The Permian Basin’s deepest pocketed explorer ExxonMobil Corp. has added about 22,000 acres to its resource base since May through a series of acquisitions and trades, it disclosed Wednesday.

The new additions are in the prolific twin sub-basins, the Delaware and Midland, which add to an estimable 6 billion boe Permian resource base.

“We continue to build on our strong position in the Permian,” said Senior Vice President Jack Williams. “Our leading presence in the Permian, from equity production through to Gulf Coast refining capacity, positions us well for the future.”

ExxonMobil provided no details about where the new acreage is located, the sellers, nor how much it paid. The Permian, like many U.S. operators, is the supermajor’s No. 1 U.S. onshore target.

Earlier this year ExxonMobilstruck a deal valued at close to $6.6 billionthat more than doubled its Permian resource, adding 275,000 acres total, mostly in New Mexico’s Delaware sub-basin. The transaction with the legendary Bass family of Fort Worth, TX, increased ExxonMobil’s estimated resource by around 3.4 billion boe.

In the Midland sub-basin, the company also has doubled its core operated acreage to more than 130,000 acres through multiple transactions over the last few years.

ExxonMobil said it currently is running 19 drilling rigs in the Permian, more than it was running during the second quarter.

Fourteen of ExxonMobil’s rigs are drilling horizontal wells in the Midland, where it has added 200 wells since mid-2014. Four rigs are drilling horizontal wells in the Delaware, where ExxonMobil recently drilled its first 12,500-foot horizontal lateral length well.