Tullow Oil reported a $415 million pretax write-off in net exploration in the first half of 2014.
The write-off comes after disappointing drilling results in Mauritania, Ethiopia, and Norway.
The company also faced various license cancellations.
Total write-offs after tax amounted to $305 million, according to the company.
Tullow also expects a loss on disposals of $115 million over the same period.
CEO Aidan Heavey said, “With potential basin-opening wells across the portfolio coming up in the second half of the year and strong revenue and cash flow, Tullow is in a strong position for the remainder of this year and into 2015.”
Tullow said gross first-half profit came to $650 million and revenue reached $1.3 billion, in line with the firm’s expectations for the year.