Staged Fracturing Fluids Enhance Subterranean Network Complexity
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Solution Overview
Problem
Current hydraulic fracturing methods in shale formations result in relatively simple fracture networks with low Stimulated Reservoir Volume (SRV), limiting hydrocarbon production due to predominantly long planar fractures and low fracture surface area.
Innovation Solution
The method involves pumping successive stages of fluids with varying breakdown pressures and orientations to enhance the complexity of the fracture network, using a combination of high and low viscosity fluids, gases, and acidic fluids to create a more complex fracture pattern, increasing SRV and fracture surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If slickwater fracturing techniques with low-viscosity fluid are used, then high injection rates (120 bbl/min or higher) can be achieved for proppant transport, but the fracture network created is relatively simple with low complexity
Solution Approach 1:
The patent applies parameter changes by systematically varying fluid viscosity across multiple fracturing stages. It uses high-viscosity fluids (e.g., linear gels, crosslinked gels) in earlier stages to create complex fracture networks with multiple orientations, then transitions to low-viscosity fluids (slickwater) in later stages for efficient proppant transport. This staged parameter change resolves the contradiction by achieving both network complexity and transport efficiency at different times in the process.
Solution Approach 2:
The patent implements periodic action through multistage fracturing treatments that alternate between high-viscosity and low-viscosity fluid stages. Each stage creates a specific fracture pattern, and the alternating sequence of viscosity levels produces a cumulative complex network. This periodic variation in fluid properties enables both complex network creation and efficient proppant delivery without requiring constant high viscosity throughout the entire treatment.
2Speed
If linear gels are used to maintain proppant transport at lower injection rates, then surface equipment damage is reduced, but the fracture network complexity remains limited
Solution Approach 1:
The patent uses parameter changes by employing linear gels with specific viscosity ranges (e.g., 10-100 cP) in intermediate stages, transitioning from high-viscosity crosslinked gels in earlier stages to lower-viscosity slickwater in later stages. This staged viscosity reduction allows proppant transport at moderate injection rates while progressively building fracture network complexity through different fracture initiation and propagation patterns at each stage.
3Ease of operation
If crosslinked gel is used to create a wide fracture near the wellbore to reduce the choke effect, then near-wellbore flow is improved, but the overall fracture network complexity is reduced
Solution Approach 1:
The patent applies segmentation by dividing the fracturing treatment into multiple sequential stages, each with different fluid viscosity characteristics. Crosslinked gels are used in specific stages to create wide fractures and reduce choke effects at particular locations, while other stages use different viscosity fluids to create fractures in different orientations. This segmented approach allows localized optimization of near-wellbore flow without sacrificing overall network complexity.
Solution Approach 2:
The patent implements local quality by selectively applying crosslinked gels in specific stages and locations where choke effect reduction is most needed, while using different fluid systems in other stages to maximize fracture network complexity in different regions. This localized application of high-viscosity fluids creates wide fractures where beneficial without uniformly reducing network complexity throughout the entire treatment zone.
4Area of stationary object
If massive multistage fracturing treatment is used to create adequate fracture surface area, then hydrocarbon production is improved, but large volume of water and chemical additives are required
Solution Approach 1:
The patent uses parameter changes by varying fluid viscosity across stages to create more complex fracture networks with better spatial distribution. High-viscosity fluids create fractures in certain orientations and locations, while low-viscosity fluids create fractures in different orientations, collectively achieving comprehensive reservoir coverage with potentially fewer stages and reduced total fluid volumes compared to uniform low-viscosity treatments.
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 the SRV and fracture surface area, leading to improved hydrocarbon production by creating a network of ancillary fractures with different orientations, thereby optimizing well performance and reducing the flow distance within the formation.
Implementation Method 1
the breakdown pressure due to the first fluid is greater than the breakdown pressure due to the second fluid
Implementation Method 2
hydraulic fracturing of a subterranean formation by pumping into the well a first fluid followed by a second fluid
Data Source
AI summary
The complexity of a fracture network within a subterranean formation may be enhanced by pumping a high breakdown pressure fluid followed by a low breakdown pressure fluid into the formation. The method increases the Stimulated Reservoir Volume (SRV) of the formation and provides for a network of ancillary fractures within the formation.