Proppant Placement in Tight Formations
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Solution Overview
Problem
In tight shale formations, conventional propping agents fail to effectively maintain open fractures due to mechanical failure and embedding, leading to decreased hydrocarbon production as fractures close, and existing methods do not adequately address the complex tortuous fracture systems common in these formations.
Innovation Solution
A method involving multiple stages of pad fluid injection, including an initial aqueous-based fluid to create fractures, a second stage with a low concentration of small proppant particles to extend fractures, a diverting agent to temporarily seal off smaller fractures, and a main proppant slurry stage with larger particles to ensure high conductivity and bridge tortuous paths, using a mixture of proppants with varying sizes, densities, and degradability to maintain fracture openness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional proppant materials are used to prop open fractures, then initial fracture conductivity is achieved, but proppant mechanical failure and embedding cause fracture closure and production decrease over time
Solution Approach 1:
The patent uses composite proppant materials combining ceramic cores with polymer coatings or biodegradable materials. The ceramic core provides initial mechanical strength and conductivity, while the polymer coating or biodegradable material prevents embedding and maintains fracture openness over time by degrading into harmless byproducts that continue to support the fracture.
Solution Approach 2:
The patent changes the physical and chemical parameters of proppant materials by using varied sizes, shapes, and surface treatments. Larger proppants prevent embedding while smaller particles fill voids, and surface treatments modify interaction with formation rock, collectively improving long-term fracture conductivity and resistance to mechanical failure.
2Ease of operation
If single-stage proppant injection is used, then placement is simple, but complex tortuous fracture systems are not adequately propped
Solution Approach 1:
The patent segments the proppant injection process into multiple stages with different proppant sizes and properties. The first stage uses larger proppants to establish main fracture conductivity, while subsequent stages use smaller proppants to fill secondary fractures and tortuous paths, ensuring comprehensive propping of complex fracture networks while maintaining operational feasibility.
Solution Approach 2:
The patent applies preliminary action by injecting larger proppants first to create the primary conductive network before injecting smaller proppants that can access and prop the complex tortuous secondary fractures. This sequencing ensures that the fracture system is progressively filled from main to minor pathways.
3Ease of manufacture
If uniform proppant size is used, then injection is straightforward, but effective bridging in tortuous fracture paths is insufficient
Solution Approach 1:
The patent applies local quality by using a blend of proppant sizes where larger particles are strategically placed in main fracture zones for structural support, while smaller particles are distributed in tortuous and secondary fracture paths for effective bridging. This size distribution optimizes proppant placement precision across different fracture geometries while maintaining relatively simple mixture preparation.
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 ensures successful proppant placement and maintains high conductivity in complex fracture networks, preventing fracture closure and enhancing hydrocarbon production by using a combination of small and large proppant particles with degradable particulates and surface coatings to create porous channels and ensure effective bridging within the fracture system.
Implementation Method 1
Treatment fluids (pad fluids) are pumped at high pressure into the formation to create fractures in the formation
Implementation Method 2
Proppants may be incorporated in the treatment fluids to prop open the created fractures when the surface treating pressure is released
Implementation Method 3
embedding of proppant into the fracture face of the well formation
Implementation Method 4
using a mixture of proppants with varying sizes, densities, and degradability to maintain fracture openness
Data Source
AI summary
A method of propping created fractures and microfractures in tight formation. The method includes injecting into a wellbore a first pad fluid stage; injecting into the wellbore a second pad fluid stage; injecting into the wellbore a diverting agent; and injecting into the wellbore a main proppant slurry stage; wherein the first pad fluid stage includes an aqueous-based fluid at a rate above the fracturing gradient to create a fracture, wherein the second pad fluid stage includes an aqueous-based fluid and a low concentration of a proppant mixture including a slurry of small proppant materials and/or a slurry of conventional proppant materials to extend the fracture and open up secondary induced fractures, and wherein the main proppant slurry stage includes an aqueous-based fluid and a proppant with a larger size than the small proppant particles in the second pad fluid stage.