Shares in US oil and gas explorer Rose Petroleum dropped after it said it would take most of the first three months of 2015 to complete a well in Utah.Rose said it had perforated the first interval of a planned seven interval programme, covering a total of 19 individual potential pay zones in the State 16-42 Paradox well in the Gunnison Valley Federal Unit in Grand County, Utah.The company said it estimated the entire completion process for the well would take the majority of the first quarter of next year to finalise, although it said that was in line with its original timetable.It said the data collected from the process would help it plan and design its first horizontal Paradox well, but the permitting process for the latter would take about six months, with completion expected in the third quarter of 2016.Rose owns nearly 80,000 gross acres in the Paradox and over 245,000 acres collectively between the Paradox and the adjacent Uinta Basin Mancos play.It also said it had started drilling the State 1-34 Mancos well in the Cisco state unit in Grand County.To cut costs, Rose has used a smaller rig to spud the well and will bring in a larger rig in early January to drill the balance of the well to total depth. Once a surface casing is cemented in-place, drilling operations will re-start in early January to a projected total depth of about 3,200 feet.Rose's John Blair said: "The completion of the 16-42 vertical well will also help Rose achieve its goal of increasing production and reserves in 2015."Shares in the group fell 0.18p or 7.45% to 2.17p at 09:33 in London.