Subsea Multiphase Separation for Flow Assurance
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Solution Overview
Problem
Current subsea oil production systems face challenges in maintaining flow rates due to clogging from wax, asphaltenes, and hydrates, and struggle with efficient water separation and disposal, especially in remote or marginal fields, leading to high costs and environmental concerns.
Innovation Solution
A subsea production unit with a multiphase separation system and integrated water treatment system, including a gas separator, dual pipe separators, and compact flotation units, which separates gas and water from the wellstream and cleans oil from water, allowing for subsea storage and offloading of oil while managing water disposal through reinjection or discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal insulation or heating is employed to maintain oil temperature above the critical threshold, then pipeline plugging by wax, asphaltenes or hydrates is prevented, but production cost and energy consumption increase significantly
Solution Approach 1:
The patent applies preliminary action by separating water from the wellstream at the subsea wellhead before the oil enters the pipeline. This preliminary water removal prevents the formation of hydrates and reduces the risk of wax deposition, thereby maintaining flow assurance without requiring continuous thermal energy input along the pipeline. The water separation unit operates at the source, preventing problems before they occur in the transmission system.
Solution Approach 2:
The invention extracts water from the multiphase wellstream at the subsea location using a water separation unit. By removing the water phase that causes hydrate formation and reduces oil quality, the system eliminates the need for expensive thermal insulation and heating measures along long subsea pipelines, significantly reducing energy consumption while maintaining flow assurance.
2Reliability
If long insulated pipelines are used to transport crude oil from remote subsea fields, then flow assurance is maintained, but development cost becomes prohibitively expensive
Solution Approach 1:
The patent implements preliminary action by performing water separation at the subsea wellhead before oil enters the transmission pipeline. This upfront water removal prevents hydrate formation and reduces wax deposition risk, maintaining flow assurance without requiring expensive long-distance thermal insulation and heating infrastructure, thereby reducing overall development costs for remote fields.
Solution Approach 2:
The invention extracts water from the wellstream at the subsea location, improving oil quality and preventing pipeline plugging. This extraction of the problematic water phase eliminates the need for costly thermal protection measures over long pipeline distances, making development of remote subsea fields economically viable.
3Device complexity
If water is not separated from the wellstream at subsea location, then subsea storage and transport are simplified, but oil quality deteriorates and environmental compliance becomes difficult
Solution Approach 1:
The patent applies preliminary action by separating water from the wellstream at the subsea wellhead before storage and transport. This preliminary treatment ensures high oil quality and low water content, enabling compliant subsea storage and transport without requiring complex downstream water removal facilities, thus simplifying overall infrastructure while maintaining oil quality.
Solution Approach 2:
The system performs preliminary water separation at the subsea location, producing high-quality dehydrated oil suitable for storage and transport. This upfront dehydration ensures compliance with environmental regulations and storage requirements without needing complex post-storage water removal systems, simplifying the overall infrastructure.
4Quantity of substance
If produced water is discharged directly into the sea, then disposal cost is minimized, but environmental regulations are violated due to high Oil-in-Water ratios
Solution Approach 1:
The patent applies preliminary action by separating water from oil at the subsea wellhead before production. This preliminary water separation produces low-volume produced water with low Oil-in-Water ratios, enabling environmentally compliant discharge or reinjection without requiring expensive surface treatment facilities, thus minimizing disposal costs while ensuring environmental compliance.
Solution Approach 2:
The invention extracts water from the wellstream at the subsea location, producing high-quality separated water with low oil content. This extraction ensures that the small volume of produced water can be discharged or reinjected in compliance with environmental regulations, avoiding the need for expensive surface treatment while maintaining environmental compliance.
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 solution enables efficient subsea treatment and storage of oil, reduces costs and power consumption, and effectively manages water disposal, enhancing flow assurance and compliance with environmental regulations by maintaining low Oil-in-Water ratios.
Implementation Method 1
an onboard multiphase separation system for separating gas and water from a wellstream containing oil
Implementation Method 2
an onboard water treatment system for cleaning oil from water that is produced by the separation system
Data Source
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AI summary
A subsea production unit for subsea treatment of oil comprises a frame that supports: an onboard multiphase separation system for separating gas and water from a wellstream containing oil; and an onboard water treatment system for cleaning oil from water that is produced by the separation system.