Oil prices are mired in their worst slump in decades, but you wouldn’t know it in West Texas, where a land grab has energized an otherwise dormant market and sent some explorers’ shares soaring. Blackstone Group BX -1.21 % LP said Thursday that it has agreed to invest $1.5 billion in a pair of drilling deals there. One came about after the New York investment firm early this year lost out to a big oil company bidding on about 12,000 acres south of New Mexico. Blackstone didn’t walk away from the auction empty-handed, though, having persuaded the sellers to join it in a new billion-dollar drilling venture in the area. The firm also committed $500 million more to another group of experienced oilmen who had purchased 16,000 acres about 100 miles to the northeast, in another section of the region’s red-hot Permian Basin. Cash for the deals came from […]