Concrete for offshore facilities

Table of content:

  1. Offshore construction
  2. Types of offshore structures
  3. Concrete in offshore structures
  4. Challenges of concrete production at open sea
  5. Types of concrete used at sea to withstand salt water
  6. Carmix/equipment for concrete production on offshore platform

Offshore construction refers to the construction of structures in the marine environment, typically in the oil and gas industry or in the field of renewable energy. This can include the building of platforms, drilling rigs, and wind farms, among other things.

source: maverickvalves.com

There are a variety of factors that need to be considered when planning and executing offshore construction projects, including the location and depth of the site, the type of structure that will be built, and the environmental conditions in the area. The process of building offshore structures typically involves a number of different stages, including site assessment and preparation, design and engineering, and the actual construction and installation of the structure.

It’s worth noting that building any of these structures requires a high degree of engineering and technical expertise, and is subject to strict safety regulations. Offshore construction can be a complex and expensive endeavor, but the potential rewards in terms of natural resources and energy production make it a worthwhile investment for many companies and countries.

Types of offshore structures:

  1. Offshore oil and gas platforms: These structures are used for the exploration and extraction of oil and gas from beneath the ocean floor.
  2. Offshore wind turbines: These structures are used to generate electricity from wind energy in areas with strong wind patterns.
  3. Offshore drilling rigs: These structures are used to drill holes in the ocean floor for the exploration and extraction of oil and gas.
  4. Offshore renewable energy platforms: These structures are used to generate electricity from renewable sources such as solar, wave, and tidal energy.
  5. Offshore pipelines: These structures are used to transport oil and gas from offshore platforms to onshore facilities
  6. Offshore storage tanks: These structures are used to store oil and gas, chemicals, and other liquids in offshore locations.
  7. Offshore LNG terminals: These structures are used for liquefying, storing, and regasifying natural gas for transport to onshore locations.
  8. Offshore container terminals: These structures are used for loading, unloading, and storing cargo containers in offshore ports.
  9. Offshore accommodation platforms: These structures are used as living quarters for workers on offshore oil and gas platforms or wind farms.
  10. Offshore helipads: These structures are used as landing and takeoff platforms for helicopters used to transport workers and cargo to and from offshore platforms.
source: 4subsea.com

It’s also important to note that there are both fixed and floating offshore structures, the type and design of which will depend on the location and specific use of the structure. Fixed offshore structures are those that are anchored to the seabed, while floating structures are those that are not anchored and are able to move with the waves and currents. Examples of fixed offshore structures include oil and gas platforms, wind turbines, and underwater pipelines, while examples of floating structures include ships, semi-submersible platforms and floating wind turbines.

Concrete in offshore structures

Concrete is a commonly used material in the construction of offshore structures, such as oil and gas platforms, wind turbines, and artificial islands. This is due to its durability, strength, and ability to withstand harsh marine environments.

Offshore structures are built in areas with high exposure to wind, waves, and saltwater, which can cause corrosion and erosion to materials. Concrete, being a porous material, can absorb and hold water. But when reinforced with steel bars, it becomes stronger and less prone to cracking or breaking.

The use of concrete in offshore structures also allows for flexibility in design as well as being relatively easy to maintain and repair, which is important for structures that need to operate for extended periods in harsh marine environments. Additionally, the use of concrete in offshore structures can help to reduce the environmental impact of these structures by reducing the need for extensive maintenance or replacement.

Additionally, advancements in technology and construction methods have led to the development of specialized concretes, such as self-healing concrete, which are able to withstand extreme conditions and prolong the life of the structure.

Concrete is used in many different parts of offshore structures, including:

Foundation piles: Concrete piles are often used to support the weight of the structure and anchor it to the sea floor.

Caissons: Concrete caissons are used to provide a stable base for the structure and to protect it from wave action.

Gravity bases: Concrete gravity bases are used in the construction of offshore wind turbines and other structures that require a stable foundation in deep waters.

Platforms: Concrete platforms are used as the base for many offshore structures, including drilling rigs, production facilities, and wind turbines.

Breakwaters: Concrete breakwaters are used to protect harbors, ports, and other coastal structures from waves and storms.

Seawalls: Concrete seawalls are used to protect coastal areas from erosion and storm surges.

Substructures: Concrete substructures are used to provide support and stability to the main structure, such as in oil and gas drilling platforms.

