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With the Deep Water Horizon explosion this past summer, and the subsequent oil leaked into the Gulf of Mexico, many people have discovered how little they actually know about offshore drilling. A better understanding of the process may make it somewhat easier to grasp what BP and other companies must do to provide the precious crude we consume every day.

 

Offshore drilling begins at the exploration stage. Ships equipped with sensitive sonic equipment and digital satellite images scan the ocean floor to find sites most likely to reveal hidden oil reserves. Once a site is identified, the oil company secures all the necessary permits and approvals before beginning to drill.

 

A mobile offshore drilling unit, or MODU, is sent to the site to begin the process. A MODU can be in the form of a platform secured to a sunken barge in shallow water, a platform resting on a surface barge, a floating platform attached to several pontoons, or a ship specifically designed to carry and operate a drilling rig.

 

A Drilling Riser is lowered from the platform to the sea floor, being assembled piece by piece as it goes. The riser carries mud, rock, and other drilling debris from the drill hole up to the surface. Water pumped down the centre of the pipe forces the debris up the riser and out the top. With the riser and water line in place, the drill bit is lowered to commence its work.

 

Engineers will drill to a pre-determined depth before temporarily stopping to install a blow out protector (BPO). The Drilling Riser is secured to the BPO and drilling is resumed. Workers must be extremely careful to make sure the riser is properly centred and working normally. Rough waters can cause movement of the riser with complications to follow.

 

When the drill reaches the level just above the oil pocket, the hole is sealed at the bottom with a combination of mud and slurry. Another plug is placed at the entrance of the drill hole until a production platform can be put in place. Before departure, the MODU crew retrieves the Drill Riser for use at the next site.

 

This simple explanation may make it seem as though offshore drilling is an easy task. But when one considers several other factors, it becomes clear that this is not the case. The first of those factors is the very nature of drilling at sea. The ocean is seldom still, so even for a platform resting on the floor, ocean currents and waves continually batter the Drilling Riser. Care must be taken to avoid damage. If foul weather should arise, things can be more difficult.

 

Consider also the fact that in deep sea locations, the Drilling Riser and drill bit must be lowered through hundreds of feet of water just to reach the floor. Then, it could be hundreds, or even thousands of feet deeper before the oil is reached. Unlike drilling on land, offshore drilling is terribly unstable. Therefore, it is also much more difficult to do safely.