Geophone Depth Calibration via Correlation Analysis
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Solution Overview
Problem
Geophone arrays in wellbores face challenges due to gravitational strain and poor positioning, leading to inconsistent spacing and overlapping measurements, which skew data and complicate calibration and correction methods for slowness profiles.
Innovation Solution
A method involving an information handling system to analyze recorded data, identify gaps and spikes, and apply depth corrections using correlation-based methods and Gaussian distribution analysis to optimize geophone array positioning and correct slowness profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If geophone array is positioned at multiple locations to cover different depth ranges, then measurement coverage is improved, but spacing consistency deteriorates due to cable strain and positioning errors
Solution Approach 1:
The geophone array is divided into multiple independent geophone sensors that can be individually positioned and depth-calibrated. Each geophone acts as a separate measurement unit, allowing the system to maintain consistent spacing between measurements even when the overall array is repositioned at multiple locations within the borehole.
Solution Approach 2:
The system uses correlation-based methods to analyze recorded acoustic wave data and provides feedback on the actual spacing between geophone measurements. This feedback is used to compute depth corrections that compensate for cable strain and positioning errors, ensuring consistent spacing in the final slowness profile.
2Length of stationary object
If geophone array is re-positioned multiple times to form complete slowness profile, then depth range coverage is improved, but data accuracy deteriorates due to overlapping and inconsistent spacing
Solution Approach 1:
The system performs preliminary depth calibration by analyzing the recorded acoustic wave data from multiple geophone positions before computing the final slowness profile. Correlation-based methods are used to identify gaps and overlaps between measurements, and depth corrections are applied in advance to ensure accurate spacing throughout the entire depth range.
Solution Approach 2:
The system changes the depth parameter by computing depth corrections based on the analyzed acoustic wave data. These corrections adjust the nominal depth locations of each geophone measurement to reflect the actual spacing, thereby maintaining data accuracy across the entire depth range covered by multiple array positions.
3Adaptability or versatility
If cable strain and slack are present in geophone array, then deployment flexibility is improved, but measurement reliability deteriorates due to inconsistent geophone spacing
Solution Approach 1:
The system uses correlation-based analysis of acoustic wave recordings to provide feedback on the actual spacing between geophones caused by cable strain and slack. This feedback enables computation of depth corrections that compensate for the inconsistent spacing, thereby maintaining measurement reliability despite deployment flexibility.
Solution Approach 2:
The system performs self-calibration by analyzing its own recorded data to identify spacing errors caused by cable effects. The correlation-based methods automatically detect gaps and overlaps, and the depth corrections are computed and applied without requiring external calibration equipment or manual intervention.
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
The method effectively corrects slowness profile data by determining accurate spacing and depth shifts, suppressing errors and maintaining data accuracy, thereby improving the reliability of formation velocity measurements.
Implementation Method 1
A vibration source, disposed on the surface, may be activated to cast acoustic waves into formations below. Geophones on the geophone array may detect and allow the recording of the acoustic waves as they traverse and/or reflected through the formation.
Data Source
AI summary
A method and system for processing a slowness profile. A method may comprise disposing a geophone array into a borehole, positioning the geophone array at a first location within the borehole; discharging a seismic source; positioning the geophone array at a second location within the borehole; discharging the seismic source, wherein the seismic source produces an acoustic wave; recording a vertical seismic profiling dataset, wherein vertical seismic profiling comprises a dataset of recorded acoustic waves by the geophone array at the first location within the borehole and the second location within the borehole; picking a first gap travel time from the vertical seismic profiling dataset; and determining the slowness profile, wherein the slowness profile comprises determining a slowness of the acoustic wave through a formation by the geophone arrays. A well system may comprise a geophone array, comprising a plurality of geophones, and an information handling system.