Drilling Technology

Offshore drilling Offshore drilling refers to a mechanical process where a wellbore is drilled through the seabed. It is typically carried out in order to explore for and subsequently produce hydrocarbons hydrocarbons which lie in rock formations beneath the seabed. Offshore Offshore drilling presents environmental challenges, both from the produced hydrocarbons hydrocarbons and the materials used during the drilling operation. There are many different types of facilities from which offshore drilling operations take place. These include (i)bottom founded drilling rigs, (ii)combined drilling and floating platforms and (iii)deepwater mobile offshore drilling units These are capable of operating in water depths up to 10,000 ft. In shallower waters waters the mobile units are anchored to the seabed, however in deeper water (>5,000 ft) the semisubmersibles or drill ships are maintained at the required drilling location using dynamic positioning.

Drilling operation How do we do it? (1) We use energy to break up the rock and create a hole

(2)The energy consists of rotation and hydraulic forces

(3) The energy is optimised by ‘tuning’ drilling parameters

(4) After drilling a section of the well, it is sealed off with steel pipe to ensure integrity for the following well section

Offshore semi submersible drilling rigs Floating Moved by towing vessels, or by its own power Station keeping through anchors or propellors (Dynamic Position) Blowout Preventer is on sea bed Any weather condition, any waters, but problems with ice 80 - 3000 m water depth Approximate costs: 50,000 - 250,000 USD/day

Drill ships Floating Moved by its own power Station keeping by anchors or propellors (dynamic position) Blowout Preventer is on sea bed Any weather condition, any waters, but problems with ice 80 - 3000 m water depth High payload capacity, will ‘travel and drill’ with minor support Good for remote areas, high speed Approximate costs: 100,000 - 250,000 USD/day

Offshore jack-up rig characteristics Present throughout the world Water depth 20 - 125 m Can drill wells through platform Can ‘skid over’ onto platform Moving a jack-up is a critical operation Approximate costs: 20,000 - 200,000 USD/day

Tender support vessel characteristics Supports a drilling operation on a platform No drilling facilities required on platform Extensively used in the Far East Quick rig-up and rig-down Effective in shallow water depths Effective in good weather conditions Approx. costs: 20,000 - 50,000 USD/day