Automatic Study Of Clay Compaction: The Denson Program

The location of drilling sites in increasing numbers in rapid sedimentation basins has led petroleum engineers to investigate phenomena of undercompaction of clays and the high pressures associated with them. Consequently, several investigative methods were developed, some of them based on the exploitation of well logs. Without going into theoretical details, we wish to observe that these methods involve following the depth wise changes in a logging parameter (travel time, density, resistivity) read at the clay sections. These plots are generally made manually. In order to exploit the possibilities offered by the computer, the authors, in 1969, developed a program designed for the automatic construction of a clay compaction profile from well logs which are previously digitalized or recorded on magnetic tapes. The compaction study is carried out essentially on the basis of sonic, formation density and resistivity logs. SP and natural radioactivity are employed as indicators of argillosity. The neutron log serves in the selection of the purest and most homogeneous clays. Finally, the caliper permits a critical appraisal of readings by the detection of caved zones which are liable to have an exaggerated effect on the study.