A B S T R A C TBorehole seismic addresses the need for high-resolution images and elastic parameters of the subsurface. Full-waveform inversion of vertical seismic profile data is a promising technology with the potential to recover quantitative information about elastic properties of the medium. Full-waveform inversion has the capability to process the entire wavefield and to address the wave propagation effects contained in the borehole data-multi-component measurements; anisotropic effects; compressional and shear waves; and transmitted, converted, and reflected waves and multiples. Full-waveform inversion, therefore, has the potential to provide a more accurate result compared with conventional processing methods.We present a feasibility study with results of the application of high-frequency (up to 60 Hz) anisotropic elastic full-waveform inversion to a walkaway vertical seismic profile data from the Arabian Gulf. Full-waveform inversion has reproduced the majority of the wave events and recovered a geologically plausible layered model with physically meaningful values of the medium.

A B S T R A C TA modified reverse-time migration algorithm for offset vertical seismic profiling data is proposed. This algorithm performs depth imaging of target areas in the borehole vicinity without taking into account the overburden. Originally recorded seismograms are used; reliable results can be obtained using only the velocity profile obtained along the well. The downgoing wavefield emitted from a surface source is approximated in the target area using the transmitted P-wave, recorded by the receivers deployed in the well. This is achieved through a reverse-time extrapolation of the direct transmitted P-wave into the target area after its separation in offset vertical seismic profiling seismograms generated using a finite-difference scheme for the solution of the scalar wave equation.The proposed approach produces 'kinematically' reliable images from reflected PPand PS-waves and, furthermore, can be applied as a salt proximity tool for salt body flank imaging based on the transmitted PS-waves. Our experiments on synthetic data demonstrate that the modified reverse-time migration provides reliable depth images based on offset vertical seismic profiling data even if only the velocity profile obtained along the borehole is used.

The optimal design of a subsoiler implement is a complex work that includes optimal design, material properties, structural reliability, random variables, soil properties, soil tillage equipment, and optimum safety measures. The main objectives of this study were to design and simulate the deep placement fertilizer applicator (DPFA) by using the finite element method (FEM). FEM simulation software was used to select the optimum material properties and improve the safety factor by considering a range of loads on DPFA. Three applied forces in a static simulation (4500, 5000 and 6000 N) were considered as were three application depths of fertilizers (0.15, 0.20, and 0.25 m), to improve the safety measures of the design. The simulation results showed that the best material property for DPFA is the AISI 4135 QT carbon steel materials. This yields a high strength of 780MPa and an ultimate tensile strength of 950 MPa (Young’s Modulus of 207 GPa and with Poisson’s Ratio of 0.33). The static simulation for 6000 N shows that the DPFA model had a maximum stress and strain of 379.9 MPa and 25.6×10−4 mm/mm respectively, with a contact pressure of 207 MPa, and a maximum displacement of 3.1 mm. The study results can provide theoretical and technical support for the development of agricultural tools, especially for DPFA in selecting optimum material properties and improving safety factors.

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This paper briefly reveals study results performed on a deep placement fertilizer applicator (DPFA) in order to measure strain gage resistances and calibrate a strain gage piece of equipment in laboratory conditions. The finite element method (FEM) simulation was performed in order to identify stress concentrated areas by strain gage attachments, and to determine optimum material properties for a DPFA prototype fabrication. New laboratory arrangements and theories of resistance force determination of a DPFA were developed in order to simulate different soil depths (0.15, 0.20, 0.25m) and apply a static load (5000N) in laboratory conditions. Unique practical knowledge was obtained in terms of different strain gage applications on the DPFA in its rigid form to obtain strain gage resistances. It was found that the strain sensitivity of the strain gages depended on the work dimensions of strain gage characteristics.