Posts Tagged natural gas

The Snohvit Field

Posted by on Sunday, 15 August, 2010

Norway’s oil company, Statoil, is drilling wells in the far north, in the Barents Sea. This offshore drilling project includes many safeguards because of Norway’s relatively strong environmental regulations. According to the University of Alaska, some of the features of this project include reinjecting carbon dioxide into the field, as well as drill cuttings. The Norwegian government does not allow any discharges during normal drilling conditions, whether the discharge is mud, oil, or water.

One interesting feature of the Snohvit, or Snow White, drilling operation is that the drilling equipment is located on the floor of the sea, and engineers on the coast operate the facility remotely. This underwater rig is 89 miles offshore, so it sets a record for operating a drill at a distance. This seems like a very long distance for remotely controlling a complicated system such as a drill. In addition, the natural gas pipeline must also be at least 89 miles long to transport the liquid natural gas to the shore facility. According to Statoil, the shore facility is located in Melkoya in the Hammerfest region.

Snohvit is also located farther north than any other oil field in the world. According to Statoil, the ocean this far north in Alaska is frozen solid, although warmer currents prevent this part of the Barents Sea from freezing. Using an underwater rig is necessary here because of the icy winter storms which would damage a rig above the waves. Underwater temperatures are much warmer than temperatures at the surface of the ocean. The freezing temperatures require additional precautions, such as using electrical heating and antifreeze to keep the pipeline free of ice. Norwegian University of Science and Technology, Trondheim plans to improve control room technology so that equipment in future oil fields can also be controlled from a long distance.

Pipelines only bring the oil from Snohvit to the shore. The main facility converts this natural gas into liquid natural gas so tankers can deliver it across the ocean to other ports. According to Norwegian University of Science and Technology, Trondheim, the Snohvit rigs collect gas as well as liquid petroleum compounds, producing a multiphase flow which is complicated to transport to the facility on the shore.

This project is also designed to reduce the use of toxic chemicals. According to Alaska University, the Snohvit operation replaces chemical or petroleum based muds with water based muds. Dope was not used to coat the pipes and casings, so this product which contains petroleum as well as metal particles will not leak into the sea. The decision not to use dope is another unique feature of this project. E and P Magazine reports that the oil company ConocoPhillips is also working on dope free projects in the North Sea, which reduce waste disposal costs and involve less risk to oil rig workers along with their environmental benefits.

Liquid Natural Gas Safety Hazards

Posted by on Friday, 28 May, 2010

Liquid natural gas terminals provide a supply of compressed fuel which tankers deliver to ports around the world. They are proposed in Ventura County periodically, and local groups often bring up safety concerns. A terminal proposal for Oxnard was cancelled by the California State Lands Commission in March 2010, according to the Ventura County Star. The Gulf Oil spill demonstrates the necessity of studying fuel extraction and delivery to determine the risk of a disaster.

The California Energy Commission explains the hazards that a liquid natural gas, or LNG, terminal presents. First of all, natural gas, like its name suggests, is a gas at room temperature. Conversion of natural gas into a more compact liquid form requires very cold temperatures. According to Technifab, liquid natural gas is primarily liquid methane, and methane melts at -183 C and boils at -164 C. That’s very close to absolute zero, -273 C. Leaked liquid natural gas will boil and form a vapor that remains incredibly cold for some time, and the vapor will cause frost damage to crops, people, buildings, and anything else it touches.

The methane vapor cloud is also dangerous because it is easy to ignite. According to the California Energy Commission, as little as five percent methane concentration in the air is enough to ignite the vapor if it passes over a heat source. The vapor cloud is lighter than air so it rises and disperses rapidly once it warms up.

The public education forum in Oxnard provided more information about liquid natural gas. Methane is not considered toxic or corrosive. The main hazard is its potential to cause fires and explosions, when not under control as a fuel. Methane also has no color or odor, so it does not create a nuisance like other gases, but it also poses a hazard since it’s difficult to know how much methane is present. Gas ovens and stoves often use natural gas which has odor creating chemicals added to it, so a homeowner can detect any gas leaks.