The Analysis Of The Sedimentary System Of Yaojia Group In The South Of Songliao Basin

Songliao basin is a large-scale Mesozoic-cenozoic era sedimentary basin in northeast of our country,which is the fault-cols type of interior basin,filled by the cretaceous non-marine fragmentary rock which reached 7000m thickness in the basin.The south of the songliao basin is consist of southeast uplift zone,the south of the center depression area and the west sloping zone and the north of southwest uplift zone,bounded by the baicheng city and tongliao city in the west,baicheng and harbin city in the north,siping city in the south and the frontier of the basin in the east,which spans the jilin,liaoning and intermongolia provices,the deminsion the basin is about 13.4*104km2。The cover coat concludes baicheng group,huoshiling group of the Jurassic,shahe group,yingcheng group,denglongku group,quantou group of the under-cretaceous,qingshakou group,yaojia group,nenjiang group,sifangtai group and mingshui group of the upper-cretaceous.This paper aims at the yaojia group, researchs the depositional system,the character of the sedimentary facies and the source nature of the yaojia group deeply. It is clear about the different deposition system boundary and the mop characteristic, and it will play a vital role in impelling the exploration and disposition of the oil and gas accumulation in south of the songliao basin.This paper has carried on the unition and contrast of the stratigraphic position to the 48 drill holes in the entire district , and carried on the system lamination to the unlamination drill holes, completed the statistics and the analysis of essential data of 48 drill holes in the Upper Crataceous Yao Jia group, such as the stratum depth, sand body thickness, mudstone thickness, the ratio of the sand body and strata thickness, and so on sandstone type. Based on this, has established Yao Jia group stratum depth isogram, the top burying depth isogram, the sandstone thickness isogram, the sand body distribution isogram and the ratio of the sand body and strata thickness isogram and so on in the entire district. This paper has carried on the fine dissection to the main purpose stratigraphic position of the key deposition sector. Has established typical sectional drawing, the top burying depth chart, the stratum isopach map, the sand body distribution map, the ratio of the sand body and strata thickness isogram , the sandstone color district chart, the mudstone color district chart of the key land sector, has portrayed sedimentary facies throughgoing ruleof the main purpose stratigraphic position.Through the system acquisition and analysis of information, and on the foundation of establishing massive graphic document, we've obtained the systematic understanding to the local deposition characteristic and the granulated substance body distribution in the south of the songliao basin, and the understanding is as follows:Yao group is a sequence unit (that is, sequencesⅦ) in which the systems tract is integral within the internal structure of the the sequence unit in the research area, and it has a bottom-up development of lowstand systems tract, transgressive systems tract, highstand systems tract and relictional systems tract.In it the lowstand systems tract grows sand body. In upper Crataceouson of the research area the sedimentary facies type is rich, the growth has six types ,and they are the alluvial fan, the braided river, the delta and the lake. And further may distinguish eleven kinds of subfacies and certain microfacies. Of them , the braided river course, the fan deposition subfacies distributions and so on braided channel are widespread, and they are specially common in the boundary zone in the south of the research area. Yao Jia group is in the later period of the depression development phase ,from the single well distribution characteristic of Yao Jia group we can be possible to know that in Upper Crataceouson of the research area : overall performance of the sedimentary facies from the southwest to the northeast has a gradation characteristic like the alluvial fan - braided river - delta–shore shallow lacustrine facies during the Yao Jia group depositional stage. In yaojia group depositional stage the information of the district of the research area named baixingtu is comprehensive. The overall performance of this district is the alluvial fan and braided river sediment system while the main source of supply is from northwest and east of the district.