Fracture Density Index Calibration for Reservoir Fracture Simulation
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Solution Overview
Problem
Reliability in constructing a model of natural fractures in hydrocarbon reservoirs is difficult due to the need for multi-disciplinary inputs, which affects hydraulic fracturing and identifying suitable intervals for extraction.
Innovation Solution
A method involving a mechanical earth model to form a fracture network model, determine fracture density index (FDI), and calibrate it using bottom hole pressure and rate to enhance matrix permeability, aiding in well location and drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a discrete fracture network model is constructed using multi-disciplinary inputs, then the representation of natural fractures becomes more accurate, but the model complexity and difficulty of construction increase significantly
Solution Approach 1:
The patent combines the discrete fracture network model with the continuous matrix permeability model into a unified dual-permeability system. The fracture density index serves as a bridge that links discrete fracture characteristics to continuous matrix properties, allowing the model to capture both discrete fracture effects and continuous flow behavior without requiring separate complex modeling approaches
Solution Approach 2:
The fracture density index acts as an intermediary parameter that translates discrete fracture network characteristics into a form that can be integrated with continuous matrix permeability. This intermediate representation simplifies the coupling between discrete and continuous models, reducing the overall model construction complexity while maintaining accuracy
2Reliability
If the fracture network model is calibrated using multiple parameters, then the reliability of reservoir simulation improves, but the time and computational resources required increase
Solution Approach 1:
The patent transforms the complex multi-parameter calibration problem into a simpler single-parameter calibration by introducing the fracture density index. Instead of calibrating multiple discrete fracture parameters separately, the system calibrates the fracture density index against observed pressure data, which automatically adjusts the effective permeability to match field observations, significantly reducing calibration time
Solution Approach 2:
The calibration process uses observed pressure data as feedback to adjust the fracture density index and effective permeability parameters. This feedback mechanism allows the model to self-correct and converge to reliable results more quickly, reducing the iterative calibration time while maintaining high simulation reliability
3Measurement precision
If natural fractures are represented as discrete elements, then fluid flow pathways are accurately captured, but the integration with matrix permeability becomes difficult
Solution Approach 1:
The patent applies local quality by modifying the matrix permeability in the vicinity of fractures based on the fracture density index. Instead of treating the entire reservoir uniformly, the system locally enhances matrix permeability in areas where fractures are present, creating a transition zone that naturally connects discrete fracture flow pathways with the continuous matrix without requiring complex interface conditions
Data Source
AI summary
Modeling natural fractures of a formation having a hydrocarbon reservoir by representing a discrete natural fracture network as a continuous property and dynamically calibrating the discrete natural fracture network for coupling into a single media for reservoir numerical simulation. A mechanical earth model and fracture model having a fracture density index for a naturally fractured reservoir may be determined. A static calibration and a dynamic calibration may be performed for the discrete natural fracture network. A history match of flow rate and bottom-hole pressure may also be performed.