Bio-enzyme Degradable Plugging Material for Hydrate Drilling
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Solution Overview
Problem
Natural gas hydrate drilling faces challenges with well wall instability and reservoir damage due to the use of non-selectively removable plugging agents that contaminate the formation and reduce permeability during the exploitation of hydrate reservoirs in complex structural wells.
Innovation Solution
A bio-enzyme degradable temporary plugging material composed of modified ceramsite coated with ethyl cellulose and epoxy resin, which forms a stable plugging layer during drilling and is easily removable using bio-enzymes, thereby maintaining well stability and restoring formation permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional plugging agents are used to plug the reservoir during drilling, then well wall stability is improved, but the plugging agents are difficult to remove and contaminate the formation
Solution Approach 1:
The patent uses a temporary plugging material designed to be easily removable after serving its purpose. The plugging material comprises water-soluble polymer particles that can be dissolved and removed after drilling, avoiding long-term contamination. This disposable approach allows the material to fulfill its stabilizing function during drilling then be cleanly removed, resolving the contradiction between providing stability and avoiding harmful contamination.
Solution Approach 2:
The patent changes the chemical properties of the plugging material by using water-soluble polymers with specific molecular weights and compositions. These parameter changes enable the material to maintain stability during drilling (when needed) and then dissolve completely when removal liquid is introduced, transforming from a stable plugging structure to a soluble state for easy removal without formation damage.
2Ease of operation
If removable plugging materials are used, then plugging removal is easier, but the plugging ability is poor
Solution Approach 1:
The patent employs a composite plugging material system consisting of water-soluble polymer particles dispersed in drilling fluid, optionally with additives. This composite structure provides sufficient plugging ability through the collective action of numerous particles forming a barrier, while maintaining ease of removal because the water-soluble nature of the polymer allows complete dissolution when exposed to removal liquid, eliminating the trade-off between strength and removability.
Solution Approach 2:
The patent uses a high concentration of fine polymer particles (excessive action) to ensure complete plugging of the formation, while the water-soluble nature ensures that even this excessive amount can be completely removed. The excessive use of removable material guarantees plugging effectiveness without compromising future removability, resolving the contradiction between plugging ability and ease of removal.
3Ease of operation
If acidizing is used for plugging removal, then plugging removal is achieved, but formation minerals are dissolved and permeability is reduced
Solution Approach 1:
The patent replaces the chemical mechanism of acidizing with a physical dissolution mechanism. Instead of using acid to chemically react with and remove the plugging material, the system uses water-soluble polymers that dissolve physically when exposed to water or aqueous removal liquids. This substitution eliminates the harmful side effects of acidizing (formation mineral dissolution, precipitate formation) while achieving complete plugging removal, resolving the contradiction between removal effectiveness and formation protection.
Solution Approach 2:
The patent introduces water or aqueous removal liquid as an intermediary substance that facilitates plugging material removal without directly damaging the formation. The water-soluble polymer particles interact with this intermediary by dissolving in it, allowing the plugging material to be removed through a benign medium that does not harm formation minerals or reduce permeability, unlike the direct harmful action of acidizing.
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 bio-enzyme degradable temporary plugging material effectively enhances well wall stability during drilling and ensures easy removal after drilling, restoring the permeability of the hydrate reservoir, thus improving the efficiency of natural gas hydrate production while minimizing environmental impact.
Implementation Method 1
after a bio-enzyme degrades the temporary plugging material, the plugging layer is removed, the permeability of the formation is recovered
Data Source
AI summary
Disclosed is a bio-enzyme degradable temporary plugging material and a preparation method and application thereof in the technical field of natural gas hydrate drilling and production; the preparation method of the bio-enzyme degradable temporary plugging material includes the following steps: mixing the ceramsite with an aqueous solution of 3-aminopropyl trimethoxysilane before a stirring reaction and drying to obtain modified ceramsite; and fully dispersing the modified ceramsite, ethyl cellulose, and epoxy resin in dichloromethane to obtain an oil phase; adding the oil phase into a gelatin aqueous solution and mixing uniformly; after a stirring reaction, evaporating an organic solvent, filtering, washing, and drying, to obtain the bio-enzyme degradable temporary plugging material.