shear wave velocity in the layers requires the use of sand to fill the empty space between the casing and the ground layers (backfill).Installing pipe and backfill that is filled with water and sand, due to the non-uniformity of the space filled with sand, causes errors in measuring the density of layers and sometimes has to be re-drilled and costs a lot . In this study we intend to use lab data and create a correlation between lab and log data to eliminate the measurement error of casing and backfilling in an acceptable way.