Australia-based Otto Energy has announced a significant hydrocarbon discovery in the D5, I2 and I3 sand intervals of the F5-ST well in the Gulf of Mexico.

The well, operated by Byron Energy within the South Marsh Island 71 lease, reached a measured depth (MD) of 7,297ft and a true vertical depth of 6,561ft.

Preliminary analysis of logging while drilling data suggests the presence of hydrocarbons in the D5, I2 and I3 sand intervals.

The I2 sand interval, spanning from 6,248ft to 6,290ft MD, shows 13ft of net hydrocarbon pay.

The I3 sand extends from 6,290ft to 6,360ft MD with 22ft of net pay, while the D5 sand has a substantial net pay of 133ft between 7,075ft and 7,204ft MD.

Unexpectedly, the well encountered a high-pressure water sand 60ft below the base of the D5 sand, leading to a delay. Subsequently, the drill string and bottom hole assembly became stuck above the D5 sand.

After unsuccessful attempts to free the pipe, it was cut and the well was cemented off below 3,673ft MD.

The financial impact of this event, including the loss of drilling equipment, is estimated at $2m (A$2.99m) net to Otto.

A bypass of the well has been proposed to redrill the D5, I2 and I3 sands, which is expected to cost $3.4m or $1.7m net to Otto.

Otto Energy has committed to participating in this bypass, which should take four days to reach the total depth of approximately 7,220ft MD.

Following the drilling and evaluation of the bypass well, if Otto chooses to participate in its completion, the process will take an additional 14 days to complete the well, with an estimated seven more days to bring it into production.