Hydrophobic Polyvinyl Alcohol Plugging Agents for Drilling Fluid Loss
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Solution Overview
Problem
Current polyvinyl alcohol compositions used in subterranean wellbore treatments lack a broad range of solubility options, which limits their utility as plugging agents and diverting materials, as their solubility performance is not adequately modifiable to suit specific downhole conditions.
Innovation Solution
Development of particulate polyvinyl alcohol compositions with a hydrolyzed copolymer of vinyl acetate and olefinically unsaturated comonomers, characterized by specific ranges of olefinic comonomer content, viscosity-average degree of polymerization, degree of hydrolysis, solubility in water at different temperatures, and crystallinity, allowing for adjustable solubility and hydrophobicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyvinyl alcohol compositions are used in subterranean wellbore treatments, then they can serve as plugging agents and diverting materials, but their solubility performance is not adequately modifiable to suit specific downhole conditions
Solution Approach 1:
The patent applies parameter changes by systematically varying the degree of hydrolysis (70-100%), olefinic comonomer content (2-10 mol%), and viscosity-average degree of polymerization (200-5000) of polyvinyl alcohol compositions to achieve a broad range of solubility performances. This allows selection of optimal compositions for specific downhole temperature and pressure conditions, resolving the contradiction between adaptability and reliability.
Solution Approach 2:
The patent employs composite materials by creating polyvinyl alcohol compositions blended with specific olefinic comonomers (ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, nonadecene, eicosene). These composites enable tailored solubility characteristics while maintaining structural integrity and plugging effectiveness in subterranean applications.
2Adaptability or versatility
If polyvinyl alcohol compositions with fixed solubility characteristics are used, then manufacturing and application are simplified, but they cannot be optimized for different downhole temperature and pressure conditions
Solution Approach 1:
The patent defines specific parameter ranges (degree of hydrolysis: 70-100%, olefinic comonomer content: 2-10 mol%, viscosity-average degree of polymerization: 200-5000) that provide a systematic framework for selecting compositions with appropriate solubility characteristics. This structured parameter approach enables adaptability across different downhole conditions while maintaining manageable complexity through clearly defined specification ranges.
3Productivity
If polyvinyl alcohol compositions are designed for high solubility, then they dissolve quickly in formation water, but they lose effectiveness as plugging agents before completing their function
Solution Approach 1:
The patent utilizes parameter changes, particularly the degree of hydrolysis (70-100%) and olefinic comonomer content (2-10 mol%), to precisely control the dissolution rate of polyvinyl alcohol compositions. By adjusting these parameters, the compositions achieve optimal balance between initial dissolution speed and sustained plugging effectiveness, ensuring complete functional duration in subterranean applications.
Solution Approach 2:
The patent employs composite materials with specific olefinic comonomers to modify the dissolution behavior of polyvinyl alcohol. The hydrophobic character introduced by olefinic comonomers (2-10 mol%) creates compositions that dissolve at controlled rates, maintaining plugging effectiveness throughout the required operational duration while eventually dissolving to restore formation permeability.
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 compositions provide improved solubility performance across a range of temperatures, enabling effective use as plugging agents and diverting materials in subterranean applications, with enhanced stability and environmental friendliness, including temporary and non-toxic properties.
Implementation Method 1
polyvinyl alcohol compositions with a hydrolyzed copolymer of vinyl acetate and olefinically unsaturated comonomers, characterized by specific ranges of olefinic comonomer content, viscosity-average degree of polymerization, degree of hydrolysis, solubility in water at different temperatures
Implementation Method 2
the compositions have a solubility performance that is modifiable in view of the polymeric properties and characteristics of the composition... characterized by specific ranges of olefinic comonomer content... degree of hydrolysis... solubility in water at different temperatures
Data Source
AI summary
A particulate compacted copolymer polyvinyl alcohol-based composition that can be used as a plugging agent for minimizing or eliminating loss of circulation of fluids during the process of well drilling, workover, completion and cementing in the production of oil and gas.