By Elena Vasquez

Nearly two-thirds of U.S. Gulf of Mexico oil output — 1.28 million barrels per day, or 62.9% of daily production — went offline Thursday as Hurricane Isaias forced operators to evacuate platforms and secure wells across the basin. The Marine Minerals Administration (MMA) reported the shut-ins by 11 a.m. CDT, with natural gas output simultaneously cut by 57.4%, or roughly 1.13 billion cubic feet per day.

The shutdown marks a sharp acceleration from Wednesday, when only about 25% of Gulf oil production had been halted. As of Thursday morning, 121 manned platforms had been evacuated — nearly one-third of the 371 manned platforms operating in the Gulf — alongside five non-dynamically positioned drilling rigs, with four dynamically positioned rigs moved out of the storm's path.

How strong is Hurricane Isaias?

The storm intensified into a Category 3 hurricane Friday morning, with maximum sustained winds reaching 120 mph as it closed on the northern Gulf Coast. The National Hurricane Center's 10 a.m. CDT advisory Thursday placed Isaias about 380 miles south of the mouth of the Mississippi River, moving east-northeast at 10 mph, with additional strengthening expected before landfall late Friday or early Saturday.

Hurricane and storm surge warnings covered portions of the coast, with forecasters warning of damaging winds, dangerous coastal flooding, and heavy rainfall extending hundreds of miles beyond the projected track.

Which operators have been hit hardest?

Shell initiated shutdowns at its Mars, Olympus, Ursa, Vito, and Appomattox facilities. Chevron suspended operations at four offshore locations. Both moves were part of standard hurricane protocols: operators close safety valves to secure wells before pulling personnel, reducing the risk of uncontrolled oil or gas releases.

The MMA's figures drew on reports from 12 offshore operators. Once the storm passes, undamaged facilities can typically return to service quickly, while installations sustaining damage may face weeks of repair work.

What does the Coast Guard expect?

The U.S. Coast Guard said it is preparing to respond to the storm's impacts, including restoring port operations once conditions allow. The agency warned that its rescue capacity could be "significantly reduced or unavailable" during the height of the hurricane.

"As soon as it is safe to operate after a storm, the Coast Guard, along with our local first responders and federal partners, will provide the life-saving support needed in storm-stricken areas," the Coast Guard said in a statement Thursday.

The agency urged commercial mariners and recreational boaters to take precautions and said port condition changes ordered by Coast Guard Captains of the Port will be announced through official unit channels.

How does this fit into the broader supply picture?

The Gulf production loss lands on top of global oil supplies already constrained by ongoing attacks on commercial shipping in the Strait of Hormuz, which have thinned tanker traffic and tightened Middle East crude flows. The combined disruption exposes Gulf Coast refineries and downstream petrochemical plants to feedstock risk, while tanker charterers and crude traders brace for a second front of volatility in a matter of months.

For shippers, the most immediate exposure runs through Gulf export terminals: loadings from LOOP, Mobile Bay, and the lightering zone off Galveston typically pause under storm-force conditions, rerouting cargoes and tightening prompt-month crude differentials. Forwarders handling refined product exports face similar delays, with the duration tied to how quickly the Coast Guard reopens ports after damage assessments.

What comes next?

Forecasters expect Isaias to make landfall late Friday or early Saturday, with the MMA due to update production figures as the storm progresses. Refiners and traders will watch post-storm aerial inspections closely: the share of output restored within 48 hours will determine whether the 1.28 million-barrel hit remains a brief supply shock or deepens into a multi-week disruption, particularly if any of the evacuated drilling rigs sustain structural damage.

Shell's separately announced $4.2 billion deal to acquire a 30% stake in Equinor's Bay du Nord project in Canada — a C$14 billion development — points to where the industry's longer-term capital is moving: away from Gulf hurricane exposure and toward less weather-vulnerable basins.