Seismic Imaging Under Obstructions via Sea Surface Reflections
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Solution Overview
Problem
Conventional marine seismic surveys face difficulties in obtaining seismic images of subsurface regions obstructed by structures like production platforms, which block shot positions and sensor placement, making it challenging to image beneath these obstructions effectively.
Innovation Solution
The technique combines seismic data from multiple surveys, including seabed sensors and sea surface reflections, to generate seismic images by interchanging source and sensor definitions and applying deconvolution or cross-correlation processes, allowing for imaging under obstructions and efficient reservoir monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional marine seismic surveys use traditional shot positions and sensor placement, then survey operations are simple and straightforward, but imaging of subsurface regions beneath production platforms is impossible due to obstructions
Solution Approach 1:
The patent applies inversion by interchanging the roles of sources and sensors in seismic data processing. Instead of treating only direct recordings as primary data, the method treats recordings of source signals reflected from the sea surface as if they originated from virtual sources beneath the sea floor. This role reversal enables imaging of subsurface regions beneath production platforms that are inaccessible to conventional survey geometries, resolving the contradiction between imaging capability and operational simplicity.
Solution Approach 2:
The patent creates virtual seismic sources and sensors by reflecting actual source and sensor positions across the sea surface. These virtual copies generate synthetic seismic data that fills in coverage gaps beneath obstructions. By copying and transforming existing survey data into virtual representations, the method achieves imaging capability in previously inaccessible regions without requiring physically complex survey operations.
2Reliability
If seismic surveys avoid shot positions under production platforms, then operational safety and equipment protection are maintained, but complete subsurface imaging coverage is lost
Solution Approach 1:
The patent uses the sea surface as an intermediary reflector to indirectly obtain seismic data from regions beneath production platforms. Instead of placing sources or sensors directly under obstructions (which would compromise equipment safety), the method uses sea surface reflections to create virtual sources and sensors that provide the necessary imaging coverage. This intermediary approach maintains equipment safety while achieving complete subsurface imaging coverage.
3Measurement precision
If multiple seismic surveys are combined to improve imaging coverage, then imaging completeness beneath obstructions is enhanced, but data processing complexity increases
Solution Approach 1:
The patent transforms the interpretation of seismic data parameters by redefining what constitutes a primary source-sensor pair. Instead of processing multiple surveys as separate datasets requiring complex integration, the method applies parameter transformation by treating reflected recordings as virtual direct recordings. This changes the fundamental parameters of source location, sensor location, and ray path interpretation, enabling seamless integration of multiple surveys with reduced processing complexity.
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 method enables effective imaging of subsurface regions previously inaccessible due to obstructions and enhances reservoir monitoring capabilities by combining data from multiple surveys, improving the accuracy and completeness of seismic data.
Implementation Method 1
Acoustic waves generated by the survey source may be transmitted to the Earth's crust and then reflected back and captured at the towed and/or seabed geophysical sensors
Data Source
AI summary
The present disclosure provides a technique for marine seismic imaging that processes data acquired from two or more different seismic surveys in a combined manner to advantageous effect. The different seismic surveys may use seabed sensors at same positions on the seabed, but they may have different shot locations and may be performed at different times. In one use case, the technique may be used to image a subsurface location that is difficult to image using either survey alone. In another use case, the technique may be used to image a subsurface location under an obstruction. The technique may also be utilized to efficiently monitor a reservoir over time.