Fracture Conductivity via Delayed-Release Acid and Degradable Proppants
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Solution Overview
Problem
Traditional hydraulic fracturing and acidizing techniques face limitations in enhancing fracture complexity and conductivity in low permeability subterranean formations, such as shale reservoirs and tight-gas sands, due to acid spending and leak-off issues, which restrict the effectiveness of fracture stimulation and fluid production.
Innovation Solution
The use of delayed-release acids and degradable and non-degradable proppant particulates to create and enhance fractures by etching channels and diverting acid to multiple intervals, thereby increasing fracture complexity and conductivity, while the degradable particulates inhibit fluid flow initially and degrade to enhance permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional acidizing is performed to enhance fracture conductivity, then fracture complexity is improved, but acid spending and leak-off occur before reaching desired intervals
Solution Approach 1:
The patent applies preliminary action by placing degradable proppant particulates into the formation before acidizing. These particulates temporarily block fracture pathways, preventing acid from leaking off into already-treated zones. The acid is then injected and the degradable particulates degrade, allowing the acid to reach and etch channels in previously inaccessible intervals, thereby enhancing fracture conductivity throughout the entire formation sequence.
2Productivity
If multiple interval acidizing is performed to maximize fracture complexity, then conductivity is improved, but acid is insufficient to reach all intervals due to spending in earlier zones
Solution Approach 1:
The patent applies parameter changes by utilizing degradable proppant particulates that change their physical state over time. Initially, the particulates maintain a solid, blocking state that prevents acid flow into treated zones. After a predetermined period, the particulates degrade and transform, changing from a blocking barrier to a permeable state, thereby allowing acid to reach subsequent intervals and maintain potency across multiple treatment zones.
3Productivity
If proppant particulates are placed to keep fractures open, then fracture conductivity is improved, but fluid flow is blocked during the treatment process
Solution Approach 1:
The patent applies dynamics by using degradable proppant particulates that dynamically change their properties during the treatment process. The particulates are initially placed to block fluid flow and maintain fracture openness, creating a temporary static barrier. As degradation occurs, the particulates transition from a static blocking state to a dynamic, degrading state, eventually breaking down to restore fluid flow pathways and enhance overall fracture conductivity.
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 effectively increases the conductivity and productivity of low permeability formations by creating a more complex network of fractures, allowing for better fluid flow and reducing the limitations of acid spending and leak-off, leading to improved hydrocarbon recovery.
Implementation Method 1
the delayed-release acid etch channels into a face of the fracture
Implementation Method 2
the degradable proppant particulates inhibit fluid flow through the fracture
Implementation Method 3
the degradable proppant particulates degrade to enhance permeability
Data Source
AI summary
Some embodiments provide a method comprising a) introducing a delayed-release acid and a gelling agent into a subterranean formation at a rate and pressure sufficient to create or enhance at least one fracture in a first treatment interval; b) contacting the delayed-release acid with a face of the fracture in the first treatment interval so as to etch one or more channels thereon; c) introducing a combination of non-degradable and degradable micro-proppant particulates into the subterranean formation so as to place them into the fracture in the first treatment interval, wherein they at least partially inhibit fluid flow therethrough; d) introducing a combination of non-degradable and degradable proppant particulates into the subterranean formation so as to place them into the fracture in the first treatment interval, wherein they at least partially inhibit fluid flow therethrough; e) repeating (a) through (d) at a second treatment interval.