Things To Consider When You Perform A Mooring Analysis

[Posted on January 29th, 2014 by Bill Stewart]

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Anytime a permanent structure is going to be built into the water, such as a pier, it’s important to conduct mooring analysis. This will help to determine the design of the structure as well as the materials to ensure that all has been taken into consideration. If analysis is not done, it can lead to problems down the road – including complete destruction of the mooring.

Many industries use mooring analysis, including offshore drilling. When an industry needs analysis conducted, it usually involves software where numbers can be added.

The software can generate a significant amount of data after some basic numbers are inputted. This includes looking at the depths of the water as well as such things as the type of water. Waves and tides can play an active role in the analysis as well because a structure needs to be high enough to compensate for such things.

There have been some instances when piers and bridges have been built without considering the highest wave. As a result, the entire structure was washed away when storm waves came crashing down. This left people to lose both time and money because of having to rebuild.

Industries do not have to take the time to learn through trial and error. There are plenty of ways to find out about the conditions of the water and worst case scenarios by conducting mooring analysis. When it comes to offshore projects, riser analysis can be important as well. Generally, anything that tells a person that they will be able to build because of having numbers in front of them to inform them it is okay is needed prior to going forward with a project.

Once a person is out on the water, they have to decide between buoy versus anchor. There are pros and cons to each. In some instances, the buoy can be more effective. It is a form of mooring that can be permanent. Boats can attach to it as opposed to dropping an anchor. This allows boats to stay stable and they don’t have to worry about an anchor dragging along the bottom of the ocean floor as the waves help to push them along.

In many instances, boats are not equipped with an anchor that is sufficient for the water depth and waves that they are in. As a result, they won’t drift as far as not having an anchor but they are still going to drift simply because they don’t have the right equipment. When it’s boating for fun, that’s fine. However, when it comes to offshore drilling and similar projects, drifting could be catastrophic.

Mooring analysis has to be done dilligently to ensure that all of the right equipment is aboard and that worst-case scenarios have been considered to avoid a loss of time, money, and destruction of property.

Why Riser Analysis Is Critical

[Posted on January 22nd, 2014 by Bill Stewart]

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When you are conducting any kind of offshore project, such as drilling, riser analysis is critical. You have to be sure you have the best designs possible, taking into consideration all environmental factors. If you do not have the best design, you may run into various problems out on the water. Accidents and incidents have occurred in the past and you can avoid many if you do the necessary advance planning.

You are always going to deal with waves in the ocean. Depending upon how extensive these waves are, they are going to affect your ability to float your entire operation.

The riser analysis is done to ensure your design has structural integrity. You may have a drilling vessel as well as a wellhead on the ocean floor. The waves in between will determine how much everything is rocking back and forth. You don’t want to run into situations where you don’t have a strong enough cable – or a long enough one.

The analysis will tell you what you need to know. You may need to obtain added equipment before leaving the shore to anticipate various problems. The rise analysis can be done on the computer, providing you with pages of data. From there, you can incorporate this data into other calculations and ensure your designs are sufficient based upon the information you are getting.

Just as you look at mooring analysis when it comes to docking stations, the same has to be done with the risers. Riser diameters and materials are going to play a role, as will the water depths. In many drilling projects, you may be dealing with depths of one thousand feet.

Many of the newer drilling operations are going into deeper waters. This means that designs you had when you were drilling into 500 feet of water are no longer valid. The riser analysis will ensure that you won’t have issues with the waves once you are out there. If you do not perform the necessary analysis, you may find that you are unable to drill effectively because of not making the necessary connections.

If you look at some catastrophic events that have taken place on oil rigs in the past, you can attribute many of them back to not having accurate numbers. Many drilling companies don’t take environmental factors into consideration at the level they need. You don’t want to make assumptions that the waves will only be a certain height or that the water depths will only be so deep.

You have to plan for the unexpected – and riser analysis is going to help. You may have begged, borrowed, and stole your way to obtain enough funds to drill. You will never get investors to give you money again if your project falls apart. A little analysis can go a long way to preventing accidents.

Stewart USA – Flexible Risers for Off-Shore Drilling

[Posted on January 8th, 2014 by Bill Stewart]

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The Off-shore oil and gas industry continues to need flexible risers to build  new structures.  The debates continue over off-shore drilling. No matter who makes the most valued point, the fact remains that it is a lucrative business with more lobbyists than gas stations, so will continue for a long while. Deep water deposits of  raw materials continue to  promise rewards, and the rising fuel cost puts pressure on all governments to go to more deep water to drill.  Oil and gas companies realize a very strong financial drive to pursue more and more off-shore oil rigs.

