InterOil Corporation announced Monday that it has suspended the Wahoo-1 well in PPL474 in Papua New Guinea (PNG) after intersecting gas and higher-than-expected pressures that could compromise rig safety. Significant concentrations of methane, ethane, propane and butane have been recorded and are believed to be entering the well bore from permeable zones above the predicted reservoir zone, which is yet to be penetrated.
The gas is characteristic of thermogenic hydrocarbons, which are indicative of an active hydrocarbon-generating source rock. The Wahoo-1 well was designed for high pressures based on data from other wells in the region but the pressures have exceeded by nearly 50 percent even those of InterOil’s Antelope discovery, 105.6 miles (170 kilometers) to the north-west. After a review by drilling and engineering teams and expert advisers, InterOil has concluded that drilling ahead would pose an unacceptable safety risk to people and the rig. The company has received approval from the PNG Department of Petroleum and Energy to suspend the well.
OPERATIONS TO RESUME AS SOON AS PRACTICABLE
InterOil intends to resume operations as soon as practicable following a detailed review of well engineering, equipment and options, when the company is satisfied it is safe to proceed, and after the regulator has approved the company’s plans. An option includes testing of the gas-bearing permeable zones encountered in the Orubadi mudstone. Progress on Wahoo-1 has confirmed an effective seal in the Orubadi mudstone, as well as the presence of thermogenic hydrocarbons, both of which are key components to a working petroleum system.
Further drilling is required to confirm the presence of a reservoir below the current total depth of the well before Wahoo can be considered a discovery.