Fracture Aperture Estimation Using Multi-Axial Induction
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Solution Overview
Problem
Current subsurface formation fracture evaluation techniques using multi-axial electromagnetic induction well logging instruments face challenges in accurately estimating fracture apertures due to complex dependencies on various formation and wellbore parameters, leading to significant anomalies in conductivity measurements.
Innovation Solution
A method is developed to determine a fracture indicator and orientation indicator from multi-axial electromagnetic induction measurements, using a relationship between these indicators and fracture aperture, along with drilling fluid resistivity, to estimate fracture aperture effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If multi-axial electromagnetic induction measurements are used to evaluate fracture aperture, then fracture detection capability is improved, but measurement precision deteriorates due to complex dependencies on formation and wellbore parameters
Solution Approach 1:
The fracture aperture estimation process is segmented into distinct computational steps: first determining the fracture indicator from transverse measurement components, then determining the orientation indicator, and finally using both indicators along with drilling fluid resistivity to estimate fracture aperture. This segmentation allows each step to be optimized independently, improving overall measurement precision while maintaining enhanced fracture detection capability.
Solution Approach 2:
The fracture indicator and orientation indicator serve as intermediary parameters that mediate between the raw multi-axial electromagnetic induction measurements and the final fracture aperture estimation. These indicators decouple the complex dependencies on formation and wellbore parameters, allowing more precise fracture aperture estimation while preserving the enhanced detection capability provided by multi-axial measurements.
2Ease of operation
If conventional fracture evaluation methods are used, then measurement simplicity is maintained, but reliability of fracture aperture estimation deteriorates
Solution Approach 1:
The method automatically determines both the fracture indicator and orientation indicator from the multi-axial electromagnetic induction measurements without requiring external intervention or complex manual processing. The system self-corrects for the effects of formation anisotropy and wellbore parameters through the mathematical relationships embedded in the indicator calculations, maintaining operational simplicity while significantly improving estimation reliability.
Solution Approach 2:
The invention transforms the raw electromagnetic induction measurements into derived parameters (fracture indicator and orientation indicator) that have more reliable and stable relationships with fracture aperture. This parameter transformation approach maintains the ease of operation by automating the transformation process while improving reliability by using parameters that are less sensitive to formation and wellbore condition variations.
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 allows for accurate estimation of fracture apertures, improving drilling and completion decisions by providing reliable data on fracture zones and their orientation, even in complex anisotropic formations.
Implementation Method 1
A tri-axial electromagnetic induction well logging tool such as one sold under the trademark RT SCANNER measures 9-component apparent conductivity tensors
Implementation Method 2
Voltages induced in each coil of one of the receivers RM/RB is shown in the tensor C represented by the voltage V
Data Source
AI summary
A method for estimating fracture aperture from multi-axial electromagnetic induction measurements made in a wellbore includes determining a fracture indicator and a fracture orientation indicator. The value of the fracture indicator is determined from components of the measurements made transverse to the tool axis. A relationship between the value of the fracture indicator and the fracture aperture for the subsurface formation is determined by estimating the fracture indicator using a plurality of values of fracture aperture and a resistivity of drilling fluid in the wellbore over a background formation with estimated horizontal resistivity and vertical resistivity. The fracture aperture is determined using the determined fracture indicator and the determined relationship.