Chelating Agent Foam for Subterranean Fluid Diversion
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Solution Overview
Problem
Current subterranean formation treatment fluids, such as acidic fluids, often fail to effectively divert treatment fluids to damaged zones during acidizing operations and can lead to fluid leak-off during fracturing, resulting in incomplete permeability enhancement and pressure issues.
Innovation Solution
Development of a foam or viscosified composition containing chelating agents like glutamic acid N,N-diacetic acid or its salts, along with a foaming agent and a viscosifying agent, which maintains stability and viscosity at elevated temperatures, allowing for better diversion and reduced leak-off, enhancing permeability without damaging the formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If standard acidic treatment fluid is injected into the formation, then the acid can reach high permeability zones, but the acid is drawn away from damaged, lower permeability zones due to lack of diversion
Solution Approach 1:
The patent changes the physical parameters of the treatment fluid by converting it into a foam composition with controlled viscosity and expansion ratio. This allows the fluid to be diverted to low-permeability zones while maintaining acid concentration effectiveness, resolving the contradiction between ease of operation and productivity.
Solution Approach 2:
The patent creates a composite foam system combining chelating agents, surfactants, and acidic components. This composite structure provides both the diversion capability needed for easy operation and the chemical effectiveness needed for productivity, simultaneously addressing both requirements.
2Productivity
If treatment fluid is injected at pressure higher than fracture pressure, then permeability can be enhanced through fracturing, but fluid leaks into the formation preventing desired pressure build-up
Solution Approach 1:
The foam composition's unique rheological parameters allow it to maintain pressure build-up while still achieving fracture-induced permeability enhancement. The foam structure prevents premature fluid leak-off, enabling the system to achieve both productivity improvement and pressure control.
3Reliability
If chelating agents are used in acidic treatment, then formation damage can be reduced, but fluid stability and viscosity decrease at elevated temperatures
Solution Approach 1:
The patent develops a composite foam system where surfactants and chelating agents work synergistically. This composite structure maintains both the formation damage prevention benefits of chelating agents and the thermal stability required for reliable performance at elevated temperatures.
Solution Approach 2:
The foam system utilizes phase transition characteristics to maintain stability at elevated temperatures. The foam structure itself acts as a stabilizing mechanism that preserves fluid composition integrity while allowing chelating agents to function for formation protection.
4Productivity
If more additives are added to improve treatment effectiveness, then permeability enhancement can be improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a multi-functional foam composition where a single integrated system performs multiple functions: diversion, fracturing, formation protection, and pressure control. This universal approach achieves permeability enhancement without requiring multiple separate additives, reducing complexity while maintaining productivity.
Data Source
AI summary
The present invention relates to a foam containing water, between5and 30wt% on total weight of the foam of a chelating agent selected from the group of glutamic aid N,N-diacetic acid or a salt thereof (GLDA), aspartic acid N,N-diacetic acid or a salt thereof (ASDA), methylglycine N,N-diacetic acid or a salt thereof (MGDA), N-hydroxyethyl ethylenediamine-N,N',N'-triacetic acid or a salt thereof (HEDTA), a foaming agent, and at least 25 vol% on total volume of the foam of a gas,and having a pH of between 2 and 5, to a viscosified composition containing water, between 5 and 30wt% on total volume of the composition of a chelating agent selected from the group of glutamic aid N,N-diacetic acid or a salt thereof (GLDA), aspartic acid N,N-diacetic acid or a salt thereof (ASDA), methylglycine N,N-diacetic acid or a salt thereof (MGDA), N-hydroxyethyl ethylenediamine-N,N',N'-triacetic acid or a salt thereof (HEDTA), and at least 0.01 wt% on total weight of the composition of a viscosifying agent,and having a pH of between 2 and 5, and to a process for treating a subterranean formation comprising introducing the above foam or viscosified composition into the formation.