China
Africa
Explore chapters and articles related to this topic
Oilfield production monitoring with fiber-optic sensors
Published in P. Dakin John, G. W. Brown Robert, Handbook of Optoelectronics, 2017
An additional and complementary approach is to image the entire oilfield in three dimensions. This is most commonly achieved using active seismic imaging, a technique by which an acoustic source is used to produce downward propagating seismic energy within the field, and the reflections of this from the various geological features of the field are detected by a network of seismic sensors. This allows a three-dimensional image of the field to be built up, in much the same way as a magnetic resonance imaging scanner produces an image of the human body (an alternative approach uses EM (Electromagnetic) fields to achieve a somewhat different image based on rock conductivity). A schematic of a PRM system is shown in Figure 21.1.
Inverse Problems
Published in Abul Hasan Siddiqi, Mohamed Al-Lawati, Messaoud Boulbrachene, Modern Engineering Mathematics, 2017
Abul Hasan Siddiqi, Mohamed Al-Lawati, Messaoud Boulbrachene
Seismic tomography is a methodology for analyzing and computing earth’s activities. Seismology is the scientific study of earthquakes and the propagation of elastic waves through the earth or other planet-like bodies. It also includes studies of earthquake effects, such as tsunamis diverse seismic sources such as volcanic, tectonic, oceanic, atmospheric and artificial process (such as explosions). A record of earth motion as a function of time is called a seismogram. Experts treat seismic tomography as a part of seismic imaging, where they are mainly concerned with estimating properties such as propagating velocities of compressional waves (P-waves) and shear waves (S-waves).
Road subsurface distress recognition method using multiattribute feature fusion with ground penetrating radar
Published in International Journal of Pavement Engineering, 2022
Guanghua Yue, Yuchuan Du, Chenglong Liu, Shili Guo, Yishun Li, Qian Gao
When road surface distress caused by subsurface distress appears, if only the road surface distress is treated and the subsurface is ignored, the road surface distress can reappear in a short time, which easily leads to frequent maintenance of the road. Therefore, it is necessary to conduct nondestructive testing techniques to detect subsurface distress and evaluate severity levels to take targeted maintenance treatment measures. At present, for the detection of subsurface distresses, many experts and scholars have made attempts with different technical methods, such as Rayleigh waves, seismic imaging, falling weight deflectometers, ultrasonic techniques, infrared thermography and ground penetrating radar (GPR). Rayleigh waves are a type of surface wave that travels near the surface of solids, and their advantage is that they can propagate over longer distances (Aggelis et al. 2009), which are used for the detection of cavities under pavement. Seismic imaging is the set of methods that obtain images of the Earth using observed seismograms as inputs, and it is a tool used to characterize subsurface geology (Guo et al. 2016). Falling weight deflectometer testing has been used to evaluate the structural condition of pavements to predict the layer moduli using a backcalculation process (Bachar et al. 1999). Ultrasonic techniques have been used as a nondestructive technique in the case of crack characterization. The transit time of longitudinal waves diffracted by the tip of the crack can be used to estimate the crack depth (Khazanovich et al. 2005). Infrared thermography is a nondestructive testing and remote sensing technique that offers the identification of subsurface flaws with reasonable accuracy (Vyas et al. 2019). GPR is a geophysical method that uses high-frequency electromagnetic waves to detect and locate underground targets and media anomalies (Saarenketo and Scullion. 2000). Ground-coupled and air-coupled GPR systems are the two common systems, and they are either used as hand-held devices or mounted on vehicles. To overcome some cases, such as mine detection, GPR sensor systems that are operated on unmanned airborne systems have been developed (Christopher and Su. 2018). Compared with other road nondestructive testing means, GPR has become the most effective long-distance road testing method due to its advantages of continuity, high speed, high accuracy, and low cost. It is widely used to detect underground cavities in urban roads (Kang et al. 2020), cracks, and loose damage to the base in the structural layer of roads (Dai and Hoegh 2017; Krysiński and Sudyka 2013).