...+ U.S.-based oil and gas exploration and production (E&P) company Northern Oil and Gas Inc. has completed its exchange of its unsecured notes for second-lien secured notes and equity. + We are raising our corporate credit rating on the company to 'B-' from '##'. The outlook is negative. + We are raising the issue-level rating on the company's unsecured debt to '###+' from 'D'. The recovery rating is '5'. + The negative outlook reflects our view that the company may be challenged to refinance debt ahead of 2020 maturities. DALLAS (S&P Global Ratings) May 29, 2018--S&P Global Ratings today raised its corporate credit rating on U.S.-based oil and gas E&P company Northern Oil and Gas Inc. to 'B-' from '##'. The outlook is negative. At the same time, we raised our issue-level rating on the company's unsecured debt to '###+' from 'D'. The recovery rating is '5', indicating our expectation of modest (10%-30%; rounded estimate: 20%) recovery in the event of payment default. The upgrade follows...