Lithologic and Hydrogeologic Data Acquisition in Deep Well Drilling: Experience from the Carson Area of the Los Angeles Basin

At the request of US EPA and State agencies, four petroleum companies with collocated facilities in the Carson area of southern California are collaborating on a regional evaluation of oxygenates potentially present in deep (200-600+ foot) aquifers in the study area. Practical challenges for this project are the development of a cost effective approach for characterizing lithology and water quality, and to establish the positions of well screens in the thick sand-rich units under investigation. The drilling program includes an evaluation of several data collection techniques to determine an “optimal” approach for data collection  Approaches to characterize lithology that are under evaluation include continuous coring, geophysical logging, and formational logging based on cuttings returns. Techniques to assess water quality that are under evaluation include soil sampling in the saturated zone and in-situ groundwater sampling using a Simulprobe sampler.  Both types of chemical data are compared to groundwater samples collected from the same intervals in well screens.  This presentation will describe the results of the data comparison and the incorporation of lessons learned into forward planning in the investigation.