However, difficulties arise as this equation is singular in the air where σ 0. This is often circumvented by applying a small artificial conductivity value to the air layer. While this allows for the system to be solved, the problem remains illconditioned and solution strategies can be slow. Following LaBrecque (1999) and Hou et al. (2006) the problem is instead reformulated using a Helmholtz decomposition in terms of vector and scalar potentials where E
Summary Many seismic datasets ar e recorded over geologic structures where lateral changes in the physical properties of the stratigraphic layers vary smoothly. For these situations, depth migration algorithms are not required and time migration imaging is known to provide a similar outcome and is more economic. In this paper, we discuss the implementation of the Full Waveform Inversion (FWI) algorithms for velocity inversion using Common Scatter Point (CSP) gathers. Since the formation of the CSP gathers are based on the Pre-Stack Kirchhoff Time Migration (PSTM), we reduce the computational effort commonly associated with depth migration. Introduction Obtaining the physical properties (i.e velocity) of the subsurface is one of the main objectives of seismic data processing.
Seismic inversion requires two main operations relative to changes in the frequency spectrum. The first operation is deconvolution, used to increase the high frequency component of the observed seismic data and the second operation is integration of a reflectivity function to decrease the high frequencies and increase low frequencies of the seismic signal. The first operation is very unstable and non-unique for noisy seismic data. The second operation is very sable in high frequencies but has problems in low frequencies due to undefined low frequency data in seismic traces. By performing both of these operations simultaneously the operation will be stable in high frequency area and can be effectively stabilized in low frequency area based on an a priori acoustic impedance power spectrum and use Tikhonov and Arsenin‟s (1979) regularization technique. This approach can be applied to poststack and pre-stack seismic data.
The use of sucker-rod pumping systems is the most common method of artificial lift in the oil-well industry. In this work, the viscous-damped-wave equation model has been developed to describe the rod-string dynamical behavior at various well depths utilizing the inputs of load and position originating from the surface-card measurement. In contrast to the existing solutions of viscous-damped-wave equation dynamics, which is based on Fourier series truncation and finite difference method, in this paper a novel technique is presented and utilized in the real time estimation framework. In particular, an infinite-differential state space representation of the viscous-damped-wave equation dynamics is developed based on appropriate boundary transformation. The spectral decomposition and truncation of an infinite number of modes is realized, so that the partial differential equation model is cast to the system of coupled ordinary differential equations, which can be solved in real time and utilized for period and non-periodic motion stroke. Finally, the new method is validated by the real case study associated with the existing well.
Nishimura, Masato (Tokyo University of Marine Science and Technology) | Shimizu, Etsuro (Tokyo University of Marine Science and Technology) | Oode, Tsuyoshi (Tokyo University of Marine Science and Technology) | Takamasa, Tomoji (Tokyo University of Marine Science and Technology)
The electric boat named “RAICHO-I” has been developed by Tokyo University Marine Science and Technology. The possible cruising time of this boat is still short compared with conventional same size boats. Currently, the operator has to estimate empirically the possible cruising time from weather (wind direction and power), state of waves (wave height and tide), voltage and State of Charge (SOC) of batteries. The situation of battery loss has to be avoided from the view point of operational safety. In order to solve this problem, a Navigation Support System (NSS) that has the following 2 functions is developed.