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To further explore the geological structure and the Mesozoic-Paleozoic hydrocarbon prospects in the northern area of the South Yellow Sea (SYS), multiple geological and geophysical data were systematically gathered and compiled, i...
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To further explore the geological structure and the Mesozoic-Paleozoic hydrocarbon prospects in the northern area of the South Yellow Sea (SYS), multiple geological and geophysical data were systematically gathered and compiled, including gravity and magnetic data, seismic surveys, drilling data, and previous research results. The characteristics and genesis of the gravity and magnetic anomalies are examined. This study employs residual gravity anomalies and multiple edge detection methods to identify fault lineament structures and assess the tectonic framework. Moreover, the study utilizes 2.5D gravity-seismic joint modellings and regression analysis to estimate the basement depth. Additionally, the study examines the basement characteristics and discusses the thickness of the Mesozoic-Paleozoic strata. Finally, the study further identifies prospects for hydrocarbons in the Mesozoic-Paleozoic. Our findings show that the faults are incredibly abundant and that the intensity of fault activity weakens gradually from NW to SE. Specifically, NE (NEE) trending faults are interlaced and cut off by NW (NWW), near-EW, and near-SN trending secondary faults, which form an en-echelon composite faults system with a dominant NE (NEE) orientation. Thick Mesozoic-Paleozoic strata are preserved, but we observe distinct variations in basement characteristics and the pre-Cenozoic structural deformation along the N-S direction. Therefore, the Northern Basin of SYS (NBSYS) and the Middle Uplift of SYS (MUSYS) are characterized by alternating sags and bulges in the S-N direction and in the E-W direction, respectively, forming a chessboard tectonic framework. Considering the oil and gas accumulation model, we identify three target hydrocarbon prospects in the NBSYS and two favorable hydrocarbon prospects in the MUSYS.
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We evaluated a method that determines the optimal grid parameters of potential-field data such as the intervals of grid nodes and the grid azimuth. Optimal grid parameters produced the best gridding results with the least amount o...
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We evaluated a method that determines the optimal grid parameters of potential-field data such as the intervals of grid nodes and the grid azimuth. Optimal grid parameters produced the best gridding results with the least amount of data distortions. We used spectral analysis of the data statistics on azimuth projections. The direction with the largest degree of periodicity was defined as the optimal azimuth of the grid. The grid line interval was determined according to the frequency point with the largest amplitude value. By spectral analysis of the data sequence projected in the direction normal to the survey lines, grid point spacing was also determined. Correlative analysis of the template matching method was used to determine the optimal grid range. Tests on simulated and field data proved that this method is rather robust and can be incorporated into gridding software packages.
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The l2-norm minimization is a common means for the 3D inversion of gravity data. The unconstrained l2-norm inversion will produce a smooth solution, which contains redundant structures and artifacts. Positivity-constrained l2-norm...
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The l2-norm minimization is a common means for the 3D inversion of gravity data. The unconstrained l2-norm inversion will produce a smooth solution, which contains redundant structures and artifacts. Positivity-constrained l2-norm inversion can eliminate redundant structures and artifacts, resulting in a more reliable solution. However, the positivity constraint restricts the applications of gravity inversion to some extent because the measured gravity data are likely to be caused by both positive and negative sources. To address this issue, we propose a strategy that combines the lp-norm regularization and fine adjustment of the depth weighting function to refine the unconstrained gravity inversion results. Synthetic tests show that the proposed strategy yields an improved smooth solution compared with the unconstrained l2-norm inversion method. The proposed strategy is also applied to the inversion of gravity data collected over a Layikeleke iron-copper skarn deposit, Xinjiang, China.
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Dual antiplatelet therapy (DAPT) was currently recommended for transcatheter aortic valve implantation (TAVI) postoperative management in clinical application. However, POPular-TAVI trial showed DAPT increased the incidence of adv...
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Dual antiplatelet therapy (DAPT) was currently recommended for transcatheter aortic valve implantation (TAVI) postoperative management in clinical application. However, POPular-TAVI trial showed DAPT increased the incidence of adverse events compared to single antiplatelet therapy (SAPT). Herein, we performed a meta-analysis to investigate the effect of SAPT versus DAPT on the adverse events after TAVI. Eleven studies were available from PubMed, Embase, Cochrane Library, and Web of Science from inception to April 1, 2021. The pooled effect size was presented as relative risk (RR) with 95% confidence intervals (CIs). The sensitivity analysis was used to assess the stability of analysis results, and Begg's test was applied to evaluate the publication bias. The Cochran Q test and the I 2 statistic were used to evaluate the heterogeneity, and the source of heterogeneity was explored by meta-regression. A total of 4804 patients were obtained, with 2257 in SAPT group and 2547 in DAPT group. Compared to the DAPT, SAPT was associated with the decreased risk of all-cause bleeding (RR: 0.51, 95% CI: 0.44–0.61), major bleeding (RR: 0.53, 95% CI: 0.32–0.86), and minor bleeding (RR: 0.58, 95% CI: 0.34–0.98). There were no significant differences in mortality and myocardial infarction events, stroke events, and acute kidney injury between the two groups. SAPT was superior to DAPT in decreasing all-cause bleeding, major bleeding, and minor bleeding, suggesting that SAPT could be preferentially recommended for TAVI postoperative management in most patients without another indication for DAPT and oral anticoagulation.
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Three-dimensional inversion for susceptibility distributions is a common approach for quantitative interpretation of magnetic data. However, this approach will fail when strong remanence exists because the total magnetization dire...
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Three-dimensional inversion for susceptibility distributions is a common approach for quantitative interpretation of magnetic data. However, this approach will fail when strong remanence exists because the total magnetization direction is unknown. Magnetic amplitude inversion can reduce remanence effects and thus improve reconstructed results. In this paper, we propose a sparse magnetic amplitude inversion method which minimizes an L0-like-norm of model parameters subject to bound constraints. By using the iteratively reweighed least squares technique, the bound-constrained L0-like-norm sparse inversion is transformed to a sequence of bound-constrained nonlinear least squares subproblems. To deal with the bound constraints, we use a logarithm barrier algorithm to solve each subproblem. Compared with the classical L2-norm inversion method, the proposed sparse method utilizes the known physical property information to produce binary results characterized by sharp boundaries. This method is tested on synthetic data produced by a dipping dyke model and a field data set acquired in Australia.
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Interpretation of geophysical material is the prospecting method. Interpretation of Gravity-megnetic data is based on data processing and inversion. When the grid is divided into several million cells, the computing task is heavy ...
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Interpretation of geophysical material is the prospecting method. Interpretation of Gravity-megnetic data is based on data processing and inversion. When the grid is divided into several million cells, the computing task is heavy and time-consuming. In order to increase efficiency of the 3D forward modeling, the paper will adopt MPI parallel algorithm and the several processes will deal with data in the method. Finally, we can gather the result. Through comparing the result of sequence algorithm with the result of MPI parallel algorithm, we can see the result is the same. When the number of processes is 2 to 8, the speed-up ratio is 1.97 to 5. The MPI parallel algorithm is very efficient.
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