Polyurethane Encapsulation for Targeted Downhole Gel Release
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Solution Overview
Problem
Current delayed gelling systems for preventing fluid loss during oil and gas exploration and production operations lack precision in controlling gelation location, making them inefficient in reducing fluid losses, especially during drilling and hydraulic fracturing.
Innovation Solution
Encapsulation of a non-amine hydrophilic compound in polyurethane breakable capsules, triggered by high shear, pressure, or temperature, allowing targeted release at specific downhole locations, such as the drill bit or fractures, without the need for additional surfactants or complex polymerization systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If delayed gelling systems are used to prevent fluid loss, then fluid loss is reduced, but the location of gelation cannot be precisely controlled
Solution Approach 1:
The system divides the gelation process into two separate components: a polymer solution and an activator. These components are injected separately and mix in the formation to trigger gelation. This segmentation allows precise control over where gelation occurs (at the mixing point) while still achieving fluid loss prevention, resolving the contradiction between reducing fluid loss and controlling gelation location.
Solution Approach 2:
The activator serves as an intermediary substance that triggers gelation only when introduced to the polymer solution at a specific location. This intermediary mechanism enables precise spatial control of gelation by determining where the two components mix, thereby solving the problem of uncontrolled gelation location while maintaining fluid loss reduction benefits.
2Manufacturing precision
If reactive components are mixed in situ to trigger gelation, then gelation location can be controlled, but sufficient mixing is difficult to ensure
Solution Approach 1:
The system uses alternating injection of polymer solution and activator through alternating nozzles, creating a periodic mixing action. This periodic injection pattern ensures thorough mixing of the two components at the injection point, guaranteeing reliable gelation trigger while maintaining precise location control. The periodic action resolves the contradiction between location control and mixing efficiency.
3Stability of the object's composition
If specific delivery tools are used to separate reactive components, then premature mixing is prevented, but the system becomes highly time-consuming
Solution Approach 1:
The system combines the polymer solution and activator delivery into a single injection tool with multiple nozzles. Both components are delivered through the same tool without requiring complex separate delivery systems, preventing premature mixing while eliminating the need for multiple tool changes or complex coordination. This merging approach resolves the contradiction between preventing premature mixing and reducing operation time.
4Manufacturing precision
If downhole mixing of reactive components is performed, then gelation can be triggered at target location, but mixing products at appropriate location is not well insured
Solution Approach 1:
The system performs preliminary mixing of polymer solution and activator at the injection point before the mixture enters the formation. By ensuring complete mixing occurs upstream at the tool, the system guarantees reliable gelation trigger at the desired location without depending on uncertain downhole mixing conditions. This preliminary action resolves the contradiction between target location gelation and mixing assurance.
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 encapsulation method provides a controlled and efficient release of the hydrophilic compound, effectively reducing fluid loss by forming a gel only under specific physical conditions, thereby minimizing well damage and enhancing operational efficiency.
Implementation Method 1
heating the obtained multiple emulsion, whereby the polyisocyanate is cured into polyurethane
Implementation Method 2
triggered by physical means (high shear, high pressure, temperature, crushing, shearing or any combination of the above)
Data Source
AI summary
The instant invention relates to a process for the encapsulation of a non-amine hydrophilic compound C, comprising the steps of: (E1) providing a reverse emulsion containing : an oil phase (O), comprising a curable mixture of isocyanate and polyalkyldiene hydroxylated or polyol dispersed in said oil phase, drops of an aqueous phase W1, containing: said non-amine hydrophilic compound C; and at least 5% by weight of a compound C carrying more than 2 amine groups; (E2) pouring the reverse emulsion of step (E1) in a second water phase W2 to make a multiple emulsion water/oil/water; and, then, (E3) curing into polyurethane all or part of the curable mixture contained in the oil phase.