Chevron Corp. agreed to purchase 228,000 acres in the Marcellus Shale from Chief Oil & Gas LLC and Tug Hill, Inc., according to the Associated Press. Terms of the deal were not disclosed. The acreage is primarily located in southwestern Pennsylvania. The transaction will give San Ramon, Calif.-based Chevron an additional 5 trillion cubic feet of natural gas reserves in its Marcellus leasehold. Chevron bought natural gas producer Atlas Energy Inc., which marked the company''s first foray into the rich gas fields in parts of the eastern U.S. Atlas is a big player in the Marcellus Shale in western Pennsylvania and elsewhere. Dallas-based Chief and Tug Hill, a Dallas-based investment firm, will be left with about 125,000 acres in the Marcellus, primarily in Bradford, Susquehanna, Tioga, Sullivan and Wyoming counties in northern Pennsylvania.