Why Anchor Analysis Is A Must Prior To Equipment Procurement

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[Posted on July 16th, 2014 by Bill Stewart]

It’s important that you know what’s going on with your rig. Anchor analysis can be done to help you maintain stability when you’re out on the water. The analysis will help you to account for worst case scenarios, which helps when the waves get rough or the water gets deeper than you anticipated. You don’t want to buy any kind of equipment until you know what you are dealing with so you don’t waste money on equipment that won’t work based upon the environment that you are going to be subjecting your rig to.

When you have an offshore drilling project, you want to make sure you buy all of the right equipment. Prior to buying, however, you need to make sure that you know all about the environment that you are taking your rig into. This includes understanding the waves, the water pressure, the depth and much more – which is why anchor analysis is critical.

You don’t want to get into anchor troubleshooting while you’re out on the water. Too many companies make the mistake of going out onto the water without knowing what they are truly dealing with. An anchor is not supposed to move. If it begins dragging against the bottom of the ocean floor, you’re in trouble.

Anchor analysis can be done to ensure that your anchor stays where you drop it. This will help you to set up your rig more effectively and be able to make sense of cable dynamics throughout the actual drilling process. If you don’t know about the environment that you are about to set up in, it could be catastrophic.

There are a lot of things going on with offshore drilling and the more you know, the better it will be for you.

A significant amount of equipment needs to be procured, but you have to know what to buy. This includes knowing the weight of the cables, the materials that should be used, and much more. A lot of analysis can be performed to tell you about what you need so that you don’t get involved with any kind of guesswork.

You can buy the software to do the analysis on your own or you can trust a third party to help you with the anchor analysis. A third party can often be the best solution to ensure you can rely on the numbers. It can also provide you with an extra set of eyes on the data to capture everything and identify problems.

Wasting money in the oil and gas industry is expensive and never an option. You can avoid all of that by doing the right analysis ahead of time and then deciding on what you need. That is the sure way to save money and make sure that your rig has what it needs to be functional.

Steel Catenary Risers for Off-Shore Drilling

[Posted on July 9th, 2014 by Bill Stewart]

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Steel catenary risers (SCR) are well-known tools used for uniting an ocean pipeline to an oil production platform. SCRs enables the movement of liquids such as water oil, and gasoline. When combined with anchor analysis, SCRs can be used precisely to improve the efficiency of virtually any drilling operation.

Steel Catenary Risers

There are several, basic components which all SCR’s have in common. First off, the SCR is connected to the platform via a coupling known as a flex joint. The riser may lie on the floor of a body of water, hundreds of feet below the surface, for this reason several buoyant must be attached so the SCR will remain buoyant. Increased buoyancy reduces the stress put upon the flex joint. If the joint was forced to support the entire weight of the riser, it would be far more likely to come undone. The riser must also be held in place on the floor of the body of water. Riser anchors must be strategically placed along the length of the riser so currents don’t move it from the desired position.

Why are SCRs Used Underwater

Many people are familiar with the oil production in the Persian Gulf and in the US in states like Texas. However, 3/4 of the Earth’s surface is covered by water, which means most of the viable drilling spots in the world lie beneath the sea. The dry land drilling sites would never be able to satisfy the world’s petroleum needs, which is why off-shore drilling is being discussed so heavily by the governments of the world. Even those who protest the use of fossil fuels still support off-shore drilling. This is because the vast majority of the world’s natural gas also lie beneath the surface of large bodies of water. Steel Catenary Risers can help to improve the world for everyone by making natural gas more accessible to replace harmful fossil fuels.

Other Benefits to Off-Shore Drilling

The US still has a volatile relationship with many of the world’s top oil producing countries. However, the US is also the country most dependent upon the fossil fuels from these countries. Off-shore drilling could make the US less dependent upon all foreign fuel sources, by providing ample petroleum and natural gas. Independence from foreign energy sources is certainly a great incentive for off shore drilling. Many European countries are also exploring off-shore drilling as a means of freeing themselves from dependence upon Russian natural gas. The Moscow based company Gazprom has been accused of using Russia’s natural gas reserves as political weapons which has countries such as Germany seeking more viable solutions. As off-shore drilling becomes more common, the need for steel catenary risers will increase as well.

Single Point Moorings Help Offloading Efforts

[Posted on July 2nd, 2014 by Bill Stewart]

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When drilling platforms need to transfer gas or liquids, single point moorings help their offloading requirements. Properly designed and anchored, these moorings can secure tankers of any size safely.

Offloading crude oil or gas to single point moored tankers is vital to getting platform production from the ocean to land-based ports. This connection between tanker and platform at a single mooring point with proper subsea design and installation makes the critical transfer of platform production easier, faster and more effective. Understanding how  single point moorings work is important to ensuring their subsea design and connections are installed properly effectively holding weathervaning tankers securely prior to and during gas or liquid transfer.

Working Description of Effective Mooring Systems

Three primary components make up mooring systems.

  • A mooring line;
  • An anchor: connecting the mooring line and a floating buoy; and
  • Various connectors, establishing the vital link of tanker and offshore platform.

Mooring lines often use different material, based on subsea and surface environmental conditions, such as wind strength, wave size and motion, and current power and direction. The most popular materials are —

  • Synthetic fiber rope;
  • Steel wire rope;
  • Chain; and/or
  • Combinations of the three materials used together for added strength.

Long-term and permanent moorings typically feature lines using chain, particularly in shallow water (usually defined as up to 100 meters). Deeper water mooring lines often use steel wire rope, maximizing the benefits of its lighter weight and increased elasticity as compared to chain. When light weight is the top consideration, mooring systems feature synthetic fiber rope, for its lighter weight properties.

Deeper water moorings, up to 2,000 meters, suggest using chain or chain and steel wire rope configurations. Combinations of all three popular mooring line materials are often used in deep water, over 2,000 meters, to get the best features of strength and elasticity.

All mooring system success depends on the strength and ‘holding capacity’ of their anchors. Outstanding anchors’ holding ability depends on their digging depth and the soil components of the sea floor. The most popular anchor type is the drag embedment style, used throughout moorings in the Gulf of Mexico.

Installing this anchor involves dragging it along the seabed until it achieves its optimal depth, penetrating sea floor soil and creating necessary resistance to hold it in place. Deep water conditions favor suction pile-type anchoring, since drag anchors lack high performance when heavy vertical forces dominate the environment, such as the pressure generated by deep water.

The third primary anchor type, vertical load devices, while similar to drag anchors perform well when facing both horizontal and vertical load issues. These types are very useful when mooring lines tend to adopt angular positions between anchor and buoy.

Steel catenary risers help the most common mooring system for shallow water allow the line to modify configurations as the surface vessel moves around. Since the mooring line lies on the seabed, it needs to be longer than water depth, increasing its weight, making catenary mooring systems less efficient as water depth increases.

When platform owners want expert advice and analysis of single point moorings, they turn to Stewart Technology Associates, industry leaders in offshore equipment and systems expertise. Our state-of-the-art technology and extensive experience analyzing and designing offshore systems help develop efficient solutions for offshore drilling and production platforms. Analysis of mooring methods is only one area of the many conditions we evaluate for our clients.

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