Abstract: A method includes obtaining recorded seismic data; obtaining a current subsurface model that includes elastic full-waveform inversion (FWI) parameters; obtaining a source elastic wavefield and a receiver elastic wavefield based on the current subsurface model; calculating a source-receiver angle between a first propagation direction of the source elastic wavefield and a second propagation direction of the receiver elastic wavefield; determining a limited range of source-receiver angles for each of the elastic FWI parameters that minimizes coupling among the elastic FWI parameters; obtaining a scaled gradient direction of an elastic FWI objective function with respect to each of the elastic FWI parameters using the limited range of source-receiver angles for each of the elastic FWI parameters; updating the elastic FWI parameters based on the scaled gradient direction to obtain updated elastic FWI parameters; and inputting the updated elastic FWI parameters into the current subsurface model to update the curren

Abstract: A method includes identifying an area of interest (AOI) in a subsurface region based on a velocity model computed based on input seismic data; muting a portion of the input seismic data based on reflection energy received from an impedance boundary in the subsurface region and applying a data mask to remaining input seismic data; performing a first full-waveform inversion (FWI) to update the velocity model from a depth associated with the impedance boundary using the input seismic data after muting and applying the data mask to obtain an updated velocity model; generating a model mask for the updated velocity model based on the AOI and the impedance boundary; and performing a second FWI to update the updated velocity model using the model mask and the input seismic data after muting and applying the data mask and smoothing the gradient to enhance a seismic image at the AOI.

Abstract: A method of performing single trace inversion to characterize changes in a subsurface region includes obtaining a base seismic trace and a monitor seismic trace of the subsurface region at different respective times. The method includes generating a predicted monitor seismic trace from the base seismic trace by a process including applying a time shift to the base seismic trace, the time shift being derived from estimated velocity perturbations occurring between the base seismic trace and the monitor seismic trace, compensating for amplitude changes between the base seismic trace and the monitor seismic trace, wherein the time shift is applied to the amplitude changes, and minimizing a difference between the predicted monitor seismic trace and the monitor seismic trace by iteratively estimating the velocity perturbations to obtain final estimated velocity perturbations. Changes of at least part of the subsurface region may be characterized using the final estimated velocity perturbations.

Abstract: A method of performing single trace inversion to characterize changes in a subsurface region includes obtaining a base seismic trace and a monitor seismic trace of the subsurface region at different respective times. The method includes generating a predicted monitor seismic trace from the base seismic trace by a process including applying a time shift to the base seismic trace, the time shift being derived from estimated velocity perturbations occurring between the base seismic trace and the monitor seismic trace, compensating for amplitude changes between the base seismic trace and the monitor seismic trace, wherein the time shift is applied to the amplitude changes, and minimizing a difference between the predicted monitor seismic trace and the monitor seismic trace by iteratively estimating the velocity perturbations to obtain final estimated velocity perturbations. Changes of at least part of the subsurface region may be characterized using the final estimated velocity perturbations.

Abstract: A lighting fixture lighter includes a frame body including a light transmitting window, a flame generator, and an illumination fixture built-in with the lighter for generating illumination light for illumination purpose. The illumination fixture includes a power source, a light source unit supported within a light compartment and aligning with the light transmitting window, and a light button to activate the light source unit for generating an illumination light, so that the illumination light is emitted out of the light transmitting window for illumination purpose. In order to enhance the light intensity of the light source unit, a light reflector is further provided within the light compartment for reflecting the illumination light from the light source unit, such that the lighter not only provides the traditional ignition function, but also provides an added on illumination function in the single compact lighter housing.