Degradable Rubber Borehole Plug for Well Drilling
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Solution Overview
Problem
Current well drilling technologies face challenges in reliably performing borehole plugging and fracturing under harsh excavation conditions, particularly at increased depths, while also incurring high costs and requiring extensive time for plug removal and flow path securement.
Innovation Solution
A plug for well drilling comprising a mandrel and diametrically expandable annular rubber members, where the mandrel and rubber members are formed from degradable materials, specifically ester-based urethane rubber, which degrades effectively under high temperatures, facilitating reliable plugging and fracturing with reduced costs and shortened processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If degradable rubber material is used for the diametrically expandable annular rubber member, then the plug can be easily removed and costs are reduced, but the material must maintain sufficient strength and sealing functionality under high temperature and pressure conditions
Solution Approach 1:
The patent applies parameter changes by selecting a degradable rubber material with specific physical and chemical properties that change under high temperature conditions. The material maintains its mechanical strength and sealing capability at downhole temperatures (e.g., 150°C or higher) but undergoes controlled degradation after use, enabling easy removal. This resolves the contradiction by using temperature-dependent parameter changes to achieve both reliable sealing during operation and easy removal afterward.
Solution Approach 2:
The patent employs a disposable degradable rubber material that serves its sealing function during the fracturing operation and then degrades to facilitate removal. This eliminates the need for complex retrieval operations and reduces costs, while the material is designed to maintain sufficient strength during its service life. The principle of using a temporary, degradable material resolves the contradiction between reliable sealing and easy removal.
2Reliability
If the plug is designed to maintain sealing functionality under harsh conditions, then reliability is improved, but the removal process becomes more complex and time-consuming
Solution Approach 1:
The degradable rubber material undergoes parameter changes based on temperature exposure. During the fracturing operation, the material maintains its mechanical properties and sealing functionality under high temperature and pressure. After completion, the material degrades through controlled chemical or physical changes, enabling rapid removal and reducing the time required for well completion operations.
Solution Approach 2:
The patent uses a disposable degradable rubber member that is designed to serve its sealing function temporarily during the fracturing operation and then degrades to facilitate quick removal. This eliminates the need for complex retrieval operations and significantly reduces the time required for plug removal, while maintaining reliable sealing during the critical operation period.
3Productivity
If conventional non-degradable materials are used for the rubber member, then the plug can be retrieved and reused, but removal costs and time increase significantly
Solution Approach 1:
The patent adopts a disposable degradable rubber material that eliminates the need for complex retrieval operations. The material is designed to maintain its functional properties during the fracturing operation and then degrade to facilitate easy removal, reducing both time and costs associated with plug removal while improving overall well drilling efficiency.
Solution Approach 2:
The degradable rubber material undergoes controlled parameter changes (degradation) after completing its sealing function. This degradation process is triggered by specific environmental conditions (temperature, time, chemical exposure) and enables the plug to be easily removed without complex retrieval operations, thereby improving productivity and reducing operational costs.
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 degradable plug enables reliable borehole plugging and fracturing under harsh conditions, reducing well drilling costs and shortening the process by facilitating plug removal and securement of a flow path, while maintaining sealing functionality for a desired duration.
Implementation Method 1
a rate of decrease of not less than 5% in 50% strain compressive stress, as measured in accordance with JIS K7181 after immersion in water at a temperature of 150°C for 24 hours
Data Source
Figure 1A~1B
AI summary
A plug for well drilling includes a mandrel and at least one diametrically expandable annular rubber member and at least one slip disposed on an outer circumferential surface orthogonal to an axial direction of the mandrel; (i) the mandrel being formed from a degradable material; and (ii) the at least one diametrically expandable annular rubber member being formed from a degradable rubber material having a rate of decrease of not less than 5% in 50% strain compressive stress after immersion in water at a temperature of 150°C for 24 hours relative to the compressive stress before immersion; and/or having a rate of loss of mass of from 5 to 100% after immersion in water at a temperature of 150°C for 72 hours relative to the mass before immersion. A well drilling method includes a step of isolating a borehole using the plug for well drilling, part or all of the plug being degraded thereafter.