(ShareCast News) - Independent Oil and Gas first operated appraisal well on its Skipper discovery failed to encounter hydrocarbons but confirmed the commerciality of the field, according to the company's directors.Skipper lay in Block 9/21a in license P1609 in the Norther Sea.The well was drilled to a total depth of 5,578ft and achieved its primary objective of retrieving good quality reservoir condition oil samples with which to progress with the field development plan.Viscosity of the samples appeared to be within the range expected by management, between 50cP - 150cP - better than estimated in the Competent Persons Report.Should the tests being carried out at the time of the announcement provide confirmation of that assessment then fewer developments would be needed, thus enhancing the economics of the development.Initial test results were expected in September 2016, the company said in a statement.Using the same well IOG also completely mapped two reservoir structures lying below the Skipper oil field in the Lower Dornoch and Maureen formations, its secondary objective.However, no hydrocarbons were encountered in those horizons and it would now be plugged and abandoned.The initial licence commitment of drilling a well into the Maureen formation to a minimum depth of 5,578ft had therefore also now been met, the company said.Commenting on the developments, OIG boss Mark Routh said: "[...] Whilst the exploration prospects did not encounter hydrocarbons, I am increasingly confident that the commerciality of the Skipper field has been confirmed now that we have the data we need to progress to the field development planning."As of 09:05 BST shares in the oil explorer were falling 12.45% to 25.50p.