Risers are in Demand

Continued off shore rig development kept high demand for components that are used to build rigs high.  Among the most needed are flexible risers.  They connect platforms with oil and gas below the ocean, and then transport fuel to where it is packaged and transported. If we did not have risers, much of the oil and gas the world is mining would remain inaccessible.

 Steel Catenaries

The steel catenaries are risers that give benefits others simply do not. These risers are  steel pipes, flexible, and follow the ocean floor to the oil platform above.  They are meant for deep water drilling and often hundreds of meters long.  The first one built was by Shell twenty years ago.  It reached a depth of 872 meters.  These powerful risers operate at pressures between 2,000 and 5,000 psi. Not exactly like the pressure washer you use around your home! The flexible risers are less costly and really reliable, known for resistance to high temperatures, ability to take high pressures and flexible movement.

Technology and Development

Flexible risers s are primarily used in fragile marine settings and  transport hazardous materials through these ecosystems. Cable dynamics are used daily in the operations of oil rigs. Much of the research and development that has gone into flexible risers actually focused on safety and creating these to be as safe as possible. Fluid dynamics, mechanical technology professionals, soil mechanics technology professionals and many other professional personnel work to design the best flexible riser possible.


Flexible risers are not the only type of riser used when for off-shore oil and gas platforms. Another way which is better suited to some specific situations, is the bottom-weighted riser. This is technically not a flexible riser but has commonalities with them. Two distinctive characteristics  of the bottom-weighted riser are (1) its rigid elbow and(2) horizontal section made of titanium.

Flexible risers are usually the best solution but each platform needs a specialized evaluation.  They are each unique.

Stewart Technologies helps companies design platforms and determine which type of riser is best for each individual off shore  platform. STA continues to be the go-to authority for off-shore rigging and its production.


Trends and Uses for Cable Dynamics Today in Off Shore Industry

[Posted on January 7th, 2014 by Bill Stewart]

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Cable dynamics represent a vital part of all offshore technology projects, procedures and error solutions.  High quality technical reports are necessary, including diagrams which enable technical reports to be well understood by not only trained experts but by average lay persons or legal counsel.  Extensive use of computer software and state-of-the-art analytical simulation techniques are vital in today’s offshore industries and their management technology professionals.  A “notebook” computer and printer should accompany technology professionals when  performing their many important offshore duties or preparing  technical reports.   Millions of dollars have been awarded to clients of Stewart over the last fifteen years as a direct result of the expertise and reporting of the owner of Stewart Technology Associates,  W. P. Stewart, P.E.

Cable Dynamics Also Vital in Reenactments

Stewart Technology Associates maintains  databases of offshore and marine mishaps,  spills, and construction.  Other offshore costs factor into their technology projects, databases of construction and other offshore costs. These are most useful in maritime law.  All of the foregoing testifies directly to the expertise of STA company in offshore cable dynamics and other significant marine solutions.

An anchoring system for offshore is controlled by factors such as site environment, operational variables and the vessel  involved in the system.  Its adequacy and ability to stay on site must be checked by proper methods of analysis. The inclusion ofcable dynamics is an extremely important consideration in the analysis of a moored vessel, permitting anchor motion. Then numerically solved timehistories of cable displacements and cable tensions for cable figurations occurring under the Initial conditions are provided through mooring line static equations.  The equations of motion of the moored vessel subjected to an open ocean are then numerically solved, yielding time histories of vessel motions and cable tensions.

An example involving a moored production barge is examined and results compared with previous incidents.  In this way the cable dynamics are used in the proving labs or court of law as importantly as they are used in their offshore capacity.

Steel Risers

Flexible Risers had a set back in recent years but now they are in high demand. The riser components are used to build off-shore rigs very elevated are needed as much as ever. Risers are most definitely needed. These risers connect platforms with fuel deep below the ocean and carry fuel to areas for packaging and transport. Without risers, much of the world’s oil and gas would remain untouchable.

 Steel Catenaries

The steel catenary risers afford industry perks that others don’t. These are flexible steel traveling from the ocean’s floor to the drilling platform. Designed for deep-water drilling, they measure several hundred meters.

Stewart Technology Associates have played an integral part in the development of America’s oil industry, from working the offshore platforms to damages litigation.

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