MEXICO CITY (Standard&Poor's) May 15, 2014--Standard&Poor's Ratings Services assigned its 'B-' debt rating to Petroleos de Venezuela S.A.'s (PDVSA; B-/Negative/--) proposed $5 billion senior unsecured notes due 2024. PDVSA Petroleo S.A., PDVSA's exploration-and-production subsidiary (not rated), unconditionally and irrevocably guarantees the notes. The rating on the notes reflects the corporate credit rating on PDVSA, which is based on the company's 'b-' stand-alone credit profile (SACP) and our opinion that there is an "almost certain" likelihood of extraordinary government support to PDVSA under financial distress scenarios, and/or extraordinary financial burden under a sovereign distress scenario. Our assessment of an "almost certain" likelihood of extraordinary support is based primarily on PDVSA's: "Critical" role as it contributes about 50%