Rotating Tool Antenna Sets for Formation Parameter Discrimination
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Solution Overview
Problem
Current electromagnetic resistivity logging techniques face challenges in accurately distinguishing between formation anisotropy and formation boundaries, particularly in deviated and horizontal wells, due to complex environmental effects and limited sensitivity of logging tools.
Innovation Solution
A method and system utilizing a logging tool with perpendicular and parallel antenna sets, where the tool comprises a perpendicular antenna set and a parallel antenna set, transmitting signals and obtaining data to determine compensated signals with different sensitivities to formation isotropy and boundaries, allowing for the identification of anisotropic formations, boundary approaches, and tool positions relative to boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electromagnetic resistivity logging is used, then resistivity measurements can be obtained, but the ability to distinguish between formation anisotropy and formation boundaries is insufficient
Solution Approach 1:
The antenna system is segmented into multiple perpendicular sets (first perpendicular set, second perpendicular set, and parallel set), each oriented at different angles. This segmentation allows independent measurement of electromagnetic responses in different orientations, enabling the system to distinguish between anisotropy effects and boundary effects by comparing responses from differently oriented antenna sets.
Solution Approach 2:
The invention adds angular/orientational dimension to the measurements by incorporating antenna sets at multiple perpendicular orientations. This multi-dimensional approach transforms a single measurement dimension into multiple dimensions, allowing the system to resolve the ambiguity between anisotropy and boundary effects that cannot be distinguished in a single measurement dimension.
2Measurement precision
If 1D inversion is used to distinguish formation effects, then some parameter separation is possible, but the accuracy is limited by tool sensitivity
Solution Approach 1:
The system uses multiple antenna sets providing redundant measurement information that feeds back into the inversion process. The additional independent measurements from differently oriented antenna sets provide feedback constraints that improve the reliability of inversion results, reducing dependency on single-measurement sensitivity and enabling more accurate distinction between formation parameters.
3Measurement precision
If multiple antenna sets with different orientations are used, then formation parameter discrimination is improved, but the device complexity increases
Solution Approach 1:
Each antenna set serves multiple functions: measuring resistivity, detecting anisotropy, identifying boundaries, and determining formation orientation. The perpendicular and parallel antenna sets collectively provide a universal measurement capability that covers all formation characterization needs, reducing the requirement for even more specialized antenna configurations.
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 approach enables more accurate discrimination of formation anisotropy from boundaries, improving the determination of formation parameters such as dip angle, strike angle, vertical resistivity, and horizontal resistivity, and enhances the precision of geosteering in hydrocarbon exploration.
Implementation Method 1
induction logging to determine resistivity (or its inverse, conductivity) of earth formations adjacent a borehole has long been a standard and important technique... a transmitter transmits an electromagnetic signal that passes through formation materials around the borehole and induces a signal in one or more receivers
Data Source
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Figure 8a~8b
AI summary
Methods and systems for characterizing a formation are disclosed. A tool (26) is placed in the formation (18). The tool comprises a perpendicular antenna set and a parallel antenna set. The perpendicular antenna set comprises at least one transmitter antenna (802, 804, 1008, 1014, 1018, 1020) oriented perpendicular to at least one receiver antenna (806, 808, 1002, 1004, 1010, 1012, 1022, 1024) and the parallel antenna set comprises at least one transmitter antenna (810, 812, 1006, 1016, 1018, 1020) oriented parallel to at least one receiver antenna (814, 816, 1002, 1004, 1010, 1012, 1022, 1024). Data is obtained from the tool and used to determine a compensated geosignal for each of the perpendicular antenna set and the parallel antenna set. The determined compensated geosignal is used to characterize the formation.