A 1% drop in crude oil prices last year didn’t stop Texas from adding nearly 100 million barrels to its crude output in 2012. The state produced at least 604 million barrels last year, compared with 509 million in 2011, even as prices slid from $91.49 to $90.58, according to Karr Ingham, the economist who tracks the Texas Petro Index (TPI), a composite index that keeps tabs on production volume, rig count, and employment numbers, among other factors.

“The tables have turned, and Texas is back to its crude oil ...