Challenges of concrete production at open sea:

  1. Weather conditions: Production of concrete at open sea can be challenging due to the unpredictable weather conditions. High winds, waves, and storms can disrupt the production process and make it difficult to maintain quality control.
  2. Accessibility: Concrete production at open sea can be difficult due to limited accessibility to the site.
  3. Limited access to resources: Open sea production requires a considerable amount of resources such as water, power and materials, due to the remoteness of the location it can pose a significant constraint on the project.
  4. Logistics: Logistics is another challenge when producing concrete at open sea, since materials and equipment need to be transported over large distances and through harsh conditions, it can be difficult to ensure the timely delivery of these items.
  5. Time-consuming: Due to the many challenges and limitations of working in open sea conditions, concrete production can be a time-consuming process, with long lead times and delays.
  6. Weather conditions: Concrete production at open sea is subject to harsh weather conditions such as high winds, waves, and storms, which can disrupt the production process and damage equipment.
  7. The limited space at open sea makes it difficult to transport equipment and materials to the production site. As well as the production site being very limited. This can lead to delays and increased costs.
  8. Stability: The instability of the ocean can make it difficult to maintain the proper mix of concrete and keep it at the right consistency.
  9. Cost: The challenges of concrete production at open sea can lead to increased costs, such as the need for specialized equipment and additional safety measures. This can make the process more expensive than production on land.

It’s important to note that designing, building, and maintaining these structures can be challenging and requires specialized knowledge and equipment. The harsh offshore environment, with its corrosive saltwater and unpredictable weather conditions, can take a toll on the structures and their equipment. Additionally, the risk of accidents and spills must also be considered, which can have significant environmental and economic consequences.

Offshore construction also requires rigorous regulatory compliance and environmental impact assessments. The design and construction of offshore structures are subject to strict safety and environmental regulations to ensure that they are built and operated in a safe and sustainable manner. Permits, licenses, and environmental assessments are often required before the start of construction.

Types of concrete used in offshore construction:

  1. Marine grade concrete: This type of concrete is specifically designed for use in marine environments, and is highly resistant to salt water and other corrosive elements. It is typically made with high-quality aggregates and reinforced with steel or other reinforcement materials.
  2. Fiber-reinforced concrete: This type of concrete is reinforced with fibers made from materials such as glass, carbon, or polypropylene. These fibers help to increase the strength and durability of the concrete, making it more resistant to salt water and other corrosive agents.
  3. High-performance concrete: This type of concrete is designed to have superior strength, durability, and resistance to salt water and other corrosive elements. It is typically made with high-quality aggregates and reinforced with steel or other reinforcement materials.
  4. Self-compacting concrete: This type of concrete is highly fluid and can be poured and spread easily, making it ideal for use in marine environments. It is also highly resistant to salt water and other corrosive agents, making it a popular choice for marine construction projects.
  5. Sulphate-resistant concrete: This type of concrete is specially designed to withstand the effects of sulphates, which can be present in salt water and other marine environments. It is typically made with low-alkali cement, which is less likely to react with sulphates and cause damage to the concrete.

Producing concrete on an offshore platform can be a challenging task due to the harsh marine environment and the limited space available on the platform. However, there are a few different methods that can be used to produce concrete on an offshore platform.

One method is to mix the concrete onshore and transport it to the platform by barge or other marine vessel. This can be a cost-effective solution, but it requires careful coordination and planning to ensure that the concrete is delivered to the platform at the right time and in the right condition. Since fresh concrete has a relatively short life cycle, this method will not be suitable for most of the construction projects in the open sea.

Another method is to use a mobile concrete batch plant such as Carmix, that can be set up on the platform itself. This can be a more flexible option, as the concrete can be produced on-demand and the mix can be adjusted as needed. However, it can be more expensive, as the batch plant and equipment will need to be transported to the platform and set up. The main benefit of Carmix in this situation will be the lack of problems related to setting up and preparing for operations. There is no lead time with carmix and it is ready to produce concrete right away.

Another serious challenge with mobile batching plants or other concrete equipment is getting permission from the environmental authorities to use it at open sea. We can tell you that it is very difficult and in most cases just impossible due to a lot of dust and other debris from operations of stationary and mobile batching plants. Carmix on the other hand does not need a special pre-authorisation by the authorities.

A third method is to use pre-casted concrete modules that can be assembled on the platform. This can be an efficient solution, as the heavy lifting and concrete pouring can be done on shore, and the modules can be transported and installed by crane. This approach also has the benefit of being more predictable. However, in a lot of cases this is not possible as concrete has to be poured in a liquid state. This is especially the case for various offshore pile construction projects.

Carmix USA has experience in this narrow but challenging fiend of offshore concrete production. Contact us and see how your project can solve it`s concrete needs with the help of self loading mobile concrete mixer!