Tullow Oil said on Tuesday that it has had to abandon a well offshore French Guiana, the latest in a string of disappointing operational updates from the FTSE 100-listed oil explorer.The company said that the Priodontes-1 well was drilled to a total depth of 6,138m in water depths of 1,750m but failed to encounter any hydrocarbons in the main target reservoir. The well has now been plugged and abandoned, the group said.The rig that was working on the well, the Stena Ice Max, is to now move to the site of the Cebus exploration well which is due to spud within the next two weeks.Tullow holds a 27.5% interest in the Guyana Maritime licence were Priodontes is located, Royal Dutch Shell owns 45%, Total owns 25% while Northern Petroluem and Wessex Exploration jointly own 2.5%."Although this well did not encounter significant hydrocarbons, we have added substantially to our knowledge of the formations in this frontier exploration area," said Exploration Director Angus McCoss. "The campaign now moves to the Cebus prospect which is located in a separate fan to Zaedyus and Priodontes. This means that there is limited read-across for Cebus from the wells drilled thus far."Nevertheless, McCoss said that all wells have demonstrated that the Cingulata fan system has been charged with oil and Cebus is an "excellent prospect". He expects a result later this year.Tullow's share price has dropped by nearly 16% over the past month due to a declining oil price and a series of disappointing updates on two of its key exploration wells - Sabisa in Ethiopia and Priodontes in French Guinea.In an update last week, the company said that Sabisa was "technically challenging" and now requires a side-track to redrill due to "instability issues".