Study On The Sequence Stratigraphy And The Gas Enrichment Regularity Of Taiyuan Formation In Yangquan Sijiazhuang Mining Area

Guided by the disciplinary theory and method of sedimentary(rock),sequence stratigraphy,coalfield geology,based on the description of drill core and field sections,using the material of 160 drilling wells in Shijiazhuang mine of Yangquan Coal Industry Group,combing with laboratory analysis,this paper analyses the relationship between sedimentary environment,sequence stratigraphy,sedimentary evolution and gas enrichment in the Taiyuan Formation.According to the phase sign,two kinds of sedimentary facies,four subfacies and five microfacies in the carbonate tidal flat and barrier bars-lagoon-tidal flat are identified in the Taiyuan Formation,and their sedimentary characteristics are summarized.According to the principle of sequence stratigraphy,the Taiyuan Formation is divided into four third-order sequences and eight system domains,and the sequence stratigraphic framework of Taiyuan Formation in the study area is established.It is pointed out that the relative sea level rise and fall tectonic movement are the main factor of sequence stratum.In the sequence stratigraphic framework,the sedimentary evolution characteristics of Taiyuan Formation are discussed,and the sedimentary facies model of Taiyuan Formation is established.Based on the change of sequence stratum and sequence stratum,the gas accumulation rule and control factor of 15# coal seam in Taiyuan Formation are analyzed.It is pointed out that the top plate of 15# coal formed in the early stage of transgression of sea(the thick layer developing steadily in the transgressive systems tract),providing favorable conditions for the gas enrichment and preservation.There is a positive correlation between the change of the base and the gas content,means that the rise of the base is favorable to the gas formation and enrichment.