The emergence of shale natural gas in European and U.S. markets could leave Russian energy giant Gazprom on the sidelines, an executive said. The United States in 2009 passed Russia as the top natural gas producer because of the shale boom and the United States is set to become a net gas exporter by 2015. Andy Flower, a former BP executive, told Bloomberg News that while energy markets were reacting to the shale boom, \"Gazprom is taking what seems to be a head in the sands position on shale gas.\" European consumers rely on Russian for about 25 percent of its natural gas. A lingering economic crisis, however, is suppressing demand. Meanwhile, countries dependent on Russia natural gas like Poland and Ukraine appear on the cusp of their own shale revolution. Gazprom shipments are down 14 percent compared with 2011 levels and its stock price has given up nearly 9 percent this year. Bloomberg reported that Gazprom officials have said European demand should at least stay level and global markets won\'t be as influenced by shale as some believe. Flower said the Russian company could be right but it appears unlikely. \"There is always the possibility that the shale gas revolution may, in the long run, produce less gas than some are now forecasting, but I think the probability is very low,\" he said.