Microproppant Fracturing Fluid for Carbonate Reservoir Stimulation
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Solution Overview
Problem
Current hydraulic fracturing methods in unconventional tight carbonate reservoirs are ineffective in stimulating small fractures due to the inability of standard proppants to reach and maintain the far-field fractures, leading to rapid production decline, as high viscosity fluids damage the formation and large proppants are not effectively transported to these small fractures.
Innovation Solution
The use of fracturing fluids containing a mixture of microproppants (0.5 μm to 150 μm in diameter) and macroproppants (greater than 100 mesh) to create a complex fracture network, where microproppants are distributed throughout the fracturing process to stimulate both induced and natural fractures, and acidic fluids are used to widen microfractures for better proppant placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard proppants (100 mesh or larger) are used in hydraulic fracturing, then the main fracture can be effectively propped open, but the far-field small fractures cannot be reached or stimulated due to proppant size and density
Solution Approach 1:
The proppant population is segmented into multiple size classes: micro-proppants (0.5-150 micrometers) for small far-field fractures, intermediate proppants for medium fractures, and standard proppants for the main fracture. This segmentation allows each size class to target specific fracture dimensions, resolving the contradiction between effectively propping the main fracture and reaching small far-field fractures.
Solution Approach 2:
Different proppant sizes are deployed to different spatial locations within the fracture network based on local requirements. Micro-proppants are concentrated in far-field small fractures where they can effectively bridge and prop, while larger proppants remain in the main fracture where they provide structural support. This local optimization resolves the contradiction by matching proppant properties to local fracture characteristics.
2Length of stationary object
If high viscosity fluid is used to transport proppants further into the formation, then proppant transport distance increases, but fracture width increases and complex fracture network creation is reduced
Solution Approach 1:
The patent utilizes hydraulic pressure dynamics to transport proppants through the formation. By optimizing pump rates and fluid pressure profiles, the system achieves effective proppant placement in far-field fractures without requiring high viscosity fluids. The hydraulic energy is sufficient to carry micro-proppants the required distance while maintaining low viscosity to preserve fracture network complexity.
3Ease of operation
If high viscosity fluids with polymers are used to transport proppants, then proppant transport capability improves, but polymer residues damage the formation and impede production
Solution Approach 1:
The patent employs biodegradable or easily degradable polymer additives that perform their proppant suspension function temporarily during injection, then break down into harmless substances. These short-lived polymers provide the necessary viscosity enhancement during the fracturing operation but decompose afterward, eliminating formation damage and production impairment from persistent polymer residues.
4Productivity
If 100 mesh proppant is used in unconventional wells, then proppant can be pumped at reasonable rates, but up to 80% remains in the main fracture and far-field fractures receive insufficient proppant
Solution Approach 1:
The proppant population is segmented into multiple size classes: micro-proppants (0.5-150 micrometers) for small far-field fractures, intermediate proppants for medium fractures, and standard proppants for the main fracture. This segmentation allows each size class to target specific fracture dimensions, resolving the contradiction between effectively propping the main fracture and reaching small far-field fractures.
Solution Approach 2:
The patent transitions from considering only proppant size to a multi-dimensional approach that includes proppant size distribution, concentration gradients, and spatial positioning within the fracture network. By controlling the dimensional distribution of proppants across different fracture zones, the system achieves both main fracture propping and far-field fracture stimulation simultaneously.
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 enhances the stimulation of the entire fracture network, including small fractures, by ensuring microproppants can reach and maintain the far-field fractures, thereby improving long-term oil and gas production by preventing premature closure of fractures and reducing fluid loss.
Implementation Method 1
a fracturing fluid, such as a low viscosity slick-water based fluid, is pumped into the formation at high rates, with proppant, to create a complex fracture
Implementation Method 2
most of the proppants will settle before they can be placed in these far field fractures, due to the density of the proppants and low viscosity of the fluid
Implementation Method 3
acidic fluids are used to widen microfractures for better proppant placement
Data Source
AI summary
A method of stimulating petroleum production includes introducing a fracturing fluid into a petroleum bearing carbonate formation, thereby creating at least one fracture to stimulate the petroleum production. The fracturing fluid is introduced into the petroleum bearing carbonate formation at a pressure above the breakdown pressure of the formation. The fracturing fluid includes a plurality of proppants where from 1 to 50 wt. % of the plurality of proppants includes micro proppants having a particle size ranging from 0.5 to 150 μm, and from 50 to 99 wt. % of the plurality of proppants includes macro proppants having a particle size greater than 100 mesh.