US supermajors Chevron and ExxonMobil have published the ingredients used in hydraulic fracturing operations in Poland as part of a new online initiative.

The explorers have disclosed the makeup of water, sand and chemicals used in six fractured wells in Poland for a new website by the Association of Oil & Gas Producers.

OGP executive director Michael Engell Jensen said the website marked a “first step, taken voluntarily by the industry” to respond to public concerns over hydraulic fracturing by releasing the data on the substances used in the drilling technique.

The site, NGS, aims to publish details on every well fractured in the European Economic Area by participating explorers dating back to 1 January 2011.

Last month, about 30% of shareholders in both companies voted in favour of calls for more details to be released on the explorers’ use of hydraulic fracturing.

The new site is similar to that of the FracFocus industry initiative in the US, where 18 US states already require oil and gas companies to disclose fracturing chemicals.