Offshore Membrane Gas Separation for Synthetic Crude Production
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Solution Overview
Problem
Offshore oil platforms face challenges in disposing of associated gases due to high costs and environmental concerns associated with flaring and reinjection, particularly due to the high compression requirements for gases containing high percentages of light hydrocarbons and CO2.
Innovation Solution
A system utilizing crosslinked polyimide polymer membranes to separate CO2 from associated gases, producing a CO2 enriched permeate stream for reinjection and a CO2 depleted product gas stream for conversion into synthetic crude oil, with the membrane unit operating at elevated temperatures to enhance efficiency and reduce equipment size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire associated gas stream (hydrocarbons and CO2) is compressed for reinjection, then the gas can be injected back into the reservoir, but the power consumption increases significantly and injection pressure must be much higher
Solution Approach 1:
The patent extracts CO2 from the associated gas stream using membrane separation technology, creating a CO2-enriched stream and a hydrocarbon-enriched stream. This extraction allows the hydrocarbon stream to be reinjected without the high compression costs associated with compressing the entire mixed gas stream, as hydrocarbons can be reinjected at lower pressures compared to CO2.
Solution Approach 2:
The associated gas stream is segmented into separate CO2 and hydrocarbon components through membrane separation. This segmentation enables different reinjection strategies for each component, with hydrocarbons being reinjected at lower pressures and CO2 being handled separately, thereby reducing the overall compression power requirements.
2Productivity
If crosslinked polyimide polymer membranes are used to separate CO2 from associated gases, then separation efficiency improves and equipment size/weight is reduced, but the membrane unit requires elevated operating temperatures
Solution Approach 1:
The patent utilizes parameter changes by operating the crosslinked polyimide polymer membranes at elevated temperatures (above their glass transition temperature). This temperature increase changes the physical state and permeability characteristics of the membrane, enhancing CO2 separation efficiency and allowing the membranes to achieve higher productivity with reduced equipment size and weight.
3Ease of manufacture
If associated gases with high CO2 content are flared, then disposal is achieved, but environmental concerns arise and valuable gas is lost
Solution Approach 1:
The patent converts the harmful aspect of high CO2 content associated gases into a benefit by separating CO2 from the gas stream. The CO2-enriched permeate stream can be reinjected into the reservoir for enhanced oil recovery, while the hydrocarbon-enriched retentate stream can be used as fuel or sold, thereby eliminating the need for flaring and converting a disposal problem into valuable resources.
4Reliability
If gas reinjection equipment is added to the platform, then associated gases can be disposed of, but the cost increases and subsurface risks are heightened
Solution Approach 1:
The patent replaces the need for extensive mechanical compression equipment with membrane separation technology. By using crosslinked polyimide polymer membranes to separate and concentrate CO2, the system eliminates or reduces the need for high-power compression equipment that would otherwise be required to reinject the entire associated gas stream, thereby reducing device complexity and cost.
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 approach allows for efficient separation and conversion of associated gases, reducing the need for extensive compression, minimizing environmental impact, and enabling the production of synthetic crude oil suitable for storage, while optimizing the recovery of oil from hydrocarbon reservoirs.
Implementation Method 1
a membrane unit comprising a plurality of polymer membranes to provide a CO2 enriched permeate stream and a CO2 depleted product gas stream
Implementation Method 2
a heat exchanger receiving a fluid from the gas conversion plant and adding heat to the associated gas stream so that the membrane unit operates at a temperature of at least 80° C.
Data Source
AI summary
A system and process for producing synthetic crude oil from produced fluids of an oil well is disclosed. The system comprises a separation plant for producing an associated gas stream from produced fluids a membrane unit comprising a plurality of polymer membranes to provide a CO2 enriched permeate stream and a CO2 depleted product gas stream, a gas conversion plant for converting the CO2 depleted product gas stream into a synthetic crude oil and a heat exchanger adding heat to the associated gas stream so that the membrane unit operates at a temperature of at least 80° C. during separation of the associated gas stream using the membrane unit. A process using the aforementioned components, including separation of the associated gas stream using the membrane unit at a temperature >80° C., into a CO2 enriched stream and a CO2 depleted product stream, is also described.