PVOH-Polyester Particulate Diverting Agents for Rapid Cleanup
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Solution Overview
Problem
Current diverting agents used in wellbore operations face challenges in achieving rapid degradation and cleanup, especially at lower temperatures, which hinders the quick resumption of hydrocarbon production, and existing polyester-based materials are not effectively degradable under normal subterranean conditions.
Innovation Solution
A particulate composition is developed by blending polyvinyl alcohol polymers with aliphatic polyester polymers, allowing for a broad range of solubility and degradability tailored for specific downhole environments, comprising from 5 to 95 weight percent of each polymer, with optional additives, and processed through methods like melt blending or solid mixing to achieve desired particle size and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyester-based materials are used as diverting agents, then stability and effectiveness during wellbore operations is improved, but degradation and cleanup become difficult especially at lower temperatures
Solution Approach 1:
The patent uses composite materials by blending polyvinyl alcohol (PVOH) polymer with polyester polymer in specific ratios (30-70 wt% PVOH and 70-30 wt% polyester). This composite structure combines the stability of polyester with the rapid degradability of PVOH, resolving the contradiction between operational stability and cleanup rate. The PVOH component ensures rapid dissolution and degradation while the polyester provides structural integrity during operations.
Solution Approach 2:
The patent changes the chemical composition parameters of the diverting agent by incorporating PVOH with specific molecular weights (10,000-1,000,000 g/mol) and degrees of hydrolysis (70-99%), blended with polyester polymers. This parameter optimization enables the material to maintain stability at downhole temperatures while ensuring rapid degradation at lower temperatures through controlled chemical properties.
2Productivity
If polyvinyl alcohol polymer is used alone, then rapid degradation and solubility are improved, but stability during wellbore operations deteriorates
Solution Approach 1:
The patent creates a composite material system where PVOH (providing rapid degradation) is blended with polyester polymer (providing stability). The specific composition range (30-70 wt% PVOH, 70-30 wt% polyester) optimizes both properties, allowing the material to remain stable during high-temperature wellbore operations while maintaining rapid degradability when exposed to lower temperatures during cleanup.
Solution Approach 2:
The patent optimizes molecular weight parameters of PVOH (10,000-1,000,000 g/mol) and controls the degree of hydrolysis (70-99%) to balance solubility and stability. By adjusting these parameters and blending with polyester, the material achieves both rapid degradation capability and operational stability simultaneously.
3Reliability
If higher molecular weight polyvinyl alcohol is used, then stability and strength are improved, but solubility and degradation rate decrease
Solution Approach 1:
The patent selects PVOH with molecular weights in the range of 10,000-1,000,000 g/mol and degrees of hydrolysis of 70-99%. This parameter optimization ensures that even at higher molecular weights, the PVOH maintains good solubility and degradation rate while providing necessary stability. The blend ratio with polyester further fine-tunes these properties.
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 composition provides improved stability during wellbore operations, allowing for effective diversion of fluids and subsequent rapid degradation, minimizing residue and enabling quicker production by being environmentally friendly and biodegradable.
Implementation Method 1
The compositions of this invention are characterized by a desirably broad range of solubilities... rapid degradation... soluble to the extent of at least about 25 percent of its weight after being held in water
Implementation Method 2
The compositions of this invention are characterized by a desirably broad range of solubilities... rapid degradation... enabling quicker production by being environmentally friendly and biodegradable
Data Source
AI summary
Disclosed are particulate compositions comprising particles of a blend of one or more polyvinyl alcohol polymers with one or more aliphatic polyester polymers, wherein such particulate compositions are useful, for example, as plugging agents for treatments applied to a subterranean formation traversed by the borehole of an oil or gas well.