AIM-listed independent oil land gas exploration and production company Gulf Keystone has commenced a drilling campaign to explore deeper and as yet untested horizons of the Shaikan field which the company operates.Shaikan-7 is the first deep exploration well in the Shaikan block, targeting the mid-to-lower Triassic and, potentially, Permian horizons, spudded late on June 16th.The well is being drilled with the Weatherford Rig 319 close to the crest of the Shaikan structure, approximately 1.0km east of the Shaikan-1 discovery well. The company said that Shaikan-7 is being drilled to the lower Triassic to evaluate the potential for significant quantities of light oil and to identify commerciality of the deeper Triassic reservoir. The well is then expected to penetrate the Permian, the deepest undrilled horizon to date on the Shaikan structure.The vertical well is planned to reach a total depth below 4,500m in the Permian and the drilling is expected to take about nine months, the company said. John Gerstenlauer, Chief Operating Officer of Gulf Keystone Petroleum, said: "As we are about to commence implementation of our Field Development Plan for the Shaikan discovery and start Jurassic production from the newly constructed Shaikan production facility, the spudding of our first deep exploration well adds a new and exciting dimension to Gulf Keystone's work programme in 2013." "With Shaikan-7, we hope to confirm our expectations of major reservoirs beneath the deepest horizon drilled to date and add to what is already recognised as one of the world's largest onshore conventional oil and gas developments."Gulf Keystone Petroleum's share price was down 1.64% to 149.50p at 10:33 on Wednesday. MF