PVA Additive for Oil Well Cement Fluid Loss Control
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Solution Overview
Problem
The fluid loss-reducing property of polyvinyl alcohol (PVA) additives for oil well cements, especially under high temperature and high pressure conditions, is insufficient, leading to increased costs and reduced cement slurry fluidity.
Innovation Solution
A PVA additive with a saponification value of 78 to 82 mol% and a viscosity-average polymerization degree of 3,000 to 4,500 is used, with particle diameters of 75 µm or less at 30 mass% or less and 500 µm or more at 10 mass% or less, to enhance fluid loss reduction in oil well cements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of fluid loss-reducing agent (PVA) is increased to reduce fluid loss under high pressure and temperature, then fluid loss-reducing property is improved, but cement slurry fluidity deteriorates due to thickening
Solution Approach 1:
The invention changes the chemical parameters of PVA by controlling the saponification degree (70-90 mol%) and polymerization degree (3000-6000) to achieve optimal fluid loss reduction while maintaining slurry fluidity. This parameter optimization allows effective fluid loss control without excessive thickening that would occur with higher additive amounts
2Reliability
If the amount of fluid loss-reducing agent (PVA) is increased to improve fluid loss reduction, then fluid loss-reducing property is improved, but cost increases
Solution Approach 1:
By optimizing the saponification degree (70-90 mol%) and polymerization degree (3000-6000) parameters of PVA, the invention achieves superior fluid loss reduction at lower additive concentrations (0.01-30% bwoc), thereby reducing the quantity of substance required and lowering overall cost while maintaining effective fluid loss control
3Reliability
If PVA with high saponification degree is used to improve fluid loss reduction, then fluid loss-reducing property is improved, but excessive hydrogen bonding occurs leading to solubilization and fluidity deterioration
Solution Approach 1:
The invention optimizes the saponification degree to a specific range (70-90 mol%, preferably 80-95 mol%) to balance fluid loss reduction capability with prevention of excessive hydrogen bonding. This parameter control prevents PVA solubilization and maintains cement slurry composition stability while achieving effective fluid loss control
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
This configuration improves the fluid loss-reducing property of the PVA additive, preventing excessive hydrogen bonding and solubilization, thereby maintaining effective cement slurry performance and reducing costs.
Implementation Method 1
preventing excessive hydrogen bonding and solubilization
Data Source
AI summary
Provided is a PVA-containing additive for oil well cement superior in fluid loss-reducing property. Specifically, provided is an additive for oil well cement, the additive containing polyvinyl alcohol having a saponification value of 75 to 85 mol % and a viscosity-average polymerization degree of 2,800 to 4,500. Also provided are a cement composition containing the additive for oil well cement in an amount of 0.01 to 30% bwoc and a cement slurry containing the additive for oil well cement in an amount of 0.01 to 30% bwoc.