In the third quarter of 2019, total oil, natural gas and NGL revenues were approximately $51 million. Of that, approximately 65% of the revenue was from natural gas sales, 21% was from oil sales, and the remaining 14% was from the sales of NGLs.
With respect to costs, operating expenses for the third quarter were approximately $39 million, which wasin-line with guidance. General and administrative costs, excluding share based compensation and severance costs, were approximately $12 million in the third quarter. Of that, approximately $9 million was incurred by the Upstream business, and the remaining $3 million was attributable to Blue Mountain. Upstream G&A, excluding share based compensation and severance costs, was at the low end of the third quarter guidance.
In the third quarter, Riviera invested approximately $42 million of capital. Riviera Upstream capital was approximately $6 million while Blue Mountain invested approximately $36 million. Riviera’s oil and natural gas capital investment during the third quarter was 33% below guidance.
Balance Sheet and Liquidity
With respect to the balance sheet and liquidity, Riviera and Blue Mountain have established separate credit facilities. As of September 30, 2019, there were no borrowings outstanding on Riviera’s revolving credit facility, and approximately $57 million of available borrowing capacity inclusive of outstanding letters of credit. In September 2019, Riviera’s borrowing base was reduced from $230 million to $90 million in connection with pending asset sales, including the expected sale of remaining Hugoton Basin properties. Additionally, the credit facility was extended for an additional year utilizing a pricing grid 50 basis points better than our previous RBL.
Blue Mountain has established a separate credit facility with total borrowing commitments of up to $200 million. As of September 30, 2019, Blue Mountain had approximately $61 million drawn on its credit facility, and approximately $126 million of available borrowing capacity, inclusive of outstanding letters of credit, subject to covenant restrictions in the Blue Mountain Credit Facility. Blue Mountain’s liquidity was positively impacted by a $17 million capital reimbursement and success fee received in the third quarter.
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