Metal Complexing Agent Remediation for Shale Blockages
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Solution Overview
Problem
In nano-darcy shale formations, typical well stimulation techniques, including hydraulic fracturing, are ineffective due to the formation's high clay content and electro-static properties, leading to reduced hydrocarbon production caused by the buildup of subterranean-formed metal-polymer complexes that block conductive pathways.
Innovation Solution
A method involving the injection of a metal-polymer complex remediation mixture containing a metal complexing agent like citric acid or EDTA at pressures below the fracture pressure, allowing contact time for dissociation and dissolution of the metal-polymer complexes, creating a low viscosity flowback fluid that removes blockages and enhances hydrocarbon production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydraulic fracturing is used to stimulate well production in nano-darcy shale formations, then fracture pressure is exceeded to create conductive pathways, but metal-polymer complexes build up and block these pathways, reducing hydrocarbon production
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by using metal complexing agents (chelating agents) to convert the harmful metal-polymer complex blockages into soluble complexes. The chelating agents bind to metal ions in the complexes, breaking them down and converting the blocking solid/semi-solid material into soluble forms that can be flowed back to the surface, thereby transforming the harmful blockages into removable substances that restore hydrocarbon production
2Adaptability or versatility
If typical well stimulation techniques are applied to nano-darcy shale formations, then treatment is performed, but the high clay content and electro-static properties make the techniques ineffective
Solution Approach 1:
The patent applies the 'Parameter changes' principle by changing the chemical parameters of the treatment fluid through the use of metal complexing agents. Instead of relying on mechanical fracturing alone, the method introduces chemical agents that can dissolve metal-polymer complexes in situ, changing the chemical environment to one that prevents complex formation and enables removal of existing complexes, thereby adapting the stimulation technique to the specific conditions of nano-darcy shale formations with high clay content
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 breaks down metal-polymer complexes, restoring hydrocarbon flow by dissolving and removing the blockages, thereby improving well production in nano-darcy shale formations.
Implementation Method 1
the metal complexing agent breaks the cross-links between the cations and the polymers used in the fracturing fluids
Implementation Method 2
allowing the fluid to dissolve the xanthan deposition
Data Source
Figure 1
Figure 2A~2D
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AI summary
This disclosure describes formulations and methods for remediating subterranean-formed metal-polymer complexes in wells in subterranean formations. In one embodiment, the method includes injecting a metal-polymer complex remediation mixture containing a metal complexing agent into a subterranean formation adjacent to a well at a pressure below the fracture pressure of the formation. A sufficient contact time is allowed and then the metal-polymer complex remediation mixture is pumped from the subsurface. This has been shown to remediate polymer-containing, subterranean-formed metal-polymer complexes in shale formations. Without being held to a particular theory it appears that the metal complexing agent is forming metal complexes with the metals in the complexes, and particularly divalent metal ions. This removal of naturally occurring metals may be un-crosslinking and causing the metal-polymer complexes to go into solution, thereby removing the blockages caused by the metal-polymer complexes.