8 Services Provided by Our Marine Consultants

Any structures that operate in a marine environment, including offshore drilling rigs, risers, mooring systems, marine vessels, wave power systems, and offshore wind generator facilities, provide unique design and operational challenges that often require significant resources and ingenuity to overcome. Many companies rely on the extensive knowledge and experience of marine consultants to help provide critical analysis of these problems and devise piratical, cost-efficient solutions.

8 Services Provided by Our Engineer Consultants image

Specializing in marine and offshore structures, fluid dynamics and related disciplines, here are just a few of the services that our marine consultants at Stewart Technology Associates can provide:

1) Hydrodynamic Analysis

Hydrodynamic analysis is used to accurately simulate the forces at work on a structure in a marine environment. This includes the movement of the waves, the action of the tides, the effects of undersea pressures, turbulence from structures or seafloor features, and the effect of high winds and inclement weather. By learning how these forces affect a structure, its design can be improved to eliminate possible failure points and to reduce costs and maintenance requirements. Hydrodynamic analysis can be used to examine both new and existing designs, and it can also be used after a maritime accident to help determine the cause of the problem.

2) Finite Element Analysis

Finite element analysis can be used to model how real-world conditions will affect the operation of a product or of a component of a larger system when subjected to forces such as vibration, heat, high pressures, fluid flow or other physical challenges. The results of the modeling can be used to improve the product’s design, reducing component failures and wear that can shorten its lifespan or lead to increased maintenance costs. Finite element analysis can also make a product safer, and help to determine the cause of failure in an existing design.

3) Structural Design and Analysis

STA can help design and analyze marine structures, such as drilling rigs, jack-ups and liftboats, to make sure that they will perform efficiently and safely in a specified environment. They can work directly with a client to create a structure that will withstand the forces in a particular marine or sub-sea environment safely, while increasing productivity and reducing long-term costs. They can also analyze existing designs to improve their structural performance, productivity and safety.

4) Riser Design and Analysis

Risers are one of the most critical components in an offshore oil drilling or production platform. They carry mud and drilling fluids to the well during drilling operations and carry oil and gas to the surface during production operations. To operate safely while maximizing production, they must be able to withstand the movement and pressure below the surface, while moving fluids efficiently. Engineer consultants can be used to design an efficient riser system for production or drilling operations, determining what type of riser will be needed, rigid, flexible or hybrid, effective mooring solutions, what equipment will be required and other factors. They can also improve the efficiency of fluid moment withing the riser, increasing production, and analyze existing designs to suggest structural, efficiency and safety improvements.

5) Anchor Performance Analysis

Anchors are critical to securing marine vessels and other structures in place temporarily, permanently or semi-permanently, and if they fail to perform adequately, they can allow vessels to drift off course or to collide with other structures, leading to injuries, property damage, productivity losses or environmental concerns. To perform effectively, the design of an anchor must take into account the weight and movement of the vessel, the surface conditions and the composition of the sea floor. With an anchor analysis, engineer consultants can model the forces at work on the anchor and suggest improvements that will make it stronger, safer and more effective.

6) Mooring Design and Analysis

Mooring systems in the offshore oil industry are critical to keep the platform in place during operation, to secure tankers while transferring oil and gas and to secure other vessels as needed. They must be able to withstand the weight of the vessel or platform, while compensating for motion at the surface of the sea and keeping transfer pipes and equipment safe. Engineering consultants can analyze the design of a mooring system, including the anchors, mooring lines and surface structure, ensuring that it can perform both safely and effectively. They can also create new designs for specific applications and analyze the performance of transfer systems.

7) Oil Spill Clean-Up and Containment

Oil spills can have far-reaching consequences, from polluting the water supply and harming animal and plant life, to making beaches less inviting and hurting economies that depend on fishing or tourism. When the worst does happen, the key to minimizing the damage is to contain the oil as close as possible to the source and to clean it up as quickly as possible. Engineering consultants can help to design effective measures for both containing the oil and cleaning it up, including effective boom systems to contain the oil and techniques that can adequately model the currents and conditions at the site to make clean-up more successful and efficient.

8) Forensic Analysis

After a maritime accident or an oil spill, the original cause of the accident can be difficult to determine and, often, there are many contributing factors that make the origin even less clear. Engineer consultants can use hydrodynamic analysis, finite element analysis and other techniques, along with advanced software and extensive knowledge of marine systems, to analyze the events leading up to the accident, as well as the accident itself and its effects, to help determine the original cause. This information can be used to determine liabilities in the aftermath of the accident, to improve designs to prevent future accidents and to establish new safety protocols and programs that can help avoid or mitigate such incidents in the future.






6 Ways Riser Analysis Can Improve Riser Design

Published by Stewart Technology Associates on July 18, 2016

Dynamically positioned drill ship in storm conditions.
Riser tensioners seen actively tensioning riser until 7:50 on the timer.
Riser emergency disconnected, EDS activated at the BOP at 7:50 and the top end raised about 3 meters.
Moonpool with hung-off riser shown after EDS activated.

