Subsea Preconditioning Unit for Pressure Boosting Temperature Control

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Solution Overview

Problem

Current subsea pressure elevation systems face challenges in managing fluid temperature increases due to pressure gains, which can lead to equipment damage downstream, as existing heat exchanger solutions lack comprehensive control over process fluid parameters.

Innovation Solution

A subsea system with a passive cooler and secondary line for temperature control, equipped with sensors for temperature and pressure measurement, and a bypass line with control valves to adjust fluid flow, ensuring the process fluid meets the operational window of the pressure boosting device, thereby preventing equipment damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pressure elevation systems are used to increase fluid pressure for efficient transport, then productivity is improved, but temperature increases proportionally which can damage downstream equipment

Engineering Contradiction:
Improvefluid transport efficiencyVSAvoidfluid temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The system performs preliminary cooling of the fluid before it enters the pressure boosting device through a cooler unit positioned upstream. This preliminary action prevents temperature-related damage to the pressure boosting device while maintaining the pressure elevation needed for efficient transport.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A cooler unit is introduced as an intermediary component between the well outlet and the pressure boosting device. This intermediary actively removes excess heat from the fluid, allowing the pressure elevation system to operate efficiently without transferring harmful thermal energy to downstream equipment.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If active heat exchangers with controlled seawater flow are used to manage temperature, then temperature control is improved, but device complexity increases

Engineering Contradiction:
Improveprocess fluid temperatureVSAvoidheat exchanger system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooler unit utilizes naturally occurring cold seawater from the subsea environment as the cooling medium. The system benefits from the ambient cold temperature without requiring active refrigeration equipment or complex thermal management systems, thereby maintaining simplicity while achieving effective temperature control.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system employs hydraulic principles by utilizing the natural flow and cold temperature of seawater to cool the process fluid through heat exchange. This passive hydraulic approach avoids the need for mechanically complex active refrigeration systems while achieving the desired temperature control.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Reliability

If comprehensive parameter control is implemented to prevent equipment damage, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improveequipment protectionVSAvoidpreconditioning system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Temperature sensors are positioned at strategic locations within the cooler unit to monitor the thermal state of the process fluid. This feedback mechanism allows the system to automatically adjust cooling operations to maintain temperatures within safe operating parameters, protecting downstream equipment without requiring complex control systems.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The preconditioning system is divided into modular components including the cooler unit with integrated temperature sensors and control mechanisms. This segmentation allows for independent optimization of each component and simplifies maintenance and operation while achieving comprehensive parameter control for equipment protection.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This system effectively controls the outlet temperature of the process fluid, ensuring it operates within the required density and temperature parameters, preventing hydrate formation and equipment damage, while avoiding the need for additional rotary equipment, thus reducing failure points.

Implementation Method 1

In a passive subsea heat exchanger, the process fluid passes through tubes in which the heat exchange occurs with the seawater, simply using the principle of thermal conduction.

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

For the active heat exchangers, the principle of thermal convection is also used to improve and/or control the thermal exchange.

Methodology Applied
Scientific EffectThermal convection: Convection

Implementation Method 3

These systems elevate the pressure of the fluids so that they can be transported to an oil rig, to an onshore location or to offshore production and/or processing units.

Methodology Applied
Scientific EffectPressure elevation: Pressurisation

Implementation Method 4

One consequence of the increase in fluid pressure is the increase in temperature. This increase in temperature in the fluid is proportional to the increase in pressure.

Methodology Applied
Scientific EffectCompression heating: Compression

Data Source

PatentEP4208622B1A subsea system comprising a preconditioning unit and pressure boosting device and method of operating the preconditioning unit
Publication Date: 2024.07.31 FMC TECH DO BRASIL
  • EP4208622B1 patent drawingFigure 1A
  • EP4208622B1 patent drawingFigure 1B
  • EP4208622B1 patent drawingFigure 2A

AI summary

Aa subsea system (1) connected to a subsea well (4) for boosting a process fluid flowing out of the well, comprising: - a preconditioning arrangement (2) connectable to a process fluid line from a well, wherein the preconditioning arrangement comprises at least one sensor for measuring temperature and one sensor for measuring pressure of the process fluid -means for estimating density of the process fluid based on measured temperature and pressure, -a cooler system (20, 21) comprising at least a first cooler for cooling the process fluid wherein the subsea system further comprises: -a pressure boosting device (3) arranged downstream of the preconditioning arrangement (2), the pressure boosting device having an operational window dictating operational parameter in terms of maximum and minimum allowable density of the process fluid entering the pressure boosting device (3).