Acoustic Formation Top Detection for Real-Time Wellbore Drilling
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Solution Overview
Problem
Accurate determination of subterranean formation layer tops during drilling is challenging due to spatial variations in the earth, leading to uncertainties in wellbore drilling and potential instability, especially when casing installation is required.
Innovation Solution
A system combining acoustic measurements from within the wellbore with depth information to determine formation layer tops by analyzing frequency spectrums and threshold changes, allowing real-time control of drilling motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If acoustic measurements are used to determine formation layer tops, then detection capability is improved, but false positives occur due to spatial variations in the earth
Solution Approach 1:
The acoustic signal analysis is segmented into multiple frequency components through Fourier transformation. By dividing the continuous acoustic signal into discrete frequency spectrums, the system can analyze specific frequency ranges that correspond to different formation layer characteristics, improving detection accuracy while reducing false positives caused by spatial variations.
Solution Approach 2:
The system transforms the acoustic measurement from a single-time-point measurement to a depth-based spectrum analysis. By plotting spectral amplitude as a function of depth and analyzing the vertical dimension of the wellbore, the system can distinguish true formation layer tops from false signals, resolving the contradiction between detection capability and reliability.
2Manufacturing precision
If real-time acoustic analysis is performed during drilling, then drilling control precision is improved, but processing time increases
Solution Approach 1:
The system performs preliminary Fourier transformation of the acoustic signal to establish a baseline frequency spectrum before drilling operations proceed. This pre-processing allows the system to quickly compare subsequent acoustic measurements against the established baseline, enabling real-time drilling control without excessive processing delays.
Solution Approach 2:
Instead of analyzing the entire frequency spectrum at all times, the system focuses on specific frequency ranges that are most indicative of formation layer changes. By applying localized frequency analysis to relevant spectral components, the system achieves high drilling control precision while minimizing processing time for irrelevant frequency data.
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
Improves the accuracy of formation layer top detection, reduces false positives, and enables real-time control of drilling operations, ensuring safe and precise casing installation based on formation layer changes.
Implementation Method 1
measured sound from within a wellbore and depth of the drill bit while drilling the wellbore
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Some systems and methods for determining depths of subterranean formation layer tops while drilling through the subterranean formation include a drill bit, a drill rig, a microphone, a depth sensor, and a processor. While drilling the through the subterranean formation, the processor receives a measured sound from the microphone and a measured drill bit depth from the depth sensor, normalizes the measured sound across all measured drill bit depths, determines frequency information of the normalized sound for each depth of the plurality of depths, determines frequency spectrums of the normalized sound for one or more depths of the plurality of depths, transforms the frequency spectrums into a depth spectrum, and determines the depths of subterranean formation layer tops based on the depth spectrum.