GRAHAM-MCCORMICK <GOP> SELLS OIL AND GAS STAKE Graham-McCormick Oil and Gas Partnership said it completed the sale of interests in two major oil and gas fields to <Energy Assets International Corp> for 21 mln dlrs. The company said it sold about one-half of its 50 pct interest in the Oak Hill and North Rucias fields, its two largest producing properties. It said it used about 20 mln dlrs of the proceeds to prepay principal on its senior secured notes. Semi-annual principal payments on the remaining 40 mln dlrs of notes have been satisfied until December 1988 as a result, it said. The company said the note agreements were amended to reflect an easing of some financial covenants, and an increase of interest to 13.5 pct from 13.0 pct until December 1990. It said the noteholders exercise price for 1,125,000 warrants was also reduced to 50 cts from 1.50 dlrs. The company said Energy Assets agreed to share the costs of increasing production at the Oak Hill field.