NEW YORK (Standard&Poor's) June 19, 2006--Standard&Poor's Ratings Services said today that it lowered its corporate credit rating on oil and gas exploration and production company Hilcorp Energy I L.P. to 'B+' from 'BB-', and affirmed its 'B' senior unsecured debt rating on the company. The outlook is stable. At the same time, Standard&Poor's assigned its 'B' rating to Hilcorp's $200 million senior unsecured notes due 2018. Houston, Texas.-based Hilcorp had $373 million of balance sheet debt as of March 31, 2006. "The rating action in part reflects the financially leveraging effect of Hilcorp's recent acquisitions of oil and gas producing properties on the Texas and Louisiana Gulf Coast," said Standard&Poor's credit analyst