Hydraulic Fracture Geometry Mapping with Cross-Well Electromagnetics
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Solution Overview
Problem
Current methods for estimating hydraulic fracture geometry in unconventional reservoirs, particularly in horizontal wells, are inaccurate and often overestimate fracture dimensions due to the inability to differentiate between tensile and shear failures, leading to uncertainties in well productivity and development strategies.
Innovation Solution
A cross-well electromagnetic survey method is employed to measure the resistivity contrast between fracturing fluid and resident fluid, allowing for precise estimation of hydraulic fracture geometry by demarcating only the open portions of fractures contributing to production, and calibrating 3D models using 2D plane interpretations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to estimate hydraulic fracture geometry, then the estimation process is simple, but the measurement precision is poor due to inability to differentiate between tensile and shear failures
Solution Approach 1:
The patent replaces mechanical/seismic measurement methods with electromagnetic survey methods. The electromagnetic survey detects resistivity contrasts created by fracturing fluid versus resident fluid, allowing precise differentiation between open fractures (tensile failure) and closed/shear failures based on electrical conductivity rather than mechanical stress analysis.
Solution Approach 2:
The patent uses resistivity contrast as an analog to 'color changes' for detection. By measuring electrical resistivity differences between fracturing fluid (lower resistivity) and resident fluid (higher resistivity), the method creates a detectable signal that delineates fracture boundaries and open portions, similar to how color changes provide visual detection cues.
2Reliability
If current estimation methods are used, then the survey process is quick, but the reliability is reduced due to overestimation of fracture dimensions
Solution Approach 1:
The patent performs preliminary electromagnetic surveying before and after hydraulic fracturing treatment. By acquiring baseline resistivity data before fracturing and post-fracturing data after treatment, the method enables direct measurement of fracture-induced resistivity changes, providing reliable fracture geometry information without requiring complex interpretation or time-consuming additional surveying.
Solution Approach 2:
The patent uses feedback from resistivity contrast measurements to validate and refine fracture geometry models. The electromagnetic survey provides direct observation of open fracture portions, allowing feedback correction of overestimations in conventional methods and improving overall reliability of fracture dimension calculations.
3Measurement precision
If traditional survey methods are used, then the equipment required is simple, but the measurement precision is insufficient to differentiate between open and closed fractures
Solution Approach 1:
The patent substitutes mechanical stress analysis with electromagnetic field measurement. Instead of trying to mechanically distinguish open from closed fractures through complex stress field analysis, the method uses electrical resistivity measurement to directly detect the presence of conductive fracturing fluid, providing simple yet precise differentiation based on electrical properties rather than mechanical state.
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 method provides precise estimation of hydraulic fracture geometry, reducing uncertainties and improving the accuracy of 3D hydraulic fracture modeling, thereby enhancing well productivity and infill well development strategies.
Implementation Method 1
A cross-well electromagnetic survey method is employed to measure the resistivity contrast between fracturing fluid and resident fluid
Data Source
AI summary
A method to estimate and model all or at least two parameters of hydraulic fracture geometry in predominantly horizontal or nearly horizontal wells, by use of inter-well electromagnetic recordings. In aspects, resistivity of the fracturing fluid is used in the modeling process.