Viscosified Chelating Fluid for Scale Removal
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Solution Overview
Problem
Scale deposits in downhole wellbore tubulars and subsurface completion equipment, caused by changes in temperature, pressure, and water chemistry, lead to reduced hydrocarbon production by clogging fluid paths and increasing surface roughness, which existing methods fail to address effectively, especially in high-temperature formations where acidic fluids are problematic.
Innovation Solution
A method involving the use of a treatment fluid comprising water, a chelating agent capable of forming a heterocyclic ring with metal and nonmetal ions, and a viscosity-increasing agent to dissolve and remove carbonate scale without acidic or corrosive compositions, enhancing fluid delivery and flowback by increasing viscosity for better coverage and particle carrying capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acidic fluids are used to remove scale deposits, then scale removal effectiveness is improved, but corrosion risk and equipment damage increase
Solution Approach 1:
The patent changes the chemical parameters of the treatment fluid by using chelating agents instead of acidic fluids. The chelating agents work through complexation reactions with metal ions in scale deposits, providing effective scale removal without the corrosive effects of low pH fluids. This parameter change resolves the contradiction by maintaining scale removal capability while eliminating corrosion risk.
Solution Approach 2:
The chelating agent acts as an intermediary substance that facilitates scale removal through a different mechanism. Instead of using acid to dissolve scale, the chelating agent forms soluble complexes with metal ions in the scale, gradually breaking it down. This intermediary approach achieves the desired scale removal effect without introducing the harmful corrosive properties of acidic fluids.
2Object-affected harmful factors
If water-based treatment fluids are used, then corrosion is reduced, but scale removal effectiveness decreases
Solution Approach 1:
The patent creates a composite treatment fluid system combining water with chelating agents and viscosity-increasing agents. This composite formulation maintains the low-corrosion advantage of water-based fluids while adding functional components that provide effective scale removal. The chelating agents contribute scale-dissolving capability, while viscosity-increasing agents enhance fluid retention and contact time with scale deposits.
Solution Approach 2:
The patent modifies the chemical composition parameters of water-based fluids by incorporating chelating agents. These additives change the fluid's chemical reactivity toward scale deposits, enabling water-based fluids to effectively remove scale through chelation mechanisms rather than relying on acidic properties. This parameter modification resolves the contradiction between low corrosion and effective scale removal.
3Reliability
If treatment fluid viscosity is increased, then fluid retention and coverage are improved, but flow rate through wellbore decreases
Solution Approach 1:
The patent employs viscosity-increasing agents that can dynamically adjust the fluid's rheological properties. These agents allow the treatment fluid to exhibit higher viscosity during the treatment phase for improved retention and coverage, while enabling adequate flow rates during injection and recovery phases. The dynamic viscosity adjustment resolves the contradiction between retention and flow rate.
Solution Approach 2:
The patent modifies the physical parameters of the treatment fluid by adding viscosity-increasing agents. This changes the fluid's viscosity parameter to optimize both retention time on scale deposits and flow characteristics through the wellbore. The controlled viscosity enhancement allows the fluid to adhere better to surfaces while maintaining sufficient mobility for effective delivery and recovery.
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 method effectively removes calcium and magnesium carbonate scale, reopens tubulars, and enhances hydrocarbon production by dissolving scale under various conditions without using acidic fluids, reducing corrosion risks and maintaining flow efficiency.
Implementation Method 1
a chelating agent capable of forming a heterocyclic ring that contains a metal ion attached to at least two nonmetal ions
Data Source
AI summary
A method for treating a wellbore tubular or subsurface completion equipment to help remove scale is provided. In general, the method comprises the steps of: (A) determining the likelihood of the presence of carbonate scale in the wellbore tubular or subsurface completion equipment; (B) forming or providing a treatment fluid comprising: (i) water; (ii) a chelating agent capable of forming a heterocyclic ring that contains a metal ion attached to at least two nonmetal ions; and (iii) a viscosity-increasing agent; and (C) introducing the treatment fluid into the wellbore tubular or the subsurface completion equipment.