Hydraulic Fracture Curvature Forecasting via Dimensionless Parameters
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Solution Overview
Problem
Hydraulic fracturing techniques face challenges in maintaining optimal fracture geometry due to mechanical interactions between growing and previously placed fractures, leading to sub-optimal results in well stimulation, mine caving, and gas sequestration, as fractures can curve and intersect, affecting their intended purpose.
Innovation Solution
A method is developed to forecast the curvature of hydraulic fractures by deriving dimensionless similarity parameters from independent physical parameters, allowing for the planning of fracture spacing and injection conditions to minimize curvature, using a coupled 2D numerical fracturing simulator to determine threshold values and select parameters that promote non-curved fracture growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple hydraulic fractures are placed at intervals along a bore hole, then well stimulation effectiveness is improved, but fracture curvature and intersection with previous fractures occur leading to sub-optimal geometry
Solution Approach 1:
The patent applies preliminary action by forecasting fracture curvature before actual fracturing operations. Dimensionless parameters are calculated in advance to predict whether fractures will curve toward or away from previous fractures, allowing operators to plan spacing and injection conditions that prevent harmful curvature before it occurs
Solution Approach 2:
The patent implements preliminary anti-action by using the forecasting method to identify conditions that would cause fracture curvature, then adjusting spacing or injection parameters in advance to counteract the curving tendency. This prevents the harmful effect of fracture intersection before it can compromise the fracture array geometry
2Quantity of substance
If fracture spacing is reduced to increase fracture density, then well stimulation is enhanced, but mechanical interaction between fractures increases causing curvature
Solution Approach 1:
The patent applies parameter changes by using dimensionless groups to identify critical thresholds for spacing, injection rate, and fluid viscosity. By changing these parameters based on the forecasting results, operators can achieve optimal fracture density while maintaining stable, non-curving fracture geometries
3Productivity
If injection rate and pressure are increased to enhance fracture propagation, then fracture conductivity is improved, but fracture curvature toward previous fractures is induced
Solution Approach 1:
The patent implements feedback by using the dimensionless parameter forecasting to inform injection rate and pressure selections. The forecasting results provide feedback on whether proposed injection conditions will cause curving, allowing operators to adjust parameters to achieve desired conductivity while maintaining linear fracture paths
Data Source
AI summary
Method and apparatus for forecasting curving of an hydraulic fracture to be initiated in the vicinity of one or more previously placed fractures along a bore hole. Physical parameters that will affect the growth of the hydraulic fracture are received by a dimensionless parameter deriver which derives a series of dimensionless parameters as groupings of the physical parameters that are selected as similarity parameters with respect to the shape of the hydraulic fracture path. The dimensionless parameters may comprise a dimensionless viscosity parameter, a dimensionless confining stress parameter, a coefficient of friction parameter and a dimensionless deviatoric stress parameter. A comparator sequentially compares the determined dimensionless parameters with predetermined threshold values to provide an indication as to possible curving of the hydraulic fracture.