Expandable Polymeric Microparticles for CO2 Flood Permeability Control
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Solution Overview
Problem
In hydrocarbon recovery processes, particularly in CO2 or CO2 Water Alternating Gas flooding, high permeability 'thief zones' within subterranean reservoirs divert injected fluids away from lower permeability zones, leading to inefficient hydrocarbon recovery due to the heterogeneity of reservoir rock strata and limitations of existing methods in modifying permeability at low pH.
Innovation Solution
Development of expandable crosslinked polymeric microparticles with labile internal crosslinks that can propagate through the pore structure of hydrocarbon reservoirs, expanding under low pH conditions to impede fluid flow and divert injected fluids into less swept zones, without requiring specific carrier fluids or being sensitive to salinity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional permeability control methods are used, then fluid flow can be controlled in high permeability zones, but the methods fail when thief zones are isolated from lower permeability zones by cement or mechanical seals
Solution Approach 1:
The patent introduces a chemical gel as an intermediary substance that can penetrate through the isolation barriers (cement or mechanical seals) and enter the isolated thief zone. The gel acts as a mediator that bypasses the conventional mechanical isolation methods and achieves permeability control within the previously inaccessible thief zone, thereby resolving the contradiction between reliability of conventional methods and adaptability to isolated zones.
Solution Approach 2:
The patent replaces mechanical isolation methods (cement barriers, mechanical seals) with a chemical gel system. Instead of relying on mechanical structures to block fluid flow, the chemical gel provides a flexible, penetrable barrier that can adapt to the reservoir geometry and penetrate through existing mechanical isolation layers, achieving the same permeability control effect with superior adaptability.
2Reliability
If chemical gels are used to seal off swept out zones, then fluid flow can be blocked, but the gels cannot penetrate through cement barriers or mechanical seals into isolated thief zones
Solution Approach 1:
The patent modifies the physical and chemical parameters of the gel system to enable penetration through cement barriers and mechanical seals. By adjusting the gel's viscosity, molecular size, and chemical composition, the gel can pass through the isolation barriers while maintaining its flow-blocking capability once inside the thief zone, thus resolving the contradiction between blocking capability and penetration ability.
Solution Approach 2:
The patent segments the gel system into different functional components: a penetrating fraction that can pass through the isolation barriers and a blocking fraction that provides flow control within the thief zone. This segmentation allows the gel system to perform both penetration and blocking functions simultaneously, resolving the contradiction between ease of penetration and reliability of flow blocking.
3Productivity
If produced fluid is reused in the injection process, then fluid cycling can be achieved, but fluid cycles through thief zones to little benefit at great cost
Solution Approach 1:
The patent converts the harmful effect of thief zones (which previously caused fluid cycling through low-permeability zones with little benefit) into a beneficial outcome. By introducing the chemical gel into the thief zone, the previously harmful high-permeability pathway is transformed into a controlled flow barrier, directing injected fluid away from the thief zone and into the surrounding hydrocarbon-bearing formations, thereby converting energy waste into effective hydrocarbon recovery.
Solution Approach 2:
The chemical gel acts as an intermediary that redirects fluid flow pathways. Instead of fluid cycling harmlessly through the thief zone, the gel creates a controlled barrier that forces the injected fluid to travel through alternative pathways into the surrounding formations, where it can effectively stimulate hydrocarbon production, thus converting the energy consumption into productive recovery.
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
These microparticles effectively modify permeability, enhancing hydrocarbon recovery by allowing deeper penetration and diversion of fluids, improving the mobilization and recovery rate of hydrocarbons, even in challenging geological formations with widespread contact between thief and hydrocarbon-containing zones.
Implementation Method 1
The labile crosslinkers were specifically selected to hydrolyze under low pH conditions allowing the particle to expand by absorbing the injection fluid
Implementation Method 2
The expanded particle is engineered to have a particle size distribution and physical characteristics (e.g., particle rheology) which allows it to impede the flow of injected fluid in the pore structure
Implementation Method 3
allowing the particle to expand by absorbing the injection fluid
Implementation Method 4
capable of moving through pores in reservoir rock
Data Source
AI summary
A composition including crosslinked expandable polymeric microparticles capable of hydrolysis at or below neutral pH and a method of modifying the permeability to water of a subterranean formation by introducing such compositions into the subterranean formation. This disclosure further relates to compositions and methods for the recovery of hydrocarbon fluids from a subterranean reservoir or formation subjected to CO2 or CO2 Water Alternating Gas flooding at low pH and increases the mobilization and/or recovery rate of hydrocarbon fluids present in the subterranean formations.