Micro-proppant Fracturing Fluid for Far Field Stimulation
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Solution Overview
Problem
In unconventional oil and gas wells, the use of conventional proppants is inefficient due to their large size and density, leading to insufficient stimulation of small fractures in the far field, resulting in rapid production decline as these fractures close without adequate propping.
Innovation Solution
The use of fracturing fluids containing a mixture of micro-proppants (0.5 μm to 150 μm in diameter) and macro-proppants (greater than 100 mesh) to effectively stimulate and keep open the small fractures in the far field, with the micro-proppants being introduced not only in the pad fluid but also throughout the main fracturing operation to ensure thorough fracture network creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional proppants (100 mesh or larger) are used in hydraulic fracturing, then the main fracture can be effectively propped open, but the small fractures in the far field cannot be stimulated due to proppant settling before reaching them
Solution Approach 1:
The proppant population is segmented into multiple size classes: coarse proppants (20/40 mesh, 30/50 mesh) for main fracture propping, intermediate proppants (70/140 mesh) for transition zones, and fine proppants (100 mesh, 120 mesh, 200 mesh) for far field small fractures. This segmentation allows each size class to target specific fracture zones based on their ability to navigate the fracture network and resist settling.
Solution Approach 2:
Different proppant sizes are deployed to different locations within the fracture network. Coarse proppants remain in the main fracture near the wellbore where they provide structural support, while fine proppants travel further into the far field small fractures where they provide propping. Each location receives the appropriate proppant size for its specific needs.
2Length of stationary object
If proppant size is reduced to reach small fractures, then far field stimulation improves, but proppant transport efficiency decreases due to higher settling velocity of fine particles
Solution Approach 1:
The proppant transport system is made dynamic by adjusting fluid viscosity throughout the fracturing process. High viscosity gel fluid is used initially to carry fine proppants to the far field, then viscosity is reduced or gel is degraded to improve return flow and prevent proppant settlement in the main fracture. This dynamic adjustment optimizes proppant delivery to different zones at different times.
Solution Approach 2:
Fluid viscosity parameters are changed during the fracturing process to match proppant delivery requirements. High viscosity is maintained during the proppant injection phase to transport fine particles, then viscosity is reduced through gel degradation or fluid replacement to facilitate fluid return and prevent proppant settlement. This parameter change enables both far field penetration and efficient proppant placement.
3Quantity of substance
If high viscosity fluid is used to transport proppants further, then proppant delivery to far field improves, but fracture width increases excessively and complex fracture networks are not created
Solution Approach 1:
The fracturing process uses periodic action by alternating between high viscosity gel phases for proppant transport and low viscosity water phases for fracture creation and fluid return. During gel phases, proppants are delivered to the far field. During water phases, the lower viscosity allows for complex fracture network creation and efficient fluid return. This periodic alternation achieves both objectives without compromise.
Solution Approach 2:
The fracturing process maintains continuous useful action by seamlessly transitioning between gel and water phases. The gel phase continuously delivers proppants to the far field, while the water phase continuously creates and extends the fracture network. This continuous alternation ensures that both proppant delivery and fracture creation occur throughout the entire fracturing process without interruption or compromise to either function.
4Speed
If high pump rates are used to pump fracturing fluid with proppants, then fracture creation speed increases, but proppant settling in the main fracture increases
Solution Approach 1:
The system dynamically adjusts fluid viscosity during high-rate pumping to counteract proppant settling. High viscosity gel is used during the high pump rate phases to maintain proppant suspension and prevent settlement in the main fracture, while still allowing rapid fracture creation. The viscosity is then reduced or gel is degraded to facilitate uniform proppant distribution and fluid return.
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 allows for the effective propping open of small fractures, enhancing the stimulated reservoir volume and maintaining production by ensuring that 90% of the fracture network is adequately stimulated, thereby reducing the rapid decline in production.
Implementation Method 1
a fracturing fluid, such as a low viscosity slick-water based fluid, is pumped into the formation at high rates
Implementation Method 2
pumped into the formation at high rates, with proppant, to create a complex fracture
Implementation Method 3
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 4
The proppant then keeps the fracture open, allowing the oil or gas to escape the formation
Data Source
AI summary
A method of stimulating petroleum production includes introducing a fracturing fluid into a petroleum formation, thereby creating at least one fracture to stimulate the petroleum production. The fracturing fluid is introduced into the petroleum 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.