Medium-Viscosity Slickwater Polymer for Shear-Resistant Drag Reduction
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Solution Overview
Problem
Existing high-molecular-weight polyacrylamides used in medium-viscosity slickwater for deep/ultra-deep oil and gas reservoir fracturing suffer from severe shear degradation, leading to reduced drag reduction and sand carrying performance, which are inadequate for long wellbores and high displacement conditions.
Innovation Solution
A shear-resistant, high-drag-reducing slickwater drag reducing agent is formulated through a polymerization reaction of acrylamide, a sulfonate ion-containing hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight modifier, and a composite initiator, enhancing solubility, viscosity, and shear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-molecular-weight polyacrylamide is used to achieve high drag reduction performance, then drag reduction performance is improved, but shear resistance performance deteriorates due to severe Reynolds shear degradation
Solution Approach 1:
The patent uses composite initiators consisting of multiple components (ammonium persulfate, organic hydrogen peroxide, sulfite, and azo-initiator) to initiate polymerization. This composite approach allows controlled formation of high-molecular-weight polyacrylamide with improved shear resistance by optimizing the initiation mechanism and reducing premature degradation
Solution Approach 2:
The patent optimizes multiple parameters including monomer ratio (acrylamide to hydrophobic monomer at 1:0.001-0.003), molecular weight (25-30 million), hydrophobic unit content (0.001-0.01%), and initiator concentrations. These parameter optimizations enable the polymer to maintain high drag reduction performance while resisting shear degradation in deep/ultra-deep well conditions
2Reliability
If high-molecular-weight polyacrylamide is used to achieve high drag reduction performance, then drag reduction performance is improved, but sand carrying performance deteriorates due to loss of viscoelasticity
Solution Approach 1:
The patent introduces hydrophobic units (0.001-0.01% content) with specific sulfonate ion-containing structures at localized positions within the polymer chain. These hydrophobic units provide local structural rigidity and viscoelasticity without compromising the overall drag reduction properties, enabling the polymer to effectively carry sand particles
Solution Approach 2:
The composite initiator system and controlled polymerization process create a composite polymer structure with optimized molecular weight distribution and chain architecture. This composite approach preserves viscoelasticity necessary for sand carrying while achieving high drag reduction performance
3Productivity
If medium-viscosity slickwater is used for deep/ultra-deep well fracturing, then fracturing effectiveness is improved, but shear degradation becomes more severe due to large displacement and long wellbores
Solution Approach 1:
The patent converts the harmful effect of shear forces in deep/ultra-deep wells into a beneficial selection criterion. By designing the polymer structure with specific hydrophobic units and optimized molecular weight, the polymer is selected to withstand the shear conditions, transforming the harsh environment into a validating test of polymer performance
Solution Approach 2:
The patent optimizes the polymer parameters specifically for deep/ultra-deep well conditions: molecular weight of 25-30 million, hydrophobic unit content of 0.001-0.01%, and controlled degree of hydrolysis. These parameter changes enable the polymer to maintain stability and performance under the severe shear conditions of long wellbores and high displacement rates
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 new agent significantly improves shear resistance and drag reduction performance, ensuring effective sand carrying capacity, meeting the demands of deep/ultra-deep oil and gas reservoir fracturing.
Implementation Method 1
The drag reducing agent is formed by a polymerization reaction of acrylamide, a sulfonate ion-containing hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight modifier, and a composite initiator
Implementation Method 2
the solubility and viscosity-increasing performances of the polymer can be significantly improved
Implementation Method 3
a sulfonate ion-containing hydrophobic monomer, a hydrophobic unit microblock regulator
Implementation Method 4
high-drag-reducing, medium-viscosity slickwater drag reducing agent
Implementation Method 5
shear-resistant, high-drag-reducing, medium-viscosity slickwater drag reducing agent
Data Source
AI summary
The invention discloses a shear-resistant, high-drag-reducing, medium-viscosity slickwater drag reducing agent and a preparation method therefor. The drag reducing agent is polymerized from acrylamide, a sulfonate ion-containing hydrophobic monomer, a hydrophobic unit microblock regulator, a molecular weight modifier, and a composite initiator. Through the special sulfonate ion-containing hydrophobic monomer, the hydrophobic unit microblock regulator matched with a hydrophobic monomer and the control of a polymer molecular weight, the solubility and viscosity-increasing performances of the polymer can be significantly improved, the shear-resistant and degradation-resistant performance of the drag reducing agent is improved, with excellent sand carrying performance and drag reducing performance, and the shortcomings of existing drag reducing agents such as weak shear resistance, rapid decline in drag reduction rate and poor sand carrying performance are overcome, thereby meeting the special requirements of deep/ultra-deep oil and gas reservoir fracturing on fracturing fluid rheology and “high drag reduction of wellbore.