Exploration and research progress of shale gas in China

There are three types of shale gas resources in China.The resources are present in large amounts and are widely distributed.Marine facies,transitional facies and continental facies resources each account for a third.Based on resource distributions,there are many wells penetrated into the Sinian,Cambrian, Ordovieian,Silurian,Devonian,Carboniferous and Permian strata of the Yangtze plate and its periphery, the North China Craton and the Tarim Basin.Many years of exploration have indicated that the marine Silurian Longmaxi shale gas is widely distributed in south China and has been industrialized in its production in the Siehuan basin.The shale gas from the Cambrian Niutitang Formation and the Sinian Doushantuo Formation are important discoveries in Yichang,Hub ei and Zhenba,Shanxi.There are also shale gas resources found within transitional facies and continental facies in different areas in China.The "two element enrichment theory"has been summarized during the exploration process of Silurian marine shale gas in the Sichuan Basin.In addition,horizontal drilling and fracturing technologies up to 3500 m in depth have been developed.Based on the understanding of shale gas accumulation in a complex tectonic zone outside the Sichnan basin,a preliminary summary of the formation of the "converse fault syneline control reservoir"and "paleo uplift control reservoir"model has been constructed.The dominant theory of "Trinity"shale gas enrichment and the high yield of the "deep water Lu Pengxiang sedimentary facies belt, structural preservation conditions and overpressure"is summarized.Guided by the above theories.Anyel well in Guizhou and Eyangyel well in Hubei were drilled."Four storey"oil and shale "gas is found in the Permian Qixia group,the Silurian Shiniulan Formation,the Longmaxi Formation and the Ordovician Baota Formation in Anyel well.Good shale gas has been gound in the Cambrian Niutitang formation inian Doushantuo formation in Eyangye lwell.This paper aims to summarize and review the main progress,theoretical technology and problems of shale gas exploration and development in recent years in China,and predicts the future exploration and development direction for shale gas and possible exploration areas.

Sedimentary lithofacies characteristics and sweet-spot interval characterization of the Sinian Doushantuo Formation in Upper Yangtze Platform, South China

The Sinian Doushantuo Formation is the oldest shale gas reservoir discovered in the world, which contains good shale gas shows as the Eyangye-1 and Zidi-1 wells in the Yichang Region of western Hubei province, China. The shales in the Doushantuo Formation feature considerable thickness (135 m), high gas content (4.83 m^3/t) and high fragile mineral content (up to 75%). Due to the influences of the sedimentary environment, the shale reservoirs here have high dolomitic content (54%) and abruptly changes in vertical lithofacies. Moreover, the characteristics of the shale sweet-spot differ significantly from that in the Wufeng Formation and Longmaxi Formation in southeast Sichuan Basin. A high-resolution sequence stratigraphic correlation was performed on the shales of the Doushantuo Formation at the Eyangye-1 well, Zidi-1 well, Zidi-2 well and some outcrop profiles in Yichang area for the identification of their sedimentary microfacies characteristics. A comprehensive comparative analysis was made by incorporating the elemental geochemistry, wireline and mud logging data of the well to further identify the sweet-spot interval therein. With the analysis of Eyangye-1 well, the sweet-spot interval of the Doushantuo Formation is 3360?3408 m, of which sedimentary microfacies is deepwater reduced environment with many pyrite laminaes, and the TOC is high to 3.42%, the Ro is 3.3%, the organic and matrix pore are well developed and the aperture more than 50 nm, the porosity is 2.7%, the desorption gas content average is 2.16%, and the main mineral is dolomitic (54%) and siliceous quartz (21%). Additionally, these parameters combined with previous studies will shed light on evaluating and characterizing the layers therein, also provide referential geological data for the following exploration and development activities of this shale system.

Single cell RNA sequencing reveals mesenchymal heterogeneity and critical functions of Cd271 in tooth development

BACKGROUND Accumulating evidence suggests that the maxillary process,to which cranial crest cells migrate,is essential to tooth development.Emerging studies indicate that Cd271 plays an essential role in odontogenesis.However,the underlying mechanisms have yet to be elucidated.AIM To establish the functionally heterogeneous population in the maxillary process,elucidate the effects of Cd271 deficiency on gene expression differences.METHODS p75NTR knockout(Cd271-/-)mice(from American Jackson laboratory)were used to collect the maxillofacial process tissue of p75NTR knockout mice,and the wildtype maxillofacial process of the same pregnant mouse wild was used as control.After single cell suspension,the cDNA was prepared by loading the single cell suspension into the 10x Genomics Chromium system to be sequenced by NovaSeq6000 sequencing system.Finally,the sequencing data in Fastq format were obtained.The FastQC software is used to evaluate the quality of data and CellRanger analyzed the data.The gene expression matrix is read by R software,and Seurat is used to control and standardize the data,reduce the dimension and cluster.We search for marker genes for subgroup annotation by consulting literature and database;explore the effect of p75NTR knockout on mesenchymal stem cells(MSCs)gene expression and cell proportion by cell subgrouping,differential gene analysis,enrichment analysis and protein-protein interaction network analysis;understand the interaction between MSCs cells and the differentiation trajectory and gene change characteristics of p75NTR knockout MSCs by cell communication analysis and pseudo-time analysis.Last we verified the findings single cell sequencing in vitro.RESULTS We identified 21 cell clusters,and we re-clustered these into three subclusters.Importantly,we revealed the cell–cell communication networks between clusters.We clarified that Cd271 was significantly associated with the regulation of mineralization.CONCLUSION This study provides comprehensive mechanistic insights into the maxillary-process-derived MSCs and demonstrates that Cd271 is significantly associated with the odontogenesis in mesenchymal populations.

Acute inferior wall myocardial infarction induced by aortic dissection in a young adult with Marfan syndrome:A case report

BACKGROUND Aortic dissection(AD)is an emergent and life-threatening disorder,and its inhospital mortality was reported to be as high as 24.4%-27.4%.AD can mimic other more common disorders,especially acute myocardial infarction(AMI),in terms of both symptoms and electrocardiogram changes.Reperfusion for patients with AD may result in catastrophic outcomes.Increased awareness of AD can be helpful for early diagnosis,especially among younger patients.CASE SUMMARY We report a 28-year-old man with acute left side chest pain without cardiovascular risk factors.He was diagnosed with acute inferior ST-segment elevation myocardial infarction(STEMI),which,based on illness history,physical examination,and intraoperative findings,was eventually determined to be type A AD caused by Marfan syndrome.Emergent coronary angiography revealed the anomalous origin of the right coronary artery as well as eccentric stenosis of the proximal segment.Subsequently,computed tomography angiography(CTA)showed intramural thrombosis of the ascending aorta.Finally,the patient was transferred to the cardiovascular surgery department for a Bentall operation.He was discharged 13 d after the operation,and aortic CTA proved a full recovery at the 2-year follow-up.CONCLUSION It is essential and challenging to differentiate AD from AMI.Type A AD should be the primary consideration in younger STEMI patients without cardiovascular risk factors but with outstanding features of Marfan syndrome.