SWRO Brine Treatment for Sulfate-Compatible Reservoir Injection Water
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Solution Overview
Problem
The disposal of seawater reverse osmosis (SWRO) brine poses environmental concerns due to high salt and mineral content, and its direct use as injection water for reservoirs is hindered by compatibility issues such as high total dissolved solids (TDS), sulfate, and other impurities that can cause fouling and damage to reservoirs.
Innovation Solution
A method and system utilizing nanofiltration and membrane distillation processes to treat SWRO brine, reducing sulfate and NaCl levels, and increasing TDS, to produce injection water suitable for reservoir pressure maintenance, with optional post-treatment for further purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If SWRO brine is used directly as injection water, then water consumption is reduced and environmental impact is minimized, but reservoir damage and fouling occur due to high TDS, sulfate, and impurities
Solution Approach 1:
The patent applies preliminary action by implementing nanofiltration and membrane distillation processes before the brine is injected into the reservoir. The nanofiltration unit pre-treats the brine to remove some impurities, and the membrane distillation unit further concentrates and purifies the brine, preventing reservoir damage and fouling while still utilizing the brine for injection water purposes.
Solution Approach 2:
The patent uses an intermediary approach by introducing treatment systems (nanofiltration and membrane distillation units) as intermediaries between the SWRO brine and the reservoir. These intermediary systems modify the brine composition to make it compatible with reservoir injection requirements, eliminating the harmful effects while preserving the useful function of maintaining reservoir pressure.
2Manufacturing precision
If brine concentration is increased to reduce sulfate and NaCl levels, then injection water quality improves, but process complexity and energy consumption increase
Solution Approach 1:
The patent applies segmentation by dividing the brine treatment process into distinct functional units: a nanofiltration unit for initial separation and a membrane distillation unit for concentration and purification. Each unit performs a specific function, making the overall complex process more manageable and modular while achieving the desired injection water quality through sequential treatment stages.
3Reliability
If multiple treatment stages are implemented to purify brine, then injection water suitability increases, but operational costs and energy consumption increase
Solution Approach 1:
The patent applies parameter changes by utilizing different driving forces for each treatment stage: the nanofiltration unit operates based on pressure-driven separation, while the membrane distillation unit utilizes temperature-driven vaporization and condensation. By changing the operational parameters and driving mechanisms between stages, the system achieves effective brine purification while managing energy consumption through optimized process conditions.
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
The process effectively transforms SWRO brine into injection water, reducing environmental impact, minimizing groundwater consumption, and enhancing membrane longevity and process efficiency by pre-treating with nanofiltration before membrane distillation or forward osmosis, allowing for flexible configuration and reduced operational costs.
Implementation Method 1
The nanofiltration unit is configured to receive a brine that is produced based on a reverse osmosis of water, perform a rejection of NaCl and sulfate of the brine, and generate a permeate and a retentate based on the brine
Implementation Method 2
The membrane distillation unit is configured to receive the permeate from the nanofiltration unit and generate, based on the permeate, a concentrated brine for use in producing injection water for a reservoir
Implementation Method 3
receiving a brine that is produced based on a reverse osmosis of water
Implementation Method 4
Performing the separation of the brine includes performing at least one of a filtration, a membrane distillation, or a forward osmosis
Data Source
AI summary
A method for producing an injection water for a reservoir includes receiving a brine that is produced based on a reverse osmosis of water, performing a separation of the brine, producing a concentrated brine based on the separation of the brine, and producing, based on the concentrated brine, the injection water suitable for use in maintaining a reservoir pressure. Performing the separation of the brine includes performing at least one of a filtration, a membrane distillation, or a forward osmosis. The concentrated brine has a lower sulfate level and NaCl level and a higher total dissolved solids (TDS) level than the brine.