Shares in Providence Resources closed 9.5% lower in Dublin after it said its Spanish Point appraisal well will not be drilled this year as planned.
The oil exploration firm said that "extensive delays" in the refurbishment of the Blackford Dolphin drilling rig, which had been due to be used for the project, means that drilling operations would not be able to start until at least October.
This would have pushed the project, located in the North Porcupine Basin off the coast of Ireland, into the winter months.
The operator of the well, Cairn Energy, said the deal for the drilling rig has therefore been cancelled and a tender to find another rig to carry out planned well operations in 2015 has started.
Providence holds a 32% share in the well, along with other consortium members including Cairn Energy (38%) and Chrysaor E&P Ireland (26%).
However, Providence said that a large 3D seismic programme planned for an area designated Spanish Point South will start later this summer - as originally planned.
"The postponement of appraisal drilling at Spanish Point is regrettable and beyond the control of the partnership," commented Providence's chief executive Tony O'Reilly.
He said that as the rig refurbishment delays became apparent, the operator evaluated various options to re-schedule the Blackford Dolphin rig and/or to secure another drilling unit for 2014, but this proved unsuccessful.
"Our ability to commence drilling in the autumn was further constrained by the rig's operational capabilities at the Spanish Point location during winter and thus the decision was taken to terminate the contract and seek a new drilling unit for 2015," he added.