X-ray Litho-Density Tool for Non-Invaded Formation Measurement
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Solution Overview
Problem
Current well logging technologies rely on radioactive isotopes for density measurements, which pose safety risks, regulatory challenges, and logistical complexities due to the need for controlled handling and disposal, and lack the ability to accurately measure non-invaded formation density without mud-weight interference.
Innovation Solution
An x-ray based litho-density tool with increased axial offset detectors and higher photon output, allowing for simultaneous measurement of invaded and non-invaded formation densities, using an x-ray source to replace radioactive isotopes and improve data resolution and logging speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If radioactive isotopes are used for density logging, then gamma ray supply is ready and continuous, but safety risks and regulatory challenges increase
Solution Approach 1:
The patent replaces long-lived radioactive isotopes with short-lived x-ray sources that can be activated only when needed. The x-ray tube generates radiation on-demand through electrical power, eliminating the need for handling, transporting, and disposing of radioactive materials while providing continuous measurement capability during the logging operation.
Solution Approach 2:
The patent substitutes the radioactive decay mechanism (nuclear physics) with an x-ray tube mechanism (electrical to electromagnetic energy conversion). This replacement eliminates all radioactive material handling requirements while maintaining the ability to generate gamma rays for density logging measurements.
2Measurement precision
If detectors are placed close to the x-ray source, then measurement sensitivity is high, but mud-invaded zone interference increases
Solution Approach 1:
The patent extends the detector offset in the axial dimension (along the borehole axis) to positions beyond the mud-invaded zone. By placing detectors at these extended offsets, the system measures density in the non-invaded formation zone while the high-output x-ray source compensates for the increased distance through elevated photon generation rates.
3Measurement precision
If detector offset is increased to avoid mud-invaded zone, then non-invaded formation measurement accuracy improves, but photon signal strength decreases
Solution Approach 1:
The patent changes the output parameter of the x-ray source (photon generation rate) to compensate for the increased detector offset. By operating the x-ray tube at higher power levels, the system maintains sufficient photon flux at extended detector positions to achieve the required measurement precision in the non-invaded zone.
4Measurement precision
If conventional density logging is performed, then formation density is measured, but logging speed is limited by radiation safety protocols
Solution Approach 1:
The patent uses periodic or pulsed activation of the x-ray source rather than continuous operation of radioactive isotopes. The x-ray tube can be rapidly activated and deactivated, enabling faster logging speeds while maintaining measurement precision through controlled exposure periods that eliminate the need for prolonged radiation safety protocols.
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
This solution enhances the accuracy of formation density measurements by avoiding mud-invaded zones, reduces the impact of mud-weight and porosity, and enables faster logging speeds while eliminating the risks associated with radioactive materials, achieving 0.01g/cc repeatability and reducing operational time.
Implementation Method 1
The number of Compton scattering collisions is related directly to the number of the electrons per unit volume, or electron density, within the formation. Consequently, the electron density determines the response of the density tool.
Implementation Method 2
the use of an x-ray source to measure the photoelectric properties of a formation directly
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An x-ray based litho-density tool for measurement of simultaneous invaded and non-invaded formation surrounding a borehole is provided, the tool including at least an internal length comprising a sonde section, wherein sonde section further includes an x-ray source; at least one radiation measuring detector; at least one source monitoring detector; and a plurality of sonde-dependent electronics. In various embodiments, the tool uses x-rays to illuminate the formation surrounding a borehole, and a plurality of detectors are used to directly measure both invaded and non-invaded formation bulk densities. Detectors used to measure borehole standoff such that other detector responses may be compensated for tool standoff; long and ultra-long space detectors disposed in electromagnetic communication with a source located within a collimated tungsten radiation shield; and wear-pads disposed such that the source and detector assembly may be pressed against the side of the borehole to reduce borehole effects are also provided.