GLDA Acidizing Fluid with Sequestering Agent for Siliceous Formations
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Solution Overview
Problem
Current acidizing methods for sandstone formations face challenges such as rapid reaction of HF with silica, leading to limited acid penetration and formation of insoluble precipitates that reduce permeability and cause formation damage, especially in high-temperature environments where clays are unstable and HCl-based fluids are ineffective.
Innovation Solution
A fluid containing glutamic-N,N-diacetic acid or its salt, a HF or HF-generating component, and an organophosphonate is introduced into the siliceous formation to form complexes with monovalent and divalent ions, preventing their precipitation and enhancing permeability by minimizing reaction with other components, thus avoiding the use of HCl and reducing formation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HCl-based acidizing fluid is used to dissolve carbonates and stimulate sandstone formations, then carbonate dissolution and permeability enhancement are achieved, but clay instability and fines migration occur at high temperatures causing formation damage
Solution Approach 1:
The patent changes the chemical composition parameters of the acidizing fluid by replacing HCl with HF and adding GLDA and organophosphonate. This parameter change allows the fluid to maintain effectiveness at high temperatures without causing clay instability, as HF reacts with siliceous materials while GLDA and organophosphonate prevent unwanted side reactions that would cause fines migration.
Solution Approach 2:
The patent uses HF as a short-acting acid component that rapidly reacts with siliceous materials and clays to dissolve damage. The HF is consumed in the reaction process, providing intense localized action without long-term residence that would cause ongoing clay instability. This disposable approach allows deep penetration and effective stimulation without sustained harmful effects.
2Length of moving object
If HF is used to react with siliceous materials and clays, then deep penetration and damage removal are achieved, but rapid reaction consumes HF quickly limiting penetration depth
Solution Approach 1:
The patent incorporates GLDA and organophosphonate into the acidizing fluid before injection. These components are pre-positioned to complex with metal ions as they are released during HF reaction with carbonates and siliceous materials. This preliminary action prevents precipitate formation that would block pores and consume HF prematurely, allowing the HF to penetrate deeper into the formation before being depleted.
Solution Approach 2:
GLDA and organophosphonate act as intermediary substances that facilitate the HF reaction process. They complex with calcium and other metal ions released during dissolution, preventing these ions from reacting with fluoride to form insoluble precipitates. This intermediary action maintains fluidity and allows HF to continue reacting with siliceous materials at greater depths.
3Productivity
If HF reacts with carbonates to produce metal fluorides, then carbonate dissolution occurs, but insoluble precipitates form blocking pores and reducing permeability
Solution Approach 1:
GLDA and organophosphonate serve as intermediary complexing agents that intercept metal ions (particularly calcium) released during HF reaction with carbonates. By forming stable soluble complexes with these metal ions, they prevent the metal ions from reacting with fluoride to form insoluble metal fluorides and fluorosilicates. This intermediary complexation allows complete carbonate dissolution without the harmful side effect of precipitate formation that would block pores.
Solution Approach 2:
The patent extracts or removes the problematic metal ions from the reaction system by complexing them with GLDA and organophosphonate. This extraction prevents the metal ions from participating in unwanted precipitation reactions. The complexed metal ions remain in solution and do not form insoluble deposits, thereby maintaining pore openness and permeability while achieving complete carbonate dissolution.
4Productivity
If preflush is used to dissolve carbonates before HF treatment, then carbonate removal is achieved, but preferential flow paths are created that may bypass damaged zones
Solution Approach 1:
The patent merges the carbonate dissolution function and the siliceous material dissolution function into a single acidizing fluid treatment. By combining HF (for siliceous material dissolution) with GLDA and organophosphonate (for carbonate dissolution and precipitate prevention) in one fluid, the treatment achieves uniform distribution through the formation without creating preferential flow paths. The single-fluid approach eliminates the sequential injection steps that cause channeling problems in traditional preflush methods.
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 increases permeability by dissolving siliceous materials, reducing matrix de-consolidation, and minimizing precipitate formation, allowing deeper acid penetration and sustained stimulation of hydrocarbon production without the corrosive effects of HCl, even at high temperatures.
Implementation Method 1
The organophosphonate may be of the formula: wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, aryl, phosphonates, phosphates, acyl, amine, hydroxy and carboxyl groups and R4 and R5 are independently selected from hydrogen, sodium, potassium, ammonium or an organic radical. During the reaction of glutamic-N,N-diacetic acid or salt or a mixture thereof and the HF or HF-generating component with the siliceous formation, un-complexed monovalent ions, divalent ions or a combination thereof are generated. A complex is formed by sequestering the un-complexed monovalent ions, divalent ions or combination thereof with the organophosphonate.
Implementation Method 2
a fluid containing a glutamic-N,N-diacetic acid or salt or a mixture thereof; a HF or HF-generating component and an organophosphonate is introduced into a well penetrating a siliceous subterranean formation. During the reaction of glutamic-N,N-diacetic acid or salt or a mixture thereof and the HF or HF-generating component with the siliceous formation
Implementation Method 3
Complexes of the organophosphonate are formed after introduction of the treatment solution into the well. The permeability of the formation is enhanced by minimizing or preventing reaction of the monovalent ions, divalent ions or a combination thereof with components in the well other than the organophosphonate.
Data Source
AI summary
Sandstone formations of oil and gas and geothermal wells may be successfully stimulated with a fluid containing GLDA or salt and HF or a HF-generating component and an organophosphonate component. The organophosphonate acts as a sequestering agent and reduces the amount of metal fluoride precipitates produced.