Chelating Etching and Microproppant Stimulation
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Solution Overview
Problem
Traditional hydraulic fracturing methods face challenges in effectively stimulating low-permeability subterranean formations, as they struggle to enhance fracture network complexity and maintain open fractures, leading to reduced hydrocarbon production and increased operational costs.
Innovation Solution
The use of a combination of chelating etching agents and micro-sized proppant particulates is employed to selectively react with and remove acid-soluble carbonate materials, creating conductive channels and enhancing fracture network complexity, while micro-sized proppants maintain open microfractures and macro-sized proppants support main fractures, thereby increasing effective fracture length and reducing re-fracturing needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional hydraulic fracturing methods are used, then fractures can be created in subterranean formations, but the fracture network complexity is insufficient and fractures close prematurely, leading to reduced hydrocarbon production
Solution Approach 1:
The patent uses micro-sized proppant particulates (1-80 mesh) to segment and fill microfractures within the fracture network, while macro-sized proppant particulates (20-100 mesh) support main fractures. This multi-scale segmentation approach maintains fracture openness at different levels, preventing premature closure and enhancing hydrocarbon production pathways.
Solution Approach 2:
The patent changes the physical and chemical parameters of the stimulation process by using chelating etching agents with specific molecular structures (DTPA, EDTA, HEDPA) that react with carbonate materials at controlled rates. The treatment fluid is injected at pressures exceeding the fracture gradient, creating and maintaining fractures while the chemical parameters of the chelating agent evolve to selectively dissolve carbonate minerals and create conductive channels.
2Productivity
If acid treatments are used to etch channels in subterranean formations, then permeability increases, but water consumption and operational costs increase
Solution Approach 1:
The patent transitions from traditional strong acid treatments to chelating etching agents that operate under different chemical parameters. The chelating agents (DTPA, EDTA, HEDPA) provide controlled, selective dissolution of carbonate materials at lower water volumes, maintaining permeability enhancement while reducing water consumption and operational costs.
Solution Approach 2:
The patent employs biodegradable chelating agents that perform their etching function and then decompose naturally, eliminating the need for large volumes of water to flush out spent acid. The chelating agents consume themselves in the process of dissolving carbonate materials, reducing overall water consumption while achieving the desired permeability enhancement.
3Reliability
If proppant particulates are used to keep fractures open, then fracture conductivity is maintained, but proppant packs may clog interstitial spaces, reducing fluid flow
Solution Approach 1:
The patent segments the proppant system into two distinct size ranges: micro-sized particulates (1-80 mesh) that fill microfractures and create conductive pathways, and macro-sized particulates (20-100 mesh) that support main fractures. This segmentation prevents clogging by ensuring each size range occupies the appropriate fracture scale, maintaining both fracture conductivity and fluid flow through the proppant pack.
Solution Approach 2:
The patent applies different proppant sizes to different locations within the fracture network: micro-sized proppant in microfractures where fine filling is needed for conductivity, and macro-sized proppant in main fractures where structural support is prioritized. This local quality differentiation optimizes both fracture conductivity and fluid flow by matching proppant characteristics to specific fracture zones.
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 increases hydrocarbon production, extends production time, reduces water consumption and costs, and creates conductive channels, resulting in a more economical and efficient stimulation process.
Implementation Method 1
The chelating etching agent is placed into the fracture network where the chelating etching agent reacts with the carbonate material, thereby removing the carbonate material and creating at least one conductive channel on a face of the fracture network
Data Source
AI summary
Methods including introducing a first treatment fluid comprising a first aqueous base fluid and a chelating etching agent into a low-permeability subterranean formation comprising carbonate material having a first fracture network at a first treatment interval therein, wherein the first fracture network comprises a first main fracture and a first microfracture. The method further comprises placing the chelating etching agent in the first fracture network and reacting it with the carbonate material in the first fracture network. In certain embodiments, the reacting removes the carbonate material, thereby creating at least one conductive channel on a face of the first fracture network. The method further comprises introducing a second treatment fluid comprising a second aqueous base fluid and micro-sized proppant particulates into the low-permeability subterranean formation and placing the micro-sized proppant particulates into the first fracture network to form a partial monolayer in the first microfracture.