The portfolio item below provides a short OrcaFlex Tutorial example of Mooring Analysis.


View list of STA software.

In the offshore oil and gas industry, risers connect drilling and production platforms to the sea floor. They transport oil and gas from the well to the platform or inject fluids into the well to facilitate drilling or production. Risers are critical to the operation of the platform, and any failure could mean a loss of production capabilities and a serious loss of profit.

Risers enable the platform to move up and down, or side to side during production and drilling operations. They also must efficiently transfer fluids to and from the sea floor. The impact of wave action, tidal action, high pressures, low temperatures, and corrosion must not affect the platform’s movement. In order to do the job properly, with minimal maintenance and downtime, an extremely efficient and reliable riser design is required.

In the past, the main way to evaluate a riser design was through building prototypes, testing them extensively in real-world conditions and redesigning the riser until it met all the requirements and specifications necessary. This could be a tedious and expensive process, and it could still yield sub-standard designs, in some cases.

Today, riser analysis takes out some of the guesswork. Using special software packages and talented engineers, riser analysis can model the forces at work on a potential riser design. It looks at waves, tides, temperature, pressure, vortex forces and vibration to determine the strong and weak points of a design, and improves them to avoid structural fatigue, leaks, inefficient fluid transfer and other common problems. This can reduce design and prototyping costs, and lead to a final product that is efficient, durable, safe and low-maintenance.

Riser analysis is now a critical tool for improving the performance of drilling and production operations, and here are a few of the ways it can help to improve riser design:

1) Determining the Right Type of Riser for the Job

The type of riser used for a particular application will depend on the type of platform, the depth of the seafloor, the depth of the well and the sub-sea conditions. Riser analysis can be used to determine the best type of riser for the application, and help perfect the design and adapt it to particular equipment. The most common types of risers include:

  • Top-tensioned riser: A rigid riser that is held in place vertically through tension, and allows both lateral and vertical movement through a flexible connection between the riser and the platform.
  • Steel centenary riser: A curved riser used to connect two platforms, or to connect the platform to the sea floor, it can withstand some motion and is used on spars, tension-leg platforms and floating production storage and offloading platforms.
  • Flexible riser: Made from flexible pipe, these risers can withstand horizontal and vertical motion.
  • Pull-tube riser: A hollow tube attached to the center of the platform, it houses a pipeline or flowline that is pulled from the seafloor with a cable, and is used primarily on fixed platforms.
  • Attached riser: Used on fixed platforms, compliant towers, and concrete gravity structures, these risers clamp to the side of the platform and are connected to the sea floor with an export pipeline or a flowline.
  • Riser tower: A combination of a steel tower and riser that is used for deepwater drilling, a buoyancy tank is used near the surface to keep it in place through tension and flexible lines connect it to the platform
  • Drilling riser: Transfers drilling mud and other fluids to the seafloor during drilling operations and is only a temporary connection.

With riser analysis, you can choose the best riser for the situation, adapt an existing design for use with your equipment, or create an entirely new or hybrid design, then test and improve the riser before it goes into production.

2) Improving Riser Structure

The overall structure of the riser must be able to withstand the waves, the tides, the high pressures and the low temperatures present below the ocean surface. Riser analysis can be used to model these forces at work on your riser design, determining how they affect individual areas and structures of the riser and how they affect maintenance requirements and the longevity of the system. Using the resulting data, the design can be improved to make the riser stronger, more stable and safer.

3) Determining Insulation Efficacy

In deep water, the temperature can drop significantly, reducing the viscosity of oil and drilling fluid and slowing down production and drilling operations. To combat this, many risers incorporate insulation to keep the fluids at a more desirable temperature so that they can flow properly. Riser analysis can be used to design and test the insulation, and find problems that may reduce the temperature and fluid flow within the riser. By improving the design of the insulation, riser analysis can help to increase production efficiency, leading to higher profits.

4) Designing and Testing Valves

Valves in the riser help control the flow of oil, hydraulic fluid, and other substances through the system, and they must operate in cold, high-pressure conditions without frequent failures or maintenance. Riser analysis can be used to model the flow of fluids through the valves and to find failure points and other problems that can reduce their life cycle or cause leaks. With the data, the valve can be reengineered to promote longevity and efficient fluid flow.

5) Designing Buoyancy Tanks

Buoyancy tanks are critical to keeping a riser stable and accessible in sub-surface conditions, and if they malfunction, oil spills or other problems could occur. Riser analysis can help to design and test the buoyancy tanks, improving their design so that they are safer and more stable, regardless of the sub-surface conditions.

6) Improving Riser Flow

Production risers must carry fuel to the surface efficiently to meet production goals and maintain the platform’s earnings. Riser analysis can be used to model how oil and drilling fluids flow through the riser, determining points of turbulence or restriction. By improving the design of the riser and eliminating these problems, production rates, and profits can be increased.

