Wintershall Holding GmbH is Germanys largest crude oil and natural gas producer. The company is based in Kassel, Germany. Wintershall is a wholly owned subsidiary of BASF, based in Ludwigshafen. The name Wintershall is derived from the surname of the enterprise co-founder Carl Julius Winter and the Old High German word for salt (hall) together. The company made a profit of 2.4 billion euros in 2011. In 2012, the company had 2164 employees worldwide. The Chairman of the board of Executive Directors is Mario Mehren. In September 2015, Wintershalls parent group BASF traded 100% of the companys gas distribution and storage business and 50% of its gas exploration arm, Wintershall Noordzee, for 25%-plus-one-share of Gazproms Achimov deposits in Western Siberias Urengoy oil, gas and condensate field in . BASF had in 2013 signed a memorandum of understanding on the assets swap but the deal ran into trouble because of US and EU sanctions against Russia and the state-controlled Russian gas producer and exporter over the government in Moscows 2014 annexation of Crimea and policy on separatist violence in eastern Ukraine. Under a binding contract signed on September 4 2015 by Gazprom chair Alexey Miller and his opposite number at BASF, Kurt Bock at the Russian governments Eastern Economic Forum in Vladivostok, the German group would invest in and develop Blocks 4A and 5A of the Achimov gas and gas condensate deposits in the Urengoy gas field with Gazprom. Blocks 4A and 5A of the Achimov deposits held estimated reserves of about 274 billion cu m of gas and 74 million t of condensate, Gazprom said.