AOGCC approves Unocal storage injection at Swanson River

Petroleum News Alaska Staff

The Alaska Oil and Gas Conservation Commission has approved an application from Unocal Alaska for underground gas storage by injection into the Tyonek formation of the Swanson River unit well 43-28. The commission said Unocal proposes to inject gas for storage during the summer months and produce the gas for sale during winter months.

The commission said Unocal was proposing to store the dry gas between measured depths of 6,375 feet and 6,443 feet, separated by 107 feet of impermeable siltstone, claystone and coal from adjacent Tyonek sands on the topside and by more than 290 feet of impermeable siltstone, claystone and coal on the bottom. The commission said that offset well control indicates that the 64-5 sand proposed for storage is of limited lateral extent, so injected gas will be confined to the pool into which it is injected.

Injection will be predominantly methane produced from a liquid extraction plant from produced gas from the Hemlock formation in the Swanson River field and estimated maximum daily injection will be 10 million cubic feet.

The commission has asked Unocal to provide annual material balance calculations of the gas production and injection volumes to provide assurance of continued reservoir confinement of the gas storage volumes.