Non-Vertical Wellbore Sensor Arrays for Seismic Data Deghosting
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Solution Overview
Problem
Traditional land seismic data acquisition methods require numerous vertical wellbores for sensor placement, leading to high drilling costs and environmental impact, and are affected by surface-reflected 'ghost' waves that interfere with accurate measurement of subsurface features.
Innovation Solution
A method and system using non-vertical wellbore segments with sensors placed at varying depths to intersect a vertical line, allowing for the separation of upgoing and downgoing acoustic waves and reducing the need for multiple vertical wellbores, thereby minimizing environmental impact and drilling costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vertically spaced sensor arrays are placed in separate vertical wellbores for deghosting, then measurement precision is improved, but device complexity and environmental impact increase due to large drilling effort and high costs
Solution Approach 1:
The patent combines multiple sensor arrays into a single wellbore structure, where multiple sensors are vertically spaced within one wellbore instead of requiring separate vertical wellbores for each sensor array. This merging approach maintains the deghosting capability while significantly reducing the number of wellbores needed.
Solution Approach 2:
The patent introduces non-vertical wellbore segments that deviate from the traditional vertical orientation. By using wellbores that extend at angles (e.g., horizontal or oblique sections), the system achieves the required vertical sensor spacing through three-dimensional wellbore geometry rather than multiple vertical holes, thereby reducing drilling complexity.
2Measurement precision
If vertically spaced sensor arrays are placed in separate vertical wellbores for deghosting, then measurement precision is improved, but loss of substance increases due to large environmental imprint
Solution Approach 1:
The patent combines multiple sensor arrays into a single wellbore structure, where multiple sensors are vertically spaced within one wellbore instead of requiring separate vertical wellbores for each sensor array. This merging approach maintains the deghosting capability while significantly reducing the number of wellbores needed.
3Ease of operation
If surface reflected waves are recorded along with seismic waves, then ease of operation is maintained, but measurement precision deteriorates due to interference from ghosts
Solution Approach 1:
The patent extracts and separates the ghost wave component from the total recorded wavefield using deghosting algorithms. By identifying and removing the surface-reflected wave contributions, the system isolates the primary seismic signals of interest while maintaining the simplicity of the original recording process.
Solution Approach 2:
The patent uses the vertically spaced sensors to capture both direct and reflected wave arrivals, then applies feedback-based deghosting algorithms that use the recorded ghost wave information to construct and remove the ghost component from the final seismic image, thereby improving data quality.
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 configuration enables cost-effective and environmentally friendly seismic data acquisition by reducing the number of wellbores and communication lines, while effectively separating useful seismic data from surface-reflected noise, improving data resolution and reducing interference.
Implementation Method 1
The sensors (e.g., geophones, hydrophones, accelerometers, etc.) are connected to each other and then deployed on or below the surface of the earth
Implementation Method 2
The seismic source is activated and generates seismic waves which propagate through the subsurface
Implementation Method 3
an upwardly directed wave may be transmitted through the weathering layer and reflected at the surface of the earth before observation by the sensor. These surface reflected waves, often called 'ghosts'
Data Source
AI summary
A method may include providing a sensor in a first wellbore segment, providing a sensor in a second wellbore segment, observing upgoing acoustic waves or downgoing acoustic waves with the sensors, and separating the upgoing acoustic waves and/or the downgoing acoustic waves from a total wavefield. The first wellbore segment and the second wellbore segment may be separated by a distance. At least one of the wellbore segments may be non-vertical and/or the first wellbore segment may not be parallel to the second wellbore segment. The first wellbore segment may be part of a first set of wellbores and the second wellbore segment may be part of a second set of wellbores. The separated upgoing and downgoing acoustic waves may be used to generate deghosted data.