NMR Logging RF Pulse Generator Tank Energy Recovery
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Solution Overview
Problem
Downhole NMR sensors are sensitive to lateral motion during T2 measurements due to their small radial extent, leading to inefficiencies in RF pulse generation, particularly due to energy losses associated with charging a tank capacitor and dumping stored energy into a critical resistor.
Innovation Solution
The proposed solution involves disconnecting the energy stored in the capacitor from the antenna at the end of the RF pulse to reuse it for subsequent pulses, minimizing energy losses and increasing the radial extent of the sensitive volume by using a high-power short RF pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a short and high-power RF pulse is used to increase the radial extent of the sensitive area, then the sensitivity to lateral motion is reduced, but energy losses increase due to charging and dumping the tank capacitor
Solution Approach 1:
The patent recovers energy that would otherwise be discarded by the critical resistor. Instead of dumping the capacitor energy into the resistor at the end of each pulse, the system recycles the capacitor back to the power source to be recharged, thereby recovering the stored energy and eliminating the wasteful dissipation that occurred in conventional systems.
Solution Approach 2:
The patent converts the harmful energy loss into a beneficial recycling process. The energy that was previously wasted as heat in the critical resistor is now captured and reused. The switch that previously served only to dump energy into the resistor now serves the dual function of protecting the resistor and enabling capacitor recycling, transforming a harmful disposal mechanism into a beneficial recovery system.
2Device complexity
If standard implementations for generating RF pulses are used, then the pulse generation is simple, but the generation efficiency suffers due to energy losses
Solution Approach 1:
The patent implements a feedback mechanism where the state of the capacitor and switch is monitored and used to control the charging process. The system detects when the capacitor has been fully charged and automatically stops further charging, preventing energy waste and enabling precise control of the RF pulse generation process while maintaining overall system efficiency.
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 enhances the efficiency of RF pulse generation, reducing energy losses and improving the sensitivity of NMR well logging tools to lateral motion, thereby enhancing data accuracy during hydrocarbon exploration and production.
Implementation Method 1
generating a Radio Frequency (RF) pulse with the RF pulse generator tank
Implementation Method 2
nuclear magnetic resonance (NMR) may be utilized to acquire data from a downhole environment. NMR logging measures an induced magnet moment of hydrogen nuclei (protons)
Data Source
AI summary
A nuclear magnetic resonance (NMR) downhole tool and method that may include a housing, a power source, a Radio Frequency (RF) pulse generator tank electrically connected to the power source, a power switch electrically disposed within the RF pulse generator tank and disposed in the housing, and an NMR signal acquisition tank electrically connected to the RF pulse generator tank and disposed in the housing. The method may include disposing the NMR downhole tool into a wellbore, charging a first capacitor with the power source that is electrically connected to the first capacitor, generating a RF pulse, disconnecting the first capacitor from the RF pulse generator tank, and storing energy from the inductive coil in the first capacitor. The method may further include connecting the inductive coil to an NMR signal acquisition tank using a decoupler switch and acquiring an NMR signal with the NMR signal acquisition tank.