HOUSTON — Royal Dutch Shell sold its oil and gas production in the Permian Basin, the biggest American oil field, to ConocoPhillips for $9.5 billion in cash on Monday.The deal marks a turning point for Shell, which had put considerable effort into developing the 225,000-acre field since buying it from Chesapeake Energy nine years ago, expanding its production to about 200,000 barrels a day.The sale is the latest sign that Shell, like other European oil companies, is under pressure to sell off oil and gas production and move toward producing cleaner energy in response to growing concerns about climate change among …
