Hydrocarbon Recovery via Layered Polymer Injection
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Solution Overview
Problem
In subterranean formations with high permeability upper layers and low permeability lower layers, existing hydrocarbon recovery methods face inefficiencies due to cross-flow issues caused by gravity and capillary forces, leading to poor sweep efficiency and reduced hydrocarbon recovery.
Innovation Solution
Injecting a polymer solution into the upper layer and an aqueous solution with lower salinity into the lower layer, where the polymer solution has a higher salinity than the aqueous solution, creating a highly viscous mixture that acts as a barrier between the layers, preventing cross-flow and enhancing sweep efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If waterflooding is used in layered subterranean formations, then hydrocarbon recovery is achieved, but cross-flow from upper to lower layer occurs due to gravity, reducing sweep efficiency
Solution Approach 1:
The patent changes the density parameter of the injected fluid by using a polymer solution with higher density than the formation fluids. This density modification creates a downward gravitational force that counteracts the natural upward cross-flow tendency, improving sweep efficiency in the lower permeability layer while maintaining overall hydrocarbon recovery
Solution Approach 2:
The patent applies different fluid properties to different layers by injecting polymer solution specifically targeted at the lower permeability layer. The polymer solution's unique combination of high density and high viscosity creates localized flow control, preventing cross-flow in critical zones while maintaining productivity across the entire formation
2Ease of operation
If polymer is added to increase water viscosity for better sweep efficiency, then sweep efficiency improves, but polymer degradation occurs due to shear forces and interaction with formation water
Solution Approach 1:
The patent modifies the chemical composition parameters of the polymer solution by adding specific salts (such as calcium chloride or sodium chloride) to adjust ionic strength and pH levels. These parameter changes enhance polymer stability against degradation while maintaining the desired high viscosity for improved sweep efficiency
Solution Approach 2:
The patent creates a composite fluid system by combining polymer molecules with specific salt components and potentially other additives. This composite formulation provides synergistic effects where the salt components protect the polymer structure from shear degradation and thermal breakdown, ensuring reliability while achieving the viscosity needed for improved sweep efficiency
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 method improves hydrocarbon recovery by maintaining each solution within its respective layer, increasing sweep efficiency and productivity in a cost-effective manner, using lower amounts of polymer and leveraging desalination processes to produce both solutions.
Implementation Method 1
creating a highly viscous mixture that acts as a barrier between the layers
Implementation Method 2
in a subterranean formation where a high permeability layer is located above a low permeability layer, gravity leads to cross-flow of injected water from the top to the bottom zone of the subterranean formation. However, in the case of oil-wet subterranean formations, capillary forces act opposite to gravity and result in a barrier which prevents water from moving downwards
Implementation Method 3
gravity leads to cross-flow of injected water from the top to the bottom zone of the subterranean formation
Data Source
AI summary
The present invention relates to methods for recovering hydrocarbons from subterranean formations. One such example embodiment injects a polymer solution into an upper layer of a subterranean formation and, likewise, injects an aqueous solution into a lower layer of the subterranean formation. Hydrocarbons displaced by at least one of the injected polymer and the injected aqueous solution are collected.