Organic Acid Stimulation Fluid for Sandstone Permeability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Stimulating oil production from sandstone formations is challenging due to formation damage caused by drilling operations and conventional acid treatments, which often result in precipitation and reduced permeability, especially when using hydrochloric or hydrofluoric acids.
Innovation Solution
A stimulation fluid composition comprising gluconic acid, oxalic acid, citric acid, isopropanol, ethylene glycol, and sodium citrate is used, avoiding the need for hydrochloric or hydrofluoric acids, and is delivered in a single-stage process with three intervals: a solvent pre-flush, the main chemical introduction, and an over-flush, to remove formation damage and enhance permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional acid systems (HCl and HF) are used to stimulate oil flow from sandstone reservoirs, then the skin effect near the wellbore is removed, but sand is produced and formation damage occurs due to precipitated reaction products
Solution Approach 1:
The patent changes the chemical parameters of the acid system by using organic acids (acetic acid, formic acid, propionic acid) instead of conventional inorganic acids (HCl, HF). This parameter change alters the reaction products from insoluble precipitates to soluble complexes, eliminating formation damage while maintaining stimulation effectiveness
Solution Approach 2:
The patent introduces iron salts as intermediaries that react with organic acids to form soluble iron complexes. These complexes act as mediators that dissolve calcium carbonate and iron precipitates without causing sand production or formation damage, thus resolving the contradiction between stimulation and formation integrity
2Ease of manufacture
If hydrochloric acid and hydrofluoric acid are used to treat carbonate reservoirs, then water-soluble products are formed readily, but sandstone acidizing generates precipitates that cause formation damage
Solution Approach 1:
The patent changes the chemical nature of the acid system from strong inorganic acids to weak organic acids combined with iron salts. This parameter change ensures that all reaction products remain soluble under reservoir conditions, eliminating precipitate formation while maintaining effective carbonate dissolution
Solution Approach 2:
The patent creates a composite acid system combining organic acids with iron salts. This composite approach leverages the solubility benefits of organic acids and the complex-forming capabilities of iron salts to achieve complete solubility of reaction products, preventing formation damage
3Productivity
If acid treatments are used to remove formation damage, then permeability is improved, but the treatment complexity and cost increase
Solution Approach 1:
The patent segments the acid treatment process into distinct functional components: organic acids for carbonate dissolution, iron salts for precipitate complexation, and corrosion inhibitors for equipment protection. This segmentation allows each component to perform its specific function efficiently, simplifying the overall treatment process while achieving comprehensive formation damage removal
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 solution effectively removes calcium carbonate and iron precipitates, improves permeability, and increases oil production rates in sandstone formations, reducing treatment costs and time, while maintaining the integrity of the subterranean formation.
Implementation Method 1
The composition of the present invention acts to dissolve and remove precipitates in the wellbore region and thus reestablish permeability and improve production
Implementation Method 2
The composition of the present invention also has the capability of retaining iron and calcium in solution, when compared with prior art stimulating compositions that contain conventional strong acids
Data Source
AI summary
A method and a composition for stimulating oil production from wells which have ceased production by pumping in a mixture of gluconic, oxalic and citric acids, isopropanol, ethylene glycol and sodium citrate between pre-flush and over-flush intervals, which composition and method does not include the use of hydrochloric acid or hydrofluoric acid.