Asset Integrity Management

CIT (subsea)

CIT (Subsea): The Chemical Injection for Trees in Oil & Gas Operations

In the complex world of subsea oil and gas extraction, every component plays a vital role in the efficient and safe retrieval of valuable resources. One such component, often overlooked but crucial to the smooth operation of subsea production systems, is the Chemical Injection Tree (CIT).

What is a CIT?

A CIT is a subsea structure designed to inject chemicals directly into the production stream before it reaches the wellhead or processing facilities on the surface. These chemicals are essential for various critical functions, including:

  • Corrosion Inhibition: Preventing the formation of rust and corrosion within the pipes and equipment, extending their lifespan and minimizing production losses.
  • Scale Inhibition: Preventing the buildup of mineral deposits, such as calcium carbonate, which can hinder flow and reduce production efficiency.
  • Wax Inhibition: Preventing the formation of paraffin wax, which can clog pipelines and equipment, especially in colder environments.
  • Hydrate Inhibition: Preventing the formation of ice-like hydrates, which can also obstruct flow and damage equipment.
  • Biocide Injection: Controlling the growth of bacteria and other microorganisms that can cause fouling and corrosion.

How does a CIT work?

A CIT typically comprises:

  • Injection Manifold: A central hub that receives chemicals from the surface through injection lines.
  • Injection Points: Individual points where chemicals are injected into the production stream at precise locations.
  • Control System: Electronic systems that monitor and control the injection of chemicals, ensuring optimal flow rates and dosages.

Benefits of Using a CIT:

  • Improved Production Efficiency: By preventing corrosion, scaling, wax, and hydrates, CITs ensure smooth and uninterrupted flow of oil and gas, maximizing production.
  • Extended Equipment Lifespan: By minimizing corrosion and wear and tear, CITs increase the longevity of subsea equipment, reducing maintenance costs and downtime.
  • Enhanced Safety: By controlling the formation of potentially hazardous substances, CITs contribute to a safer and more stable production environment.
  • Reduced Environmental Impact: By optimizing production and preventing leaks, CITs minimize the risk of spills and environmental damage.

Future of CITs:

As the oil and gas industry continues to explore new and challenging environments, the role of CITs will become even more critical. Advancements in technology, such as remote monitoring and control systems, are further enhancing the efficiency and reliability of these essential components.

Conclusion:

The Chemical Injection Tree is an unsung hero in subsea oil and gas production, playing a vital role in ensuring the safe, efficient, and sustainable extraction of valuable resources. As the industry continues to evolve, CITs will remain essential in meeting the challenges of this demanding environment.

Test Your Knowledge

CIT (Subsea) Quiz:

Instructions: Choose the best answer for each question.

1. What is the primary function of a Chemical Injection Tree (CIT)?

a) To regulate the flow of oil and gas. b) To inject chemicals directly into the production stream. c) To monitor pressure and temperature in the subsea pipeline. d) To separate water and gas from the oil.

Answer

b) To inject chemicals directly into the production stream.

2. Which of these is NOT a function of chemicals injected by a CIT?

a) Corrosion inhibition b) Scale inhibition c) Fluid viscosity reduction d) Hydrate inhibition

Answer

c) Fluid viscosity reduction

3. What is the central hub of a CIT that receives chemicals from the surface?

a) Injection manifold b) Injection point c) Control system d) Production stream

Answer

a) Injection manifold

4. Which of the following is NOT a benefit of using a CIT?

a) Increased production costs b) Extended equipment lifespan c) Improved production efficiency d) Enhanced safety

Answer

a) Increased production costs

5. What is a key technological advancement that is improving the efficiency and reliability of CITs?

a) Manual control systems b) Remote monitoring and control systems c) Automated drilling systems d) Subsea robotic platforms

Answer

b) Remote monitoring and control systems

CIT (Subsea) Exercise:

Problem: A subsea production system experiences a significant drop in flow rate. The operator suspects a build-up of paraffin wax in the pipeline.

Task: Explain how a CIT can be used to address this problem, outlining the specific chemicals and their functions.

Exercice Correction

The CIT can be used to address this problem by injecting a chemical specifically designed for **wax inhibition**. This chemical would be a **dispersant or solvent** that would break down the paraffin wax already present in the pipeline and prevent further wax build-up. Here's how it works:

  • The CIT's control system would be adjusted to increase the dosage of the wax inhibitor.
  • The inhibitor would be injected into the production stream, targeting the affected sections of the pipeline.
  • The inhibitor would work to dissolve the existing wax deposits, allowing the flow to be restored.
  • The continuous injection of the inhibitor would prevent further wax formation, maintaining a smooth flow in the pipeline.

This illustrates how CITs can actively address production challenges by providing targeted chemical solutions.

Books

  • Subsea Engineering Handbook by Paul D. S. Evans - This comprehensive handbook covers various aspects of subsea engineering, including chemical injection systems.
  • Subsea Production Systems by Knut B. Johansen and Einar Dybedal - This book provides a detailed overview of subsea production systems, including the role of CITs.

Articles

  • Chemical Injection in Subsea Production Systems: A Review by J. S. H. Lee, et al. - This article presents a comprehensive review of chemical injection in subsea production systems, focusing on challenges and solutions.
  • Subsea Chemical Injection: A Technological Overview by P. J. N. van der Merwe - This article provides an overview of the technologies used in subsea chemical injection systems.
  • The Role of Chemical Injection in Subsea Production Optimization by S. M. Smith - This article discusses the importance of chemical injection in optimizing subsea production.

Online Resources

  • Subsea World - This website provides news and information about the subsea industry, including articles and case studies related to CITs.
  • Subsea 7 - This company website offers insights into the design, installation, and operation of subsea production systems, including chemical injection systems.
  • OneSubsea - This company website provides information about their subsea production systems, including chemical injection technology and solutions.

Search Tips

  • Use specific keywords: When searching for information on CITs, use specific keywords like "subsea chemical injection tree," "subsea production chemical injection," or "subsea corrosion inhibition."
  • Combine keywords with industry terms: Try searching for "subsea CITs," "subsea chemical injection systems," or "subsea production chemicals."
  • Explore industry publications: Search for articles and papers on subsea engineering, oil and gas production, and corrosion inhibition.
  • Check company websites: Look for information about CITs on websites of major subsea equipment suppliers and service providers.

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