15.3 3D and 4D seismic surveys
3 min read•august 9, 2024
3D seismic surveys create detailed subsurface images using multiple source-receiver pairs. This technique improves accuracy in identifying potential hydrocarbon reservoirs and reduces drilling risks by offering a comprehensive understanding of complex geological structures.
4D seismic surveys, or time-lapse surveys, repeat 3D surveys over time to monitor reservoir changes. This method helps optimize production strategies by detecting fluid movement, pressure changes, and saturation variations within the reservoir.
3D and 4D Seismic Surveys
Advanced Seismic Survey Techniques
Top images from around the web for Advanced Seismic Survey Techniques
SD - Geohazard detection using 3D seismic data to enhance offshore scientific drilling site ... View original
Is this image relevant?
GMD - GO_3D_OBS: the multi-parameter benchmark geomodel for seismic imaging method assessment ... View original
Is this image relevant?
SE - Uncertainty assessment for 3D geologic modeling of fault zones based on geologic inputs and ... View original
Is this image relevant?
SD - Geohazard detection using 3D seismic data to enhance offshore scientific drilling site ... View original
Is this image relevant?
GMD - GO_3D_OBS: the multi-parameter benchmark geomodel for seismic imaging method assessment ... View original
Is this image relevant?
1 of 3
Top images from around the web for Advanced Seismic Survey Techniques
SD - Geohazard detection using 3D seismic data to enhance offshore scientific drilling site ... View original
Is this image relevant?
GMD - GO_3D_OBS: the multi-parameter benchmark geomodel for seismic imaging method assessment ... View original
Is this image relevant?
SE - Uncertainty assessment for 3D geologic modeling of fault zones based on geologic inputs and ... View original
Is this image relevant?
SD - Geohazard detection using 3D seismic data to enhance offshore scientific drilling site ... View original
Is this image relevant?
GMD - GO_3D_OBS: the multi-parameter benchmark geomodel for seismic imaging method assessment ... View original
Is this image relevant?
1 of 3
- creates detailed three-dimensional images of subsurface structures using multiple source-receiver pairs
- Employs a grid pattern of sources and receivers to capture data from various angles and depths
- Provides high-resolution images of complex geological structures (salt domes, faults)
- Improves accuracy in identifying potential hydrocarbon reservoirs
- Reduces drilling risks by offering a more comprehensive understanding of the subsurface
Time-Lapse Seismic Monitoring
- (time-lapse) involves repeating 3D surveys over the same area at different times
- Monitors changes in reservoir properties over time due to production or injection activities
- Detects fluid movement, pressure changes, and saturation variations within the reservoir
- Helps optimize production strategies and enhance oil recovery
- Typically conducted at intervals ranging from months to years, depending on reservoir dynamics
Survey Design and Data Visualization
- Seismic acquisition geometry determines the layout of sources and receivers on the surface
- Includes various patterns (orthogonal, brick, zigzag) optimized for target depth and desired resolution
- Volume visualization techniques transform 3D seismic data into interpretable images
- Utilizes advanced software to render subsurface structures in three dimensions
- Enables geoscientists to navigate through the data volume and identify features of interest (stratigraphic traps, fracture networks)
Seismic Survey Parameters
Spatial Resolution and Coverage
- Bin represents the basic unit of spatial resolution in 3D seismic surveys
- Defined as the area on the surface where seismic traces are grouped and averaged
- Smaller bin sizes provide higher lateral resolution but require more data acquisition
- Fold refers to the number of seismic traces that contribute to each bin
- Higher fold improves signal-to-noise ratio and data quality
- Typical fold values range from 20 to 100, depending on survey objectives and budget constraints
Directional and Distance Considerations
- Azimuth describes the angle between the source-receiver line and a reference direction (usually north)
- Wide-azimuth surveys capture data from multiple directions, improving subsurface imaging
- Helps resolve complex structures and reduces the effects of anisotropy
- Offset represents the distance between the seismic source and receiver
- Near-offset data provides information about shallow structures and velocities
- Far-offset data captures deeper reflections and allows for better
- Optimal offset range depends on target depth and desired resolution
Seismic Data Analysis
Advanced Interpretation Techniques
- Seismic attributes extract specific features or characteristics from seismic data
- Include amplitude-based attributes (RMS amplitude, sweetness) for lithology and fluid content prediction
- Frequency-based attributes (spectral decomposition) reveal layer thickness and tuning effects
- Geometric attributes (coherence, curvature) highlight structural and stratigraphic features
- Machine learning algorithms increasingly used to combine multiple attributes for improved interpretation
Dynamic Reservoir Characterization
- Reservoir monitoring tracks changes in reservoir properties over time using 4D seismic data
- Detects fluid contacts (oil-water, gas-oil) and their movement during production
- Identifies bypassed pay zones and optimizes infill drilling locations
- Monitors the effectiveness of enhanced oil recovery techniques (water injection, CO2 flooding)
- Integrates with well data and production history for comprehensive reservoir management
- Helps extend field life and maximize ultimate recovery
Key Terms to Review (19)
3D seismic survey: A 3D seismic survey is a geophysical exploration technique that involves the collection of seismic data in three dimensions to create detailed images of subsurface geological structures. This method enhances the ability to analyze complex geological formations, making it essential for locating and assessing oil and gas reserves, as well as understanding earthquake dynamics and hazards. By using multiple sensors and advanced computing technology, 3D surveys provide a more accurate representation of the subsurface compared to traditional 2D surveys.
4D seismic survey: A 4D seismic survey is an advanced geophysical imaging technique that involves the repeated acquisition of 3D seismic data over time to monitor changes in subsurface conditions, particularly in the context of oil and gas reservoirs. This technique provides valuable insights into how reservoirs behave over time, allowing for better management and optimization of resource extraction. By integrating time as a fourth dimension, it enables geoscientists to track fluid movements and changes in pressure within the reservoir, leading to enhanced decision-making in exploration and production activities.
