Staged Propping of Fracture Networks Using Microproppants
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Solution Overview
Problem
In tight subterranean formations, especially shales and tight-gas sands, the small widths of natural or induced microfractures are not effectively maintained open by traditional propping agents, leading to reduced hydrocarbon production and increased costs and time for subsequent fracturing and propping operations.
Innovation Solution
The method involves staged propping operations using a series of fluids to place different-sized proppants within the fracture network, starting with microproppants in microfractures and larger proppants in fractures and branches, enhancing hydrocarbon production by effectively maintaining the fracture network open.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional propping agents are used in tight formations, then larger fractures can be maintained open, but microfractures close due to their small widths being smaller than the propping agents
Solution Approach 1:
The propping operation is segmented into multiple stages with different propping agent sizes. First, microproppants (e.g., 20-40 mesh) are placed to prop microfractures, followed by larger proppants (e.g., 20-40 mesh then 40-70 mesh) for larger fractures. This segmentation allows each propping agent size to target specific fracture width ranges, ensuring both microfractures and larger fractures remain open for hydrocarbon flow.
Solution Approach 2:
Different regions of the fracture network receive differently sized propping agents based on local fracture width requirements. Microfractures receive microproppants while larger fractures receive larger proppants. This local quality approach ensures that each part of the fracture network is propped with the appropriate particle size, maximizing overall fracture network effectiveness.
2Productivity
If microfractures close after pressure release, then the fracture network effectiveness is reduced, but repeating fracturing and propping operations increases costs and time
Solution Approach 1:
Microproppants are placed in microfractures during the initial fracturing operation before production begins. This preliminary action ensures microfractures are propped open from the start, preventing closure that would otherwise require repeat fracturing operations and associated time losses.
3Ease of manufacture
If single-stage propping with traditional proppants is used, then the process is simple, but microfractures cannot be effectively propped due to particle size mismatch
Solution Approach 1:
The propping operation is divided into multiple stages with different propping agent sizes injected at different times. This segmentation provides manufacturing precision by ensuring the right proppant size reaches the right fracture width, while maintaining operational simplicity through a systematic multi-stage process that can be managed with standard fracturing equipment.
Solution Approach 2:
The proppant particle size parameter is changed between stages of the fracturing operation. First, finer proppants are used for microfractures, then coarser proppants are used for larger fractures. This parameter change enables precise proppant placement matching fracture width, improving propping effectiveness without requiring complex custom equipment.
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 from tight formations by ensuring that microfractures remain open, reducing the need for frequent fracturing and propping operations, thereby decreasing costs and time associated with hydrocarbon production.
Implementation Method 1
The propping agents hold open the fracture network thereby maintaining the ability for fluid to flow through the fracture network
Data Source
AI summary
Creating a fracture network extending from a wellbore into a subterranean formation. The method includes introducing a series of fluids into the fracture network in a subterranean formation, thereby forming a proppant pack in the fracture network. The series of fluids comprise: a microproppant slurry comprising a microproppant having an average diameter less than about 25 microns; a proppant slurry comprising a proppant having an average diameter of about 75 microns to about 500 microns; and a sweep fluid having a microproppant weight percentage by weight of the sweep fluid that is from 0 to about the same of the microproppant weight percentage in the microproppant slurry by weight of the microproppant slurry. The introduction of the microproppant slurry is not immediately followed by introduction of the proppant slurry. The introduction of the proppant slurry is not immediately followed by introduction of the microproppant slurry.