Mitigating hydrate formation during a shutdown of a deep water fpso

Abstract

The present invention relates to a system and method for avoiding hydrate formation during a shutdown of a deep-water floating production, storage and offloading unit with a long distance tie back. In one embodiment the system is configured such that during a shutdown at least a portion of fluids in the production flow loop are delivered to the one or more wash tanks in the hull. Advantageously, this may allow one to avoid having to oversize the expensive top-side equipment.

Description

FIELD OF THE INVENTION[0001]Embodiments disclosed herein relate to methods and systems for mitigating hydrate formation during a shutdown of a deep-water floating production, storage and offloading unit with long distance tie backs.BACKGROUND AND SUMMARY[0002]Deep-water floating production, storage and offloading (FPSO) units are frequently used in offshore production to process hydrocarbons and store oil until it can be offloaded to a tanker or in some cases transported through a pipeline. In many instances one FPSO unit may be connected to multiple subsea production wells some of which are very remote and some of which may be in very deep water. In such cases the production flow loops connecting the wells and FPSO units may be quite long and are therefore referred to as long distance tie-backs.[0003]Long distance tie-backs present a number of technical challenges. One challenge is that during a decrease in flow and / or during a complete shut-down of flow in the production flow loop...

AI Technical Summary

Benefits of technology

The patent text describes a method for managing hydrates in a subsea production system during a shutdown. The method involves delivering hydrocarbon fluids produced from remote subsea production wells to an offshore production facility through a production flow loop. During a shutdown, hydrates can form and cause problems in the production flow loop. The invention provides new methods and systems for preventing hydrates formation and managing them during a shutdown using conventionally available equipment. The technical effect is to mitigate hydrates and prevent them from causing damage to the production system during shutdowns.

Problems solved by technology

Long distance tie-backs present a number of technical challenges.

One challenge is that during a decrease in flow and / or during a complete shut-down of flow in the production flow loop, hydrates may tend to form in the presence of CH4 and H2O in a low temperature and / or high pressure environment.

Once formed these hydrates may cause significant problems.

For example, since the hydrates are ice-like crystals they will often hinder and / or completely block the production flow loop.

Once this occurs costly and complicated remediation efforts to unplug the production flow lines to resume production are usually necessary.

Unfortunately, in addition to other disadvantages such approaches are often complex, expensive, or both.

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