Faulting: Faulting is the process by which rocks break and slip along a fracture or fault line due to stress and strain in the Earth's crust. This movement can result in earthquakes and is a key mechanism for how energy is released in seismic events. Understanding faulting helps explain global seismic patterns, the formation of mountains through continental collisions, and is essential in 3D and 4D seismic surveys used for resource exploration.
Geophones: Geophones are sensitive devices used to detect ground motion caused by seismic waves. They convert the mechanical energy of these waves into electrical signals, allowing for the analysis and interpretation of subsurface geological structures. Geophones play a crucial role in both 3D and 4D seismic surveys by providing accurate data on wave propagation and helping to create detailed images of the Earth's subsurface.
Geothermal energy: Geothermal energy is the heat that comes from the sub-surface of the earth, created by the decay of radioactive materials and the residual heat from the planet's formation. This renewable energy source can be harnessed for various applications, including electricity generation and direct heating. It is closely connected to seismic surveys as these methods help locate and assess geothermal resources beneath the Earth's surface.
Hydrocarbon exploration: Hydrocarbon exploration is the process of searching for natural resources such as oil and gas beneath the Earth's surface. This involves various techniques, including seismic surveys, to locate potential reservoirs where hydrocarbons can be extracted. By using advanced technologies like 3D and 4D seismic surveys, geologists can create detailed images of subsurface structures, helping to identify promising drilling sites.
Migration: In seismology, migration refers to the process of repositioning seismic data to accurately reflect the true location of subsurface structures. This technique is essential for improving the interpretation of seismic images and involves correcting for the effects of wave propagation, ensuring that reflected signals from geological features are displayed in their correct spatial arrangement. The significance of migration lies in its ability to enhance the clarity and accuracy of seismic data, aiding in the identification of resources and understanding subsurface geology.
P-waves: P-waves, or primary waves, are the fastest type of seismic waves that travel through the Earth, moving in a compressional manner. They can propagate through both solid and liquid materials, making them essential for understanding the Earth's internal structure and behavior during seismic events.
Reflection seismology: Reflection seismology is a geophysical method used to explore subsurface structures by analyzing the reflections of seismic waves off different geological layers. This technique provides detailed images of the Earth's subsurface, which are crucial for identifying resources like oil, gas, and minerals, as well as for understanding geological formations and hazards. By utilizing both 3D and 4D seismic surveys, reflection seismology enhances our ability to visualize complex geological features over time.
Refraction Seismology: Refraction seismology is a technique used to determine the structure of the Earth's subsurface by analyzing seismic waves that bend or refract as they encounter different geological layers. This method relies on measuring the travel times of seismic waves that are refracted at interfaces between materials of varying densities and elastic properties, helping to map subsurface features in both 3D and 4D seismic surveys.
Reservoir modeling: Reservoir modeling is the process of creating a representation of a subsurface reservoir to understand its structure, behavior, and the flow of fluids within it. This technique integrates geological, geophysical, and engineering data to simulate the reservoir's performance over time, aiding in resource management and extraction strategies. It is especially relevant in understanding hydrocarbon reservoirs, where accurate modeling can optimize production and enhance recovery techniques.
S-waves: S-waves, or secondary waves, are a type of seismic wave that move through the Earth during an earthquake. They are characterized by their transverse motion, which means they move the ground perpendicular to the direction of wave propagation, and are only able to travel through solid materials, making them crucial for understanding Earth's internal structure.
Seismic inversion: Seismic inversion is a geophysical technique used to convert seismic reflection data into a quantitative model of subsurface properties, such as rock type and fluid content. This process enhances the interpretation of 3D and 4D seismic surveys by providing clearer insights into the geological structure and fluid dynamics within the Earth's subsurface, allowing for better resource exploration and management.
Seismometers: Seismometers are sensitive instruments used to detect and record the motion of the ground caused by seismic waves during an earthquake or other ground-shaking events. They are crucial in the study of earthquakes as they provide valuable data on the intensity, duration, and location of seismic activities. The data collected from seismometers is essential for understanding seismic events and for conducting 3D and 4D seismic surveys.
Stacking: Stacking is a signal processing technique used to enhance the clarity of seismic data by combining multiple seismic traces that originate from the same event. This method helps to improve the signal-to-noise ratio by reinforcing coherent signals while reducing random noise, making it a vital process in various seismic analysis applications.
Stratigraphy: Stratigraphy is the branch of geology that studies rock layers (strata) and layering (stratification). This field plays a vital role in understanding the chronological sequence of geological events, enabling scientists to interpret Earth's history and the processes that shaped it, including the deposition of sedimentary layers over time, which is particularly important in 3D and 4D seismic surveys.
Surface Waves: Surface waves are seismic waves that travel along the Earth's exterior and are typically responsible for the most damage during an earthquake. They move slower than body waves but have larger amplitudes, leading to greater surface displacement and destruction. Understanding surface waves is crucial for interpreting seismic data, assessing earthquake impacts, and improving building designs in earthquake-prone areas.
Time-lapse imaging: Time-lapse imaging is a technique used in seismic surveys to capture and analyze changes in subsurface structures over time. By repeatedly measuring seismic waves at various intervals, this method allows for the visualization of dynamic geological processes, such as fluid movement or subsidence, providing valuable insights for resource management and hazard assessment.
Velocity Analysis: Velocity analysis is a technique used in seismic data processing to determine the velocity of seismic waves through different geological layers. This process is crucial for accurately interpreting seismic data, as it helps in constructing models of subsurface structures and identifying potential hydrocarbon reservoirs in 3D and 4D seismic surveys.