Another thing on investors’ minds: Any additional cost blowouts could hit Inpex’s credit rating. Moody’s wrote in a May 29 report, “Given the large size of the project, a significant further delay or cost overrun would pressure Inpex’s credit rating in the next 12 months.”

As rumors of a major crack began to brew, a team of investors and an analyst tried to carry out on-site reconnaissance themselves, according to multiple sources.

The team climbed to the top of tall buildings near the site in an attempt to get a better view, one member of the group told CNBC, because they couldn’t access the construction yard — let alone get more information on the crack from Inpex. But the unit was blocked from view, the team member said.

Although doubts about the unit are now creeping through the investment community, the project still holds much promise. Energy consultancy Wood Mackenzie called the project a “game changer” for Inpex, writing in a recent note that “once up and running, it will bring Inpex into the elite LNG club of global LNG operators, dominated by the major international oil companies”

To be a member of that club, however, Inpex may have to race to the field and start drilling quickly.

Another large-scale LNG project is coming right next door to the Ichthys field. Royal Dutch Shell’s Prelude floating LNG production facility was towed from South Korea to waters near Australia late last month. Analyst Saul Kavonic from Wood Mackenzie added in his note that, “whichever project starts up first will end up taking some of the neighboring gas and producing more gas overall. So it’s a case of ‘whoever sucks first will suck most.'”

Inpex says it currently has more than 70 projects in more than 20 countries. That makes it Japan’s largest oil and gas exploration and production company.