Patterns of gas hydrate accumulation in mass transport deposits related to canyon activity: Example from Shenhu drilling area in the South China Sea

Since 2017, a plenty of gas hydrates have been drilled in a new area of Shenhu, and good heterogeneity has been found throughout the spatial distribution of the reservoir. After distinguishing different sedimentary sequence types and matching their formation with slope deposition settings, this study proposes three mass transport deposit(MTD) patterns related to canyon activity that occurred contemporaneously or epigenetically with it: well preserved MTDs, MTDs eroded by canyon migration, and MTDs dislocated by contemporaneous faults. Based on seismic reflection characteristics, this study proposed methods of quantitatively analyzing sedimentary factors,such as measuring the turbidities flow rate in the canyon, and results are interpreted with respect to canyon activity. Combining the above parameters and their relationship with gas hydrate accumulation, fine-grained seals overlapping coarse MTDs reservoirs are found to be indispensable to gas hydrate accumulation, as they prevent the release of free gas. Based on grain size data of hydrate samples from drilling wells, multi-layered gas hydrate reservoirs capped by fine-grained sediments and overlapping mud show favorable hydrate-bearing prospects. The release of gas hydrates, however, is mostly caused by the lack of mud sealing in relation to canyon activity, such as turbidities flow erosion and contemporaneous fault breaking. Canyon migration with respect to MTDs may be the actual cause of erosion of overlapping syn-sedimentary layers, and high bottom flows may contribute to an increase in the release of free gas. It is believed that contemporaneous faults caused by unstable canyon walls may break the muddy over layers and decrease the accumulation pressure of gas hydrate bearing.Thus, according to the sedimentary characteristics of MTDs and the hydrate accumulation process, three responding accumulation or releasing patterns are proposed, which respond to the different types of MTDs distinguished above: a well-preserved MTD accumulation pattern; a canyon migration eroded MTD release pattern; and a micro-contemporaneous fault dislocated MTD release pattern.

Bed type and flow mechanism of deep water sub-lacustrine fan fringe facies:an example from the Middle Permian Lucaogou Formation in Southern Junggar Basin of NW China

Submarine or sub-lacustrine lobe deposits are important reservoirs,but the fan fringe deposits form heterogeneities within deep water fan deposits.Fan fringe facies records the complex sediment gravity flow types.By understanding of the bed types and flow mechanisms,we can identify the fan fringe deposit,which aids in the reconstruction of deep water fan and reservoir evaluations.The Jiucaiyuanzi and Dalongkou sections in the West Bogda Mountains preserve well-exposed 536-m and 171-m thick successions,respectively,of a deep water lacustrine depositional system from the Middle Permian Lucaogou Formation.Bed types of the Lucaogou Formation include high-density turbidite,low-density turbidite,incomplete Bouma-type turbidite,hybrid event beds,and slump deposits.The Lucaogou Formation is interpreted here as a fan fringe facies due to the thin bed thickness that characterize turbidites and hybrid event beds,as well as the predominance of the isolated sheet architecture.Previous studies suggest that these deposits were considered as deposited in a deep water setting due to the absence of wave-related structures.The presence of abundant mud clasts in massive medium-coarse grained sandstone beds reflects the significant erosional capability and interactions between high-density turbidity currents and lake floor.The fan fringe facies here contains amalgamated and thick-bedded homolithic facies(~30%)and thin-bedded heterolithic facies(~70%).The examination of the bed type is of wider significance for facies prediction and reservoir heterogeneity in the sub-lacustrine fan fringe facies.

A Local Cluster of Omicron Variant COVID-19 Likely Caused by Internationally Mailed Document——Beijing Municipality,China,January 2022

On January 15,2022,a 26 years old female(Case A)went to a sampling site for coronavirus disease 2019(COVID-19)testing due to excessive fatigue and fever for two days.This patient preliminarily tested positive for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)using a quantitative real-time reverse transcription polymerase chain reaction(qRT-PCR)method.

Citation Recommendation Based on Community Merging and Time Effect

The accuracy of information network partition is not high and the characteristics of metapath cannot represent the attributes of network nodes in the existing academic citation recommendation algorithms.In order to solve the problems,a similarity measurement algorithm,community merging and time effect PathSim(CMTE-PathSim),based on community merging and time effect is proposed.On the premise of dividing heterogeneous information network(HIN)effectively,the algorithm considers the influence of node information on the characteristics of metapath.The results of Top-k query verify the effectiveness of CMTE-PathSim on real datasets and improve the quality of citation recommendation.

Prediction of Enzyme Species by Graph Neural Network

Choosing an effective classification and recognition method in a large protein database plays a crucial role in the classification of enzymes.In previous studies on enzyme classification,only node characteristic information of amino acid were generally considered in the process of model training.The characteristics of amino acid nodes and topological structure in enzyme protein structure are proposed in this paper.The model was trained by graph neural network.By comparing with K nearest neighbor,support vector machine,random forest and multi-layer perceptron,it is shown that the graph neural network method has great advantages.The accuracy obtained by graph neural network is obviously higher than others.