Any company involved in oil accords may operate shale gas exploration and exploitation works, Alexandru Patruti, head of Romania's National Agency for Mineral Resources (ANRM) said in an interview with HotNews.ro. Beside Chevron, several other oil companies have shown interest in exploring shale gas. Patruti said the main environmental effect would be a possible contamination of subterranean waters, but "this impact may be kept in check and at a minimal level by sticking to good practices". Patruti also said hydraulic fracturing was a standard method used by the oil industry in Romania for decades. The difference is that in the case of unconventional gas deposits it also involves horizontal drilling.