The simple development engineering project of W10-3 North (W10-3 N) oil field has its own significance in the history of the simple oil field development for China's offshore oil industry and is a crystal of research fruits on " early production system" in the offshore engineering field of China. This article introduces the development of the marginal oil fields and the conversions of the two production platforms from drilling rigs and their engineering features. It provides necessary and referable information for understanding the cases of the simple development engineering for marginal oil field in Beibu Gulf and the conversions of jack—up rigs "Nai Hia No. 1" (NH1) and "Bo Hai No. 6" (BH6) to double purpose of drilling and production rigs.
Key words: marginal oil field, simple development engineering