Resistivity Tool Antenna Orientation Calibration
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Solution Overview
Problem
Existing methods for determining the effective tilt angle of tilted electromagnetic antennae in formation resistivity measurements and geo-steering applications are prone to errors due to interference and limitations in mapping table data, leading to incorrect resistivity determinations and geo-steering.
Innovation Solution
The method involves using a resistivity tool with a tilted transmitter and two tilted receiver antennae, undergoing air-hang calibration to determine the effective tilt angle by decoupling multi-component signals and using forward modeling to validate the orientation, allowing for accurate formation resistivity measurements and geo-steering decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mapping table data is used to verify antenna orientation, then verification of antenna design is possible, but measurement precision deteriorates due to limited data and signal interference
Solution Approach 1:
The patent introduces an air hang calibration procedure as an intermediary step between antenna installation and formation measurement. This calibration process uses air hang data (measurements taken in air without formation interference) as a mediator to establish baseline antenna orientations and create calibration factors that compensate for manufacturing variations, thereby improving measurement precision without sacrificing verification reliability
Solution Approach 2:
The patent performs air hang calibration as a preliminary action before actual formation measurements. By determining effective tilt angles and creating calibration factors in advance (when no formation interference exists), the system prepares corrected orientation data that can be applied during subsequent formation measurements, improving precision while maintaining verification capability
2Use of energy by moving object
If ferrites and conductive mandrel are used to improve antenna efficiency, then signal propagation efficiency is improved, but orientation accuracy deteriorates due to unexpected interference effects
Solution Approach 1:
The patent implements a feedback mechanism where air hang calibration measurements are used to detect actual antenna orientations that differ from designed orientations. The system calculates calibration factors based on these measurements and applies them to correct subsequent formation measurements, thereby compensating for the orientation errors introduced by ferrites and conductive mandrels while maintaining their efficiency benefits
Solution Approach 2:
The patent changes the operational parameters by introducing calibration factors that adjust the effective tilt angle based on measured performance rather than relying solely on designed geometric parameters. This allows the system to account for parameter shifts caused by ferrites and conductive mandrels, maintaining both efficiency and orientation accuracy
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 accurate determination of the effective antenna orientation, reducing errors in resistivity measurements and improving geo-steering precision by accounting for variations in antenna design and operating frequencies.
Implementation Method 1
tilted electromagnetic (EM) antennae have been widely used in formation resistivity determinations
Implementation Method 2
a conductive mandrel of a bottom hole assembly (BHA) that is underneath the tilted antennae, may affect actual orientation (e.g., effective tilted orientation) for propagating signals into the formation
Data Source
AI summary
Systems and methods of the present disclosure relate to calibration of a resistivity tool. A calibration method comprises deploying a transmitter in a known formation with a known resistivity property with a physical tilted angle θ relative to a longitudinal axis of the tool; deploying receivers in the known formation, wherein a physical tilted angle of a first receiver is θ relative to the longitudinal axis of the tool, and wherein a physical tilted angle of a second receiver is −θ, relative to the longitudinal axis of the tool; transmitting signals with the transmitter and measuring the signals at the receivers; combining measurements at two receivers with respect to a transmitter signal in the known formation; producing synthetic responses of the tool in the known formation using forward modeling; and calculating an effective tilted angle θ′ from real measurements and the synthetic responses.