Subsurface Formation Radial Profiling With Combined Resistivity Tools
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Solution Overview
Problem
The industry lacks efficient and cost-effective methods to generate multiple-depth resistivity curves for radial profiling of formations during hydrocarbon exploration, which is necessary to understand the extent of the invaded zone and obtain a radial profile of the formation.
Innovation Solution
Combine measurements from omni-directional and pad-type tools, such as dual laterolog and microspherically focused logging tools, to generate a radial resistivity profile by calibrating and processing the data to match depth and resolution, and use stochastic inversion to determine hydrocarbon saturation and volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate logging tools are used to generate multiple-depth resistivity curves, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines measurements from multiple different logging tools (induction tool, laterolog tool, and resistivity imager) into a single integrated data set. By merging the omnidirectional measurements from the induction/laterolog tools with the high-resolution pad-based measurements from the resistivity imager, the system achieves multiple-depth resistivity profiling without requiring multiple separate tool passes or complex multi-functional tools.
Solution Approach 2:
The patent makes existing legacy tools serve multiple functions by combining their data. The induction tool provides deep investigation measurements, the laterolog tool provides shallow investigation measurements, and the resistivity imager provides high-resolution invaded zone measurements. Together, these tools universally cover multiple depth of investigation requirements that would traditionally require specialized multi-functional tools.
2Ease of manufacture
If legacy tools are used to generate multiple-depth resistivity curves, then cost is reduced, but productivity is worsened due to lack of efficient methods
Solution Approach 1:
The patent performs preliminary processing of the combined measurements from different tools, including depth matching and resolution matching, to prepare the data for radial profiling. This preliminary integration and calibration of multiple data sets enables efficient generation of multiple-depth resistivity curves without requiring additional field operations or complex post-processing of separate tool passes.
Solution Approach 2:
The patent uses a data processing framework that acts as an intermediary between the raw measurements from multiple legacy tools and the final radial resistivity profile. This intermediary processing system integrates measurements from tools designed for different purposes, reconciles their different depth of investigation characteristics, and produces unified multiple-depth curves efficiently.
3Measurement precision
If omni-directional and pad-type tool measurements are combined, then hydrocarbon saturation estimate accuracy is improved, but data processing complexity increases
Solution Approach 1:
The patent segments the combined measurement data by depth of investigation and measurement type, processing each segment appropriately before integration. The omnidirectional measurements (induction/laterolog) are processed separately from the pad-type measurements (resistivity imager), with each segment undergoing specific calibration and depth-matching procedures before being combined to generate the final radial profile and hydrocarbon saturation estimates.
Solution Approach 2:
The patent transforms the raw measurements from different tools by applying parameter changes including depth matching, resolution matching, and calibration adjustments. These parameter transformations convert measurements from tools with different physical characteristics and measurement principles into a unified parameter space that can be directly compared and combined for accurate hydrocarbon saturation estimation.
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 estimate of hydrocarbon saturation and volume, assisting in assessing hydrocarbon production feasibility by generating a detailed radial resistivity profile of subsurface formations.
Implementation Method 1
A current is transmitted from a current electrode and returns to a far-away return electrode. Guard electrodes may help focus the current into the formation. By measuring the impedance seen at the current electrode, a resistivity measurement may be made.
Implementation Method 2
Resistivity imagers are pad-based tools that can produce a high-resolution resistivity image of the invaded zone surrounding the borehole by measuring the impedance seen by an array of button electrodes located on each pad.
Implementation Method 3
an induction tool which operates by inducing EM fields in a formation using a transmitting antenna. These fields in turn induce a voltage in a receiving antenna.
Implementation Method 4
Dielectric tools measure the complex permittivity of the formation. Formation resistivity may be calculated as a by-product of this measurement. These tools are high-frequency, pad-based tools.
Data Source
AI summary
Systems and methods to generate radial resistivity profiles of formations using combined measurements from omni-directional and pad-type tools are described. Measurements from a pad-type resistivity tool are obtained along a wellbore drilled through a subsurface formation. Measurements from an omni-directional resistivity tool (e.g., a dual laterolog) are also obtained. The measurements from the pad-type and omni-directional tools are then combined and used to generate a radial resistivity profile of the formation.