A new presentation from the Dallas Fed has a chart that caught my eye. It shows how employment in one key part of the industry — extraction and supporting activities — has not bounced back alongside U.S. production, which fell sharply in 2015 after prices collapsed but has been moving up again for a year and heading for record levels.

Between the lines: Kunal Patel, a senior research analyst with the Dallas Fed, offered some insight in an email exchange:

"There are likely a variety of factors causing employment to not keep up with rising production. Primarily, efficiency gains (faster drill times and more production output per well) are allowing operators to produce more with less people," Patel said.

• Some evidence: He notes that the oil rig count as November 10 was 738, which is slightly under half of the 2014 average, yet production has risen by by about a million barrels per day over the last year to the current level of roughly 9.6 million barrels per day.

"Additionally, greater use of technology is likely leading to automation of some tasks and allowing operators to be streamlined and more efficient. Big data has also allowed the industry to be more efficient," Patel said.

Go deeper: He highlighted this Bloomberg piece on industry adoption of advanced tech and data analysis, and this Dallas Morning News story on industry employment trends and technology.