Abstract: The disclosure provides a method for preparing ultra-low molecular weight Dendrobium oligosaccharides by enzymatic hydrolysis and its application, and belongs to the technical field of bioengineering. In the disclosure, Thermobifida halotolerans-derived glycosidases are recombined to an Escherichia coli expression system to realize high activity expression. The recombinantly expressed ThDPS enzyme can hydrolyze Dendrobium polysaccharides, and produced oligosaccharide products mainly include ultra-low molecular weight (<1000 Daltons) Dendrobium disaccharides, Dendrobium trisaccharides, Dendrobium tetrasaccharides and Dendrobium pentasaccharides, and low-molecular weight (<10000 Daltons) Dendrobium hexaoses, Dendrobium heptaoses and Dendrobium octacoses, and higher Dendrobium oligosaccharide products.

Abstract: The embodiment of the disclosure relates to an elastic wave stress tensor double-dot product seismic imaging method and device. The method comprises: obtaining a decoupled particle vibration velocity vector wavefield by utilizing the existing decoupled wave equation method for the receiver wavefield; then obtaining a decoupled pseudo-stress wavefield by constructing the decoupled pseudo-stress equation by using the obtained decoupled particle vibration velocity vector wavefield; and finally computing a source second-order stress tensor wavefield and the decoupled receiver second-order stress tensor wavefield by using the double-dot product cross-correlation imaging condition algorithm, to obtain the final scalar imaging results. With the embodiment of the present disclosure, the combined P-wave and S-wave stress exploration can be realized, therefore, the obtained imaging results can be used to accurately predict the risk of gas exploration.

Abstract: This disclosure relates to the technical field of exploration geophysics, in particular to a method, a device, and a computer device for decoupling anisotropic elastic wave. The method includes: determining a set of Thomsen parameters included in an anisotropic model based on a received to-be-decomposed wave field decomposition request; transforming the set of Thomsen parameters to obtain a set of initial elastic parameters; performing S-wave and P-wave velocities separation processing for the set of initial elastic parameters to obtain a set of target P-wave elastic parameters and a set of target S-wave elastic parameters; and substituting those into the anisotropic model to process the to-be-decomposed wave field and obtain a target P-wave matrix and a target S-wave matrix. The process of decomposing S-wave and P-wave fields is simplified and the calculation cost is reduced according to the embodiments of this disclosure.

Abstract: The embodiment of the disclosure relates to an elastic wave stress tensor double-dot product seismic imaging method and device. The method comprises: obtaining a decoupled particle vibration velocity vector wave field by utilizing the existing decoupled wave equation method for the detected wave field; then obtaining a decoupled pseudo-stress wave field by constructing the decoupled pseudo-stress equation by using the obtained decoupled particle vibration velocity vector wave field; and finally computing a source second-order stress tensor wave field and the decoupled detected second-order stress tensor wave field by using the double-dot product cross-correlation imaging condition algorithm, to obtain the final scalar imaging results. With the embodiment of the present disclosure, the combined P-wave and S-wave stress exploration can be realized, therefore, the obtained imaging results can be used to accurately predict the risk of gas exploration.

Abstract: This disclosure relates to the technical field of exploration geophysics, in particular to a method, a device, and a computer device for decoupling anisotropic elastic wave. The method includes: determining a set of Thomsen parameters included in an anisotropic model based on a received to-be-decomposed wave field decomposition request; transforming the set of Thomsen parameters to obtain a set of initial elastic parameters; performing S-wave and P-wave velocities separation processing for the set of initial elastic parameters to obtain a set of target P-wave elastic parameters and a set of target S-wave elastic parameters; and substituting those into the anisotropic model to process the to-be-decomposed wave field and obtain a target P-wave matrix and a target S-wave matrix. The process of decomposing S-wave and P-wave fields is simplified and the calculation cost is reduced according to the embodiments of this disclosure.

Abstract: This disclosure relates to the technical field of exploration geophysics, in particular to a method, a device, and a computer device for decoupling anisotropic elastic wave. The method includes: determining a set of Thomsen parameters included in an anisotropic model based on a received to-be-decomposed wave field decomposition request; transforming the set of Thomsen parameters to obtain a set of initial elastic parameters; performing S-wave and P-wave velocities separation processing for the set of initial elastic parameters to obtain a set of target P-wave elastic parameters and a set of target S-wave elastic parameters; and substituting those into the anisotropic model to process the to-be-decomposed wave field and obtain a target P-wave matrix and a target S-wave matrix. The process of decomposing S-wave and P-wave fields is simplified and the calculation cost is reduced according to the embodiments of this disclosure.

Abstract: This disclosure relates to geophysical exploration and seismic imaging, and more particularly to a seismic imaging method, system, and device based on pre-stack high-angle fast Fourier transform (FFT). The method includes: acquiring seismic data acquired during seismic exploration; extracting a common shot point gather from the seismic data followed by conversion into a frequency wavenumber domain common offset gather; calculating wave propagation angles; dividing an imaging region into a first region and a second region; solving constant coefficients of the first region and the second region; performing frequency-division layer-by-layer wavefield continuation on a frequency-wave number domain common offset gather to obtain imaging results at different depths and frequencies; subjecting the imaging results to integration followed by transformation to a spatial domain to obtain common offset imaging profiles; and subjecting the common offset imaging profiles to superposition obtain final imaging results.

Abstract: The seismic imaging resolution analysis method comprises: obtaining common-shot gathers and common-detector gathers; in the common-shot gathers, conducting detector focusing analysis on a focus point at (xj, zn) in each source point gather to obtain a source point focal-beam gather; looping all the focus points at a depth zn, and conducting computation on a weighted source-focusing operator Pik† (zn, zn); in the common-detector gathers, conducting source point focusing analysis on an focus point at (xj, zn) in each source point gather to obtain a detector focal-beam gather; Loop all the focus points at a depth zn, and conducting computation on a weighted detector-focusing operator Pik (zn, zn); and conducting computation on a normalized resolution function of a single focus point so as to obtain a horizontal resolution and a definition.

Abstract: A method, a system, and a device for full-waveform inversion deghosting for a marine variable depth streamer data acquisition are provided for solving existing problems that deghosted seismic data has low accuracy and is accompanied by artifacts due to a large error in ghost prediction. The provided method includes: acquiring seismic data, jointly solving Lippmann-Schwinger equations to obtain normal derivatives of an incident wave field and a wave field of a receiver surface, performing a wave field extrapolation by a Kirchhoff equation that includes only an integral on the receiver surface to obtain a wave field of a sea surface recorded by a horizontal streamer, calculating a ghost operator, and subjecting the ghosted wave field of the sea surface recorded by the horizontal streamer to full-waveform inversion deghosting to obtain deghosted seismic data. The provided method improves the accuracy and signal-to-noise ratio (SNR) of deghosted seismic data.

Abstract: This disclosure relates to geophysical exploration and seismic imaging, and more particularly to a seismic imaging method, system, and device based on pre-stack high-angle fast Fourier transform (FFT). The method includes: acquiring seismic data acquired during seismic exploration; extracting a common shot point gather from the seismic data followed by conversion into a frequency wavenumber domain common offset gather; calculating wave propagation angles; dividing an imaging region into a first region and a second region; solving constant coefficients of the first region and the second region; performing frequency-division layer-by-layer wavefield continuation on a frequency-wave number domain common offset gather to obtain imaging results at different depths and frequencies; subjecting the imaging results to integration followed by transformation to a spatial domain to obtain common offset imaging profiles; and subjecting the common offset imaging profiles to superposition obtain final imaging results.