What Are the Causes of Ice Crystals in Deep Sea Oil Wells?

Hazardous ice crystals found deep beneath the sea have been pinned as a culprit for catastrophic oil drilling accidents. The crystals are actually naturally occurring methane structures, transforming in a special way upon reaching the depths of the ocean floor. Oil wells at times uncover a pocket of crystalline methane, resulting in an effect akin to an explosion.

Crystalline Methane

• Also known as methane clathrate or hydrate, the substance that forms when water and methane are mixed is often the type of ice crystal found on an underwater oil well. Methane in its isolated form occurs most commonly as a gas. Methane gas exposed to extremely low temperatures and high amounts of pressure, found only in the incredible depths of the deep sea, can crystallize into liquid or solid form.

Rapid Crystal Formation

• When sea water is added to the slushy methane, the temperature required for methane to crystallize into a solid drops significantly allowing methane ice to form almost instantly. When the oil well taps the methane pocket, methane rushes out and mixes with the water forming ice crystals on the well and other surfaces. The addition of water to the methane reduces the freezing point for the methane making it solidify rapidly.

Drilling Into Methane

• Oil rigs that have drilled into isolated pockets of methane have historically been met with catastrophic results. When the drill from an oil rig punctures a pocket of trapped methane a couple of things can happen. The methane can enter the drill chamber and due to the lack of pressure it will expand rapidly and create an explosion causing damage, or it can mix with water and freeze.

Pressure and Temperature

• The freezing point of methane is minus 182.4 degrees Celsius, not a temperature that you are likely to find at the bottom of the ocean. The pressure experienced at the ocean floor also adds to the ability of methane hydrate to take on solid form, but one of the most important factors is the actual structure of the methane hydrate molecule itself. The water molecules surround the methane like a four-sided fence. The complex nature of the structure is what makes the ice.