Friction Reducer Precipitation Mitigation via Iron Control Agents
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Solution Overview
Problem
Hydraulic fracturing fluids containing friction reducers can form precipitates when exposed to multivalent ions like iron, calcium, and magnesium, leading to reduced friction reduction efficiency and equipment damage in hydrocarbon-producing wells.
Innovation Solution
Incorporating iron control agents, such as ethylenediaminetetraacetic acid (EDTA), and adjusting the concentration of dissolved species in the fracturing fluid to mitigate precipitation, along with screening methods to select compatible friction reducers and water sources, helps maintain the stability and solubility of friction reducers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If friction reducers are used in hydraulic fracturing fluids to reduce turbulence and friction, then friction reduction efficiency is improved, but precipitates form when multivalent ions are present, leading to reduced solubility and equipment damage
Solution Approach 1:
A scale inhibitor is introduced as an intermediary substance that preferentially binds to multivalent cations (Fe2+, Ca2+, Mg2+) in the presence of friction reducers. This mediator prevents the direct interaction between multivalent ions and anionic friction reducers, thereby preventing precipitate formation while maintaining the friction reduction capabilities of the polymer. The scale inhibitor acts as a protective intermediary that sacrifices itself to prevent damage to the primary friction reduction system.
Solution Approach 2:
The patent uses a laboratory model system that replicates downhole conditions to predict and prevent friction reducer precipitation. By creating a simplified laboratory version of the complex downhole environment with controlled concentrations of multivalent ions and friction reducers, the system can identify compatible combinations before field deployment, effectively copying the problematic conditions to avoid them in actual operations.
2Ease of manufacture
If water sources with multivalent ions are used to prepare fracturing fluid, then fluid preparation is simplified, but friction reducer solubility is reduced and precipitation occurs
Solution Approach 1:
The patent performs preliminary compatibility screening in the laboratory before field operations by mixing friction reducers with water sources containing multivalent ions and observing for precipitate formation. This preliminary action identifies compatible friction reducer-water source combinations beforehand, allowing operators to proceed directly to field preparation without encountering solubility issues, thus maintaining both ease of manufacture and composition stability.
Solution Approach 2:
A scale inhibitor is added as an intermediary agent during fluid preparation that binds to multivalent cations in the water source, preventing them from interacting with and precipitating the friction reducer. This allows the use of water sources with multivalent ions without compromising friction reducer solubility, maintaining both ease of fluid preparation and composition stability.
3Productivity
If friction reducers are added to hydraulic fracturing fluid, then turbulence is reduced and friction is lowered, but precipitates form that plug and foul surface and downhole equipment
Solution Approach 1:
A scale inhibitor serves as an intermediary that preferentially reacts with multivalent cations in the fracturing fluid, preventing these ions from interacting with anionic friction reducers to form precipitates. This protective intermediary maintains the flow rate efficiency benefits of friction reducers while preventing equipment fouling by eliminating the precipitation mechanism.
Solution Approach 2:
The patent employs a laboratory model system that replicates downhole conditions to identify friction reducer-water source combinations that do not form precipitates. By copying and testing problematic conditions in the lab, the system can select combinations that maintain high flow rate efficiency without the harmful side effect of precipitate formation and equipment fouling.
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 use of iron control agents and appropriate screening methods effectively reduces friction reducer precipitation, maintaining friction reduction efficiency and preventing equipment and formation damage in hydraulic fracturing operations.
Implementation Method 1
Incorporating iron control agents, such as ethylenediaminetetraacetic acid (EDTA), and adjusting the concentration of dissolved species in the fracturing fluid to mitigate precipitation
Implementation Method 2
Some common friction reducers may include long chain water soluble polymers which may aid in moderating turbulence by reducing eddy currents within a conduit
Implementation Method 3
When hydrolyzed friction reducing polymers contact with multivalent ions such as Fe ions, Ca ions, or Mg ions in formation brine, the solubility of the hydrolyzed friction reducing polymers may be reduced which may form insoluble precipitates
Data Source
AI summary
A method may include: preparing or providing an aqueous fluid containing iron ions; screening at least one iron control agent against the aqueous fluid; selecting at least one iron control agent and iron control agent concentration based at least in part on the step of screening; and preparing a fracturing fluid comprising an aqueous base fluid and the at least one iron control agent wherein a concentration of the iron control agent in the fracturing fluid is greater than or equal to the selected iron control agent concentration.