Closed-Loop Downhole Resonant Source for Seismic Monitoring
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Solution Overview
Problem
Conventional seismic source systems for monitoring hydrocarbon reservoirs are prone to interference with production operations, require frequent repositioning, and struggle with maintaining consistent recording conditions over extended periods, leading to unreliable data due to mechanical movement and environmental changes.
Innovation Solution
A closed-loop borehole seismic source system that includes a resonant cavity and a control unit, using a smart fluid or hydraulic fluid to generate resonant energy independently of the borehole production string, allowing for controlled pressure pulses and frequency adjustments to produce seismic waves without disrupting production, and utilizing a smart fluid to extend operating capabilities and control parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seismic source systems are used in boreholes, then seismic waves can be generated for reservoir monitoring, but the systems interfere with production operations and require frequent repositioning
Solution Approach 1:
The patent extracts the seismic source function from the production string by using the production string itself as a acoustic waveguide. The seismic source is positioned in the annulus between the production string and borehole wall, separating the monitoring function from production operations while utilizing the production string structure for both purposes
Solution Approach 2:
The production string serves dual functions: as a conduit for hydrocarbon production and as an acoustic waveguide for seismic wave propagation. This multi-functionality eliminates the need for separate seismic source equipment that would interfere with production operations
2Adaptability or versatility
If conventional seismic source systems are repositioned frequently, then different reservoir zones can be monitored, but consistent recording conditions cannot be maintained
Solution Approach 1:
The system pre-establishes a stable acoustic waveguide structure (the production string) before monitoring begins. This predetermined structure provides consistent acoustic properties for all monitoring operations, eliminating variability introduced by repositioning equipment
Solution Approach 2:
The production string acts as an intermediary acoustic waveguide that mediates between the seismic source and the reservoir zones. This intermediate structure provides a stable, consistent transmission path that maintains recording conditions consistency while enabling monitoring of different zones through controlled wave propagation
3Adaptability or versatility
If mechanical movement is used for repositioning seismic sources, then different monitoring positions are achieved, but environmental interference increases
Solution Approach 1:
The patent replaces mechanical repositioning systems with acoustic wave propagation control. Instead of physically moving the seismic source through mechanical means, the system uses the acoustic properties of the production string waveguide to direct and control seismic wave propagation to different reservoir zones
Solution Approach 2:
The system introduces dynamic control of acoustic wave propagation through the static production string waveguide. By controlling the timing, frequency, and characteristics of seismic wave generation, the system achieves flexible monitoring of different zones without mechanical movement, thereby eliminating environmental interference from repositioning operations
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 system provides a reliable, long-term monitoring solution for hydrocarbon reservoirs by generating seismic waves that are not intrusive to production operations, maintaining consistent energy output, and reducing environmental interference, enabling accurate time-lapse monitoring of reservoir attributes.
Implementation Method 1
a resonant cavity for generating resonant energy... The resonant cavity receives pressure energy from a drive source and thereby develop seismic waves in a resonant cavity that is designed to impart these waves into a surrounding formation
Implementation Method 2
A plurality of resonant tubes... Each tube has an excitation coil for providing an excitation signal that induces a change in a selected material property of a smart fluid within the resonant chamber
Implementation Method 3
The pump, accumulator and excitation valve cooperate to draw fluid from the reservoir at a first pressure and inject a pressure pulse having a second pressure into the cavity
Data Source
AI summary
An apparatus for generating seismic body waves in a hydrocarbon reservoir includes a closed-loop borehole source having a resonant cavity for generating resonant energy, a drive source and a control unit. The drive source injects pressure pulses to the resonant cavity at a predetermined or selectable pressure and frequency. The fluid circulates between the cavity and the drive source in a closed-loop fashion. In another embodiment, the borehole source utilizes a smart or controllable material that is responsive to an applied excitation field. The cavity includes an excitation coil for providing an excitation field that changes a material property of the smart fluid. The control unit is programmed to adjust operating parameters to produce seismic waves having a selected frequency and amplitude. In one embodiment, a control unit adjusts operating parameters in response to measured parameters of interest or surface commands.