This blog explains the meaning of oil platforms, types of offshore oil rigs and workers safety on all oil rigs in the oil and gas industry.
INTRODUCTION
In the late 1950s, the oil industry began to push itself out into deeper and deeper waters for oil exploration. As onshore resources started to shrink and competition in the industry continued to grow, oil producers invested in ways to drill in ever-deeper water. At this time, “deep water” was considered to be anything below 60 feet. Technology has come a long way since then and Offshore platforms play a critical role in meeting global oil demands. Recently-built drilling vessels can now access oil up to 12,000 feet deep. As the economy has grown and the nation’s oil use has climbed, technology has had to advance more quickly to meet demand.
What is Oil Production Platform?
An oil production platform also called an oil rig, offshore platform is a large structure used to house workers and machinery needed to drill and then produce oil and natural gas wells in the ocean that lie in rock formations beneath the seabed. The biggest offshore oil platforms reach hundreds or thousands of feet down to the seabed and extend high above the water. They are immense structures that must not only house drilling equipment and storage facilities but must also accommodate their large crews.
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Types of Offshore Oil Rigs
Variations in sea level, weather conditions and a desire for platform mobility has led to the construction of many different types of rigs, including:
Submersible Platforms: In waters too deep for a barge, but less than 50-70 feet deep, a submersible rig can be used. Columns or posts are submerged into the water and filled to specific levels that determine their depth. Drilling equipment on the platform above drives a floating drill unit below.
Barge Rigs: A barge rig is designed to work in shallow water (less than length:20 ft deep). The rig is floated to the drill site, and the lower hull is sunk to rest on the sea bottom. The large surface area of the lower hull keeps the rig from sinking into the soft mud and provides a stable drilling platform
Jack-Up Rigs: Jack-up rigs are often used for shallow wells. Standing on three (sometimes four) legs secured to the ocean floor, the oil platform can travel up and down the legs as water levels shift. The “jacking” of the platform up and down is where this technology gets its name. For the first time, jack-up rigs provided a stable platform from which to drill oil offshore. There are two types of jack-up rigs:
- Cantilevered Jack-up, with a drilling derrick mounted on an extending arm
- Keyway or Slot Jack-up, which has a drilling unit on the platform over an opening it drills through
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Platform Rigs: Many offshore oil rigs are anchored platforms. They use a steel framework anchored to the ocean floor as a foundation for a surface drilling rig, equipment, and living quarters. Platforms may drill in many directions from this base, and they are broken down into specific types suited for various depths, they are as follow:
- Fixed Platforms: Fixed platforms are made of steel or cement and are intended to be permanent structures. They house large facilities, heavy equipment, and big crews. Most are located on the continental shelf in deep water up to 1700 feet. They can drill directionally with a radius of up to five miles. The platform is held in place by large steel or concrete legs that attach to the ocean floor
- Compliant Towers: When the oil or gas is even deeper, from 1500 up to 4900 feet, a compliant tower may be used. These structures are made of concrete and steel and are tall and narrow. They are intended to flex and sway with the wind and waves. Up to 3000 feet, they attach firmly to the sea bed, but, for greater depths, a tension leg platform may be used. These towers are technically floating platforms that are secured with a series of anchors and cables. They are fixed but also floating, and they can reach depths of 7000 feet.
Floating Rigs or Floaters: In very deep water, it is not practical to attach an offshore rig to the bottom of the ocean. Floating oil rigs are kept in place by anchors or dynamic positioning systems that keep them over target. There are several types of floaters in use at various deep water drilling locations worldwide.
- Semi-Submersible Platforms: This type of drilling platform is a massive floating vessel. The platform rests on huge columns that are secured to large pontoons. It uses dynamic positioning systems (thrusters) or anchors to stay in place during drilling. The BP Deepwater Horizon was this type of drilling rig. Among floating rigs, semi-submersibles are considered the most stable. When drilling is being considered for rough waters, oil companies will often use semi-submersibles for their ability to remain stationary in less-than-ideal settings. Contemporary rigs can drill below 3,000 feet—the newest below 10,000. Two notable types of semi-submersible rigs include:
- Sea Star Platforms, which use flexible steel legs rather than anchors, usually in less than 3500 feet of water.
- Spar Platforms, which sit on a hollow cylinder that hangs below the water at a depth of approximately 700 feet. This stabilizes the platform, allowing drilling up to 10,000 feet.
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- Drill Ships: For new exploration and the drilling and capping of new wells, drill ships are typically used. Drill ships have the drilling equipment installed directly on the deck, typically in the middle of the deck. The well is drilled through the “moon pool,” an opening in the center of the ship. They are kept in place by dynamic positioning.
Workers safety on all oil rigs in the oil and gas industry.
Workers must wear compulsory personal protective equipment (PPE). This includes steel boots, safety goggles, hard hats, hand gloves, and fireproof outfit. Many workers do not wear some of their protective gear because it makes them uncomfortable. The company should insist on them wearing it or they do not enter the site. One of the most hazardous jobs is working on an offshore oil rig. Oil rig injuries occur despite the most careful situations. There are numerous occurrences of falls, fires, explosions and deaths on oil rigs. Oil rig injuries do not occur in Nigeria alone. In the global oil and gas industry, the rate of workplace deaths that occurred during activities for oil and gas operations is 62%.
The international oil and gas industry has adopted the “safety first, job second” culture to reduce the rate of accidents and fatalities on offshore oil rigs.