Iron Control Agent for Acidizing Sludge Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The formation of insoluble ferric iron solids and iron-induced sludge in crude oils during oil and gas well stimulation and industrial equipment cleaning procedures, caused by the presence of ferric ions in acidic solutions, which hinders the effectiveness of acidizing processes and leads to reduced permeability and increased sludge formation.
Innovation Solution
The combination of sulfur dioxide, sulfurous acid, sulfite salts, bisulfite salts, or thiosulfate salts with copper ions and iodine or iodide ions, along with additional reducing agents like stannous chloride, 2-mercaptoethanol, or thioglycolic acid, effectively reduces ferric iron to the ferrous form in strong acidic solutions, preventing sludge formation and precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ferric ion is present in acid solution used for formation acidizing, then the acid can react with and dissolve calcareous formation materials to increase permeability, but ferric iron-containing compounds precipitate when pH increases above 4, forming insoluble solids that plug pore spaces and reduce permeability
Solution Approach 1:
The patent changes the oxidation state parameter of iron from ferric (Fe³⁺) to ferrous (Fe²⁺) through chemical reduction. This parameter change prevents precipitation because ferrous iron remains soluble at higher pH values, allowing the acid to maintain its ability to dissolve formation materials and increase permeability without being counteracted by iron solid formation
Solution Approach 2:
The patent converts the harmful effect of ferric iron precipitation into a beneficial outcome by reducing ferric iron to ferrous iron. The reduction process transforms a harmful precipitating substance into a beneficial soluble form that allows continued acid effectiveness in enhancing formation permeability while preventing pore plugging
2Productivity
If high concentration hydrochloric acid (15% and greater) is used to react with subsurface formation, then dissolution of calcareous materials is enhanced, but sludge formation occurs when the acid contacts certain types of crude oil
Solution Approach 1:
The patent changes the chemical state of iron from ferric to ferrous through reduction, which fundamentally alters the interaction between the acid system and crude oil. This parameter change prevents the formation of iron-induced sludge while maintaining the high concentration hydrochloric acid's ability to dissolve formation materials at enhanced rates
3Device complexity
If conventional acidizing procedures are used without iron control, then the process is simple and cost-effective, but solid iron reaction products form and plug formation pore spaces, frustrating the objective of increasing formation permeability
Solution Approach 1:
The patent introduces an intermediary substance (reducing agent) that mediates between the ferric iron in the acid solution and the desired ferrous iron state. This intermediary enables the conversion process without requiring complete system redesign, maintaining relative process simplicity while effectively preventing solid iron product formation and pore plugging
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 approach efficiently converts ferric iron to ferrous iron in acidic solutions, preventing sludge formation and reducing the toxicity, odor, and cost associated with previous methods, while maintaining effectiveness in strong acids like 28% hydrochloric acid, thereby enhancing the permeability and reducing sludge issues during well treatments.
Implementation Method 1
the combination of sulfur dioxide, sulfurous acid, sulfite salts, bisulfite salts, or thiosulfate salts with copper ions and iodine or iodide ions, along with additional reducing agents like stannous chloride, 2-mercaptoethanol, or thioglycolic acid, effectively reduces ferric iron to the ferrous form in strong acidic solutions
Data Source
AI summary
An iron control agent capable of reducing ferric iron containing compounds to ferrous iron containing compounds in an acidic solution, such as one used for formation acidizing. The iron control agent comprises a combination of a sulfur dioxide, sulfurous acid, sulfite salts, bisulfite salts, or thiosulfate salts or mixtures thereof, with a source of copper ions and a source of iodine or iodine ions. The iron control agent may also include small amounts of an adjunct such as stannous chloride, 2-mercaptoethanol, and thioglycolic acid and its salts.