Hong Kong-listed CNOOC Limited said that its offshore Huizhou 19-3/2/1 fields have started producing crude oil. The Huizhou 19-3-1 well recently began yielding 6,500 barrels of oil per day.   More wells will be brought on stream gradually, the company said.   The Huizhou 19-3/2/1 fields are located in block 16/08 and 16/19 about 120…