The oil and gas industry began exploring for oil and gas on Federal leases offshore Alaska in 1975. Since then more than 80 exploratory wells have been drilled.

 

These well were drilled in Cook Inlet, the Gulf of Alaska, Norton Sound, and in the Bering, Chukchi, and Beaufort Seas. There are several different types of drilling units that are used to drill exploratory wells.

 

Jackup Drilling Unit In Cook Inlet

Exploring for Oil in Cook Inlet

Jack-up drilling units are used in shallow water areas like Cook Inlet and Norton Sound.

 

Jack-ups are floated into place and the "legs" are lowered to the sea floor. The body of the structure is then "jacked" above the water surface to provide a stable platform for drilling operations. In the photo to the right, the jack-up is being prepared to be raised. In the photo above, the jack-up is in place and ready to drill.

 

Jack-up Drilling Unit in Alaska

Semi-submersible drilling units are used in open ocean areas like the Gulf of Alaska and the Bering Sea. They can drill in very deep water.

 

These structures are called semi-submersibles because their legs are flooded with water for extra stability in the open ocean.

 

Semi-submersibles float on the water and utilize a series of anchors and winches to maintain their position over the drilling location.

 

Semi-submersible Drilling Unit

Semi-submersible Drilling Unit

Drillships are also used in deep water areas. They have been used in Cook Inlet and in the Beaufort and Chukchi Seas.

 

A few specialized drillships have been built for working in areas with sea ice. Their hulls have been strengthened so they can withstand the crushing forces of ice. These drillships must also be able to operate in cold weather and in remote locations.

 

Drillship

Drillship in the Beaufort Sea

Drilling systems have been developed for year-round use in the Beaufort Sea. These include manmade gravel islands, and massive steel and concrete drilling platforms. The first development projects in the Beaufort Sea will be built on concrete-armored gravel islands.

 

Drilling offshore Alaska is a challenge, but the technologies developed for these activities have proven safe and reliable.

Concrete Island Drilling System (CIDS) in the Beaufort Sea, Alaska

Concrete Island Drilling System (CIDS), Beaufort Sea

Jack-ups, semi-submersibles, drillships, and other drilling structures must be capable of safely operating in all kinds of weather. For most areas of Alaska, these systems must be capable of working in ice.

 

It is MMS's responsibility to ensure that all drilling activities are done in a safe and responsible manner.