Dynamic Wellbore Loading for Secondary Fractures in Tight Reservoirs
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Solution Overview
Problem
Conventional hydraulic fracturing methods struggle to access and extract hydrocarbons efficiently from unconventional reservoirs with low permeability due to limited contact with the rock, leading to a lower hydrocarbon recovery factor.
Innovation Solution
A method and system that applies dynamic loads to primary fractures in a wellbore to generate secondary fractures, including bedding-parallel delaminations and bedding-perpendicular tensile cracks, enhancing hydrocarbon access by creating additional permeability pathways through time-varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hydraulic fracturing is used to create primary fractures, then hydrocarbon access is improved, but hydrocarbon recovery factor remains low due to limited contact with rock in low permeability reservoirs
Solution Approach 1:
The patent divides the fracture system into two levels: primary fractures created by conventional hydraulic fracturing, and secondary fractures created by dynamic loading. This segmentation allows the system to first establish main conduits for fluid flow, then create additional branching pathways that increase rock contact area without requiring a complete redesign of the fracturing process
Solution Approach 2:
The patent applies dynamic mechanical loading (vibration) to the wellbore at frequencies ranging from 10 Hz to 10 kHz to induce secondary fractures. This mechanical vibration causes the rock to fail in tension along the primary fracture surfaces, creating delaminations and tensile cracks that expand the fracture network and increase contact area with hydrocarbon-bearing rock
2Productivity
If dynamic loading is applied to generate secondary fractures, then permeability pathways are enhanced, but device complexity increases
Solution Approach 1:
The patent makes the wellbore itself serve multiple functions: it acts as both the conduit for hydraulic fracturing fluid and the medium for transmitting dynamic mechanical loads. By using the existing wellbore structure for dual purposes, the patent avoids adding separate complex delivery systems while still achieving the desired secondary fracture generation
Solution Approach 2:
The system uses the wellbore's own structural integrity and the reservoir rock properties to generate the secondary fractures. The dynamic load applied through the wellbore leverages the existing stress field and rock mechanics to create delaminations and tensile cracks, rather than requiring external fracturing equipment to be deployed into the fractures
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
The method increases hydrocarbon production by connecting primary fractures to more oil-bearing rock, improving hydrocarbon recovery by creating secondary fractures that enhance permeability and access to hydrocarbons in low-permeability reservoirs.
Implementation Method 1
bedding-perpendicular tensile cracks
Implementation Method 2
applying a dynamic load via the wellbore to primary fractures
Data Source
AI summary
An apparatus and corresponding method for generating secondary fractures in reservoirs are described herein. The method includes applying a dynamic load via a wellbore to primary fractures in reservoir to generate secondary fractures along the primary fractures. The system includes extracting hydrocarbons from the wellbore via the secondary fractures in the reservoir.