Riser Analysis: an Integral Part of Sub-sea Analysis Services Provided

[Posted on December 26th, by Bill Stewart]

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Why Sub-sea Engineering Requires Exceptional Riser Analysis Technologies

Sub-sea engineering has extremely high financial stakes as it is still a relatively young discipline. Riser analysis presents a clearer understanding of principle parameters influencing riser behavior within the sub-sea riser design’s mode of influence. Finding clear procedures for the analysis of tricky problems like issues surrounding risers of multi-barrier anisotropic materials that are often subject to varying pressures, temperatures, and fluids; are key aspects of the expertise of Stewart Technology Associates.

Any conduit that is providing temporary extension for a sub-sea oil well for on-surface type drilling facilities, is called a drilling riser. These risers are divided into two categories.

  • Tieback drilling risers which are used with surface blowout preventers, (BOP), and deployed from spar or tension leg fixed platforms, which are very stable.
  • Marine drilling risers, flexible risers, used with sub-sea blowout preventers, (BOP), used by floating drilling vessels.

The confusing aspects of riser design require good qualitative explanations. The means of creating reliable analysis, both before and after running sophisticated FE riser analysis programs, can include using Excel spreadsheets for simplified riser analysis, 2H offshore riser systems analysis, fatigue analysis, and sub-sea integrity management programs, with riser and conductor engineering designs.

Our company, Stewart Technology Associates, can also assist with understanding counter-intuitive buoyant pipe mechanics and fluid-filled columns. Our marine engineering software products will provide on-bottom stability analysis and static pipe-lay analysis programs, and more. We use many software applications, many we have developed and others we market and support for our vendors, to ensure diversified and comprehensive reports among other sub-sea engineering analysis.

Risers are the most critical product of an offshore pipeline project. Needed to withstand extremely negative service conditions and dynamic loads, our dependable services at Stewart Technology Associates help deep-sea engineering crews who are required to reach reservoirs in increasingly deeper waters, subjecting risers to greater fatigue loads, and more challenging tolerances, environmental conditions, and mechanical properties.

Your team can count on our professional staff for answers to your difficult design and analysis questions. We have decades of experience in an extensive variety of marine industry and offshore services, from risk assessments to marine simulators and training. We use state-of-the-art software like Orcaflex for riser design and analysis, and we are also a U.S. agent for Orcina Software, including Orcalay for pipe-laying analysis, and Orcabend for bend-stiffener design and analysis.

Our proven dedication to excellence and safety since 1986 is a testament to our proficiency in providing proprietary software and designs for complex marine simulators for training emergency crews on lift-boats, semi-submersibles and jack-ups.  Also, Stewart Technology Associates has the ability to effectively help our U.S. marine clients with CE marking in conformance with the 98/37/EC Machinery Directive, as well as a wide-range of disciplines to assist major oil and engineering clients globally.

5 Reasons To Consider Cable Dynamics

[Posted on December 8th, by Bill Stewart]

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Cable dynamics may not be something you think of when you talk about going out on an oil rig. Any time you are on the water with an anchor, drilling equipment, or anything else, you have to look at the dynamics of a cable because there are various factors that need to be considered.

Depths of the Sea

There are going to be cables connected to your rig. They go up and down as the water goes up and down. When you are drilling, you have to consider the depth of the sea. It is very much like an anchor. An anchor is only going to be effective if it is able to reach the bottom. Otherwise, it is simply going to dangle from the boat and cause you to drift. The anchor is therefore not as effective as it could be and all because you were unprepared for the depth of water that you would be in. the same goes for the cables. Understanding depth is vital to the success of your project.


The physics of waves should be explored in depth when you’re going to be out on the water. You need to know when they are going to occur, where, the height of the waves, and more. All of these are going to play a role in the equipment you choose and the training you give your employees. Failure to recognize the importance of waves can result in problems on the water – and you could end up injuring someone or destroying a part of the rig.

Movement on the Rig

There’s going to be movement on the rig due to all sorts of factors – wind, weight of what’s on the surface, and even movement of employees. These are going to be factors when calculating the cable dynamics.

Overall Stability

Stability is critical and when you’re on a rig or even fishing, there are going to be cables or other lines in the water and then connected to your boat or rig. When working with steel catenary risers, they are responsible for the fluid transfer from one area to another. If the cable dynamics haven’t been explored to the fullest, the transfer could be broken simply because of one variable that was missed during the setup, such as bigger waves or deeper water.

Accident Prevention

It’s important to prevent accidents and when you are dealing with being on a rig that could be on the water for months at a time, you have to think about everything. The more you know about potential accidents on the water, the more you can prepare your employees for what could happen. Having analysis at your fingertips as to what you could experience can be invaluable when you are looking to train employees, purchase equipment, and stock the rig before leaving the shore.

How To Determine If Single Point Moorings Are Effective

[Posted on December 3rd, by Bill Stewart]

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Every project is different. If you are going to use single point moorings, you have to be confident that they are going to hold up within the environment of your platform. There are various problems that can go wrong in the water and you need to be sure you do sufficient analysis before making assumptions about what you will face.

The last thing you want is to face stronger waves than initially anticipated. Waves are powerful surges of water that can have a negative impact on the way that you keep an oil rig, boat, or any other vessel in place.

You cannot risk damaging your rig in any capacity. Single point moorings can be effective, but they are not always the most effective depending upon your setup and the location where you will be.

Orcaflex is a type of software that is capable of providing substantial amounts of analysis. This will allow you to choose the right number of points for a mooring. You may decide that a single point is sufficient enough or you may decide that multiple points or the use of an anchor is going to be the best solution.

Worst-case scenarios should always be factored in. Once you are out on the water, you are going to depend on boat moorings to keep you in place so that you don’t drift. You may also be using them so that you can get off of the boat or vessel for one reason or another.

When you leave the vessel, you need it to be where you left it. If there are higher waves, storms, or other issues, the single point moorings may not work, causing problems. It could be enough to damage the vessel or cause a break from the mooring, which means that your vessel could end up drifting through the ocean. Depending on the storm and the waves, it could be positioned miles away from you – and that can leave you stranded.

The best thing to do is focus on analysis of the moorings as well as the environment that they will be forced to perform to avoid any incidents. There are countless boating and marine accidents every year because people fail to do sufficient analysis. Regardless of whether you are in the gas and oil industry or any other industry, if you are going to be on the water, it is imperative that you bring the right supplies with you.

Knowledge is going to go a long way to protecting you, your staff, as well as all of your gear. New software can do a substantial amount of the analysis for you so that there is no question as to what you really need. The software can provide recommendations and give you calculations that you can rely on for all of your projects.

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