Multi-component seismic data can enhance imaging of complex geological structures, lithology classification, and hydrocarbon reservoir characterization. In the multi-component processing workflow, reconstructing velocities for P S waves (Vp Vs) is a critical step. We have previously proposed an efficient Eikonal equation-based adjoint state characteristic reflection traveltime tomography (ASCRT) method, which automatically picks traveltimes maps reflectors using fast kinematic acoustic...

Wave-equation reflection traveltime inversion is a powerful tool for reconstructing the low wavenumber components of velocity model. One main challenges in precisely estimating shifts between synthetic and observed data. Crosscorrelation widely used shifts. However, prestack seismic data usually contain multiple primary events, are nonstationary. Because global crosscorrelation result generally dominated by strong reflections data, it essential to select appropriate time windows estimate...

Abstract Stable water isotopes (δ 18 O and δ 2 H) are an important source signature for understanding the hydrological cycle altered climate regimes. However, mechanisms underlying atmospheric vapour in northeast Qinghai‐Tibetan Plateau of central Asia remain poorly understood. This study initially investigated isotopic composition its controls during premonsoon monsoon seasons. Isotopic compositions precipitation exhibited high variability across seasons, with most negative average values...

Reconstructing the deep background velocity model is crucial for imaging subsurface structures. The reflection traveltime inversion (RTI) capable of recovering kinematic information in under a limited seismic observation aperture. estimation residuals between synthetic and observed waves key to RTI. However, it difficult accurately obtain rapidly changing shifts prestack data domain. Estimating difference especially where discrepancy noisy demigrated includes waveform distortion,...

Automatically picking reflection traveltimes from the prestack shot gathers and positioning updating reflector depths during inversion are challenging in conventional eikonal-equation-based adjoint-state traveltime tomography methods. To solve these problems, we develop an characteristic (ASCRT) method. This method automatically extracts by sequentially applying depth migration section, followed calculation event-tracking algorithm. We also efficient kinematic imaging to rapidly position...

Abstract Adjoint‐state‐based transmission and reflection traveltime inversion are promising approaches for reconstructing a macro velocity field in both shallow deep depths. However, the contaminated gradient by uneven illumination impedes recovery of an optimal model results slow convergence rate inversion. To mitigate this issue, we propose novel preconditioned + joint tomography method with compensation. The proposed compensation operator is theoretically demonstrated as diagonal elements...

Abstract The high accuracy and efficiency of traveltime calculation are critical in seismic tomography, migration, static corrections, source locations anisotropic parameter estimation. fast‐sweeping method is an efficient upwind finite‐difference approach for solving the eikonal equation. However, accurate only along axis directions. In two‐dimensional or higher dimensional cases, severely decreased diagonal directions due to numerical errors these These similar also arose order method. To...

Summary Seismic traveltime tomography is a promising tool for recovering the low-wavenumber components of subsurface parameters. However, absolute affected by time-picking criteria and many other factors which will reduce accuracy reliability inversion results. We have proposed an efficient Eikonal equation-based adjoint state double-difference (ASDDT) method to increase precision. The ASDDT more than wave method. Furthermore, sensitive traditional velocity variations in both shallow deep...

Summary Adjoint-state based traveltime inversion is proved to be effective reconstruct the subsurface velocity. However, Singular values are existed in gradient calculated directly using traditional adjoint-state method, resulting slow convergence. To eliminate singular gradient, we utilize an approximate diagonal Hessian precondition transmission plus reflection joint tomography. After preconditioning, more accurate result achieved with fewer iterations comparing method.

In this paper, the conjugate boundary value problem –u''(t) = f(t,u(t)) for t ∈ [0,1]\{η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ,η xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ,⋯ xmlns:xlink="http://www.w3.org/1999/xlink">m-2</sub> } subject to u'(0) u(1) 0 and u' xmlns:xlink="http://www.w3.org/1999/xlink">+</sub> (η xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> ) - u'_(η α u'(1) (i 1, 2, ⋯, m 2), of m-point -v''(t)...

Summary The high accuracy and efficiency of travel time calculation are critical in seismology. fast sweeping method (FSM) is an efficient approach to solve the Eikonal equation. However, FSM accurate only along axis directions. In two-dimensional or higher dimensional cases, severely decreased diagonal directions due numerical errors these ray To improve space, a shortest-path-aided (SPAFSM) proposed. solution embedded into process standard SPAFSM very easy implement without extra...

The conventional adjoint-state reflection traveltime tomography (ASRT) method based on the Eikonal equation is limited with respect to two aspects: first automatically picking traveltimes in prestack seismic data, and other determining updating reflector positions during inversion. To solve these problems, we propose an adjoint state characteristic (ASCRT) reconstruct subsurface velocity model. This extracts pre-stack data by combining Eikonal-equation-based calculation a reliable shift...

Summary With the increasing difficulty of exploration and oil development, broadband seismic has gotten more attention. At present variable-depth streamer acquisition is generally considered one most popular methods to obtain data. In this paper, we propose a new deghosting method data which based on iterative inversion wave equation. The recorded first used create mirror through wave-field extrapolation in shot domain, then both are get receiver ghost free by using conjugate gradient...

Near-surface velocity model building is an key problem for subsequent seismic imaging and waveform inversion. Based on a unified wave forward engine, new first arrival multi-information joint inversion method proposed to cope with this problem. In our method, the traveltime, envelope of observed modelled arrivals are fitted simultaneously variable weighting factors. It not only reduces dependence initial but also naturally realizes multi-scale every iteration inversion, one-time simulated...

Summary Velocity model building is an essential step in seismic exploration, which runs through the whole process of data acquisition, processing, and interpretation. The velocity information conventionally obtained by iterative optimization methods such as full-waveform inversion or tomography. These traditional are computationally expensive, they require initial human interactions. To simplify problem, we develop a supervised end-to-end conventional neural network to reconstruct P-wave...