Deepwater drilling is the process of oil and gas exploration and production in depths of more than 500 feet. By this definition, there are approximately 600 deepwater wells in the Gulf of Mexico.

It has been economically infeasible for many years, but with rising oil prices, more companies are investing in this area. Major companies working in this sector include Diamond Offshore

Diamond Offshore Drilling

Diamond Offshore Drilling, Inc. is a deepwater drilling contractor which provides drilling services to the oil and gas industry. The company's headquarters are located in Houston, Texas, but they have offices in Metairie, Louisiana, Africa, Australia, Brazil, Indonesia, Scotland, Singapore, Norway...

, TransOcean

Transocean

Transocean Ltd. is one of the world's largest offshore drilling contractors. The company rents floating mobile drill rigs, along with the equipment and personnel for operations, to oil and gas companies at an average daily rate of US$282,700...

, and Baker Hughes

Baker Hughes

Baker Hughes Baker Hughes provides the world's oil & gas industry with products and services for drilling, formation evaluation, completion, production and reservoir consulting. Baker Hughes operates in over 90 countries worldwide mainly based in countries with a mature petroleum industry as is...

.

There are basically two kinds of mobile deepwater drilling rigs: semi-submersible

Semi-submersible

A semi-submersible is a specialised marine vessel with good stability and seakeeping characteristics. The semi-submersible vessel design is commonly used in a number of specific offshore roles such as for offshore drilling rigs, safety vessels, oil production platforms and heavy lift cranes.The...

 drilling rigs and drillship

Drillship

A drillship is a maritime vessel that has been fitted with drilling apparatus. It is most often used for exploratory offshore drilling of new oil or gas wells in deep water or for scientific drilling. The drillship can also be used as a platform to carry out well maintenance or completion work such...

s. Drilling can also be performed from a fixed-position installation such as a floating spar (platform)

SPAR (platform)

A spar, named for logs used as buoys in shipping and moored in place vertically, is a type of floating oil platform typically used in very deep waters. Spar production platforms have been developed as an alternative to conventional platforms...

or tension-leg platform.

Recent industry analysis has estimated that the total expenditure in the global deepwater infrastructure market will reach $145bn in 2011.