Delayed Gelation Agents via Degradable Polymeric Cages
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Solution Overview
Problem
Current methods for enhancing oil recovery through water injection are limited by the washout of polymer gels from high permeability zones, leading to incomplete sweep of less permeable zones, and rapid gelation prevents deep penetration into oil-bearing formations.
Innovation Solution
A degradable polymeric cage system is developed to encapsulate gelation agents, which delay their release and subsequent gelation by degrading at higher temperatures or pH changes, allowing for extended gelation times and deeper penetration into target zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If gelation agents are released immediately upon injection, then gelation occurs rapidly, but the polymer cannot penetrate deep into oil-bearing formations before gelling
Solution Approach 1:
The gelation agents are pre-encapsulated within degradable polymeric cages that protect them during injection and initial circulation. The cages degrade in situ under reservoir conditions (temperature, pH), releasing the gelation agents at the target location after sufficient penetration has occurred, thus achieving both deep penetration and controlled gelation timing
Solution Approach 2:
The degradable polymeric cages act as intermediaries that temporarily hold the gelation agents during transport through the reservoir. These cages protect the gelation agents from premature action while allowing the polymer to penetrate deep into the formation, then degrade to release the agents at the desired location and time
2Productivity
If polymer is injected to block thief zones, then sweep efficiency improves, but subsequent water injections wash out the polymer from high permeability zones
Solution Approach 1:
Polymer gels are pre-placed in the thief zones during initial water injection to block high permeability pathways and improve sweep efficiency. The degradable cages with encapsulated gelation agents are co-injected and degrade after placement, converting the polymer solution into stable gels that resist subsequent washout
Solution Approach 2:
The system exploits changes in reservoir conditions (temperature, pH) to trigger cage degradation and gelation. This parameter-based activation ensures that the polymer transforms from a mobile solution to a stable gel structure in situ, maintaining blockage effectiveness while resisting washout by subsequent injections
3Length of moving object
If gelation time is extended to allow deep penetration, then placement accuracy improves, but the polymer remains in liquid form and susceptible to washout
Solution Approach 1:
The polymer is injected in liquid form with encapsulated gelation agents protected within degradable cages. After deep penetration is achieved, the cages degrade under reservoir conditions, triggering in situ gelation that converts the liquid polymer to a stable gel structure at the target location, simultaneously achieving deep placement and long-term stability
Solution Approach 2:
The degradable polymeric cages serve as temporary intermediaries that maintain polymer stability during transport and penetration. Once the polymer reaches the target zone, the cages degrade and release gelation agents that stabilize the polymer as a gel, ensuring both deep placement capability and long-term retention
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 system significantly extends gelation times from weeks to months, enabling more effective placement and retention of gels in oil-bearing formations, reducing washout and ensuring thorough sweep of less permeable zones.
Implementation Method 1
The cages degrade, or at least partially degrade, on exposure to higher temperatures or changes in pH, thus releasing the gelation agents
Implementation Method 2
The cages degrade, or at least partially degrade, on exposure to higher temperatures or changes in pH, thus releasing the gelation agents
Implementation Method 3
The resulting released gelation agents can then crosslink a second polymer to produce gels
Data Source
AI summary
The invention is directed to delayed gelation agents comprising a degradable polymeric cage containing therein one or more gelation agents. The cage degrades in situ, e.g, in an oil reservoir, thus releasing the gelation agent(s), which can then crosslink second polymers in situ to form a gel.