DIAMOND SHAMROCK OFFSHORE <DSP> IN FIND Diamond Shamrock Offshore Partners said it has started development drilling on West Cameron 178 block off Louisiana in the Gulf of Mexico after a significant natural gas find on the block. It said the discovery well there encountered 46 feet of net natural gas pay. No flow tests have been conducted, it said. Diamond Shamrock Offshore said it has a 46.15 pct interest in the block, Phillips Petroleum Co 28.85 pct and Santa Fe Energy Partners LP <SFP> 25.00 pct. Diamond Shamrock Corp <DIA> owns 80.3 pct of Diamond Shamrock Offshore.