Riser analysis is a powerful tool that can make an oil platform safer, more efficient, and more productive by improving every aspect of riser design, from the seals to the valves and the overall structure.





4 Ways Riser Analysis Can Reduce Costs and Improve Performance

Published By:Stewart Technologies on: February 18, 2016

During exploration and production operations in both the gas and oil industry, the riser is a critical component in the process. Production risers bring gas and oil to the surface for transportation and processing, and drilling risers inject mud and drilling fluids into the well bore during drilling operations.


As off-shore rigs move further and further away from land, the challenges in designing a riser that both performs well and rests damage from the natural forces acting on it underwater increase dramatically. Waves, tides, storm systems, high pressures and salinity all combine in an ocean environment to create a destructive force that slowly wears away at the riser, eventually causing structural failures or fluid leaks.

One of the best ways to prevent such problems is to have a riser analysis done, which models the effect of hydrodynamic forces on the riser components, allowing the design to be modified in order to make it more resilient.

Riser analysis is an important first step in any drilling operation, and when done correctly, it can have many benefits. Here are just a few of the ways that riser analysis can help you to save money and improve the performance of your exploration and production operations:

#1 Selecting the Best Type of Riser For the Situation

There are many types of risers common today, both rigid and flexible, and they each have strengths and weaknesses, deepening on the environment.

Attached risers are rigid structures that are connected to the side of a rigid platform, compliant tower or concrete gravity structure, connecting the well bore to the platform.
Pull tube risers run through the center of a fixed platform, and consist of an outer tube through which a flowline or pipeline is pulled from the sea floor.
A steel catenary riser is a curved riser used to connect the sea floor to a fixed or floating platform, or to connect two separate platforms.
A top-tensioned riser is a rigid vertical riser that ends just below a floating platform, with the final connection from the riser to the platform made with flexible pipe.
A riser tower is common in deep water environments, and uses a combination of a steel tower, buoyancy tanks for tension and flexible risers to deliver oil or gas to a floating platform.
Flexible risers are a hybrid system that is entirely flexible, allowing it to move both vertically and horizontally.
Drilling risers are rigid risers that are used only during the drilling process to inject drilling mud into the well.
Some types of risers are best used in shallow areas where the force at work on the system are minimal, and vertical or horizontal motion is limited. Other types of risers are used specifically for deeper waters, where the wave action, tides and pressure have a greater effect, and where there are significant amounts of both horizontal and vertical forces working on the riser and the production platform.

Selecting which type of riser will be the best in a certain situation can be difficult, but by performing a riser analysis, you can model the effects of wave action, tides, weather systems and other natural forces at a particular location. This data can then be used to select the best type of riser for the job, and avoid the costly mistake of choosing the wrong riser, then having to replace it after it proves to be an inefficient option for the region or when it fails completely.

#2 Improving the Riser Design

Once you have the basic type of riser selected, a riser analysis can help you to improve its design for use in a particular environment. By modeling the potential damage caused by corrosion, wave action, tides and pressure on the riser components, you can determine the weak spots in the design, and improve it to perform as expected in the field. This saves money by eliminating poor designs before they ever make into production.

The analysis can also be expanded to include moorings, lines, anchors and other components that are associated with the riser system, to make sure they are designed well for their intended use and placement.

#3 Reducing Maintenance Costs

Over time, the motion of the waves, the salinity of the ocean and the large amount of pressure under the water’s surface will cause riser and mooring components to fail, requiring significant amounts of labor to repair the problems.

By having a riser analysis done on your riser design, you can minimize the possibility of failure and reduce wear on structurally-significant components by modeling the hydrodynamic forces that are at work on the system. Using the results, the components can be replaced or redesigned to stand up to the forces better, reducing the amount of maintenance required, as well as the downtime and costs associated with it. This also helps to improve the safety of the rig workers, by reducing the amount of maintenance that must be performed and by making platform operation safer.

#4 Increasing Riser Performance

Riser analysis can also be used to model the fluid dynamics within the riser system itself. This will help to design a riser that transfers gas and oil to the surface, or drilling fluids to the well bore, in the most efficient way possible, increasing production amounts and the performance of the riser system.

Additionally, the analysis can help model the forces at work on gaskets and seals in the system, allowing them to be redesigned to last longer and to prevent spills. Leaks of oil, gas or drilling fluids can potentially have serious environmental effects, and by using riser analysis to design a better riser system, you can avoid environmental problems and the costs associated with the cleanup.

Riser analysis is an easy and affordable way to improve the design of your riser system, increase the performance of your exploration or production platform, reduce associated maintenance costs, and increase the overall safety of platform operation. One of the most common tools used for riser analysis is the OrcaFlex software package, which is capable of modeling the hydrodynamic forces present in nearly any marine environment, and it can help you to design and build a riser system that will withstand all of the forces present beneath the waves.






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