Oil and gas explorer Sound Oil said a reservoir engineering report showed that the initial gas in place in its fully-owned Marciano-1 St well in Italy is insufficient for commercial production, wiping off more than a quarter of its market value.The Italy- and Indonesia-focused company said the present operations at the site will cease pending a future review of the permit. "The news from Marciano is clearly disappointing, especially after such an encouraging initial flow rate. The Marciano project was, however, a small part of the value of our portfolio," chief executive officer Gerry Orbell said.Shares of the AIM-listed company slumped 28% to 2.30p in London.AR