Crude oil extracted from shale formations across the United States may be more challenging to transport and process than previously considered, due to the presence of highly volatile gases, the Wall Street Journal reported.

Industry representatives and regulators already knew that crude oil extracted in North Dakota's Bakken Shale was more likely to cause problems than oil extracted elsewhere. Following several railway incidents, which have led to explosions and fires, investigators concluded that Bakken crude oil was very volatile due to its high concentration of gases and should be transported with extra care.

But apparently, oil from other shale plays has the same properties, making it highly combustible. This includes crude from the Eagle Ford Shale and the Permian Basin in Texas, as well as the Niobrara Shale in Colorado, energy experts claim.

The bulk of crude oil extracted in the United States through the method of fracking is ultralight and refiners have already started to complain that facilities are not fitted with equipment to process such crude. In 2011, light and ultralight crude accounted for 96 percent of the entire production and its proportion is believed to have increased since then. Because of the glut of ultralight crude, many refiners are investing billions to upgrade and modify their processing units, so that they are capable of dealing with it, according to the Wall Street Journal.