Alternating Proppant Pillars for Fracture Conductivity
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Solution Overview
Problem
Conventional hydraulic fracturing methods face challenges in effectively propping open low-permeability reservoirs, requiring large amounts of proppant and viscous fluids to create long fractures, while fine proppants have low flow capacity and tend to settle, leading to unsatisfactory results.
Innovation Solution
A method involving alternating stages of proppant-laden and proppant-free fluids are pumped into the reservoir, creating vertically extending pillars with conductive channels between them, allowing for enhanced fluid flow and increased conductivity, even in low-permeability formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional proppants (sand) are used to hold fracture faces apart, then fracture support is provided, but flow capacity remains low
Solution Approach 1:
The fracture is segmented into multiple proppant beds spaced along the fracture length. These discrete beds provide structural support while leaving gaps between them that serve as high-conductivity flow channels, thus resolving the contradiction between needing continuous support and maintaining flow capacity.
Solution Approach 2:
Different regions of the fracture are given different properties: proppant beds provide structural support in localized zones, while the gaps between beds provide high-conductivity flow paths. This spatial differentiation of function allows both support and flow capacity to be optimized in their respective locations.
2Length of moving object
If viscous fluids are used to transport proppant far into the fracture, then long fracture lengths are achieved, but large volumes of fluid and proppant are required
Solution Approach 1:
Instead of using a single continuous proppant-laden viscous fluid stage, the treatment is segmented into alternating proppant-laden and proppant-free stages. This allows the viscous fluid to be used only when needed for proppant transport, while proppant-free stages sweep the fracture and reduce overall fluid volume requirements.
Solution Approach 2:
The proppant concentration in the fracturing fluid is varied through stages - sometimes high (proppant-laden) to transport proppant deep into the fracture, sometimes low or zero (proppant-free) to sweep and clean. This partial application of proppant-laden fluid reduces overall fluid and proppant volumes while still achieving long fracture lengths.
3Length of moving object
If fine proppant is used to carry over long distances, then transport distance is increased, but flow capacity becomes extremely low
Solution Approach 1:
The proppant transport and support function is segmented from the flow capacity function. Fine proppant is used only in proppant-laden stages to achieve deep transport and create proppant beds, while proppant-free stages create clear flow channels. This segmentation allows fine proppant to be used for transport without permanently compromising flow capacity.
Solution Approach 2:
The fracturing treatment uses periodic alternation between proppant-laden stages (where fine proppant is injected for deep transport) and proppant-free stages (where flow channels are cleared). This periodic action allows fine proppant to be used effectively for transport while maintaining high flow capacity in the gaps between proppant beds.
4Length of moving object
If large amounts of proppant are used to create long propped fractures, then fracture length is increased, but proppant consumption increases
Solution Approach 1:
The proppant distribution is segmented into discrete beds spaced along the fracture rather than continuous proppant filling. This segmentation reduces total proppant requirements while maintaining structural support at critical locations and creating high-conductivity gaps for flow.
Solution Approach 2:
Proppant is applied partially and intermittently through alternating proppant-laden and proppant-free stages rather than continuously. The proppant-free stages sweep the fracture and reduce proppant consumption while still achieving long fracture lengths through the periodic placement of proppant beds.
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 maintains fracture openness with reduced proppant usage, achieving higher flow capacity and conductivity compared to conventional methods, particularly in tight gas shale reservoirs with low permeability.
Implementation Method 1
fine proppant tends to slowly settle from its transport fluid
Implementation Method 2
a fluid substantially free of proppant is then pumped into the reservoir
Data Source
AI summary
A method of distributing proppant in a spatial arrangement throughout a created or enlarged fracture by pumping into a subterranean formation penetrated by a well multiple stages of fracturing fluid wherein a fluid laden with proppant is pumped into the well and a fluid substantially free of proppant is then pumped into the well; the fluid of the fluid laden with proppant and the fluid substantially free of proppant being the same. Vertically extending pillars are created within the formation. Fluid produced from the hydrocarbon-bearing reservoir is then flowed at least partially through channels between the vertically extending pillars.