Calculation of Surface Offset Gathers Based on Reverse Time Migration and Its Parallel Computation with Multi-GPUs

As an important method for seismic data processing, reverse time migration (RTM) has high precision but involves high-intensity calculations. The calculation an RTM surface offset (shot–receiver distance) domain gathers provides intermediary data for an iterative calculation of migration and its velocity building. How to generate such data efficiently is of great significance to the industrial application of RTM. We propose a method for the calculation of surface offset gathers (SOGs) based on attribute migration, wherein, using migration calculations performed twice, the attribute profile of the surface offsets can be obtained, thus the image results can be sorted into offset gathers. Aiming at the problem of high-intensity computations required for RTM, we put forth a multi-graphic processing unit (GPU) calculative strategy, i.e., by distributing image computational domains to different GPUs for computation and by using the method of multi-stream calculations to conceal data transmission between GPUs. Ultimately, the computing original efficiency was higher relative to a single GPU, and more GPUs were used linearly. The test with a model showed that the attributive migration methods can correctly output SOGs, while the GPU parallel computation can effectively improve the computing efficiency. Therefore, it is of practical importance for this method to be expanded and applied in industries

Distribution pattern and exploration prospect of Longwangmiao Fm reservoirs in the Leshan-Longnüsi Paleouplift, Sichuan Basin

The Longwangmiao Fm gas pool was found in 2012 in Moxi area in Leshan-Longnüsi Paleouplift, central Sichuan Basin. Previous geological studies showed that the Lower Cambrian Longwangmiao Fm reservoir is mainly pore type reservoir of grain shoal facies, locally superimposed by the vuggy reservoir formed by Caledonian karstification, and the distribution of the reservoir has a critical control effect on the gas pool there. Therefore, the reservoir prediction in this area follows the approach of “looking for the overlap of shoal facies, karst, bright spots, and traps”. First, the favorable facies boundary and karstification effect range are defined based on sedimentary facies; on the basis of precise correlation of the top and bottom horizons of the reservoir, the favorable development area of the reservoir was then predicted according to the seismic response characteristics of “bright spots” of the Longwangmiao Fm reservoir; finally, favorable exploration areas were selected according to the effective configuration of reservoir and trap. Due to the horizontal change in reservoir and lithology, Longwangmiao Fm top has no uniform interface features on the seismic profile, making it difficult to trace. In the actual interpretation process, the underlying reference horizon is sought out first, then the bottom boundary of Longwangmiao Fm is correlated, and finally its top boundary is correlated. The prediction results indicated that the Longwangmiao reservoir distributes in band shape in a wide range around the Paleouplift; and the exploration prospects mainly involve three domains: lithologic-stratigraphic traps near the pinchout line of Longwangmiao Fm; lithologic traps formed by isolated shoal body; and structural and lithologic traps at the north flank of the Paleouplift

Comparative Analysis of Thiophene-Based Interlayer Cations for Enhanced Performance in 2D Ruddlesden–Popper Perovskite Solar Cells

2D Ruddlesden–Popper (RP) perovskites have appeared as a promising prospective material owing to their tunable optoelectronic peculiarities and structural stability. The choice of interlayer cations greatly influences the performance of the 2D RP perovskites. In this study, through theoretical calculations and experimental investigation, we demonstrate the intrinsic and device performance differences between two perovskites based on cations of thiophenemethylamine (TMA) and thiopheneethylamine (TEA). Using density functional theory (DFT) calculations, it exposes that as compared to (TMA)2PbI4, (TEA)2PbI4 exhibits more pronounced distortion of [PbI6]4– units and possesses a wider band gap and larger effective mass. The experimental results on the TMA- and TEA-based 2D perovskites further show that when TEA is used as the interlayer cation, the crystallization process tends to form more low-n phases, which hinder charge transfer and decrease light harvesting. On the other hand, when TMA is used as the interlayer cation, excessive low-n phases are not observed, and the thin film exhibits excellent quality with significantly improved electron mobility. The (TMA)2­(FA)n−1PbnI3n+1 (n = 5) perovskite device shows a remarkable conversion efficiency of 16.56%, much higher than that of TEA-based devices (PCE = 2.58%). Moreover, the unencapsulated devices based on TMA were able to maintain 88% of their initial efficiency even after being exposed to the environment (RT, RH = 30 ± 5%) for a duration of 1080 h. These findings provide important insights into the differences between thiophene-based cations and the selection of organic interlayer cations for 2D RP perovskite solar cells