Downhole Fiber Optic Seismic Acquisition Using Drill Bit Signals
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Solution Overview
Problem
Conventional seismic acquisition methods in the oil and gas industry face significant challenges due to noise contamination and signal attenuation, particularly when sources and receivers are located at large offsets, leading to inaccurate seismic data readings.
Innovation Solution
A seismic acquisition system that uses a drill bit as a source and a fiber optic cable cemented downhole behind a casing string as the receiver, allowing for cleaner signal reception and reduced noise interference, enabling the generation of high-resolution velocity profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional seismic acquisition methods are used with sources and receivers at large offsets, then seismic surveys can cover larger areas, but noise contamination and signal attenuation increase significantly
Solution Approach 1:
The fiber optic cable is divided into multiple segments with receiver stations spaced at intervals along the wellbore. This segmentation allows the system to capture seismic signals at multiple depths simultaneously, enabling the separation of signal components and reduction of noise through processing, while maintaining effective survey coverage.
Solution Approach 2:
The fiber optic cable acts as an intermediary between the seismic source and the receiver system. It transmits seismic signals from the drill bit through the wellbore to multiple receiver stations, enabling clean signal transmission without the noise contamination that occurs with conventional surface-based receivers at large offsets.
2Ease of manufacture
If conventional seismic acquisition methods are used, then existing infrastructure can be utilized, but processing complexity and data quality issues arise
Solution Approach 1:
The fiber optic cable system serves multiple functions: it acts as both the seismic receiver medium and the signal transmission conduit, and can be integrated with existing drilling operations. The system processes seismic signals at multiple depths simultaneously, reducing the need for complex post-processing while improving data quality through cleaner signal acquisition.
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 approach results in cleaner seismic data with reduced attenuation and scattering, providing accurate high-resolution velocity profiles and improving the accuracy of single well profiling data.
Implementation Method 1
detecting, at each of a plurality of receiver stations located along a fiber optic cable disposed behind a casing string within the wellbore, a seismic signal created by the drill bit drilling the wellbore
Data Source
AI summary
A method includes drilling a wellbore into a subsurface using a drill bit and, for each of a plurality of depths of the drill bit in the wellbore, detecting, at each of a plurality of receiver stations located along a fiber optic cable disposed behind a casing string within the wellbore, a seismic signal created by the drill bit drilling the wellbore, sending an optical signal generated by the detection of the seismic signal from each of the plurality of receiver stations to an interrogator, sorting, using a computer processor, the optical signals by receiver station, and determining, using the computer processor, a seismic velocity using first breaks picked from the sorted optical signals.