NMR Well Logging Wait-Time Optimization for Faster Borehole Evaluation
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Solution Overview
Problem
Conventional well-logging methods employ a standard parameter configuration that is often conservative and inefficient for varying geological formations, leading to suboptimal logging speed and data quality, particularly in NMR well-logging where fluids with different T1/T2 values require tailored acquisition parameters.
Innovation Solution
Implement methods to optimize NMR well-logging configuration by performing pre-logs to identify optimal parameters at different depths, analyzing data to determine variable wait times and logging speeds, and adjusting tool settings in real-time to match fluid and formation properties, using techniques such as classification and inversion methods to enhance data acquisition efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a standard conservative parameter configuration is used for NMR well-logging, then the logging operation can be performed with predefined settings, but the logging speed and data quality are suboptimal for varying geological formations
Solution Approach 1:
The patent implements dynamic adjustment of logging parameters (wait time, logging speed, power settings) based on real-time analysis of pre-log data and formation properties. The system transitions from static predefined parameters to dynamic adaptive parameters that optimize both logging speed and data quality for different geological formations encountered during the logging operation.
Solution Approach 2:
The patent systematically changes key parameters including wait time (adjusted based on T1 relaxation times), logging speed (optimized for signal-to-noise ratio), and power settings (adjusted for formation properties) to resolve the contradiction between logging speed and data quality. These parameter changes are driven by real-time formation evaluation and fluid property determination.
2Measurement precision
If slower logging speed is used to achieve better signal-to-noise ratio, then data quality improves, but the logging operation becomes more costly and time-consuming
Solution Approach 1:
The patent performs pre-logging operations to collect initial data about formation properties and fluid characteristics before the main logging run. This preliminary action enables optimization of logging parameters (wait time, speed, power) in advance, allowing the main operation to achieve high signal-to-noise ratio without excessive time loss by using pre-determined optimal parameters tailored to specific formations.
Solution Approach 2:
The system uses the pre-log data and formation evaluation results to automatically determine optimal logging parameters without requiring external intervention or conservative default settings. The logging system serves itself by using its own preliminary data to optimize its operational parameters, achieving efficient logging speed with adequate signal quality.
3Measurement precision
If high electrical power is used to generate more neutrons for better statistics and accuracy, then measurement quality improves, but the lifetime of the neutron generator is shortened
Solution Approach 1:
The patent dynamically adjusts power settings based on formation properties, fluid types, and logging depth. Rather than using consistently high power, the system optimizes power levels for each specific logging interval, using higher power only when necessary for accurate measurement and lower power when adequate signal is already obtained, thereby extending neutron generator lifetime while maintaining measurement accuracy.
4Measurement precision
If high power for CMR+ is used in high saline environment, then signal strength improves, but tool failure risk increases
Solution Approach 1:
The patent implements feedback mechanisms where pre-log data and real-time formation evaluation results are used to adjust power settings for CMR+ operations in high saline environments. The system monitors formation properties and fluid salinity, then automatically adjusts power levels to achieve adequate signal strength without exceeding safe operational limits, thereby maintaining tool reliability while obtaining usable data.
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
Improves data quality and reduces logging time and cost by optimizing NMR well-logging parameters, ensuring accurate fluid and formation property determination across varying geological conditions.
Implementation Method 1
nuclear magnetic resonance (e.g. CMR) to determine pore size and fluid properties
Implementation Method 2
applying a magnetic field to the volume around the borehole
Implementation Method 3
applying a series of electromagnetic pulses to the volume around the borehole
Implementation Method 4
a pulsed neutron tool to determine neutron density and porosity
Implementation Method 5
neutron measurement of porosity requires knowledge of formation lithology/mineralogy
Implementation Method 6
induction tool for resistivity
Implementation Method 7
density log to determine bulk density
Implementation Method 8
nuclear spectroscopy (e.g. Schlumberger Lithoscanner) to determine mineralogy
Implementation Method 9
a cerium-doped lanthanum bromide (LaBr3:Ce) gamma ray detector to provide quantitative measurements of elements and mineralogy
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
Methods and systems are provided for optimizing well-logging using an optimized wait time determined by analysis nuclear magnetic resonance data to achieve faster and better quality borehole evaluation. The method comprises performing a nuclear magnetic resonance pre-log testing; identifying a wait time for a portion of a signal from the pre-log testing with a long T1 and T2, value at each depth of the pre-log testing, wherein T1 is defined as a longitudinal relaxation time and T2 is a transverse relaxation time ascertained from the nuclear magnetic resonance prelog testing; and constructing a logging program with a logging program wait time being consistent with the wait time identified.