Systems and processes for upgrading natural gas liquids from shale gas
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Solution Overview
Problem
Current processes for upgrading natural gas liquids (NGLs) to liquid hydrocarbons are inefficient, particularly in shale gas fields like Marcellus and Bakken, where significant amounts of C2+ are lost during separation, leading to wasted resources and increased transportation costs.
Innovation Solution
A process that involves dehydrogenating C2+ hydrocarbons to produce olefin derivatives, followed by oligomerization to create C4 to C26 oligomers, using a liquid absorbent to separate methane from the oligomers, and recycling the oligomers to enhance the separation efficiency and reduce waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional separation processes are used to separate methane from NGLs, then methane can be recovered for pipeline transport, but significant amounts of C2+ hydrocarbons are lost during separation
Solution Approach 1:
The patent applies preliminary action by performing dehydrogenation and oligomerization reactions on C2+ hydrocarbons before the separation step. By converting C2+ alkanes to olefins and then oligomerizing them into C4-C26 oligomers beforehand, the process ensures that these valuable hydrocarbons are transformed into liquid products that can be efficiently separated and recovered, preventing their loss during conventional separation operations.
Solution Approach 2:
The patent utilizes parameter changes by altering the chemical state of C2+ hydrocarbons through dehydrogenation (changing saturation level) and oligomerization (changing molecular weight and phase). These parameter transformations convert gaseous C2+ alkanes into liquid oligomers with different physical and chemical properties, enabling efficient separation from methane while minimizing losses.
2Ease of manufacture
If NGLs are transported to downstream processing plants, then they can be upgraded to liquid hydrocarbons, but the transportation cost becomes capital intensive
Solution Approach 1:
The patent applies the taking out principle by extracting the upgrading function from centralized downstream processing plants and moving it to the wellhead location. By implementing dehydrogenation and oligomerization units directly at the gas processing site, the process eliminates the need to transport NGLs over long distances, thereby removing the transportation cost burden while maintaining high NGL utilization efficiency.
Solution Approach 2:
The patent introduces an intermediary approach by using a liquid absorbent (such as heavy naphtha or diesel range hydrocarbons) to separate and recover the oligomerized C4-C26 products from the reaction mixture. This intermediary substance enables efficient product separation and recovery at the wellhead, making the in-situ upgrading process economically viable and reducing dependence on expensive transportation infrastructure.
3Productivity
If dehydrogenation and oligomerization are performed before separation, then liquid hydrocarbon yield increases, but the process complexity increases
Solution Approach 1:
The patent applies merging by combining multiple functions into integrated processing units. The dehydrogenation and oligomerization reactions are performed in sequence within a unified process train at the wellhead, and the liquid absorbent serves multiple purposes including product separation, purification, and potential recycle to the reaction units. This integration reduces overall system complexity compared to transporting NGLs to separate processing facilities.
Solution Approach 2:
The patent implements self-service by using a portion of the produced liquid hydrocarbons or other available liquid streams as the absorbent medium for separation. This eliminates the need for external purchase of specialized absorbents and reduces the requirement for complex external supply chains, making the processing unit more self-sufficient and operationally simpler.
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 process significantly increases the yield of liquid hydrocarbons, reduces C2+ loss, and lowers transportation costs by efficiently converting NGLs into value-added products, thereby optimizing the utilization of shale gas resources.
Implementation Method 1
separating the methane from the one or more liquid hydrocarbons using a liquid absorbent
Implementation Method 2
converting at least a portion of the natural gas liquids to one or more olefins
Implementation Method 3
oligomerizing the first converted stream to provide a second converted stream comprising methane and one or more C4 to C26 oligomers
Data Source
AI summary
Systems and processes for upgrading natural gas liquids (NGL). A natural gas, preferably a shale gas, comprising methane and one or more natural gas liquids can be converted to one or more liquid hydrocarbons. Methane can be separated from the one or more liquid hydrocarbons using a liquid absorbent to provide a first separated stream comprising the methane from the converted stream and a second separated stream comprising the one or more liquid hydrocarbons from the converted stream. At least a portion of the one or more liquid hydrocarbons can be recycled as the liquid absorbent.