EnglishViews: 0 Author: Site Editor Publish Time: 2025-11-20 Origin: Site
When talking about seismic exploration, we must start with seismic waves. Essentially, seismic waves are elastic waves generated when rock formations fracture or are artificially excited. They act as "messengers" from the Earth's interior, carrying abundant underground information. According to their different propagation modes and characteristics, seismic waves are mainly divided into three categories: P-waves, S-waves, and surface waves.
P-waves, also known as Primary Waves, are the fastest propagating type of seismic wave and can travel through solids, liquids, and gases. During propagation, the vibration direction of medium particles is consistent with the wave propagation direction. It is similar to the movement of particles on a spring that moves back and forth along the spring when the spring is compressed and stretched. When an earthquake occurs, P-waves reach the ground first, and people will feel up-and-down jolting, which is why P-waves are called "first-arrival waves".
S-waves, or Secondary Waves, propagate slower than P-waves and can only travel through solids. During the propagation of S-waves, the vibration direction of particles is perpendicular to the wave propagation direction. Imagine fixing one end of a rope and shaking the other end up and down; the wave formed on the rope is similar to an S-wave, where particles vibrate perpendicular to the rope direction. When S-waves reach the ground, people will feel left-right swaying. Since S-waves can only propagate through solids, they are of great significance for detecting the solid properties of underground media, such as the structure and nature of rocks.
Surface waves are mixed waves propagating on the ground surface. They are secondary waves generated by the interaction of body waves (P-waves and S-waves) with the ground surface when the body waves propagate to the surface. Surface waves have the slowest propagation speed but relatively large amplitude and concentrated energy, so they often cause the most significant damage to ground buildings. The characteristics of surface waves make them play a key role in studying shallow stratum structures and geological structures in seismic exploration.
Whether it is the massive release of energy from the Earth's interior during a natural earthquake or the purposeful and controllable excitation of artificial seismic sources, when seismic waves propagate underground, they will produce reflection and refraction phenomena once they encounter elastic differences in the medium, such as stratum interfaces with different lithologies. These reflected and refracted waves carry information about the underground medium, like drawing "perspective images" of the underground world, providing a basis for us to deeply understand the underground structure.
Different from the uncontrollable energy release of natural earthquakes, artificial seismic sources in seismic exploration are our "secret weapons" for actively exploring the underground world. Currently, common artificial seismic sources include explosive seismic sources and controllable seismic sources, etc. They have their own characteristics, but their purpose is to generate stable and detectable seismic waves.
Taking explosive seismic sources as an example, when explosives detonate at a specific underground location, they release enormous energy instantly, which propagates around in the form of seismic waves. During propagation, when seismic waves encounter interfaces of different strata, such as interfaces with changing lithologies and boundaries of ore bodies, the propagation path and waveform of the seismic waves will change due to the difference in elastic modulus between the upper and lower media. A part of the seismic waves will be reflected back to the ground, and the other part will be refracted into deeper strata.
Controllable seismic sources are a more advanced and environmentally friendly type of artificial seismic source. They generate controllable vibrations through mechanical devices and emit seismic waves with specific frequencies and amplitudes to the underground. The advantage of controllable seismic sources lies in their ability to accurately control the parameters of the seismic source, thereby obtaining more abundant and accurate underground information.
In the process of seismic exploration, receiving equipment acts as sensitive "ears" responsible for capturing these reflected and refracted seismic waves. These receiving devices record parameters such as the propagation time, amplitude, and frequency of the seismic waves. Subsequently, these original data are transmitted to a professional data processing center. There, through complex data processing algorithms and technologies, such as filtering, stacking, and migration, the original data are converted into images and information that can intuitively reflect the underground structure. It is like performing a detailed "CT scan" on the Earth, allowing us to clearly see the distribution of underground strata, the shape of structures, and the possible locations of mineral resources.
In the energy field, the exploration of oil and gas resources has always been a top priority, and seismic exploration technology is the "pathfinder" for accurately locating reservoirs. In the exploration history of major oilfields in China, such as Daqing and Shengli, seismic exploration technology has played an irreplaceable key role. In the early stage, 2D seismic technology helped explorers initially determine the general structure of oil and gas reservoirs, laying the foundation for subsequent exploration. With the continuous progress of technology, the application of 3D seismic technology has greatly improved the exploration accuracy, which can more clearly present the details of underground geological structures, like drawing a high-definition map of the underground world.
Modern high-density 3D seismic technology has achieved a qualitative leap. It can distinguish meter-level changes in reservoir thickness, enabling us to have a more accurate understanding of reservoirs. By combining with wide-band acquisition equipment, seismic exploration can obtain more abundant underground information and realize the effective detection of 10,000-meter deep oil and gas reservoirs. In 2023, the project "Key Technologies and Equipment for Onshore Wide-Band, Wide-Azimuth and High-Density Seismic Exploration", which won the first prize of the National Technology Invention Award, successfully broke through the technical bottleneck of 10,000-meter exploration depth. This achievement has opened a new door for the development of deep oil and gas resources in China, greatly expanded the space for oil and gas exploration, and effectively guaranteed national energy security.
In the field of infrastructure construction, seismic exploration technology is the "safety guardian" for ensuring project safety. Whether it is a magnificent bridge spanning rivers, lakes and seas, a winding tunnel passing through mountains and hills, or a convenient subway shuttling underground in cities, seismic exploration technology plays a crucial role in the early stage of these project constructions.
Through shallow seismometers, we can effectively detect the distribution of unfavorable geological bodies such as underground faults, karst caves, and weak interlayers. For example, when constructing highway tunnels in mountainous areas, the use of shallow seismic exploration technology can help detect potential fault fracture zones in advance, providing important basis for engineering design, avoiding sudden geological disasters during construction, and ensuring the safety of construction personnel and the smooth progress of the project.
Cross-hole CT technology is another powerful tool of seismic exploration in engineering geological surveys. It uses the travel time difference of seismic waves in different strata and accurately reconstructs the stratum velocity distribution through complex inversion algorithms, providing a high-precision geological model for subway shield construction. This is like installing a pair of "perspective eyes" for the shield machine, enabling it to predict the geological conditions ahead in advance, avoiding obstacles during the construction process, and improving construction efficiency and safety.
In terms of slope stability monitoring, surface wave exploration technology shows its prowess. By analyzing the propagation characteristics of surface waves, it can accurately identify potential sliding surfaces and provide key data for slope stability evaluation. Once changes in the geological conditions of the slope are detected, the system can issue early warnings in a timely manner, striving for precious time for relevant departments to take protective measures and effectively reducing the risk of geological disasters.
