PGA/PLA/PLGA Molded Articles for Pressure-Retaining Downhole Tools
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Solution Overview
Problem
Existing degradable materials for downhole applications in oil and gas production do not meet the requirements of rapid degradation under high-pressure and high-temperature conditions, necessitating the development of materials that can maintain structural integrity while quickly degrading.
Innovation Solution
A downhole tool member comprising a degradable polymer matrix, specifically a blend of polyglycolic acid (PGA) with polylactic acid (PLA) and poly(lactic acid-co-glycolic acid) (PLGA) copolymer, which exhibits controlled degradation rates and maintains structural integrity under high pressure and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If degradable materials are used in downhole applications, then they can eliminate retrieval needs and provide temporary functions, but they fail to maintain structural integrity under high-pressure and high-temperature conditions
Solution Approach 1:
The patent employs a composite polymer system consisting of polyglycolic acid (PGA) as the primary degradable matrix, reinforced with thermoplastic polymer fibers or filaments. This composite structure allows the material to maintain structural integrity under downhole conditions while retaining degradable properties. The thermoplastic reinforcement provides mechanical strength and pressure containment, while the PGA matrix provides biodegradability and temporary functionality.
Solution Approach 2:
The patent modifies the degradation parameters of PGA by controlling its molecular weight, crystallinity, and composition ratios. By adjusting these parameters, the material maintains structural stability at high temperatures and pressures while ensuring controlled degradation over the desired time period. The thermoplastic polymer content and fiber orientation are also optimized to balance structural integrity with degradation rate.
2Productivity
If traditional degradable materials like rock salt, wax beads, or oil-soluble resins are used, then they can provide temporary plugging and diversion functions, but they do not degrade rapidly enough under downhole conditions
Solution Approach 1:
The composite structure combines rapidly degradable PGA with thermoplastic polymer reinforcement. The thermoplastic component maintains pressure holding capability by providing structural framework, while the PGA matrix degrades rapidly through hydrolysis. This allows the material to fulfill temporary plugging functions while maintaining reliability under pressure.
Solution Approach 2:
The patent creates different regions within the molded article with varying compositions and degradation rates. The thermoplastic polymer fibers are distributed throughout the PGA matrix, creating a heterogeneous structure where different regions degrade at different rates. This local quality variation allows the material to maintain structural integrity in load-bearing regions while enabling rapid degradation in non-structural regions.
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 PGA/PLA/PLGA blend provides rapid mass loss under downhole conditions, ensuring effective degradation and pressure retention, making it suitable for hydrocarbon resource recovery applications.
Implementation Method 1
degradable polymer matrix... when held in downhole fluid... has an initial mass loss about 14% for a holding period of 2 days
Data Source
AI summary
The patent application discloses a degradable downhole tool member for hydrocarbon resource recovery. The downhole tool member comprises a shaped body comprising a degradable polymer matrix, wherein the downhole tool member, when held in downhole fluid at about 80° C., has an initial mass loss about 14% for a holding period of about 2 days in a pressure holding test.