P-Wave Velocity Selection Using Density Volumes in Low-Reflectivity Reservoirs
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Solution Overview
Problem
Existing methods for seismic velocity analysis in low reflectivity reservoirs, particularly in Arab carbonate rock lithology with heterogeneous rock types, face challenges due to low seismic impedance contrast and the ineffectiveness of derived equations like Gardner's, leading to difficulties in characterizing reservoirs and accurate well placement.
Innovation Solution
A method and system for selecting P-wave velocities based on density volumes, involving interpolation of wells-density logs, computation of impedance background models, spectral blueing, and scaling of seismic amplitudes to enhance seismic data, enabling accurate P-wave velocity estimation for optimized pre-stack time and depth imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Gardner's equation is used to relate seismic P-wave velocity to bulk density, then velocity estimation is simplified, but the method becomes ineffective for heterogeneous carbonate rock lithology
Solution Approach 1:
The patent changes the fundamental parameter approach by abandoning empirical equations (Gardner's) that assume homogeneous rock properties, and instead using actual measured density values from well logs. This parameter change allows accurate velocity calculation for heterogeneous carbonate rocks by directly incorporating real density measurements rather than estimating from seismic data alone.
2Measurement precision
If wells are used to guide seismic velocity analysis, then velocity constraints are provided, but the method fails in new fields with limited well data and cannot be applied between wells
Solution Approach 1:
The patent introduces density volumes as an intermediary that bridges the gap between limited well data and regional velocity analysis. By interpolating density logs from wells to create continuous density volumes across the entire survey area, the method enables velocity constraints to be applied everywhere, not just at well locations, thus solving the adaptability problem.
Solution Approach 2:
The patent creates a continuous density volume model that copies and extrapolates well log density data to locations between wells. This copying approach allows the velocity analysis to be performed across the entire field using density information derived from sparse well measurements, enabling method application in areas without direct well control.
3Measurement precision
If spectral blueing is applied to boost higher frequencies, then seismic resolution is improved, but noise amplification occurs
Solution Approach 1:
The patent applies spectral blueing selectively and partially, focusing enhancement on specific frequency ranges and spatial locations where it provides maximum benefit. By not applying aggressive blueing across the entire dataset, the method achieves improved resolution while controlling noise amplification through moderated application strength and targeted frequency selection.
Data Source
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AI summary
The present invention relates generally to enhancement and optimization of processing seismic data. The present invention relates to systems and methods of accurate selection of P-wave velocity based on density volumes in low reflectivity reservoirs. More particularly, the embodiments of the present invention provide P-wave velocity selection based on density volumes in low reflectivity reservoirs, to predict accurate velocity and using this accurate velocity for optimized pre-stack time and pre-stack depth seismic imaging. The present invention provides advantage in characterizing reservoirs enabling user to perform better mapping of the target with confidence, proper well placement and better reserves' estimation.