e-journal of petrophysics is a peer-reviewed, open access journal published by Petroleum Journals Online covering original research, studies and reviews in formation evaluation. We do not charge readers any access fees. Papers are published within 2 to 3 months of initial submission. This journal participates in LOCKSS and CLOCKSS archival systems. Authors retain their copyright. Articles are covered by Creative Commons CC BY-NC-ND 4.0 license terms.