Sonic Logging Analysis for Laminated Reservoir Multiple Arrivals
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Solution Overview
Problem
Interpreting compressional and shear velocities in laminated hydrocarbon reservoirs is challenging due to multiple arrivals from refracted waves, complicating porosity estimation and completion planning in highly deviated or horizontal wellbores.
Innovation Solution
An automated method involving slowness time coherence analysis and ray tracing inversion is employed to detect and characterize multiple compressional and shear arrivals, incorporating well and formation geometry to determine tool and shoulder bed slownesses and distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sonic logging methods are used in laminated formations, then compressional velocity estimates can be obtained, but multiple compressional and shear arrivals from refracted waves complicate the interpretation and reduce measurement precision
Solution Approach 1:
The patent segments the complex waveform into multiple distinct arrivals (direct compressional, indirect compressional, shear arrivals) by analyzing slowness-time coherence. This segmentation allows each arrival to be individually identified and measured, resolving the complexity of interpreting multiple overlapping waves in laminated formations.
Solution Approach 2:
The patent introduces a slowness dimension to the traditional time-domain analysis by performing slowness-time coherence analysis. This additional dimension enables the separation and identification of multiple arrivals that would be difficult to distinguish in the time domain alone, improving measurement precision while managing interpretation complexity.
2Measurement precision
If manual interpretation methods are used to identify multiple arrivals, then detailed analysis can be performed, but the process is time consuming and reduces productivity
Solution Approach 1:
The patent implements an automated system that performs slowness-time coherence analysis and arrival identification without requiring manual interpretation. The system self-determines the arrival times and slownesses of multiple compressional and shear arrivals by automatically analyzing the waveform data, thereby maintaining measurement precision while dramatically improving productivity.
Solution Approach 2:
The patent replaces manual mechanical interpretation methods with an automated computational system that uses slowness-time coherence analysis. This substitution eliminates the time-consuming manual process while preserving the ability to accurately determine arrival times and slownesses through algorithmic analysis of the waveform data.
3Productivity
If simple 1D models are used for slowness estimation, then computational speed is improved, but accuracy in laminated formations with dipping layers is reduced
Solution Approach 1:
The patent employs a dynamic approach by using an iterative optimization process that starts with a simple 1D model and progressively refines it to account for dipping layers and laminated formation complexity. The model adapts to the actual formation geometry by adjusting parameters based on the observed slowness-time coherence patterns, thereby maintaining computational efficiency while improving slowness determination accuracy.
Solution Approach 2:
The patent changes the model parameters from a simple 1D assumption to a more complex model that incorporates dipping angles and layer thicknesses. By iteratively adjusting these parameters to match the observed arrival times and slownesses, the system achieves accurate slowness determination in laminated formations while maintaining reasonable computational efficiency through the iterative refinement approach.
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
Provides a more accurate and efficient method for determining geological properties of laminated reservoirs, enabling optimal completion design decisions.
Implementation Method 1
multiple compressional (and shear) arrivals generated by refracted waves propagating through the formation layer containing the logging tool
Implementation Method 2
multiple compressional (and shear) arrivals generated by refracted waves propagating through the formation layer
Data Source
AI summary
Aspects provide for methods that successfully evaluates multiple compressional and shear arrival events received by a sonic logging tool to evaluate the presence of structures, such as shoulder beds, in downhole environments. In particular, the methods described herein enable automated determination of properties of laminated reservoir formations by, for example, enabling the automated determination of arrival times and slownesses of multiple compressional and shear arrival events received by a sonic logging tool.