Multi-Depth Downhole Tool Resolving Borehole Fluid Distortion
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Solution Overview
Problem
Current downhole tools face challenges in accurately determining formation properties without requiring correction steps, especially when the properties of the borehole fluid significantly differ from those of the formation, leading to distorted measurements.
Innovation Solution
A downhole tool equipped with a nuclear source for irradiation, multiple detectors and antennas capable of measuring at multiple radial depths, and a controller to perform resistivity and sigma measurements, allowing for direct determination of formation properties by combining these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional single-depth detectors are used, then the device complexity is reduced, but the measurement precision at multiple radial depths deteriorates
Solution Approach 1:
The tool divides the measurement function into multiple segments by using multiple detectors positioned at different radial depths. Each detector is responsible for measuring properties at its specific depth, allowing simultaneous multi-depth measurement without requiring a single complex detector to perform all measurements.
Solution Approach 2:
The patent transitions from single-depth measurement to multi-depth measurement by adding the radial depth dimension. Multiple detectors are arranged at different radial positions to capture formation properties across multiple depths, transforming a one-dimensional measurement approach into a multi-dimensional one.
2Measurement precision
If borehole fluid properties differ significantly from formation properties, then the formation characterization accuracy is improved, but the measurement distortion increases
Solution Approach 1:
The patent applies local quality by measuring formation properties at multiple specific radial depths where the borehole fluid invasion is minimal or known. By selecting measurement locations with distinct local characteristics (different depths with different invasion levels), the tool can characterize the formation while accounting for the distorting effect of borehole fluid at each local position.
Solution Approach 2:
The multi-depth detector system acts as an intermediary that captures both the formation properties and the borehole fluid invasion profile. The measurements at multiple depths serve as intermediate data that can be used to model and correct for the distorting effect of borehole fluid, allowing accurate formation characterization despite the presence of invading fluid.
3Productivity
If multiple detectors and antennas are used for simultaneous measurements, then the productivity is improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple measurement functions (resistivity and sigma measurements) and multiple depth measurements into a single tool configuration. The detectors and antennas are positioned to perform multiple measurements simultaneously, combining what would traditionally require separate tools or sequential operations into one integrated system.
Solution Approach 2:
The tool achieves universality by designing a multi-functional downhole tool that can simultaneously perform resistivity measurements, sigma measurements, and multi-depth property determination. The same detector and antenna array serves multiple measurement purposes, eliminating the need for separate specialized tools.
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
Enables simultaneous and accurate resistivity and sigma measurements at multiple depths, providing invasion-corrected formation properties, which improves the characterization of hydrocarbon reservoirs and reduces the need for post-measurement corrections.
Implementation Method 1
a nuclear source for irradiating the formation
Implementation Method 2
perform a resistivity and a sigma measurement for the multiple radial depths
Implementation Method 3
perform a resistivity and a sigma measurement for the multiple radial depths
Data Source
AI summary
A downhole tool and method for determining properties of a formation. The method comprising irradiating the formation with a nuclear source; performing both a resistivity and a sigma measurement at each of different radial depths into the formation with a plurality of detectors; and inputting the measurements into a predetermined model for determining the properties of the formation.