UK-based oil explorer Tullow Oil says its well offshore Ghana had hit a significant column of light oil, indicating that its Jubilee field in the area is larger than earlier thought."The confirmation that Mahogany-2 is in communication with both Mahogany-1 and Hyedua-1, reinforces our interpretation that Jubilee is a major discovery and is likely to lead to a material upgrade of current resource estimates," Aidan Heavey, Chief Executive of Tullow said.U.S. explorer Anadarko Petroleum is a shareholder in the Jubilee field.Shares in Tullow Oil added more than 16 percent to top the FTSE 100.Source: GHP